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ABSTRACT

The present study was carried out to evaluate the antidiabetic activity of Costus pictus

(C.pictus) D. Don, on alloxan induced diabetic rats. Oral administration of fresh leaf extract (200

and 400 mg/kg body weight) for 60 days treatment resulted in significant decrease in blood

glucose level and lipid profiles. There were also significant changes observed in carbohydrate

metabolizing enzymes and antioxidants. The nitrogenous wastes such as urea, uric acid and

creatinine were also found decreased after the treatment. The study clearly shows that the

effect of the drug (400 mg/kg body weight) was equally effective with the standard drug

glibenclamide. To find out the biomarkers, pharmacognostic and phytochemical studies were

carried out . The leaf of C. pictus is characterized by simple unicellular, pointed non-glandular

trichomes, absence of palisade layer and hypodermal layers containing shattered crystals.

Micromorphological characters of the leaf are also given. The leaves are found to contain

flavonoids such as kaempferol, 3’, 4’-di O-Me-quercetin and 4’-OMe-Kaempferol and phenolic

acids such as gentisic, 2, 5-dihydroxy benzoic acid, o-coumaric, melilotic, α-resorcyclic, 3,5-

dihydroxy benzoic acid, p- hydroxy benzoic acid, cis and trans-p-coumaric acid.

INTRODUCTION

Diabetes mellitus is a disorder very well known and widespread all over the world. Different

types of oral hypoglycemic agents such as insulin, suphonylurea etc. are used for the treatment

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of this disease, but they cause side effects on continued use. There is a growing interest in

phytomedicine because of their effectiveness, fewer side effects and low costs. Many Indian

medicinal plants are reported to be useful in diabetes. C. pictus D.Don. (Costaceae) an

ornamental plant of Mexico, is one such plant newly introduced to India. It is an erect herb

growing up to 3 meters tall, having stem horizontally striped at base; leaves narrowly

lanceolate, dark green above, lighter green below; small leaves are present on the basal part;

bracts green, with outer margin coloured maroon. Flowers yellow; lip with maroon striations,

darker yellow stripe down the middle region; anther cream coloured. This plant is distributed

along the coast from Mexico to Costa Rica and is locally known as cana agria or cana de jabali in

Mexico. In Mexico, it is used to treat diseases of the kidney. It is reported to have effects on

renal functions and its anti-inflammatory and hypoglycemic actions. The practitioners in

Mexico used an infusion of this plant in the treatment of renal disorders; the plant also

possesses diuretic activity. The plant was reported to contain flavonoids, saponins, reduced

sugars and tannins.

The present study was undertaken to test the plant for its antidiabetic activities, toxicity of the

extract on normal rats and the effect of the extract on the antioxidant enzymes, non- enzymatic

antioxidant, carbohydrate metabolizing enzymes and lipid profile. Pharmacognostic and

phytochemical analysis of the leaves were also conducted.

Insulin plant is a relatively new entrant to Kerala and India. Insulin plant has not got a

Malayalam name yet, except the occasional use of insulin chedy or insulin chedi, where chedy

means a plant. The catchphrase of this plant is ‘ a leaf a day keeps diabetes away’ .

The plant is characterized by large fleshy looking leaves. It grows very quickly. Propagation is by

stem cutting. It grows in slightly shady areas.

Diabetes patients are advised to chew down a leaf in the morning and one in the evening for a

month. Allopathic doctors too recommend it and it is found to be effective in bringing blood

sugar levels under completely under control. There is also dried and ground powder of the

leaves now available in the market.

* With FBS below 200, take ONE leaf daily before breakfast and drink a glass of

water

* With FBS above 200, take TWO leaves in the morning and TWO at night on a

daily basis.

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MATERIALS AND METHODS

Preparation of aqueous extract

The leaves of C. pictus (Costaceae) were collected from Vadodara City, Gujarat. A Voucher

specimen was deposited in the herbarium of the Botany department of M. S. University. For

preparing the extract, 500 g of Fresh leaves were boiled in water for 30 min. The extract was

then filtered and the process of boiling was repeated three times with the residue, each time

collecting the extract. The collected extract was pooled and passed through a fine muslin

cloth. The filtrate upon evaporation at 40°C yielded 14.5% semi solid extract.

Lipids in the diabetic subjects is mainly due to an increase in the mobalization of free fatty acids

from the peripheral fat deposit [34]. The hypolipidemic effect of C. pictus could be explained as

a direct result of the reduction in blood glucose concentration.

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CONCLUSION

The present findings suggest that the plant extract is non- toxic, since no marked changes were

observed in the normal rats fed with the extract. Thus, at normal therapeutic doses, the extract

was considered to be safe for long-term treatment in diabetic condition. The leaf extract

showed potent antidiabetic activity and the dose 400mg/kg body weight was more effective

than 200 mg/kg body weight. 400 mg dose was all most equally effective with the standard

drug glibenclamide. Apart from this the plant extract also improved the activity of

enzymatic and non-enzymatic antioxidants, thereby scavenging the free radical that initiates

the lipid peroxidation. The decreased level of urea, uric acid and creatinine in the treated rats

clearly shows that the plant extract, protects the diabetic rats from alloxan induced renal

damage. The plant extract also lowered the plasma lipid levels, the antihyperlipidemic

effect of the extract in particular can be considered as a possible therapeutic value. The

result observed in all these parameters were statistically significant (p<0.05). Thus all these

activities exhibited by the extract can be attributed to the presence of the active constituent of

the plant. Longer duration studies of C. pictus extract and its isolated compounds are necessary

to develop a potent antidiabetic drug.