Blackberry Extract

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Czech J. Food Sci. Vol. 29, 2011, No. 2: 181–189

Antioxidant Capacity and Antioxidants of Strawberry, Blackberry, and Raspberry Leaves

Lucie BuřičoVá1, Mirjana ANdJeLkoViC 2, Anna čerMákoVá1, Zuzana réBLoVá1, ondřej Jurček 3,4,5, erkki koLehMAiNeN 4, roland Verhé 2

and František kVASNičkA6

1department of Food Chemistry and Analysis, 3department of Chemistry of Natural Compounds and 6department of Food Preservation and Meat Technology, Faculty of Food and Biochemical Technology, institute of Chemical Technology in Prague, Prague, Czech republic;

2department of organic Chemistry, Ghent university, Ghent, Belgium; 4department of Chemistry, Laboratory of organic Chemistry, university of Jyväskylä, Jyväskylä, Finland;

5institute of experimental Botany, Academy of Sciences of the Czech republic, isotope Laboratory, Prague, Czech republic

Abstrakt

BuřičováL.,AndjelkovicM.,ČermákováA.,RéblováZ.,JurčekO.,KolehmainenE.,VerhéR.,KvasničkaF.(2011):Antioxidant capacity and antioxidants of strawberry, blackberry, and raspberry leaves. CzechJ.FoodSci., 29:181–189.

Thetotalphenoliccontent(Folin-Ciocalteumethod),freeradicalscavengingabilityexpressedasDPPHvalue,ferricre-ducingantioxidantcapacity(FRAP),andoxygenradicalabsorbancecapacity(ORAC)weredeterminedinwaterextractsof leavesfromrosaceae familyplants(Fragaria vescaL.,rubus fructicosusL.,and rubus idaeusL.).Theantioxidantcapacitiesoftheextracts(intheorderoftheabovementionedmethods)were73.6–88.9%,60.1–71.4%,49.7–78.0%re-spectively,and45.3–66.5%ofthatofgreenteawaterextract.Further,thepresenceof15compounds(gallicacid,rutin,ellagic acid, caffeic acid, p-coumaric acid, quercetin, kaempferol, myricetin, quercetin-3-d-glucoside, ascorbic acid,(+)-catechin,(–)-epicatechin,epicatechingallate,epigallocatechin,procyanidinB1)wasstudiedbyHPLC-ECDandtheirantioxidantcapacitieswerecomparedtotheantioxidantcapacityoftheextracts.Outofthecompoundsstudied,mostly(+)-catechin,ellagicacid,and(–)-epicatechinparticipatedintheantioxidantcapacitiesofthestudiedplantleaveswaterextracts.Theantioxidantcapacityofleavesinfusions(determinedbyDPPHmethod)waslowerthanthoseofredwinesandteainfusions,butcomparabletotheantioxidantcapacitiesofwhitewinesandfruitbeverages.

Keywords:DPPH;Folin-Ciocalteaumethod;Fragaria vesca; rubus fructicosus; rubus ideaus; FRAP;HPLC;ORAC

SupportedbytheMinistryofEducation,YouthandSportsoftheCzechRepublic,ProjectNo.MSM6046137305,andbyspecificuniversityresearchofMinistryofEducation,YouthandSportsoftheCzechRepublic,ProjectNo.21/2010.

Inthescreeningstudycomparingtheantioxidantcapacities(AC)(measuredbyDPPHmethod)ofseventeenCzechmedicinalplants,theleavesofstrawberry(Fragaria vescaL.),blackberry(rubus fructicosusL.)andraspberry(rubus idaeusL.)

belongedtothemostefficientplantstested(Buři-čová&Réblová2008).TheACoftheirextractswerecomparabletoandinsomecasesevenhigherthanACofthestudiedplantsfromthefamilyLamiaceae(oregano,sweetbalm,thyme,dead-

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nettle,andmint),whichareknownasrichsourcesofantioxidants(Dormanet al.2004;Capeckaet al.2005).GoodACofthelistedplantsfromtherosaceaefamilywasalsoconfirmedbyotherarticles.Katalinicet al.(2006)determinedtheAC(ferricreducingantioxidantcapacity(FRAP))andphenoliccontentof70medicinalplants.Theleavesofraspberry,blackberry,andstrawberrywereamongelevenofthemosteffectiveplants.Inanotherstudy(Wang&Lin2000), theAC(oxygenradicalabsorbancecapacity(ORAC))ofleavesandberriesofstrawberry,blackberry,andraspberrywerecompared.Theleaveswerearichersourceofantioxidantsandhadagreatercontentofphenolicsubstancesthanberries.

However,fortheestimationofthepossibleanti-oxidanteffectin vivoisitimportanttoknownotonlytheACofherbextracts,butalsothecontentsofparticularantioxidantsandtheparticipationofthesecompoundsintheACofextracts.AlotofcompoundspossessingACwereidentifiedintheleavesofstrawberry,raspberry,andblackberryasprocyanidinB1,epigallocatechin, (+)-cate-chin,procyanidinB2,(–)-epicatechin,astringin,epicatechin-3-gallate,piceid,quercetin-4-glu-coside,trans-resveratrol(Mudnicet al.2009),ellagicacid(Gudej&Rychlínska1996;Gudej&Tomczyk2004;Skupien&Oszmianski2004;Hukkanenet al.2007),p-coumaricacid(Gudej2003;Skupien&Oszmianski2004;Hukkanenet al.2007),quercetin,kaempferol(Gudej&Rych-línska1996;Gudej2003;Gudej&Tomczyk2004;Skupien&Oszmianski2004),myricetin(Skupien&Oszmianski2004),gallicacid,agri-moniin,casuarictin,lambertianinC,potentillin,sanguiinH-10,nobotaninA(Hukkanenet al.2007),ascorbicacid(Wang1999),quercetin-3-o-β-d-glucopyranoside,quercetin-3-o-β-d-galacto-pyranoside,quercetin-3-O-α-l-arabinopyranose,kaempferol-3-o-β-d-galactopyranoside,kaempfe-rol-3-o-α-l-arabinopyranose(Gudej&Rychlín-ska1996;Gudej2003),quercetin-3-o-glucoside,rutin,quercetinglucuronide(Venskutoniset al.2007),andsomeotherphenylethanolderivativesofphenylpropanoidglucosides(Hanhinevaet al.2009).However,thecontentsofthesecompoundsinwaterextractsandinfusionshavenotbeenstudiedsufficiently,aswellastheirparticipationintheantioxidantcapacitiesoftherespectiveplants.

Withrespecttotheprevioustext,theaimofthisresearchwastovalidatethehighACofstrawberryleaves,blackberryleaves,andraspberryleaveswater

extractsusingfourdifferentmethodsappliedtothesamesamples.Fortheevaluationofthepossibleeffectsoftheextractsin vivo,quantificationoftheselectedphenoliccompounds(gallicacid,rutin,ellagicacid,caffeicacid,p-coumaricacid,quercetin,kaempferol,myricetin,quercetin-3-d-glucoside,ascorbicacid,(+)-catechin,(–)-epicatechin,epica-techingallate,epigallocatechin,procyanidinB1)inthestudiedextractswasdoneandtheparticipati-onofthesecompoundsinACoftheextractswascalculated.Further,theAC(measuredbyDPPHmethod)ofleaveswaterinfusionswerecomparedwithACofothersourcesofantioxidantsinhumandietsuchasgreenandblackteas,whiteandredwines,andfruit(vegetable)beverages.

MAteRiAL And MethodS

Materials.Threeleafsamplesofeachofthemedicinalplantsstudied,i.e.strawberryleaves(Fragaria vesca L.),blackberryleaves(rubus fru-ticosus L.),andraspberryleaves(rubus idaeus L.),werepurchasedfromaCzechproducerandmedicinalherbsdistributor(Natura,Děčín,CzechRepublic), frompharmacies(respectively),theplantshavingbeengrownintheareaoftheCzechRepublic.Greenandblackteas,redandwhitewi-nes,fruitandvegetablebeverageswerepurchasedinordinaryCzechshopsorspecialisedteashops.Allthesampleswereusedwithintherecommendedconsumptionperiod.

AllstandardsusedforHPLC,Folin-Ciocalteureagent,2,4,6-tripyridyl-S-triazine,ferroussul-phate,Trolox,2,2-diphenyl-1-picrylhydrazyl,andformicacid,andallchemicalsforelectrophoresiswerepurchasedfromSigma-AldrichChemie(Stein-heim,Germany).Sodiumcarbonate,AAPH,andfluoresceinwerepurchasedfromAcros(Geel,Belgium),sodiumchloridewasfromLachemaNeratovice,CzechRepublic.Organicsolventswereofanalyticalgrade,acetonitrilewasofHPLCgrade.AllsolventswerepurchasedfromMerck(Darmstadt,Germany).

Samples preparation.Forthewaterextractspreparation,theleavesofthemedicinalplants(orgreentea)weregroundand1gofthegroundleaveswasleft in50mlofdeionisedwaterforextractionduring20minutes.Thetemperatureofthewaterwas98°C.

Waterinfusionsofmedicinalplantsandgreenandblackteaswerepreparedasrecommendedby

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theproducers.Theamountofthesampleusedforinfusionanditsdurationwereadjustedaccordingtotheplanttypeinthefollowingmanner:1.5–2gofthemedicinalplantsper250mlwaterwithinfusionperiodof15min;2gofteaper150mlor250mlwaterwithinfusionperiodof2–4min(greentea)or3–5min(blacktea).

Afterthepreparation,theextractsandinfusionsweredilutedwiththerespecttothedetectionmethodusedandwereanalysedshortlyafterthepreparation.Redandwhitewinesandfruitandvegetablebeveragesweredilutedwithrespectthedetectionmetodused.

Total phenolics assay (Folin-Ciocalteu method, TPC).TotalphenolicscontentwasmeasuredusingtheFolin-CiocalteucolorimetricmethoddescribedbySingletonet al.(1999).Theabsorbancewasmeasured at 760 nm with Varian UV-VisibleSpectrophotometer(Cary50BIO,Mulgrave,Aus-tralia).Theresultswereexpressedasmgofgallicacidequivalentsper1gofdrysample.

Ferric reducing antioxidant capacity (FRAP).TheferricreducingabilitywasdeterminedusingtheassaydescribedbyBenzieandStrain(1996).Theabsorbancewasmeasuredevery10sduring30minreading(spectrophotometerCary100BioVarian,PaloAlto,USA).TheresultswereexpressedasmmolofFeSO4perlitre.

Oxygen radical absorbance capacity (ORAC).ThedeterminationofoxygenradicalabsorbancecapacitywasbasedonthemethodusedbyHuanget al.(2002).ThemeasurementswerecarriedoutonamicroplatefluorimeterSPECTRAmaxGeminixS(MolecularDeviceCorporation,Sunnyvale,USA)usingthe490nmexcitationand515nmemissi-onfilters.ThefluorescencewasrecordedeveryminuteaftertheadditionofAAPHuntilitsvaluewas<5%oftheinitialreading.TheresultswereexpressedasmicromoleTroloxequivalentsper1gofdrysample.

Free radical scavenging ability by the use of a stable DPPH radical.TotalantioxidantcapacitywasmeasuredusingDPPHmethod,whichpresentsradicalscavengingabilityofDPPH(2,2-diphenyl-1-picrylhydrazyl) radicals.ThismethodwasdescribedpreviouslybyGadowetal.1997,andwasmodifiedindetailbyBuřičováandRéblová(2008).Theabsorbanceat522nmwasmeasuredbyaVarianUV-VisibleSpectrophotometer(Cary50BIO,Mul-grave,Australia).Theresultswereexpressedasmgofascorbicacidper1gofdryplantmaterialorasmgofascorbicacidper100mlofthebeverage.

Determination of selected antioxidants.TheextractswereanalysedbyHPLC-RP-ECD,speci-ficallywithanamperometricdetectorHP1049A(HewlettPackard,Avondale,USA)equippedwithaglassy-carbonelectrode(operatingatapotentialof+0.8V),areferenceAg/AgClelectrodeandaplatinumcounterelectrode,andanisocraticnon-steelpumpLCP4020.31(ECOM,Prague,CzechRepublic).ThedatawererecordedusingaClari-ty2.6.4.402chromatographysystem(DataApex,Prague,CzechRepublic).ThecompoundswereseparatedonaRPC18column(HypersilODS:4.0mm×250mm,5μm;Agilent,USA)maintainedattheroomtemperature.Isocraticelutionwasperformedattheflowrateof1ml/min,usingamixtureofacetonitrileand0.13%(m/m)formicacidcontainingsodiumchloride(0.005mol/l)asamobilephase.Theproportionnofacetonitrileinthemobilephasedependedonthecompoundofinterest(5%acetonitrile(ACN):gallicacid;10%ACN:caffeicacid,p-coumaricacid,(+)-catechin,epigallocatechin,(–)-epicatechin,procyanidinB1;20%ACN:rutin,ellagicacid,quercetin-3-d-galactoside,quercetin-3-d-glucoside,(–)-epica-techingallate;30%ACN:quercetin,kaemferol,myricetin;0%ACNandchangeddetectionpotentialto+0.3:ascorbicacid).Theinjectionvolumewas20μl.Thesamples,standards,andspikedsampleswereanalysed.Thepeaksidentificationwasper-formedbythecomparisonoftheretentiontimeswiththoseofreferencestandards.

Isolation and confirmation of (+)-catechin.TheextractofstrawberryleaveswaspurifiedusingSPEC18(Supelco,USA),wherewaterwasusedforpurificationandmethanolfortheelutionofthesamplefromthecolumn.Thepurifiedextractwasconcentratedwithavacuumevaporator.ThesubsequentisolationofcatechinwasdonebyHPLC-RP-DADtechniqueusingUV/VISphotodiodearraydetectorSPD-M20A(Shimadzu,Kyoto,Japan),anautomaticsamplerinjectorSIL-10AP(Shimadzu,Kyoto,Japan),apreparativeLCpumpunitLC-8A(Shimadzu,Kyoto,Japan),afractioncollectormoduleFRC-10A(Shimadzu,Kyoto,Japan),andLCworkstationLabSolutions/LCsolutionversion1.2.ThecompoundswereseparatedonaRPC18column(HypersilODS:4.0mm×250mm,5μm;Agilent,SantaClara,USA)and10%acetonitrilecontained0.13%(m/m)formicacidwasusedasamobilephase.Theabsorbancewasreadat280nm.

Fortheconfirmationofcatechin,MSandNMRanalyseswereused.Themassspectrawererecorded

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onaBrukermicromassLCT.Thesamplesweredis-solvedinmethanoltoanappropriateconcentration,ionisedinapositiveandnegativeESImodes,andanalysedwithTOFdetector.NMRspectraweremeasuredinthesamplesdilutedindeuteratedwaterat303,thesolventsignalwassuppressed.1HNMR,protondecoupled(waltz-16)13CNMR,PFG1H,13CHMQC,andHMBCmeasurements(detailedacquisitionandprocessingparametersareavailableonrequest)werecarriedoutonaBrukerAvanceDRx500spectrometer(BrukerBioSpinAG,Fällanden,Switzerland)equippedwithaninversedetection5mmprobeheadandz-gradientaccessory.

EnantioseparationofcatechinwascarriedoutonaHewlett-Packard3DCEcapillaryelectrophore-ticsystem(HPSTLtd.,Prague,CzechRepublic)equippedwithadiodearraydetector(Konfiket al.2007).Theseparationwasperformedinafusedsilicacapillaryofthetotallengthof750mm(665mmeffectivelength,50μm i.d.),theconstantvoltageappliedtothecapillarywas+30kV.Thesampleswereinjectedbypressure(25mbarfor10s)andtheseparatedcompoundsweredetectedat280nm.Theelectrolytecontained63.4mMH3BO3+9.3mMNa2B4O7·10H2O(pH8.5)andchi-ralselectormaltosyl-β-cyclodextrin(0.5mM).

ReSuLtS And diSCuSSion

Antioxidant capacity of the plants water extracts determined using different methods

TheACofthewaterextractsoftheplantsstudiedasobtainedusingfourselectedmethods(TPC,DPPH,FRAP,ORAC)areshowninTable1.TheACgenerallydependsonthemethodusedandeventheresultsobtainedbythesamemethod

maynotbereproducibleindifferentlaboratories(forexampledependingonthepHofthereactionmedium,solventsused,calibrationstandardsorwayoftheresultsexpression)(Huanget al.2005;Roginsky&Lissi2005).Duetothis,itisdifficulttointerpretthedataofAC.Therefore,theACofthestudiedleaveswaterextractswerecomparedwiththeACofgreentea,whichisknownasarichsourceofantioxidant(Linet al.1996;Kris-Ether-tonet al.2002).TheACofwaterplantextractswere73.6–88.9% (TPC),60.1–71.4% (DPPH),49.7–78.0%(FRAP),and45.3–66.5%(ORAC)oftheACofgreenteaextract.Itisobviousthatwaterextractsofstrawberry,blackberry,andraspberryleavesshowverygoodACindependentlyofthemetodused.

Compounds participated on the AC of the plant extracts studied

Thecontentsoftheselectedantioxidantsinthestudiedextracts(togetherwiththeparticipationofthesecompoundsintheACoftheextracts)isshowedinTable2.Notallofthecompoundsstudied(i.e.gallicacid,rutin,ellagicacid,caf-feicacid,p-coumaricacid,quercetin,kaempferol,myricetin,quercetin-3-d-glucoside,ascorbicacid,(+)-catechin,(–)-epicatechin,epicatechingallate,epigallocatechin,procyanidinB1)wereidentifiedintheplantwaterextracts.Themainreasonforthisdisproportioncanbethewayofextraction.Thestudiedcompoundswereidentifiedinthepreviousstudiesintheextractspreparedusuallybyusingorganicsolventsasbenzene,chloroform(Gudej&Rychlínska1996;Gudej2003),ace-tone(Hukkanenet al.2007),methanol(Gudej&Tomczyk2004)orethanol(Venskutoniset al. 2007).However,fromthenutritionalpointof

Table1.ACofmedicinalplantswaterextractsdeterminedusingfourmethodsandtheircomparisonwiththeanti-oxidantcapacityofgreenteawaterextract

Medicinalplant DPPH FRAP ORAC TPC

Strawberry 110.1±16.6 23.3±1.4 1062.0±143.9a 62.4±1.0

Blackberry 125.2±2.9a 36.7±1.1 1304.3±232.4a 75.4±1.2

Raspberry 105.2±12.9 26.6±1.0 888.0±106.8a 68.9±5.6

Greentea 175.2±20.9b 47.0±2.4 1628.6±62.8 84.8±1.0

Dataareexpressedasmean±SD(n=3,an=4,bn=6);DPPHinmgascorbicacid/gofdrysample;FRAPinmmolFeSO4/l;ORACinμmolTrolox/gofdrysample;TPCinmggallicacid/gofdrysample

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view,wewereinterestedinthisstudyinwaterextractsinordertomimicthecommonprepara-tionofherbsinfusion.

Onthecontrary,forthefirsttime,inthisstudy(–)-epicatechin,(+)-catechin,andprocyanidinB1weredetectedinbothraspberryandblackberryleaveswhileepicatechingallatewaspresentonlyinblackberryleaves.Thesecompoundswereprevi-ouslydetectedonlyinstrawberryleaves(Mudnicet al.2009).

Thecontentsofthecompoundsvariedinthestudiedextractsandweredependentonthetestedplantsandevenontheindividualtestedsamples

ofthesameplant.Evenso,theAC(DPPH)oftheindividualextractspreparedfromdifferentsamplesofthesameplantdidnotlargelydeviate(Table2).Ellagicacidoccurredinsignificantamountsintheextractsofallsamples(ofalltestedplants).Itscon-tentrangedfrom10to35mg/l,whichcorrespondsto0.5–1.8mg/gofdryleaves.Intheextractsofstrawberryleaves,butnotinthoseofotherleavesstudied,(+)-catechinwasalsopresentinsignificantamountsrangingfrom29mg/lto99mg/l,whichcorrespondsto1.5–4.9mg/gofdryleaves.Thisismorethaninapreviousstudy(Mudnicet al.2009),where(+)-catechinwasdeterminedintheamount

Table2.Concentrationofantioxidantsinleaveswaterextractsandtheirparticipation(%AC)intotalantioxidantcapacitiesoftheextracts

Medicinalplant/compound c(mg/l) %AC c(mg/l) %AC c(mg/l) %AC

Strawberry sampleI(2202±332)*

sampleII(3295±357)*

sampleIII(2241±225)*

Haklicacid 1.2 <1 5.9 <1 2.0 <1

Ellagicacid 21.9±0.1 9.9 34.5±3.6 10.5 21.2±1.3 9.7

(+)-Catechin 45.6±2.4 10.1 29.8±12.2 4.4 98.8±9.9 21.6

Epigallocatechin 3.1 <1 4.1 <1 8.0±1.3 1.6

ProcyanidinB1 3.0 <1 11.8±0.2 1.8 5.4±0.8 1.4

Total >20.0 >16.7 >34.3

Blackberry sampleI(2504±58)*



Gallicacid 1.4 <1 1.1 <1 1.6 <1

Ellagicacid 22.7±2.1 8.6 15.7±1.6 5.0 14.0±1.5 4.7

Quercetin-3-d-glucoside 6.2 <1 23.7 <1 21.8 <1

(+)-Catechine - - 2.6 <1 1.2 <1

(–)-Epicatechine 6.8±1.9 1.4 70.9±4.5 11.6 4.6 <1

Epicatechingallate 0.8 <1 3.6 <1 1.8 <1

ProcyanidinB1 8.5±0.0 1.8 2.8 <1 3.6 <1

Total >11.8 >15.6 >4.7

Raspberry sampleI(2104±258)*



Gallicacid 1.2 <1 1.9 <1 1.5 <1

Ellagicacid 16.4±0.9 7.8 19.7±4.6 11.0 10.8±0.1 7.7

(+)-Catechine 0.6 <1 0.3 <1 0.5 <1

(–)-Epicatechine 3.6 <1 1.9 <1 1.5 <1

ProcyanidinB1 3.8 <1 3.7 <1 - -

Total >7.8 >11.0 >7.7

Thedataareexpressedasmean±SD(n=3forcompoundswith%AC>1);*Antioxidantcapacities(DPPH)ofleaveswaterextractsareexpressedasmeans±SD(n=3),mgascorbicacid/l

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of0.5mg/gofadrysampleofstrawberryleaves.Thecontentsofotherantioxidantsweregenerallylowerthan10mg/l(0.5mg/gofdryleaves)withtheexceptionsof(–)-epicatechin(71mg/l)inoneextractofblackberryleavesandprocyanidinB1(12mg/l)inoneextractofstrawberryleaves.

(+)-Catechinwasdetectedasthedominantcom-poundpresentintheextractsofstrawberryleaves(andinverysmallamounts inotherextracts).Therefore, itmaybeusedasamarker for thedistinctionofstrawberryleavespreparationsfromotherrelatedplantspreparations(ofblackberryandraspberryleaves).Consequently,(+)-cate-chin(Figure1)wasconfirmedintheseextractsbyMSandNMRaftertheisolation.ESI-TOFMSm/z(%):289.08(100),578.98(56),868.95(10),145.02(12),245.11(11).1HNMR(D2O,δppm):2.36(1H,dd,H-4a),2.75(1H,dd,H-4b),3.96(1H,m,H-3),4.47(1H,d,H-2),5.85(1H,s,H-8),5.95(1H,s,H-6),6.73(1H,d,H-5'),6.82(1H,d,H-6'),6.84(1H,s,H-2');13CNMR(D2O,δppm):26.89(C-4),66.75(C-3),80.96(C-2),95.08(C-8),95.94(C-6),100.56(C-10),115.09(C-2'),116.26(C-5'),120.11(C-6'),130.35(C-1'),144.07(C-4'),144.34(C-3'),154.83(C-9),155.07(C-5),155.14(C-7).TheseNMRresultswereconfirmedbyNMRdatapredictor(softwareACD/ChemSketchC+HNMRPredictorsandDB(Productversion10.04))andbycomparisonwiththepublishedresults(Mendoza-Wilson&Glossman-Mitnik2006).Enantiomerof (+)-catechinwasconfirmedbychiralelectrophoresis.

The contents of the compounds weres alsoexpressedas%oftheirparticipationinDPPHantioxidantcapacityintherespectiveextracts(Table2).DPPHmethodwasusedforthispurposebecauseitappearedtosuffertheleastsynergism

interferencesincomparisontoothermethods(Murakamiet al. 2003).Thestudiedcompoundsintheleavesofrosaceaeplantsmoderatelycon-tributedtotheantioxidantcapacityoftheirwaterextracts.Futureresearchshouldenlightentheremainingfractionsoftheantioxidantcapacitiestoofferacomprehensiveoverviewofthehealthandnutritionalvaluesoftheseplants.

Ofthecompoundsstudied,ellagicacid(mainly),(+)-catechin,and(–)-epicatechinparticipatedintheACofthewaterextractsofstrawberry,raspberry,andblackberryleaves.Ellagicacidisassumedtopossessantioxidant,anti-mutagenic,anti-inflam-matory,andcardioprotectiveactivities(Priya-darsiniet al. 2002).Catechinandepicatechinareantioxidantswhichaffectplasmaantioxidantbiomarkersandenergymetabolism(Williamson&Manach2005).Providedthatthesecompoundshavebeendetectedinthisstudy,theabovementi-onedmayimplyapossibleeffectofwaterrosacaeplantextractsorinfusionsin vivo.

Comparison of the antioxidant capacities of herbal infusions with other sources

of antioxidants

Antioxidantsarerecommendedtobeprimari-lyconsumedaspartofadailydiet(Halliwell2006).Therefore,theACofherbalinfusionswerecomparedtothecapacitiesofothersourcesofantioxidantsintheformsinwhichtheyaretakeninacommondiet(Figure2).Theselectedbevera-gesliketea,wine,vegetable,andfruitbeveragesarepreferredamongconsumersandsignificantlycontributetothetotalintakeofantioxidants(Svi-laaset al.2004;Pellegriniet al.2007).ThemethodwiththestableDPPHradicalwasusedforthedeterminationoftheAC.InFigure2,averyhighvariabilityoftheACinsidethegroupofwine,tea,andfruitbeveragesamplescanbeobserved.Thisvariabilityofbeveragesreflectsthedifferencesinthetypeoftheplantmaterial,typeofwine,localitiesandgrowingconditions,industryproceduresofbeveragespreparation,portionofrawmaterialinfruitandvegetablebeveragesetc.Moreover,someantioxidantsareaddedtosomefruitbeveragesduringtheproductionwhichmaycontributetothefinalresult.

TheAC(radicalscavengingcapacities)oftheplantsinfusionsstudiedaretypicallythreetimeslowerthanthecapacityofgreentea infusionsFigure1.Structureof(+)-catechin

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andtwotimeslowerthanthecapacityofblackteainfusions.Asmentionedabove,greenteaisprobablythemostefficientsourceofantioxidantsinourdiet(Linet al.1996;Kris-Ethertonet al.2002;Farhooshet al.2007).However,greenteaaswellasblackteacontainscaffeine(Farhooshet al.2007)andanexcessiveintakeofcaffeinecanberelatedtohypertension,dehydration,anxiety,orinsomnia(Gardneret al.2007),whereasnoadverseeffecthasbeenobservedondrinkingbeve-ragesmadefromleavesofstrawberry,blackberry,andraspberry.Therefore,thestudiedplantsmaybeseenasanattractivealternativesourceofanti-oxidantsforthegroupofconsumersconsciouslyselectingtheintakeofhigherlevelsofantioxidantswithoutcaffeine.

TheresultsofACinwineshowedthatredwinehadhigherACthanwhitewine.ThisagreeswiththereportofKatalinicet al.(2004).Moreover,besidesgreentea,redwineisseenasoneofthemostsignificantsourcesofantioxidants(Kata-linicet al.2004;deLangeet al.2007;Loganet al.2008).TheACofthestudiedplantinfusionswerecomparabletotheACofwhitewineandwere,onaverage,fourtimeslowerthanthatofredwine.However, inthecaseof“monitoringdribling”(whendailynomorethan100–200mlofwineisrecommended),twocupsofthetestedmedicinalplantsinfusiongiveusthesameamountofantioxidantslikeredwine.

TheACofthestudiedplantinfusionswerehigherorcomparabletothecapacitiesofdifferentfruit(vegetable)beverages.However,accordingtosomeauthors,fruitandvegetablebeveragescontributetothetotal intakeofantioxidantsthroughthediettoasmallerextentthanwine,tea,orcoffee(Svilaaset al.2004;Pellegriniet al.2007).

ConCLuSion

TheAC(TPC,DPPH,ORAC,FRAP)ofthestu-diedwaterextractsofstrawberry,blackberry,andraspberryleavesweredeterminedtobeintherangefrom49.7%to89.9%oftheantioxidantcapacityofgreenteawaterextract,andgoodanti-oxidantcapacitiesofthestudiedherbsinfusions(determinedbyDPPHmethod)wereobservedincomparisonwiththoseofteainfusions,wines,andotherbeverages.

Forthefirsttime(–)-epicatechin,(+)-catechin,andprocyanidinB1weredetectedinraspberryleaves,andallthesecompoundstogetherwithepicatechingallateinblackberryleaves,whereasbiologicallyactive(+)-catechin,ellagicacid,and(–)-epicatechinsignificantlyparticipatedintheACoftheleaveswaterextractsofallplantsstudied.Therefore,theanalysedmedicinalplantscanbeconsideredtobeagoodsourceofantioxidants.Theycanbeusedfordirectconsumptionasvariouskindsofbeveragesorasextractsofantioxidantstoincreasethenutritionalvalueofdifferentfoodsanddiets.

R e f e r e n c e s

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Corresponding author:

Ing.LucieBuřičová,Vysokáškolachemicko-technologickávPraze,Fakultapotravinářskéabiochemickétechnologie,Ústavchemieaanalýzypotravin,Technická5,16628Praha6,ČeskáRepublikatel.:+420220445120,e-mail:[email protected]

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