Review Article Zingiber officinale (Ginger): A Future ...

Review ArticleZingiber officinale (Ginger) A Future Outlook on Its Potentialin Prevention and Treatment of Diabetes and Prediabetic States

Basil D Roufogalis

Discipline of Pharmacology School of Medical Sciences Sydney Medical School University of Sydney Sydney NSW 2006 Australia

Correspondence should be addressed to Basil D Roufogalis basilroufogalissydneyeduau

Received 3 March 2014 Revised 20 June 2014 Accepted 25 June 2014 Published 23 September 2014

Academic Editor Eric Hajduch

Copyright copy 2014 Basil D Roufogalis This is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited

Diabetes is reaching pandemic levels in both developing and developed countries and requires safe affordable and effectivetherapiesThis report summarises work in our laboratory on the effects ofZingiber officinale (ginger) and its components in diabetesmodels and provides a future outlook on the potential for their use in type 2 diabetes A high fat diet rat model showed modulationof body weight gain and normalisation of glucose and lipid metabolic disturbances with reduction of insulin resistance in a highfat-high carbohydrate diet model Ginger extract inhibits enhanced NF-120581B in liver of high fat-fed rats through inhibition of theIKKI120581B120572NF-120581B classical pathway The major active component (S)-[6]-gingerol inhibited elevated cytokines in inflamed HuH-7 cells through suppression of COX2 expression and protection against the ROS pathway Ginger extract and gingerols enhancedglucose uptake in L6myotubes by enhancing translocation of GLUT4 to the surfacemembrane and activation of AMPK1205721 througha Ca2+calmodulin-dependent protein kinase kinase pathway (S)-[6]-Gingerol also enhanced energy metabolism through markedincrement of peroxisome proliferator-activated receptor-120574 coactivator-1120572 (PGC-1120572) gene expression and mitochondrial contentin L6 skeletal muscle cells Future studies will require well designed clinical trials on ginger preparations of defined chemicalcomposition

1 Introduction

11 Diabetes and Prediabetic States The Scope of the ProblemAccording to recent estimates the prevalence of diabeteshas reached pandemic proportions with 382 million peopleworldwide living with this condition A further 316 million(69) adults worldwide with impaired glucose tolerance areat high risk of developing diabetes [1] By the endof 2013 it wasestimated that there would be 51 million deaths and a cost ofUSD 548 million in health care spending Estimates indicatethat there will be 592 million people living with the diseasewithin 25 years without positive action yet it is consideredthat most of these cases are preventable [1] Contrary toexpectations 80 of people with diabetes live in low- andmiddle-income countries [1]There is also a growing trend foryounger people to develop diabetes leading to an increasingincidence of premature deaths [2]

Diabetes mellitus is characterised by chronic hypergly-cemia resulting from impaired insulin actionsecretion [3]Type 2 diabetes accounting for gt90 of diabetes [3] is

associated with metabolic disorders of both lipid and car-bohydrate [4] Effective control of hyperglycemia in diabeticpatients is critical for reducing the risk of micro- and macro-vascular disease [5ndash7]The recent growth in obesity is associ-ated with lifestyle changes especially increased caloric intakeand decreased physical activity Obesity is associated withan increased prevalence of chronic diseases including type 2diabetes mellitus with insulin resistance atherosclerosis andnonalcoholic fatty liver disease (NAFLD) [8ndash10] Althoughlifestyle changes including exercise and better nutrition havebeen found effective in reducing the debilitating effects ofdiabetes these changes have been difficult to implementand the battle is being lost [11] Therapy therefore continuesto rely heavily on pharmacological agents but side effectsof varying severity of the presently available hyperglycemicagents especially in the elderly have limited their usefulnessas antidiabetic agents This has led to continued efforts toexplore the effectiveness and potential of agents from naturalsources for the control of diabetes mellitus A vast array ofplant and related products with antidiabetic effects were

Hindawi Publishing CorporationNew Journal of ScienceVolume 2014 Article ID 674684 15 pageshttpdxdoiorg1011552014674684

2 New Journal of Science

Gingerols Shogaols

Sesquiterpenes

HO HO

O OH O

H HH

[6]-S-Gingerol (n = 4) [6]-Shogaol (n = 4)[8]-S-Gingerol (n = 6) [8]-Shogaol (n = 6)[10]-S-Gingerol (n = 8) [10]-Shogaol (n = 8)

(mdash)-Zingiberene ar-Curcumene 120573-Sesquiphellandrene 120573-Bisabolene

CH3 CH3CH3O CH3O

Phenylalkanols

(CH2)n (CH2)n

Figure 1 Chemical structures of components of Zingiber officinale

identified in reviews of the literature on natural products[12 13] Metformin currently the drug of choice in themanagement of hyperglycemia in fact has its origins ina natural product [14] The combination of hyperglycemicand hyperlipidemic disturbances and their interdependencepresents major risk factors for the development of diabetesand its life threatening cardiovascular complications [15]Thus the control of both these underlying disturbances isconsidered optimal for the management of diabetes and itscomplications

12 Ginger Ginger (Zingiber officinale Roscoe Zingiber-aceae) is one of the most widely consumed spices worldwideFrom its origin in Southeast Asia and its spread to Europeit has a long history of use as herbal medicine to treat avariety of ailments including vomiting pain indigestionand cold-induced syndromes [16 17] Although ginger isnot widely known for its effectiveness in diabetes preventionandor treatment modern pharmacological studies supportits potential for treating both the hyperlipidemic and hyper-glycemic aspects of diabetes However there is much lessinformation on themechanism of action of ginger underlyingits effects in diabetes Whilst the chemical composition ofZingiber officinale is well investigated it is much less clearwhich of the many components in ginger are responsible forits effects in diabetes

13 The Importance of Chemical Composition of Gingerand Other Herbal Products It is expected that the multi-ple components in ginger may lead to multiple effects onmetabolic pathways and to involve multiple mechanismsaffecting various aspects of chronic metabolic disorders suchas diabetes [18] Some of the main chemical components ofginger are shown in Figure 1 Crude ginger contains up to 9lipids or glycolipids and about 5ndash8 oleoresin The pungent

principles accounting for 25 of the oleoresins consistmainly of gingerols [6]-Gingerol is the major gingerol andother gingerols include [8]-gingerol or [10]-gingerol as wellas methylgingerol and gingerdiol dehydrogingerdione [10]-dehydrogingerdione diarylheptanoids diterpene lactonesand galanolactone (in some species) Ginger contains up to3 essential oil accounting for 20ndash25 of the oleoresins Gaschromatographymass spectrometry identified other numer-ous compounds in the essential oil of ginger of which majorcompounds are camphene b-phellandrene and 18-cineol[19] The oil also contains sesquiterpenes and sesquiterpenealcohols impacting the smell of ginger whilst the taste ofginger is mainly affected by various monoterpenes Sho-gaols contained in semidried ginger are more pungentthan gingerols [20] are a major degradation product of thethermally labile gingerols and are rarely found in fresh ginger[21] Another minor component zingerone is a degradationproduct which indicates low quality plantmaterial A numberof other coactive constituents could also contribute to thetreatment of various diseases

14 Evidence for Efficacy from Clinical and PharmacologicalStudies on Ginger Sigrun Chrubasic in collaboration withour laboratory undertook a comprehensive review of animaland clinical studies on Zingiber officinale [18] In nauseaand vomiting it was concluded that clinical evidence beyonddoubt is only available for pregnancy-related nausea andvomiting whilst meta-analyses could not demonstrate effec-tiveness in postoperative nausea motion sickness or nau-seavomiting of other aetiology It remains to be confirmed towhat extent various proprietary ginger preparations are clin-ically useful to alleviate osteoarthritic or other pains and toinfluence platelet aggregation Ginger exerts in vitro antiox-idative antitumorigenic and immunomodulatory effects andis an effective antimicrobial and antiviral agent Animal

New Journal of Science 3

studies demonstrate effects on the gastrointestinal tract thecardiovascular system and experimental pain and fever andantioxidative antilipidemic and antitumor effects as well ascentral and other effects More recently Li et al [26] fromour group reviewed in vitro in vivo and clinical studies onthe effectiveness of ginger in diabetes diabetic complica-tions and associated lipid and other metabolic disorderswith particular emphasis on the mechanisms underlying theantihyperglycemic effects of ginger Prominent mechanismsunderlying these actions are found to be associated withinsulin release and action and improved carbohydrate andlipid metabolism Ginger has shown prominent protectiveeffects on diabetic liver kidney eye and neural systemcomplications

15 Aims and Objectives of This Report Studies on Zingiberofficinale in inflammatory conditions have been undertakenin this laboratory since 2001 Our objective has been to vali-date the traditional andmodern literature on the effectivenessof ginger in chronic metabolic conditions and to providenew potential therapeutic modalities based on a thoroughunderstanding of the underlying molecular mechanisms ofaction of Zingiber officinale and in particular its major activecomponents Given the still unmet needs of treatment ofdiabetes and its complications we have focused our effortson the potential of ginger for the prevention and treatmentof the underlying causes of diabetes and the prediabeticstate Natural productsmay provide safer andmore accessiblematerials for the prevention of diabetes and its treatment inboth the developed and developingworldThis report reviewsour studies and provides a perspective and future outlook foradditional research and development needed to provide newtherapies based on ginger as a natural product The methodsemployed are found in detail in the original articles cited

2 Ginger in Animal Models ofDiabetes and Prediabetes

The concept of ldquoreverse pharmacologyrdquo [27] often applies toresearch in herbal medicine whereby a plant or other naturalproducts with a history of safe and traditional use undergoscientific evaluation to validate that traditional use and tounderstand the likely major mechanisms of action Animalstudies are widely used especially for the validation phase assuch models are of value to study both preventative aspectsand management of the condition under investigation Ini-tially studies have been undertaken to investigate the effectsof Zingiber officinale (ginger) in animals made hyperglycemicand hyperlipidemic by exposure to high fat diets of the typeoften associated with some ldquocafeteria-stylerdquo foods consumedby humans Although a number of animalmodel studies havebeen done the results of our studies are summarized belowRelated studies will be found in the original articles cited

21 A High Fat Diet Model [28] In the earliest model exam-ined [28] we investigated the effect of an ethanolic extract ofginger (which contained not less than 10 [6]-gingerol) onWistar strain rats (150ndash200 g) fed with a high fat diet with

moderate levels of carbohydrate The high fat diet (HFD)contained 60 fat 15 carbohydrate 175 protein 5 crudefibre and 2 cholesterol The HFD group was compared to astandard diet containing 5 fat and 60 carbohydrate A 95ethanol extract of Zingiber officinale rhizome (20 1) preparedcommercially was used in this study The ethanol extract ofZingiber officinale was found by mass spectrometry to con-tain three major gingerol-related compounds [6]-gingerol[8]-gingerol and [6]-shogaol (see Figure 1) at 156mgg024mgg and 1170mgg respectively

Ethanolic ginger extract (100ndash400mgKg) given by oralgavage for 6 weeks suppressed the body weight gain andlowered serum glucose and insulin induced by the high fatdiet It also dose-dependently increased insulin sensitivity asdetermined by the HomeostaticModel Assessment of InsulinResistance (HOMAR-IR) analysis This effect was similar tothat of the control rosiglitazone

211 Effects of Ginger on Lipid Biochemical Markers [29]Animal studies allow the testing of the effects of herbalextracts on lipid changes and key enzymes and gene andreceptor expression in the chosen animalmodel It is acceptedthat both hyperglycemia and dyslipidemia are important con-tributing factors to the development of atherosclerosis in type2 diabetes [30] and hyperlipidemia represents a significantmodifiable risk factor In the HFD-treated rats [28] gingerextract effectively reduced the elevated levels of serum totalcholesterol and LDL-cholesterol towards control levels inaddition to producing a marked reduction in elevated serumtriglycerides free fatty acids and phospholipids Similarresults were found in another HFD study (60 fat and 106carbohydrate) where Zingiber officinale extract (400mgkgfor 6 weeks) reduced the enhanced triglyceride levels andshowed a small but not significant decrease in hepaticcholesterol level [29] Rosiglitazone as a positive control had asimilar effect Zingiber officinale extract prevented the HFD-induced decrease in LDL receptor protein and increasedHMG-CoA reductase protein in the liver of the HFD ratsboth important mechanisms in the uptake and synthesis ofcholesterol By contrast rosiglitazone (3mgkg) was withouteffect on these activities

22 Effects of Ginger on a High Fat High Carbohydrate Ani-mal Model with Insulin Resistance [31] It is now widelyrecognized that a high calorie western food diet contributesgreatly to the development of metabolic syndrome [32 33]Recent literature suggested that diets with high content offat and simple carbohydrate especially fructose are stronglyassociated with insulin resistance [34ndash36] We undertook astudy of the effect of ginger extract on insulin resistance inrats fed with a high fat diet together with a high content ofsimple sugars (fructose and sucrose) [31]

The ginger extract in this studywas a freeze-dried powderof ginger rhizome (Grade A provided by Buderim GingerLimited Queensland Australia) extracted with ethanol atlow temperatures and reduced pressure affording a totalginger extract containing 156 (S)-[6]-gingerol The HFHCdiet (with simple sugars as the main carbohydrate source)


contained 177 sucrose 177 fructose 194 protein and40 fat with a digestible energy of 241MJkg this contrastswith the standard chow with 594 total carbohydrate ascereal grain as the main carbohydrate source and 48 fatcontaining digestible energy of 140MJkg In contrast toour earlier study where rats were fed with a high fat (60)diet with moderate carbohydrate the growth rate duringthe 10-week feeding of the HFHC group was not differentfrom that of standard chow fed rats possibly due to thelower amount of food consumption and similar digestiveenergy intake An oral glucose tolerance test conducted overa period of 120 minutes at the end of week 10 resulted ina lower AUC of glucose in ginger extract (200mgkg) andmetformin (200mgkg) treated rats compared to the HFHCcontrol In addition higher serum insulin concentrationsand a reduced HOMAR-IR in the HFHC diet indicatingdevelopment of insulin resistance weremarkedly reversed byoral ginger extract (200mgkg) administration Metforminalso effectively ameliorated the HFHC diet-induced insulinresistance as expected from clinical studies It is of interestthat in this study the ginger extract used was high in contentof (S)-[6]-gingerol but not in shogaol

Summary We concluded from the high fat and high fathigh carbohydrate studies that the ethanolic extract of gin-ger showed remarkable protection from the diet-inducedmetabolic disturbances especially insulin resistance provid-ing a rational basis for the potential medicinal value of therhizome ofZingiber officinale and its traditional consumptionfor the prevention of glucose and lipid disorders

23 Studies of Inflammatory Mechanisms in High Fat DietAnimal Models of Metabolic Syndrome and Prediabetes [23]Another series of studies investigated the effect of gingeron inflammatory mediators in liver of high fat fed rats Theobesity explosion is associated with an increased prevalenceof chronic diseases including type 2 diabetes mellitus [8ndash10] and a growing body of evidence supports the role ofhepatic inflammation in the pathogenesis of these chronicdiseases [37 38] The anti-inflammatory properties of gingerhave been known for centuries [39 40] and a number ofdifferent laboratories showed that ginger extracts suppressinflammation through inhibition of the classical NF-120581Bpathway in various cell types and tissues [41 42]We thereforeinvestigated the anti-inflammatory effect of ethanolic extractof Zingiber officinale on cytokine expression associated withhepatic NF-120581B activity in the high fat diet (HFD) rat model

Treatment withZingiber officinale (400mgkg) was foundto suppress the increased hepatic nuclear NF-120581B activationand the nuclear NF-120581B levels in liver of the HFD-treated rats[23] The ginger administration decreased hepatic expres-sion of IL-6 and TNF-120572 consistent with defence againstinflammatory insult in the liver We therefore concluded thatZingiber officinale ameliorates liver inflammation throughsuppression of the master inflammatory mediator NF-120581Bdecreasing the secretion of proinflammatory cytokines andchemokines which contribute to a feed-forward amplificationof inflammatory signalling and progression of diabetes andmetabolic syndrome [43] These findings open the door to

the potential development of ginger-based therapy for hepaticinflammation associated with the development of insulinresistance

3 Determining the Chemical Compositionand the Major Active Components in Ginger

Determining the mechanism of action of herbal medicines isa critical component of understanding the effects andmecha-nisms of action of natural products assisting with validationand further understanding of the traditional knowledgeand medicinal properties of natural products Furthermoreestablishing the mechanisms of action of major chemicalcomponents allows a deeper understanding of the overallbiological and physiological effects observed It also providesinformation of possible side effects and interactions withother drugs Natural products typically have multiple effectsgiving rise to multitarget action mechanisms from multiplepathways As the pharmacological effects may be determinedby the particular dose used determining the potency of thevarious chemical components for various biological activitiesmay predict the expected clinical effects of a herbal extractWe undertook fractionation of ginger to determine the mostactive components likely to be responsible for the observedantidiabetic activities using glucose uptake in cultured L6myotubes as the biological assayThe fractionation and activ-ities of the resulting ginger extract fractions are illustratedin Figure 2 Fractionation of this extract using a hexaneand ethyl acetate mixture gave fractions ranging from mostnonpolar to moderately polar Fraction F7 had the greatestglucose uptake activity and from 1H-NMR analysis wasshown to be concentrated in (S)-[6]-gingerol (around 434)Other fractions contained smaller amounts of gingerolsas well as flavonoids triterpenoids fatty acids and lipidsby NMR analyses The effects of purified gingerols weresubsequently determined in anti-inflammatory and myotubeglucose uptake assays

4 Mechanism of Action of Ginger fromIn Vitro Studies

41 In Vitro Studies on the InflammatoryResponse in Hepatocytes

411 Effects of Zingiber officinale on Inflammatory MarkersTo further understand the mechanism of anti-inflammatoryaction of Zingiber officinale we undertook a series of studiesto examine the effect of ginger extract in hepatocytes in vitro[23]

Cultured human hepatocyte (HuH-7) cells transfectedwith a NF-120581B-luciferase reporter vector were incubatedwith Zingiber officinale (100 120583gmL) prior to exposure tointerleukin-1120573 (IL-1120573 8 ngmL for 3 h) to induce an inflam-matory phenotype We showed first that increased NF-120581Bactivity induced by IL-1120573 exposure was markedly reducedby 16ndash36 h preincubation with Zingiber officinale It wasthen shown that ginger extract treatment dose-dependently


Freeze-dried ginger powder

Extracted with ethyl acetate at room temperature

Total ginger extract

Fractionated with NP-SCVC

F3F2F1 F7F6F5F4

Further purification with NP-SCVC

Glucose uptake

0005101520253035404550

2-D

G u

ptak

e (fo

ld ch

ange

)

Con

trol

Met

form

in

Tota

l ext

ract

F1(20120583

gm

L)

F2(20120583

gm

L)

F3(20120583

gm

L)

F5(10120583

gm

L)

F6(20120583

gm

L)

F7(20120583

gm

L)

F7(40120583

gm

L)

lowastlowastlowast

lowastlowastlowast

lowastlowastlowast

lowastlowastlowast

lowast

and identification with 1H-NMR

(S)-[6]-Gingerol(S)-[8]-Gingerol(S)-[10]-Gingerol

Figure 2 Fractionation of ginger and analysis and activity of chemical composition of major active fractions [22] Freeze-dried ginger wasextracted with ethyl acetate to give the total ginger extract containing 15 (S)-[6]-gingerol 17 (S)-[8]-gingerol 27 (S)-[10]-gingerol and06 [6]-shogaol Fractions were separated by short-column vacuum chromatography (NP-SCVC) into seven fractions from nonpolar tomoderate polarity The bar graph shows the 2-deoxyglucose uptake activities of the ginger extract metformin and fractions tested at themaximum noncytotoxic doses 1H-NMR analysis showed that gingerols were the major constituents in F7 HPLC analysis of active fractionF7 indicated 434 (S)-[6]-gingerol 29 (S)-[8]-gingerol 15 (S)-[10]-gingerol and 007 [6]-shogaol The effect on glucose uptake wasevaluated using radioactive labelled 2-[1 2-3H]-deoxy-D-glucose in L6 myotubes [22ndash24] lowast119875 lt 005 lowastlowastlowast119875 lt 0001

decreased NF-120581B-target inflammatory gene expression of IL-6 IL-8 and serum amyloid A1 (SAA1) The decrease in SAA1was of particular interest since its secretion by hepatocytes isdramatically upregulated during an inflammatory response[44] and given its central role in insulin resistance may be akey pathway for the preventive effects of Zingiber officinale

Under basal conditions nuclear factor-kappa B (NF-120581B) is present in the cytoplasm of hepatocytes in a latentform bound to the NF-120581B inhibitory protein inhibitorkappa B (I120581B120572) Upon exposure to proinflammatory stimulithe I120581B kinase (IKK) complex is activated and catalysesthe phosphorylation of I120581B120572 Phosphorylated I120581B120572 is thentargeted for degradation by the 26S proteasome complexthereby liberating NF-120581B to migrate to the cell nucleus anddirect transcription of target genes [45] We showed that the

decrease in NF-120581B activity by ginger extract was associatedwith a large reduction of activated I120581B120572 kinase (IKK) activityrelative to the vehicle control whilst the degradation of theNF-120581B inhibitory protein I120581B120572 was considerably decreasedrelative to vehicle control in the IL-1120573-activated HuH-7 cellsAt these concentrations Zingiber officinale had little or noeffect on cell viability A schematic of the effects of ginger andits components on NF-120581B pathways is shown in Figure 3

412 Studies on Inflammatory Pathways with (S)-[6]-Gingerol[46] To investigate the chemical component that may beresponsible for the anti-inflammatory activities we investi-gated the effects of the major component (S)-[6]-gingerolon inflammatory pathways in hepatocytes Our studies andother studies in the literature have shown that ginger extracts


NucleusCytoplasm binding site

PPIKK

PP

Ginger extractCytokine

expression

NF-120581B

NF-120581BNF-120581B target gene

NF-120581B

NF-120581B

I120581B120572

I120581B120572I120581B120572

Phosphorylation Ubiquitination

degradationand

Figure 3 Influence of ethanolic ginger extract on the NF-120581Binflammatory pathway in liver Ginger extract decreases NF-120581B-target inflammatory gene expression by suppression of NF-120581Bactivity through stabilisation of inhibitory I120581B120572 and degradation ofI120581B120572 kinase (IKK) activity (adapted from Li et al [25])

suppress inflammation through inhibition of the classicalnuclear factor-kappa B (NF-120581B) pathway in various cell typesand tissues [42 47] Upon exposure to proinflammatorystimuli activated NF-120581B directs transcription of target genes[45] including genes encoding cytokines chemokines andthe enzyme cyclooxygenase 2 (COX2) [48] Cyclooxygenase(COX) is an important proinflammatorymediator andCOX2is responsible for persistent inflammation [49] As (S)-[6]-gingerol exhibits anti-inflammatory and antioxidant prop-erties [50ndash52] we studied the mechanisms that underlie theanti-inflammatory effects of (S)-[6]-gingerol isolated in ourlaboratory in the IL1120573-treated HuH-7 hepatocyte cell model

Pretreatment of HuH-7 cells with (S)-[6]-gingerol for6 h significantly inhibited IL1120573-induced NF-120581B activity sug-gesting that the protective effects of (S)-[6]-gingerol againstIL1120573-induced inflammation are at least in part associatedwith inhibition of NF-120581B activation in HuH-7 cells Fur-thermore (S)-[6]-gingerol attenuated IL1120573-induced inflam-matory response as evidenced by its decrease of mRNAlevels of inflammatory interleukins IL-6 and IL-8 and serumamyloid A1 (SAA1) In keeping with this result pretreatmentwith 50 120583M pyrrolidine dithiocarbamate (PDTC) a selectiveinhibitor of NF-120581B before exposure to IL-1120573 abrogated IL1120573-induced COX2 IL-6 IL-8 and serum amyloid A1 (SAA1)expression (S)-[6]-Gingerol reduced IL1120573-induced COX2upregulation and as a control PDTC the NF-120581B inhibitoralso attenuated IL1120573-induced overexpression of COX2 It wasalso shown that the level of inhibition of the expression of IL-6 IL-8 and SAA1 achieved by (S)-[6]-gingerol was similar tothat mediated by the COX2 inhibitor NS-398 suggesting thatthe (S)-[6]-gingerol effect on these cytokines was mediatedby COX2 inhibition In earlier studies we had shown thatgingerols inhibit COX2 directly [53] Together these datasuggest that COX2 is most likely a central player inmediatingthe anti-inflammatory effects of (S)-[6]-gingerol

413 Effects of (S)-[6]-Gingerol on ROS Pathways In thenext phase of this series of experiments we showed that

(S)-[6]-gingerol protects HuH-7 cells against IL1120573-inducedinflammatory response by suppression of reactive oxy-gen species (ROS) generation and increasing mRNA lev-els of antioxidant enzyme 24-dehydrocholesterol reductase(DHCR24) Decreasing oxidative stress underlies many anti-inflammatory effects [54] and it is well recognized thatinflammation is a manifestation of oxidative stress whichinduces the pathways that generate the inflammatory factorssuch as cytokines [55] The effect of (S)-[6]-gingerol on IL1120573-induced oxidative stress was determined from its effects onintracellular superoxide and DHCR24 levels Pretreatmentof HuH-7 cells with (S)-[6]-gingerol led to a decrease insuperoxide generation induced by IL-1120573 The ability of (S)-[6]-gingerol to inhibit IL-1120573-induced NF-120581B activation andsuppression of the expression of COX2 and IL-6 IL-8 andSAA1 paralleled the results we obtained when we treatedthe cells with the ROS scavenger butylated hydroxytoluene(BHT) Together with the inhibitory effect on DHCR24 levelsin HuH-7 cell the results indicate that (S)-[6]-gingerol exertsan antioxidative effect on IL-1120573-stimulated HuH-7 cells andhence improvement in the cellular defence mechanismsGiven that antioxidant enzymes are able to block NF-120581Bactivation by various stimuli our findings suggest that theanti-inflammatory effects of (S)-[6]-gingerol are mediated atleast in part by suppressing oxidative stress

42 Conclusions on Inflammation Studies Our series ofstudies on the effects of Zingiber officinale and its majoractive component (S)-[6]-gingerol has shown that the naturalproduct inhibits IL-6 IL-8 and SAA1 expression in cytokine-stimulated HuH-7 cells via suppression of COX2 expressionthrough blockade of the NF-120581B signalling pathway Hepaticinflammation can drive insulin resistance (S)-[6]-Gingerolprotects HuH-7 cells against IL-1120573-induced inflammatoryinsults through inhibition of the ROS pathway These resultsmay open up novel treatment options whereby (S)-[6]-gingerol could potentially protect against hepatic inflamma-tion which underlies the pathogenesis of chronic diseases likeinsulin resistance and type 2 diabetes mellitus

43 Identifying the Gingerol Receptor and Calcium SignallingPathway in Hepatocytes [56] Whilst much herbal medicinesresearch has successfully determined signalling pathwaysat the enzyme and gene level there is often a paucity ofinformation on the receptor sites through which such effectsare mediated In our earlier studies we reported that [6]-gingerol is an efficacious agonist of the capsaicin-sensitivetransient receptor potential cation channel subfamily Vmember 1 (TRPV1) in neurons [57] Gingerols possess thevanillyl moiety which is considered important for activa-tion of TRPV1 expressed in nociceptive sensory neurons[58] Calcium signals in hepatocyte regulate glucose fattyacid amino acid and xenobiotic metabolism [59 60] Theymediate essential cellular functions including cell move-ment secretion and gene expression thereby controlling cellgrowth proliferation and cell death

We therefore investigated if (S)-[6]-gingerol interactedwith TRPV1 receptors in liver hepatocyte cells We first


HO

O

OH

CH3O

(a)

OH

HO

CH3O

(b)

Figure 4 Structures of synthetic analogs of gingerol and shogaol (a) 2-Hydroxy-1-(4-hydroxy-3-methoxyphenyl)dodecane-3-one (ZTX42)(b) [6]-Dihydroparadol (6-DHP)

determined if functional TRPV1 receptors were present inthese cells Exposure of HuH-7 cells to the TRPV1 channelagonist capsaicin (10 120583M) caused a significant increase inthe mRNA levels of TRPV1 Application of 10 120583M capsaicinto cultured HuH-7 cells loaded with Fluo-4 probe alsoincreased intracellular Ca2+ levels an effect inhibited bythe selective capsaicin inhibitor capsazepine These datathus indicated that HuH-7 cells express the TRPV1 calciumchannel We found that (S)-[6]-gingerol dose-dependentlyinduced a transient rise in Ca2+ in HuH-7 cells with theeffect being abolished by preincubation with EGTA anexternal Ca2+ chelator and inhibited by the TRPV1 channelantagonist capsazepine The rapid (S)-[6]-gingerol-inducedNF-120581B activation was found to be dependent on the calciumgradient and TRPV1 activation A functional correlate of theCa2+ dependence was also examined by investigating theeffect of (S)-[6]-gingerol on the known antiapoptotic actionof NF-120581B activation [61 62] The rapid NF-120581B activationby (S)-[6]-gingerol increased mRNA levels of NF-120581B-targetgenes cIAP-2 XIAP and Bcl-2 which encode antiapoptoticproteinsTheir expression was blocked by the TRPV1 antago-nist capsazepine The relationship between TRPV1 activationand the anti-inflammatory effects of (S)-[6]-gingerol remainsto be clarified

44 Effect of Gingerols on Nitric Oxide Pathways [63] In-ducible nitric oxide is an important proinflammatory medi-ator Overproduction of NO or cytotoxic NO metabolitescontribute to numerous pathological processes includinginflammation We investigated the role of the nitric oxidepathway in the inhibitory effects of ginger in inflammationusing stable metabolites and analogues of gingerols andshogaols in a macrophage system The compounds synthe-sised in our laboratory by Dr Tran and AProfessor Dukewere analogues in which the 120572-hydroxy ketone groups werechanged to more stable 120573-hydroxyketone (rac-2-hydroxy-1-(4-hydroxy-3-methoxyphenyl)dodecan-3-one) or a singlehydroxyl side chain-containing analog (rac-(6)-dihydropar-adol) (Figure 4) [63] Both compounds dose-dependentlyinhibited lipopolysaccharide- (LPS-) induced nitric oxideproductionThe inhibition was due to suppression of levels ofinducible nitric oxide protein rather than a direct effect on theiNOS enzyme itselfThis occurred at the transcriptional levelsince the compounds stabilised the LPS-induced breakdownof the NF-120581B inhibitory protein I120581B120572 and prevented nucleartranslocation of NF-120581B p65 thereby reducing NF-120581B activity

Thus the gingerol analogs reduced nitric oxide productionvia attenuation of NF-120581B-mediated iNOS gene expressionproviding another pathway for anti-inflammatory activitylikely associated with insulin resistance

5 Studies on Glucose Uptake

51 Ginger Extract and Gingerols Enhance Glucose Uptake inSkeletal Muscle Cells [24] An important aspect of our workand of others is the study of the mechanisms underlyingreduction of blood glucose and glucose tolerance observedin the animal models For these studies we used in vitromodels of glucose uptake and their cellular pathways inskeletal muscle cells Under physiological conditions theblood glucose level is strictly maintained within a narrowrange mediated by both insulin-dependent and insulin-independent mechanisms [64 65] Skeletal muscle is themajor site of glucose clearance in the body and accounts forover 75 of insulin-stimulated postprandial glucose disposal[66 67] The rate-limiting step of glucose metabolism inskeletal muscle is glucose transport through the plasmamembrane via GLUT4 one isoformof the 12-transmembranedomain sugar transporter family predominantly expressed inskeletal muscle [68 69] It has been established that GLUT4translocates from intracellular storage compartments to thecell surface in response to acute insulin stimulation or otherstimuli [70] In type 2 diabetic (T2D) patients the capacityof skeletal muscle to uptake glucose is markedly reduced dueto impaired insulin signal transduction [71ndash73] Howeverthe insulin-independent pathways remain unchanged duringexercise or muscle contraction [74]

Total ginger extract increased glucose uptake in L6myotubes in a concentration-dependent manner similar tothat observed with metformin as a positive control Asmentioned earlier a ginger extract subfraction concentratedin (S)-[6]-gingerol showed enhanced glucose uptake Anexample of the dose dependence of stimulation of glucoseuptake by (S)-[6]-gingerol is shown in Figure 5 Although (S)-[6]-gingerol and (S)-[8]-gingerol showed similar maximumactivities (S)-[8]-gingerol was the more potent homologueand was studied for its mechanism of glucose uptake Theconcentration-dependent promotion of glucose uptake by(S)-[8]-gingerol occurred in the presence or absence ofinsulin suggesting a pathway independent of insulin (S)-[8]-Gingerol while only slightly increasing the protein level ofGLUT4 substantially increased its plasmamembrane surface


0

1

2

3

4

5

Control 40 80 120 160

2-D

G u

ptak

e (fo

ld ch

ange

)

( )-[6]-Gingerol (120583M)

lowast lowastlowast

lowastlowastlowast

lowastlowastlowast

Metformin S

Figure 5 Dose dependence of (S)-[6]-gingerol enhancement ofglucose uptake in L6 skeletal muscle cells lowast119875 lt 005 lowastlowast119875 lt 001lowastlowastlowast119875 lt 0001 (from [23 24])

distribution in a dose-dependent manner as determined inL6 myotubes by measurement of the cell surface distributionby HA epitope-tagged GLUT4 imaging in L6 myotubesWe calculated based on a pharmacokinetic study in rats[75] that the concentrations of (S)-[6]-gingerol (160 120583M or016 120583MolmL) found to enhance glucose transport in the invitro study can be achieved in vivo

52 The Role of AMPK and Ca2+ in the Effect ofGinger on Glucose Uptake [76]

521 AMPK Activation It was not fully understood at thisstage how gingerol induced GLUT4 translocation in L6myotubes In the normal physiological condition GLUT4resides in intracellular storage compartments and cyclesslowly to the plasma membrane Insulin stimulation causesGLUT4 to undergo exocytosis and relocate to the plasmamembrane [77] Recent studies showed that stimuli evokingAMP-activated protein kinase (AMPK) can induce GLUT4translocation to the cell surface by pathways distinct fromsignalling pathways of insulin [78] The next phase of ourstudy therefore aimed to investigate the mechanism of gin-gerols in promoting glucose uptake in L6 skeletal musclecells We focused on investigating AMPK which is knownto have a key role in regulating energy fuel [79 80] andis an important drug target [81] In skeletal muscle AMPKactivation in response to metabolic stress leads to a switchof cellular metabolism from anabolic to catabolic statesAcute activation of AMPK has been shown to increaseglucose uptake by promoting glucose transporter (GLUT4)translocation to the plasma membrane as well as facilitatedfatty acid influx and 120573-oxidation [82ndash84] Repetitive AMPKactivation results in upregulation of numerous genes andproteins involved in energymetabolism Activation of AMPKoccurs by phosphorylation at threonine172 (Thr172) on theloop of the catalytic domain of the 120572-subunit [85 86]Concomitant with its enhancement of glucose uptake (S)-[6]-gingerol induced a dose- and time-dependent enhancement

of threonine172 phosphorylated AMPK120572 in L6 myotubesConsistent with this activation phosphorylated acetyl-CoAcarboxylase (p-ACCSerine79) one of the downstream targetsof AMPK was elevated maximally within 5min and wasmaintained thereafter

522 Gingerols Increase Ca2+ Signalling in Muscle Cells (S)-[6]-Gingerol was shown to increase intracellular Ca2+ con-centration in a dose-dependent manner within 1 minute inL6 myotubes although the increase appeared more gradualthan that seen with carbachol as a control Pretreatment ofL6 myotubes with the intracellular Ca2+ chelator BAPTA-AM abolished the stimulation of glucose uptake by (S)-[6]-gingerolTheCa2+calmodulin-dependent protein kinasekinase (CAMKK) which is triggered by increased intra-cellular Ca2+ concentration is one of two major upstreamkinases known to regulate AMPK [87ndash89] We showed that(S)-[6]-gingerol-induced AMPK phosphorylation was me-diated by CaMKK in L6 myotubes Enhanced glucose up-take was also abolished by pretreatment with the CaMKKinhibitor STO609 (7-oxo-7H-benzimidazo[2 1-119886]benz[de]isoquinoline-3-carboxylic acid acetate) The increase in (S)-[6]-gingerol (50minus150120583M) induced AMPK120572Thr172 phospho-rylationwas blocked by STO609 added 30minutes before (S)-[6]-gingerol treatment These results indicated that (S)-[6]-gingerol-induced AMPK120572 phosphorylation was modulatedby raised intracellular Ca2+ and mediated via CaMKK

523 Which AMPK120572 Isoform Is Involved in (S)-[6]-GingerolGlucose Uptake AMPK1205721 and AMPK1205722 encoded by differ-ent genes [90] are considered to have different physiologicalroles in mediating energy homeostasis [91] To determinewhich AMPK120572 isoform is involved in (S)-[6]-gingerol glu-cose uptake the two genes were selectively knocked downby transfecting their corresponding siRNAs In our studythe (S)-[6]-gingerol-stimulated increase of glucose uptakerequired AMPK1205721 in L6 myotubes indicating that AMPK1205721was the dominant isoform involved in (S)-[6]-gingerol-stimulated glucose uptake in L6 skeletal muscle cells [76]

53 Effect of Ginger on AMPK and GLUT4 Expression in RatSkeletal Muscle In vitro studies showed that ginger extractand its major pungent principle (S)-[6]-gingerol enhancedglucose uptake with associated activation of AMPK120572 incultured L6 skeletal muscle cells Here we examined theAMPK120572Thr172 phosphorylation and the GLUT4 expressionin isolated skeletal muscle tissue after ginger extract treat-ment for 10 weeks in the high fat high carbohydrate (HFHC)diet fed rat model described above [31] AMPK120572Thr172phosphorylation level and protein content of AMPK120572 werenot significantly altered in skeletal muscle tissue of theHFHCrats Ginger extract however increased AMPK proteinexpression by 290 and AMPK120572Thr172 phosphorylationby 460 above the HFHC control although the increasedid not reach statistical significance Metformin significantlyincreased AMPK120572 phosphorylation consistent with its pre-viously reported effects [92 93]


Blood total cholesterol darr

Blood HDLNo change

Blood LDL darr

Body weight darr

Blood glucose darr

Liver triglycerides darr

Liver total cholesterol darr

HMGCoA reductase darr

LDL cholesterol receptors uarr

NF-120581B darr

Blood triglycerides darr

Figure 6 A summary of the effects of ginger from animal and in vitro studies (with thanks to Dr Srinivas Nammi for the diagram layout)

54 Influence of Ginger on Peroxisome Proliferator-ActivatedReceptor-120574 Coactivator-1120572 (PGC-1120572) and Mitochondria Wenext investigated the significance of the finding that (S)-[6]-gingerol increased AMPK120572 phosphorylation in L6 myotubes[31]We showed that the increase in (S)-[6]-gingerol-inducedAMPK 120572-subunit phosphorylation in L6 skeletal muscle cellswas accompanied by a time-dependent marked incrementof PGC-1120572 mRNA expression and mitochondrial content inL6 skeletal muscle cells AMPK activation leads to enhancedenergy expenditure and is strongly associated with tran-scriptional adaptation including increased PGC-1120572 PGC-1120572 is expressed at high levels in tissues active in oxidativemetabolism including skeletal muscle heart and brownadipose tissue and is considered a key ldquomaster regulatorrdquoof mitochondrial biogenesis [94] Recent clinical findingsstrongly indicate that downregulation of PGC-1120572 and defectsin mitochondrial function are closely associated with thepathogenesis of insulin resistance and type 2 diabetes [9596] Mitochondria in insulin resistant offspring of type 2diabetic patients were lower in density compared to controlsubjects and were impaired in activity [97 98] A similarfindingwas reported in the skeletalmuscle of insulin resistantelderly subjects [99] Our study showed that (S)-[6]-gingeroltreatment significantly increased mRNA expression of PGC-1120572 within 5 hours in L6 myotubes and markedly increasedmitochondrial content detected at a later time From theoverall results obtained we hypothesized that the metaboliccapacity of skeletal muscle is enhanced by feeding total gingerextractThese results suggest that the improvement ofHFHC-diet-induced insulin resistance by ginger is likely associatedwith the increased capacity of energymetabolism by itsmajoractive component (S)-[6]-gingerol

6 Future Outlook and Perspective

Herbal natural product medicine research can be thought toinvolve the science of ldquoreverse pharmacologyrdquo [27] Whilethe allopathic pharmaceutical drug discovery approach startswith a new molecule (a chemical molecule isolated from a

natural product or obtained by chemical synthesis) and isfollowed by cellular and animal studies leading to clinicalinvestigation in phase 1ndash4 clinical trials reverse pharma-cology has as its base traditional knowledge of use andsafety over hundreds or even thousands of years Extensivetraditional knowledge on ginger can be validated by modernpharmacological studies relevant to diabetes managementemphasising the chemical nature of ginger its effects onparameters of hyperglycemia and hyperlipidemia underlyinginsulin resistance and inflammatory responses in animalmodels and in vitro cell studies as well as detailed studies ofthe mechanisms of the observed biological actions Howeverthis information alone is not sufficient to provide evidencefor safety and efficacy of a natural product and requires addi-tional investigation Studies on the mechanism of biologicaleffects allow greater understanding of the factors underpin-ning the safe use of the medicine including interactions withother drugs or nutritional factors If the totality of theseresults confirms and explains the traditional uses a clinicalstudy in volunteers or patientsmay be justified for the specificoutcome being proposed Our work on ginger has largelyfollowed this path In this report the studies underlying thechemical composition and biomedical actions of Zingiberofficinale rhizome from our laboratory have been reviewedwith major findings summarised in Figure 6 Future devel-opments require translation of the traditional informationand pharmacological studies to clinical outcomes of provenbenefit in the pandemic of diabetes and metabolic syndromefacing the developing world in particular Some of the issuesthat need to be addressed are discussed in this section

61 Further Clinical Studies on Ginger Are Needed Manyherbs have demonstrated antidiabeticantihyperlipidemiceffects in vitro and in animal studies in the literature Aconsiderable amount of information exists about the under-lying mechanism of their actions and we as well as othershave reviewed this literature [12 13] It is now necessary tofollow up the traditional knowledge and the large amountof pharmacological investigation in well-designed clinical


programs on these herbs and development of appropriatestrategies for prevention and treatment of diabetes and pre-diabetic and cardiovascular conditions Such studies will bebest undertaken by international cooperation and targetedappropriately funded programs

Despite the large number of in vitro and animal stud-ies performed on Zingiber officinale extracts surprisinglyfew clinical studies are available in the chronic metaboliccondition of prediabetes diabetes and hyperlipidemia ofcardiovascular diseases This lack of clinical data is also truefor most herbal medicine investigation and is the resultof a number of factors including the difficulty of fundingsuch research due to limited commercial support and thecomplexity of the herbal and natural productmaterials In thecase of ginger extract the limited clinical studies done wereoften contradictory and difficult to interpret In one studyafter consumption of 3 g of dry ginger powder in divideddose for 30 days significant reduction in blood glucosetriglyceride total cholesterol LDL and VLDL cholesterolwas observed in diabetic patients [100] A number of newclinical studies have been published recently In a randomizeddouble-blind placebo controlled trial 64 patients with type 2diabetes were assigned to ginger or placebo groups (receiving2 gday of each) Various parameters were determined beforeand after 2 months of intervention Ginger supplementationsignificantly lowered the levels of insulin LDL-C triglyc-eride and the HOMA index (39 versus 45) and increasedthe insulin-sensitivity check index (QUICKI) in comparisonto the control group while there were no significant changesin FPG total cholesterol HDL-C and HbA1c [101] In adouble-blinded placebo-controlled clinical trial 70 type 2diabetic patients consumed 1600mg ginger versus 1600mgwheat flour placebo daily for 12 weeks Ginger reduced fastingplasma glucose HbA1C insulin HOMA triglyceride totalcholesterol CRP and PGE2 significantly compared with theplacebo group there were no significant differences in HDLLDL and TNFa between the two groups [102] In anotherstudy 3 g of dry ginger powder given to diabetic patientsfor 3 months and compared to a control showed significanteffects at the end of the treatment on fasting blood glucose(105 decrease) HbA1c and the quantitative insulin sensi-tivity check index (QUICKI) Whilst both treatment groupsshowed a decrease in insulin resistance index (HOMAR-IR)thesewere not different betweenplacebo and treatment groupand no significant effects were seen on fasting insulin 120573-cellfunction (120573) and insulin sensitivity (S) [103] By contrastother studies failed to show a positive effect in diabetes In astudy by Bordia et al [104] the effect of ginger and fenugreekon blood sugar and lipid concentration was investigated inpatients with coronary artery disease (CAD) and diabeticpatients (with or without CAD) Consumption of 4 g gingerpowder for 3 months was not effective in controlling lipids orblood sugar

Discrepancy of results from clinical studies may beattributed to a number of factors Most studies fail to providea chemical composition profile of the sample used in theclinical trial and ginger preparations may vary enormouslyin their composition depending on the extract preparationmethod the origin of the ginger and storage duration and

conditions [105 106] Variations are found in the contentof gingerols and their relative distributions between [6]-[8]- [10]- and [12]-(S)-gingerols the content of shogaols(which varies greatly between fresh and stored samples) andother components such as sesquiterpenes and volatile oilswhich may all be significant to various extents for the finalbiological effect Differences in the study protocols may alsocontribute to different clinical results especially the lengthof treatment inclusion and exclusion criteria and powerof the studies For ethics reasons most studies in diabeticsare carried out without restriction of the normal diabeticmedication so that the extracts are often evaluated on top ofthis medication Finally it is possible that pharmacodynamicand pharmacokinetic differences between rodent animalsand humans influence differences in the effectiveness of gin-ger observed between human trials and animal studies Thismay reflect differences in metabolism and bioavailability ofcomponents between animals and humans Pharmacokineticstudies in rats have shown rapid absorption of [6]-gingerolfollowing oral administration of a ginger extract (containing53 of [6]-gingerol) reaching a maximum plasma concen-tration of 424 120583gmL after 10-minute postdosing and thendeclining with time with an elimination half-time at theterminal phase of 177 h and apparent total body clearanceof 408 lh Maximum concentrations of [6]-gingerol wereseen in the majority of tissues examined at 30 minutes withthe highest values being 534120583gg in stomach followed by294 120583gg in small intestine [75] By contrast when humanvolunteers took 100mg to 2 g of ginger extract there were nofree forms of gingerols and shogaol detected using standardassays in plasma but these were found as the glucuronideand sulphate conjugates [107] However with amore sensitivetechnique free forms of [10]-gingerol (95 ngmL) and [6]-shogaol (136 ngmL) were observed as well as glucuronideand sulphate metabolites of [6]- [8]- and [10]-gingeroland [6]-shogaol with half-lives of the free compounds andtheir metabolites of 1ndash3 h in human plasma [108] It canthus be concluded that gingerols and shogaols are rapidlyabsorbed and accumulate in a number of tissues in animalsand are extensively metabolised In humans [6]-gingerol isfound only as the glucuronide and sulphate at peak levelsof 047 120583gmL There is of course limited ability to studylevels of free gingerols and shogaols or their metabolitesin relevant tissues in humans To demonstrate effectivenessof ginger further pharmacodynamic and pharmacokineticstudies in humans will be necessary and achievingmaximumeffectiveness will likely require modern formulation of theginger extracts to maximise absorption and optimum tissuedistribution of free forms of gingerols and shogaols or otheractivemetabolites still to be determined Clearlymore clinicalstudies with appropriate design and on well-defined gingerpreparations are required to evaluate the effectiveness andthe pattern of effects of ginger in human subjects in the pre-vention andor treatment of diabetes and related metabolicdisorders

62 New Drug Development from Ginger Another importantdirection in natural product research is the use of the


chemical template of the natural product for the develop-ment of new molecules as pharmaceutical agents from itsknown traditional use Current drug therapy of diabetesand especially prediabetic metabolic syndrome is limited byeffectiveness and side effects of existingmedications and newdrugs are clearly needed There are many examples wherenatural product research on plant materials has led to thedevelopment of new drugs [109] and it is estimated thataround 50 of currently used drugs are natural productsor derivatives of natural products In our work we haveinvestigated the effectiveness of the major component ofZingiber officinale (S)-[6]-gingerol as summarised aboveWealso undertook a program to develop more potent and morestable analogs of gingerols as potential new drug molecules[110] Two chemically stable derivatives of gingerols werefound to be about an order of magnitude greater in potencythan [6]-gingerol in their blocking of iNOS production [63]A range of synthetic derivatives were made in an attemptto increase potency and selectivity Whilst the syntheticderivatives showed considerable enhancement of potencyin animal models of inflammation the decrease in thetherapeutic safety index from the natural products remaineda challenge ([111] [112] Roufogalis et al unpublished results2003) Additional studies are therefore needed not only toenhance the potency of compounds based on the gingeroltemplate but also to increase selectivity and the therapeuticindex of effectiveness and safety

63 Identifying the Binding Sites for Ginger ComponentsWhilst many studies on natural products have in recenttimes identified the cellular pathways and gene and proteinmodifications involved in various disease models few studieshave identified receptor sites of the major active constituentsWhilst transient receptor potential cation channel subfamilyV member 1 (TRPV1) also known as the capsaicin receptorand the vanilloid receptor 1 has been identified as a targetof gingerols [57] it has been more difficult to determine ifthese or other related or unrelated receptors are important inthe mode of action of gingerols in enhancing glucose uptakein muscle and in inflammation and other actions associatedwith insulin resistance Such studies will require the appli-cation of gene-knockoutknockdown technology where cellreceptors are functionally removed and the effects of addedginger extracts or active components are reinvestigated

64 The Multiple Targets of Ginger Action Whilst we andothers have investigated the effects of ginger extracts in avariety of cell systems and in animal models the action ofherbal medicines is often characterised by biological effectsat multiple targets arising from multiple components Thusit is difficult to determine with certainty which pathways areof greatest relevance in the actions of Zingiber officinale indiabetes and prediabetic states One possible way to achievethis is to compare the potency (ie effective dose or con-centration) of individual components relevant to a measuredeffect on the assumption that therapeutic efficacy is morelikely to correspond to those effects which demonstrate thehighest potency that occurs at the lowest doses However this

is bound to be an oversimplification since pharmacokineticstudies are needed to determine concentrations in differentorgans and cell compartments whilst the optimal therapeuticeffects may be contributed by multiple activities Othermechanisms ofZingiber officinale and its components includeupregulation of adiponectin by 6-shogaol and 6-gingerol andPPAR-120574 agonistic activity of 6-shogaol (but not 6-gingerol)[113] activation of hepatic cholesterol-7120572-hydroxylase tostimulate the conversion of hepatic cholesterol to bile acids[114 115] increase in the faecal excretion of cholesterol andpossible block of absorption of cholesterol in the gut [116]and inhibition of cellular cholesterol biosynthesis describedin an apolipoprotein E-deficient mouse [117] Other possibleeffects are related to its COX2 actions in diabetic chronicinflammation and effects on carbohydrate through inhibitionof hepatic phosphorylase (to prevent the glycogenolysis inhepatic cell) and increase of enzyme activities contributing toprogression of glycogenesis and inhibition of the activity ofhepatic glucose-6-phosphatase (thereby decreasing glucosephosphorylation and contributing to lowering blood glucose)[40] Additional mechanisms of ginger action were providedin our recent review [26] Thus the molecular mechanismsresponsible for the observed effects of ginger on lipid andglucose regulation are likely due to both single and multipleeffects of its active components at various potential sites ofaction

7 Final Summary and Conclusion

Many animal and cell biological studies have been conductedon ginger (Zingiber officinale) a traditional medicine used ininflammation and related conditions Studies conducted inour laboratory over a number of years have contributed toan understanding of themechanismunderlying the beneficialeffects of ginger in type 2 diabetes and the metabolic syn-drome A number of clinical trials have shown positive effectson both lipid and blood glucose control in type 2 diabetes butfurther studies on ginger preparations of defined chemicalcomposition and their specific mechanisms are required

Conflict of Interests

The author declares that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The author would like to acknowledge and thank many peo-ple who have worked on the study of ginger in his laboratoryand have been responsible for the studies described in thispaper These include former postdoctoral fellows (SrinivasNammi X-H (Lani) Li and Vadim Dedov) research fellows(Van Hoan Tran Fugen Aktan) PhD students (Yiming LiBhavani Prasad Kota Nooshin Koolaji Effie TjendraputraMoon Sun (Sunny) Kim MK (Min) Song and TH-W (Tom)Huang) collaborators (Qian (George) Li Kristine McGrathand Alison Heather) and academic colleagues (ProfessorsColin Duke Sigrun Chrubasik and Alaina Ammit) The


author also thanks the granting agencies that made this workpossible (ARC Linkage National Institute of ComplementaryMedicine (NICM) and the NHMRC)

References

[1] MHirst IDFDiabetes Atlas International Diabetes Federation6th edition 2013

[2] N H Cho IDF Diabetes Atlas International Diabetes Federa-tion 6th edition 2013

[3] K G M M Alberti and P Z Zimmet ldquoDefinition diagnosisand classification of diabetesmellitus and its complications Part1 diagnosis and classification of diabetes mellitus provisionalreport of aWHO consultationrdquoDiabetic Medicine vol 15 no 7pp 539ndash553 1998

[4] M Parillo and G Riccardi ldquoDiet composition and the risk oftype 2 diabetes epidemiological and clinical evidencerdquo BritishJournal of Nutrition vol 92 no 1 pp 7ndash19 2004

[5] K K Ray S R K Seshasai S Wijesuriya et al ldquoEffect ofintensive control of glucose on cardiovascular outcomes anddeath in patients with diabetes mellitus a meta-analysis ofrandomised controlled trialsrdquoThe Lancet vol 373 no 9677 pp1765ndash1772 2009

[6] R R Holman S K Paul M A Bethel D R Matthews and HA W Neil ldquo10-Year follow-up of intensive glucose control intype 2 diabetesrdquoThe New England Journal of Medicine vol 359no 15 pp 1577ndash1589 2008

[7] F Ismail-Beigi T Craven M A Banerji et al ldquoEffect of inten-sive treatment of hyperglycaemia onmicrovascular outcomes intype 2 diabetes an analysis of the ACCORD randomised trialrdquoThe Lancet vol 376 no 9739 pp 419ndash430 2010

[8] Y Arad D Newstein F Cadet M Roth and A D Guerci ldquoAs-sociation of multiple risk factors and insulin resistance withincreased prevalence of asymptomatic coronary artery diseaseby an electron-beam computed tomographic studyrdquoArterioscle-rosis Thrombosis and Vascular Biology vol 21 no 12 pp 2051ndash2058 2001

[9] K Tayama T Inukai and Y Shimomura ldquoPreperitoneal fatdeposition estimated by ultrasonography in patients with non-insulin-dependent diabetes mellitusrdquo Diabetes Research andClinical Practice vol 43 no 1 pp 49ndash58 1999

[10] I R Wanless and J S Lentz ldquoFatty liver hepatitis (steatohepati-tis) and obesity an autopsy study with analysis of risk factorsrdquoHepatology vol 12 no 5 pp 1106ndash1110 1990

[11] Executive Summary IDF Diabetes Atlas International DiabetesFederation 6th edition 2013

[12] E A Omara A Kam A Alqahtania et al ldquoHerbal medicinesand nutraceuticals for diabetic vascular complications mecha-nisms of action and bioactive phytochemicalsrdquo Current Phar-maceutical Design vol 16 no 34 pp 3776ndash3807 2010

[13] T H Huang B P Kota V Razmovski and B D RoufogalisldquoHerbal or natural medicines as modulators of peroxisomeproliferator-activated receptors and related nuclear receptorsfor therapy ofmetabolic syndromerdquo Journal of Basic andClinicalPharmacology and Toxicology vol 96 no 1 pp 3ndash14 2005

[14] C J Bailley and C Day ldquoMetformin its botanical backgroundrdquoPractical Diabetes International vol 21 pp 115ndash117 2004

[15] D Lender and S K Sysko ldquoThe metabolic syndrome and car-diometabolic risk scope of the problem and current standardof carerdquo Pharmacotherapy vol 26 no 5 pp 3Sndash12S 2006

[16] B White ldquoGinger an overviewrdquo The American Family Physi-cian vol 75 no 11 pp 1689ndash1691 2007

[17] W Wang and Z Wang ldquoStudies of commonly used traditionalmedicine-gingerrdquoZhongguo Zhongyao Zazhi vol 30 no 20 pp1569ndash1573 2005

[18] S Chrubasik M H Pittler and B D Roufogalis ldquoZingiberisrhizoma a comprehensive review on the ginger effect and effi-cacy profilesrdquo Phytomedicine vol 12 no 9 pp 684ndash701 2005

[19] H Zhou L Wei and H Lei ldquoAnalysis of essential oil fromrhizoma Zingiberis by GC-MSrdquo Zhongguo Zhong Yao Za Zhivol 23 no 4 pp 234ndash256 1998

[20] W Blaschek R Hansel L Keller J Reichling H Rimpler andG Schneider inHagersHandbuch der Pharmazeutischen PraxisL-Z Drogen Ed pp 837ndash858 Springer Berlin Germany 1998

[21] S Bhattarai H van Tran and C C Duke ldquoThe stability ofgingerol and shogaol in aqueous solutionsrdquo Journal of Pharma-ceutical Sciences vol 90 no 10 pp 1658ndash1664 2001

[22] Y LiA study on the enhancement of glucose uptake by gingerols ofZingiber officinale via AMPK activation in skeletal muscle [PhDthesis] University of Sydney 2013

[23] X Li K C Y McGrath S Nammi A K Heather and B DRoufogalis ldquoAttenuation of liver pro-inflammatory responsesby Zingiber officinale via inhibition of NF-kappa B activationin high-fat diet-fed ratsrdquo Basic and Clinical Pharmacology andToxicology vol 110 no 3 pp 238ndash244 2012

[24] Y Li V H Tran C C Duke and B D Roufogalis ldquoGingerolsof zingiber officinale enhance glucose uptake by increasing cellsurface GLUT4 in cultured L6 myotubesrdquo Planta Medica vol78 no 14 pp 1549ndash1555 2012

[25] X-H Li K McGrath A K Heather and B D RoufogalisldquoEthanolic extract of zingiber officinale suppresses hepatic NFkappa Brdquo in Proceedings of the OzBio Conference MelbourneVIC Australia 2010

[26] Y Li V H Tran C C Duke and B D Roufogalis ldquoPreventiveand protective properties of Zingiber officinale (Ginger) indiabetes mellitus diabetic complications and associated lipidand other metabolic disorders a brief reviewrdquo Evidence-BasedComplementary and Alternative Medicine vol 2012 Article ID516870 10 pages 2012

[27] B Patwardhan and A D B Vaidya ldquoNatural products drugdiscovery accelerating the clinical candidate developmentusing reverse pharmacology approachesrdquo Indian Journal ofExperimental Biology vol 48 no 3 pp 220ndash227 2010

[28] S Nammi S Sreemantula and B D Roufogalis ldquoProtectiveeffects of ethanolic extract of Z ingiber officinale rhizome on thedevelopment of metabolic syndrome in high-fat diet-fed ratsrdquoBasic and Clinical Pharmacology and Toxicology vol 104 no 5pp 366ndash373 2009

[29] S Nammi M S Kim N S Gavande G Q Li and B DRoufogalis ldquoRegulation of low-density lipoprotein receptor and3-hydroxy-3- methylglutaryl coenzyme A reductase expressionby zingiber officinale in the liver of high-fat diet-fed ratsrdquo Basicand Clinical Pharmacology and Toxicology vol 106 no 5 pp389ndash395 2010

[30] S D J M Niemeijer-Kanters J D Banga and D W ErkelensldquoLipid-lowering therapy in diabetes mellitusrdquoNetherlands Jour-nal of Medicine vol 58 no 5 pp 214ndash222 2001

[31] Y Li V H Tran B P Kota S Nammi C C Duke and B DRoufogalis ldquoPreventative effect of Zingiber officinale on insulinresistance in a high-fat high-carbohydrate diet-fed rat modeland its mechanism of actionrdquo Basic amp Clinical Pharmacology ampToxicology vol 115 no 2 pp 209ndash215 2014


[32] P L Lutsey L M Steffen and J Stevens ldquoDietary intake andthe development of themetabolic syndrome the atherosclerosisrisk in communities studyrdquo Circulation vol 117 no 6 pp 754ndash761 2008

[33] M J Hill D Metcalfe and P G McTernan ldquoObesity and dia-betes lipids ldquonowhere to run tordquordquo Clinical Science vol 116 no2 pp 113ndash123 2009

[34] I Sluijs Y T van der Schouw D L van der A et al ldquoCarbo-hydrate quantity and quality and risk of type 2 diabetes in theEuropean Prospective Investigation into Cancer and Nutrition-Netherlands (EPIC-NL) studyrdquoTheAmerican Journal of ClinicalNutrition vol 92 no 4 pp 905ndash911 2010

[35] H Basciano L Federico and K Adeli ldquoFructose insulin resis-tance and metabolic dyslipidemiardquo Nutrition and Metabolismvol 2 article 5 2005

[36] L H Storlien L A Baur A D Kriketos et al ldquoDietary fats andinsulin actionrdquo Diabetologia vol 39 no 6 pp 621ndash631 1996

[37] G S Hotamisligil ldquoInflammation and metabolic disordersrdquoNature vol 444 no 7121 pp 860ndash867 2006

[38] P Marceau S Biron F-S Hould et al ldquoLiver pathology and themetabolic syndrome X in severe obesityrdquoThe Journal of ClinicalEndocrinology amp Metabolism vol 84 no 5 pp 1513ndash1517 1999

[39] M Afzal D Al-Hadidi M Menon J Pesek and M S IDhami ldquoGinger an ethnomedical chemical and pharmacolog-ical reviewrdquoDrug Metabolism and Drug Interactions vol 18 no3-4 pp 159ndash190 2001

[40] R Grzanna L Lindmark and C G Frondoza ldquoGingermdashan herbal medicinal product with broad anti-inflammatoryactionsrdquo Journal of Medicinal Food vol 8 no 2 pp 125ndash1322005

[41] L Lindmark ldquoAn in vitro screening assay for inhibitors of proin-flammatory mediators in herbal extracts using human syn-oviocyte culturesrdquo In Vitro Cellular amp Developmental BiologymdashAnimal vol 40 pp 95ndash101 2004

[42] H W Jung C Yoon K M Park H S Han and Y ParkldquoHexane fraction of Zingiberis RhizomaCrudus extract inhibitsthe production of nitric oxide and proinflammatory cytokinesin LPS-stimulated BV2 microglial cells via the NF-kappaBpathwayrdquo Food and Chemical Toxicology vol 47 no 6 pp 1190ndash1197 2009

[43] D Cai M Yuan D F Frantz et al ldquoLocal and systemic insulinresistance resulting from hepatic activation of IKK-120573 and NF-120581Brdquo Nature Medicine vol 11 no 2 pp 183ndash190 2005

[44] T A Pearson G AMensah RW Alexander et al ldquoMarkers ofinflammation and cardiovascular disease application to clinicaland public health practice A statement for healthcare profes-sionals from the centers for disease control and prevention andthe AmericanHeart AssociationrdquoCirculation vol 107 no 3 pp499ndash511 2003

[45] S Ghosh M J May and E B Kopp ldquoNF-120581B and rel proteinsevolutionarily conserved mediators of immune responsesrdquoAnnual Review of Immunology vol 16 pp 225ndash260 1998

[46] X H Li K C Y McGrath V H Tran et al ldquoAttenuation ofPro-Inflammatory Responses by [6]-S-gingerol via Inhibitionof ROSNF-kappa BCOX2Activation inHuH7 cellsrdquoEvidence-Based Complementary and Alternative Medicine vol 2013Article ID 146142 8 pages 2013

[47] C Frondoza A G Sohrabi A Polotsky P V Phan D SHungerford and L Lindmark ldquoAn in vitro screening assayfor inhibitors of proinflammatory mediators in herbal extractsusing human synoviocyte culturesrdquo In Vitro Cellular amp Devel-opmental Biology vol 40 no 3-4 pp 95ndash101 2004

[48] J W Christman L H Lancaster and T S Blackwell ldquoNuclearfactor 120581 B a pivotal role in the systemic inflammatory responsesyndrome and new target for therapyrdquo Intensive Care Medicinevol 24 no 11 pp 1131ndash1138 1998

[49] S A Abd-El-Aleem M W J Ferguson I Appleton ABhowmick C N McCollum and G W Ireland ldquoExpressionof cyclooxytenase isoforms in normal human skin and chronicvenous ulcersrdquo Journal of Pathology vol 195 no 5 pp 616ndash6232001

[50] A A Oyagbemi A B Saba and O I Azeez ldquoMolecular targetsof [6]-gingerol its potential roles in cancer chemopreventionrdquoBioFactors vol 36 no 3 pp 169ndash178 2010

[51] S Tripathi K G Maier D Bruch and D S Kittur ldquoEffectof 6-gingerol on pro-inflammatory cytokine production andcostimulatory molecule expression in murine peritoneal ma-crophagesrdquo Journal of Surgical Research vol 138 no 2 pp 209ndash213 2007

[52] C Lee G H Park C Kim and J Jang ldquo[6]-Gingerol attenuates120573-amyloid-induced oxidative cell death via fortifying cellularantioxidant defense systemrdquo Food and Chemical Toxicology vol49 no 6 pp 1261ndash1269 2011

[53] E Tjendraputra V H Tran D Liu-Brennan B D RoufogalisandCCDuke ldquoEffect of ginger constituents and synthetic ana-logues on cyclooxygenase-2 enzyme in intact cellsrdquo BioorganicChemistry vol 29 no 3 pp 156ndash163 2001

[54] K C Y McGrath X H Li R Puranik et al ldquoRole of 3120573-hydroxysteroid-Δ24 reductase in mediating antiinflammatoryeffects of high-density lipoproteins in endothelial cellsrdquo Arte-riosclerosis Thrombosis and Vascular Biology vol 29 no 6 pp877ndash882 2009

[55] K A Roebuck ldquoOxidant stress regulation of IL-8 and ICAM-1gene expression differential activation and binding of the tran-scription factors AP-1 and NF-kappaB (Review)rdquo InternationalJournal of Molecular Medicine vol 4 no 3 pp 223ndash230 1999

[56] X H Li K C Y McGrath V H Tran et al ldquoIdentification ofa calcium signalling pathway of S-[6]-gingerol in HuH-7 cellsrdquoEvidence-Based Complementary and Alternative Medicine vol2013 Article ID 951758 7 pages 2013

[57] V N Dedov V H Tran C C Duke et al ldquoGingerols a novelclass of vanilloid receptor (VR1) agonistsrdquo British Journal ofPharmacology vol 137 no 6 pp 793ndash798 2002

[58] C S J Walpole R Wrigglesworth S Bevan et al ldquoAnaloguesof capsaicin with agonist activity as novel analgesic agentsstructure-activity studies 1The aromatic ldquoA-regionrdquordquo Journal ofMedicinal Chemistry vol 36 no 16 pp 2362ndash2372 1993

[59] M F Leite and M Nathanson ldquoCalcium signaling in thehepatocyterdquo inTheLiver Biology and Pathobiology pp 537ndash554Lippincott Williams ampWilkins Philadelphia Pa USA 2001

[60] C J Dixon P JWhite J F Hall S Kingston andM R BoarderldquoRegulation of human hepatocytes by P2Y receptors control ofglycogen phosphorylase Ca2+ and mitogen-activated proteinkinasesrdquo Journal of Pharmacology and Experimental Therapeu-tics vol 313 no 3 pp 1305ndash1313 2005

[61] M Karin andA Lin ldquoNF-120581B at the crossroads of life and deathrdquoNature Immunology vol 3 no 3 pp 221ndash227 2002

[62] S Shishodia and B B Aggarwal ldquoNuclear factor-120581B activationa question of life or deathrdquo Journal of Biochemistry and Molecu-lar Biology vol 35 no 1 pp 28ndash40 2002

[63] F Aktan S Henness V H Tran C C Duke B D Roufo-galis and A J Ammit ldquoGingerol metabolite and a syntheticanalogue Capsarol inhibit macrophage NF-120581B-mediated iNOS


gene expression and enzyme activityrdquo PlantaMedica vol 72 no8 pp 727ndash734 2006

[64] G Pacini K Thomaseth and B Ahren ldquoContribution toglucose tolerance of insulin-independent vs insulin-dependentmechanisms in micerdquo The American Journal of PhysiologymdashEndocrinology and Metabolism vol 281 no 4 pp E693ndashE7032001

[65] C L Yun and J R Zierath ldquoAMP-activated protein kinase sig-naling inmetabolic regulationrdquo Journal of Clinical Investigationvol 116 no 7 pp 1776ndash1783 2006

[66] R A DeFronzo R Gunnarsson O Bjorkman M Olsson andJ Wahren ldquoEffects of insulin on peripheral and splanchnicglucose metabolism in noninsulin-dependent (type II) diabetesmellitusrdquoThe Journal of Clinical Investigation vol 76 no 1 pp149ndash155 1985

[67] A D Baron G Brechtel P Wallace and S V Edelman ldquoRatesand tissue sites of non-insulin- and insulin-mediated glucoseuptake in humansrdquo The American Journal of PhysiologymdashEndocrinology and Metabolism vol 255 pp E769ndashE774 1988

[68] K Kubo and J E Foley ldquoRate-limiting steps for insulin-mediated glucose uptake into perfused rat hindlimbrdquoTheAmer-ican Journal of PhysiologymdashEndocrinology and Metabolism vol250 no 1 pp E100ndashE102 1986

[69] L M Perriott T Kono R R Whitesell et al ldquoGlucose uptakeand metabolism by cultured human skeletal muscle cells rate-limiting stepsrdquoThe American Journal of Physiology Endocrinol-ogy and Metabolism vol 281 no 1 pp E72ndashE80 2001

[70] M Larance G Ramm and D E James ldquoThe GLUT4 coderdquoMolecular Endocrinology vol 22 no 2 pp 226ndash233 2008

[71] A Krook M Bjornholm D Galuska et al ldquoCharacterizationof signal transduction and glucose transport in skeletal musclefrom type 2 diabetic patientsrdquo Diabetes vol 49 no 2 pp 284ndash292 2000

[72] W T Garvey L Maianu J Zhu G Brechtel-Hook P Wallaceand A D Baron ldquoEvidence for defects in the trafficking andtranslocation of GLUT4 glucose transporters in skeletal muscleas a cause of human insulin resistancerdquo Journal of ClinicalInvestigation vol 101 no 11 pp 2377ndash2386 1998

[73] G W Cline K F Petersen M Krssak et al ldquoImpaired glucosetransport as a cause of decreased insulin-stimulated muscleglycogen synthesis in type 2 diabetesrdquoTheNew England Journalof Medicine vol 341 no 4 pp 240ndash246 1999

[74] NMusi N Fujii M F Hirshman et al ldquoAMP-activated proteinkinase (AMPK) is activated in muscle of subjects with type 2diabetes during exerciserdquo Diabetes vol 50 no 5 pp 921ndash9272001

[75] S-Z Jiang N-S Wang and S-Q Mi ldquoPlasma pharmacokinet-ics and tissue distribution of [6]-gingerol in ratsrdquo Biopharma-ceutics amp Drug Disposition vol 29 no 9 pp 529ndash537 2008

[76] Y Li V H Tran N Koolaji C C Duke and B D Roufogalisldquo(S)-[6]-Gingerol enhances glucose uptake in L6 myotubesby activation of AMPK in response to [Ca2+]irdquo Journal ofPharmacy and Pharmaceutical Sciences vol 16 no 2 pp 304ndash312 2013

[77] J A Lopez J G Burchfield D H Blair et al ldquoIdentification of adistal GLUT4 trafficking event controlled by actin polymeriza-tionrdquoMolecular Biology of the Cell vol 20 no 17 pp 3918ndash39292009

[78] I Kojima andH Shibata ldquoMicrotubule disruption with BAPTAand dimethyl BAPTA by a calcium chelation-independentmechanism in 3T3-L1 adipocytesrdquo Endocrine Journal vol 2 pp235ndash243 2009

[79] R Lage C Dieguez A Vidal-Puig and M Lopez ldquoAMPK ametabolic gauge regulating whole-body energy homeostasisrdquoTrends in Molecular Medicine vol 14 no 12 pp 539ndash549 2008

[80] CAWitczak CG Sharoff and L J Goodyear ldquoAMP-activatedprotein kinase in skeletal muscle from structure and localiza-tion to its role as a master regulator of cellular metabolismrdquoCellular and Molecular Life Sciences vol 65 no 23 pp 3737ndash3755 2008

[81] A Gruzman G Babai and S Sasson ldquoAdenosine monophos-phate-activated protein kinase (AMPK) as a new target forantidiabetic drugs a review onmetabolic pharmacological andchemical considerationsrdquo Review of Diabetic Studies vol 6 no1 pp 13ndash36 2009

[82] G F Merrill E J Kurth B B Rasmussen and W W WinderldquoInfluence of malonyl-CoA and palmitate concentration onrate of palmitate oxidation in rat musclerdquo Journal of AppliedPhysiology vol 85 no 5 pp 1909ndash1914 1998

[83] G F Merrill E J Kurth D G Hardie and W W WinderldquoAICA riboside increases AMP-activated protein kinase fattyacid oxidation and glucose uptake in rat musclerdquoTheAmericanJournal of PhysiologymdashEndocrinology and Metabolism vol 273no 6 part 1 pp E1107ndashE1112 1997

[84] E J Kurth-Kraczek M F Hirshman L J Goodyear and WW Winder ldquo5rsquo AMP-activated protein kinase activation causesGLUT4 translocation in skeletal musclerdquo Diabetes vol 48 no8 pp 1667ndash1671 1999

[85] S A Hawley M Davison A Woods et al ldquoCharacterizationof the AMP-activated protein kinase kinase from rat liverand identification of threonine 172 as the major site at whichit phosphorylates AMP-activated protein kinaserdquo Journal ofBiological Chemistry vol 271 no 44 pp 27879ndash27887 1996

[86] S C Stein A Woods N A Jones M D Davison and DCabling ldquoThe regulation of AMP-activated protein kinase byphosphorylationrdquo Biochemical Journal vol 345 no 3 pp 437ndash443 2000

[87] S A Hawley M A Selbert E G Goldstein A M EdelmanD Carling and D G Hardie ldquo51015840-AMP activates the AMP-activated protein kinase cascade andCa2+calmodulin activatesthe calmodulin-dependent protein kinase I cascade via threeindependent mechanismsrdquoThe Journal of Biological Chemistryvol 270 no 45 pp 27186ndash27191 1995

[88] A Woods S R Johnstone K Dickerson et al ldquoLKB1 is theupstream kinase in the AMP-activated protein kinase cascaderdquoCurrent Biology vol 13 no 22 pp 2004ndash2008 2003

[89] M Momcilovic S Hong and M Carlson ldquoMammalian TAK1activates Snf1 protein kinase in yeast and phosphorylates AMP-activated protein kinase in vitrordquo Journal of Biological Chem-istry vol 281 no 35 pp 25336ndash25343 2006

[90] A Woods I Salt J Scott D G Hardie and D Carling ldquoThe1205721 and 1205722 isoforms of the AMP-activated protein kinase havesimilar activities in rat liver but exhibit differences in substratespecificity in vitrordquo FEBS Letters vol 397 no 2-3 pp 347ndash3511996

[91] I Salt J W Celler S A Hawley et al ldquoAMP-activated proteinkinase greater AMP dependence and preferential nuclearlocalization of complexes containing the 1205722 isoformrdquo Biochem-ical Journal vol 334 no 1 pp 177ndash187 1998

[92] N Ruderman and M Prentki ldquoAMP kinase and malonyl-CoAtargets for therapy of the metabolic syndromerdquo Nature ReviewsDrug Discovery vol 3 no 4 pp 340ndash351 2004


[93] J An D M Muoio M Shiota et al ldquoHepatic expression ofmalonyl-CoA decarboxylase reverses muscle liver and whole-animal insulin resistancerdquo Nature Medicine vol 10 no 3 pp268ndash274 2004

[94] B B Kahn T Alquier D Carling and D G Hardie ldquoAMP-activated protein kinase ancient energy gauge provides clues tomodern understanding of metabolismrdquo Cell Metabolism vol 1no 1 pp 15ndash25 2005

[95] D E Kelley J He E V Menshikova and V B Ritov ldquoDys-function of mitochondria in human skeletal muscle in type 2diabetesrdquo Diabetes vol 51 no 10 pp 2944ndash2950 2002

[96] M E Patti A J Butte S Crunkhorn et al ldquoCoordinatedreduction of genes of oxidative metabolism in humans withinsulin resistance and diabetes potential role of PGC1 andNRF1rdquo Proceedings of the National Academy of Sciences of theUnited States of America vol 100 no 14 pp 8466ndash8471 2003

[97] K Morino K F Petersen S Dufour et al ldquoReduced mitochon-drial density and increased IRS-1 serine phosphorylation inmuscle of insulin-resistant offspring of type 2 diabetic parentsrdquoJournal of Clinical Investigation vol 115 no 12 pp 3587ndash35932005

[98] K F Petersen S Dufour D Befroy R Garcia and G I Shul-man ldquoImpaired mitochondrial activity in the insulin-resistantoffspring of patients with type 2 diabetesrdquo The New EnglandJournal of Medicine vol 350 no 7 pp 664ndash671 2004

[99] K F Petersen D Befroy S Dufour et al ldquoMitochondrial dys-function in the elderly possible role in insulin resistancerdquoScience vol 300 no 5622 pp 1140ndash1142 2003

[100] B Andallu B Radhika and V Suryakantham ldquoEffect of aswa-gandha ginger and mulberry on hyperglycemia and hyperlipi-demiardquo Plant Foods for Human Nutrition vol 58 no 3 pp 1ndash72003

[101] S Mahluji V E Attari M Mobasseri L Payahoo AOstadrahimi and S E Golzari ldquoEffects of ginger (Zingiber offic-inale) on plasma glucose level HbA1c and insulin sensitivity intype 2 diabetic patientsrdquo International Journal of Food Sciencesand Nutrition vol 64 no 6 pp 682ndash686 2013

[102] T Arablou N Aryaeian M Valizadeh F Sharifi A F Hosseiniand M Djalali ldquoThe effect of ginger consumption on glycemicstatus lipid profile and some inflammatory markers in patientswith type 2 diabetes mellitusrdquo International Journal of FoodSciences and Nutrition vol 65 no 4 pp 515ndash520 2014

[103] H Mozaffari-Khosravi B Talaei B-A Jalali A Najarzadehand M R Mozayan ldquoThe effect of ginger powder supplemen-tation on insulin resistance and glycemic indices in patientswith type 2 diabetes a randomized double-blind placebo-controlled trialrdquo Complementary Therapies in Medicine vol 22no 1 pp 9ndash16 2014

[104] A Bordia S K Verma and K C Srivastava ldquoEffect of ginger(Zingiber officinale Rosc) and fenugreek (Trigonella foenum-graecum L) on blood lipids blood sugar and platelet aggrega-tion in patients with coronary artery diseaserdquo ProstaglandinsLeukotrienes and Essential Fatty Acids vol 56 no 5 pp 379ndash384 1997

[105] S D Jolad R C Lantz J C Guan R B Bates and B NTimmermann ldquoCommercially processed dry ginger (Zingiberofficinale) composition and effects on LPS-stimulated PGE2productionrdquo Phytochemistry vol 66 no 13 pp 1614ndash1635 2005

[106] S D Jolad R C Lantz A M Solyom G J Chen R B Batesand B N Timmermann ldquoFresh organically grown ginger(Zingiber officinale) composition and effects on LPS-induced

PGE2 productionrdquo Phytochemistry vol 65 no 13 pp 1937ndash1954 2004

[107] SM Zick Z DjuricM T Ruffin et al ldquoPharmacokinetics of 6-gingerol 8-gingerol 10-gingerol and 6-shogaol and conjugatemetabolites in healthyhuman subjectsrdquo Cancer EpidemiologyBiomarkers and Prevention vol 17 no 8 pp 1930ndash1936 2008

[108] Y Yu S Zick X Li P Zou BWright andD Sun ldquoExaminationof the pharmacokinetics of active ingredients of ginger inhumansrdquo AAPS Journal vol 13 no 3 pp 417ndash426 2011

[109] D J Newman and G M Cragg ldquoNatural products as sourcesof new drugs over the 30 years from 1981 to 2010rdquo Journal ofNatural Products vol 75 no 3 pp 311ndash335 2012

[110] B D Roufogalis C C Duke and V H Tran ldquoPreparationand pharmaceutical uses of phenylalkanolsrdquo PCT InternationalApplication 86 WO 9920589 1999

[111] B D Roufogalis C Duke and V Tran ldquoMedicinal uses ofphenylalkanols and derivatives assigned to ZingoTXrdquo Aust PN758911 US PN 6518315 Canada PAN 2307028 Europe PN1056700 NZ PAN 503976

[112] N Ede B Roufogalis DOwenDG BourkeH Tran andCCDuke ldquoPreparation of phenylalkanol derivatives as modulatorsof vanilloid receptor for treatment of pain PCT Int Applrdquo WO2006-AU710 20060526 Priority AU 2005-902745 20050527CAN 1467694 AN 20061252945 2006

[113] Y Isa Y Miyakawa M Yanagisawa et al ldquo6-Shogaol and 6-gingerol the pungent of ginger inhibit TNF-120572mediated down-regulation of adiponectin expression via different mechanismsin 3T3-L1 adipocytesrdquo Biochemical and Biophysical ResearchCommunications vol 373 no 3 pp 429ndash434 2008

[114] R S Ahmed and S B Sharma ldquoBiochemical studies on com-bined effects of garlic (Allium sativum Linn) and ginger (Zin-giber officinale Rose) in albino ratsrdquo Indian Journal of Experi-mental Biology vol 35 no 8 pp 841ndash843 1997

[115] K Srinivasan and K Sambaiah ldquoThe effect of spices on choles-terol 7 alpha-hydroxylase activity and on serum and hepaticcholesterol levels in the ratrdquo International Journal for Vitaminand Nutrition Research vol 61 no 4 pp 364ndash369 1991

[116] L-K Han X-J Gong S Kawano M Saito Y Kimura andH Okuda ldquoAntiobesity actions of Zingiber officinale RoscoerdquoYakugaku Zasshi vol 125 no 2 pp 213ndash217 2005

[117] B Fuhrman M Rosenblat T Hayek R Coleman and MAviram ldquoGinger extract consumption reduces plasma choles-terol inhibits LDL oxidation and attenuates development ofatherosclerosis in atherosclerotic apolipoprotein E-deficientmicerdquo Journal of Nutrition vol 130 no 5 pp 1124ndash1131 2000

Submit your manuscripts athttpwwwhindawicom

PainResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom

Volume 2014

ToxinsJournal of

VaccinesJournal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

AntibioticsInternational Journal of

ToxicologyJournal of


StrokeResearch and TreatmentHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Drug DeliveryJournal of



Advances in Pharmacological Sciences

Tropical MedicineJournal of


Medicinal ChemistryInternational Journal of


AddictionJournal of



BioMed Research International

Emergency Medicine InternationalHindawi Publishing Corporationhttpwwwhindawicom Volume 2014


Autoimmune Diseases


Anesthesiology Research and Practice

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of


Pharmaceutics


MEDIATORSINFLAMMATION

of


Gingerols Shogaols

Sesquiterpenes

HO HO

O OH O

H HH

[6]-S-Gingerol (n = 4) [6]-Shogaol (n = 4)[8]-S-Gingerol (n = 6) [8]-Shogaol (n = 6)[10]-S-Gingerol (n = 8) [10]-Shogaol (n = 8)

(mdash)-Zingiberene ar-Curcumene 120573-Sesquiphellandrene 120573-Bisabolene

CH3 CH3CH3O CH3O

Phenylalkanols

(CH2)n (CH2)n

Figure 1 Chemical structures of components of Zingiber officinale

identified in reviews of the literature on natural products[12 13] Metformin currently the drug of choice in themanagement of hyperglycemia in fact has its origins ina natural product [14] The combination of hyperglycemicand hyperlipidemic disturbances and their interdependencepresents major risk factors for the development of diabetesand its life threatening cardiovascular complications [15]Thus the control of both these underlying disturbances isconsidered optimal for the management of diabetes and itscomplications

12 Ginger Ginger (Zingiber officinale Roscoe Zingiber-aceae) is one of the most widely consumed spices worldwideFrom its origin in Southeast Asia and its spread to Europeit has a long history of use as herbal medicine to treat avariety of ailments including vomiting pain indigestionand cold-induced syndromes [16 17] Although ginger isnot widely known for its effectiveness in diabetes preventionandor treatment modern pharmacological studies supportits potential for treating both the hyperlipidemic and hyper-glycemic aspects of diabetes However there is much lessinformation on themechanism of action of ginger underlyingits effects in diabetes Whilst the chemical composition ofZingiber officinale is well investigated it is much less clearwhich of the many components in ginger are responsible forits effects in diabetes

13 The Importance of Chemical Composition of Gingerand Other Herbal Products It is expected that the multi-ple components in ginger may lead to multiple effects onmetabolic pathways and to involve multiple mechanismsaffecting various aspects of chronic metabolic disorders suchas diabetes [18] Some of the main chemical components ofginger are shown in Figure 1 Crude ginger contains up to 9lipids or glycolipids and about 5ndash8 oleoresin The pungent

principles accounting for 25 of the oleoresins consistmainly of gingerols [6]-Gingerol is the major gingerol andother gingerols include [8]-gingerol or [10]-gingerol as wellas methylgingerol and gingerdiol dehydrogingerdione [10]-dehydrogingerdione diarylheptanoids diterpene lactonesand galanolactone (in some species) Ginger contains up to3 essential oil accounting for 20ndash25 of the oleoresins Gaschromatographymass spectrometry identified other numer-ous compounds in the essential oil of ginger of which majorcompounds are camphene b-phellandrene and 18-cineol[19] The oil also contains sesquiterpenes and sesquiterpenealcohols impacting the smell of ginger whilst the taste ofginger is mainly affected by various monoterpenes Sho-gaols contained in semidried ginger are more pungentthan gingerols [20] are a major degradation product of thethermally labile gingerols and are rarely found in fresh ginger[21] Another minor component zingerone is a degradationproduct which indicates low quality plantmaterial A numberof other coactive constituents could also contribute to thetreatment of various diseases

14 Evidence for Efficacy from Clinical and PharmacologicalStudies on Ginger Sigrun Chrubasic in collaboration withour laboratory undertook a comprehensive review of animaland clinical studies on Zingiber officinale [18] In nauseaand vomiting it was concluded that clinical evidence beyonddoubt is only available for pregnancy-related nausea andvomiting whilst meta-analyses could not demonstrate effec-tiveness in postoperative nausea motion sickness or nau-seavomiting of other aetiology It remains to be confirmed towhat extent various proprietary ginger preparations are clin-ically useful to alleviate osteoarthritic or other pains and toinfluence platelet aggregation Ginger exerts in vitro antiox-idative antitumorigenic and immunomodulatory effects andis an effective antimicrobial and antiviral agent Animal





























F3F2F1 F7F6F5F4


Glucose uptake

0005101520253035404550

2-D

G u

ptak

e (fo

ld ch

ange

)

Con

trol

Met

form

in

Tota

l ext

ract

F1(20120583

gm

L)

F2(20120583

gm

L)

F3(20120583

gm

L)

F5(10120583

gm

L)

F6(20120583

gm

L)

F7(20120583

gm

L)

F7(40120583

gm

L)

lowastlowastlowast

lowastlowastlowast

lowastlowastlowast

lowastlowastlowast

lowast










PPIKK

PP


expression

NF-120581B


NF-120581B

NF-120581B

I120581B120572

I120581B120572I120581B120572


degradationand










HO

O

OH

CH3O

(a)

OH

HO

CH3O

(b)









0

1

2

3

4

5

Control 40 80 120 160

2-D

G u

ptak

e (fo

ld ch

ange

)

( )-[6]-Gingerol (120583M)

lowast lowastlowast

lowastlowastlowast

lowastlowastlowast

Metformin S











Blood HDLNo change

Blood LDL darr

Body weight darr

Blood glucose darr





NF-120581B darr























Acknowledgments




References































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of





























F3F2F1 F7F6F5F4


Glucose uptake

0005101520253035404550

2-D

G u

ptak

e (fo

ld ch

ange

)

Con

trol

Met

form

in

Tota

l ext

ract

F1(20120583

gm

L)

F2(20120583

gm

L)

F3(20120583

gm

L)

F5(10120583

gm

L)

F6(20120583

gm

L)

F7(20120583

gm

L)

F7(40120583

gm

L)

lowastlowastlowast

lowastlowastlowast

lowastlowastlowast

lowastlowastlowast

lowast










PPIKK

PP


expression

NF-120581B


NF-120581B

NF-120581B

I120581B120572

I120581B120572I120581B120572


degradationand










HO

O

OH

CH3O

(a)

OH

HO

CH3O

(b)









0

1

2

3

4

5

Control 40 80 120 160

2-D

G u

ptak

e (fo

ld ch

ange

)

( )-[6]-Gingerol (120583M)

lowast lowastlowast

lowastlowastlowast

lowastlowastlowast

Metformin S











Blood HDLNo change

Blood LDL darr

Body weight darr

Blood glucose darr





NF-120581B darr























Acknowledgments




References































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of



PPIKK

PP


expression

NF-120581B


NF-120581B

NF-120581B

I120581B120572

I120581B120572I120581B120572


degradationand










HO

O

OH

CH3O

(a)

OH

HO

CH3O

(b)









0

1

2

3

4

5

Control 40 80 120 160

2-D

G u

ptak

e (fo

ld ch

ange

)

( )-[6]-Gingerol (120583M)

lowast lowastlowast

lowastlowastlowast

lowastlowastlowast

Metformin S











Blood HDLNo change

Blood LDL darr

Body weight darr

Blood glucose darr





NF-120581B darr























Acknowledgments




References































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of


HO

O

OH

CH3O

(a)

OH

HO

CH3O

(b)









0

1

2

3

4

5

Control 40 80 120 160

2-D

G u

ptak

e (fo

ld ch

ange

)

( )-[6]-Gingerol (120583M)

lowast lowastlowast

lowastlowastlowast

lowastlowastlowast

Metformin S











Blood HDLNo change

Blood LDL darr

Body weight darr

Blood glucose darr





NF-120581B darr























Acknowledgments




References































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of


0

1

2

3

4

5

Control 40 80 120 160

2-D

G u

ptak

e (fo

ld ch

ange

)

( )-[6]-Gingerol (120583M)

lowast lowastlowast

lowastlowastlowast

lowastlowastlowast

Metformin S











Blood HDLNo change

Blood LDL darr

Body weight darr

Blood glucose darr





NF-120581B darr























Acknowledgments




References































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of



Blood HDLNo change

Blood LDL darr

Body weight darr

Blood glucose darr





NF-120581B darr























Acknowledgments




References































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of
















Acknowledgments




References































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of



References































































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of
































































































Volume 2014

ToxinsJournal of

VaccinesJournal of















AddictionJournal of






Autoimmune Diseases




Journal of


Pharmaceutics



of

Review Article Zingiber officinale (Ginger): A Future ...

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Transcript of Review Article Zingiber officinale (Ginger): A Future ...