Antidiabetic potential of unripe Carissa carandas Linn. fruit extract

Ethnopharmacological relevance: Carissa carandas commonly known as Karanda have a long history of use in traditional system of medicine. It is used by tribal healers of Western Ghat region of Karnataka as hepatoprotective and antihyperglycemic. However, no scientific data is available to validate the folklore claim. The present study has been designed to evaluate its unripe fruit for the antidiabetic activity. Aim: In the present study, methanol extract of unripe fruits and its fractions were studied for its antidiabetic potential. Materials and methods: The methanol extract and its fractions were screened for antidiabetic activity in alloxan induced diabetic rats. The polyphenolic, flavonoid and flavanone contents of methanolic extract and its fractions were also determined and correlated with its antidiabetic activity. Results: The experimental data indicated that the methanol extract and its ethyl acetate soluble fraction has significantly lowered the elevated blood glucose levels by 48% (p<0.001) and 64.5% (p<0.001) respectively at dose level of 400 mg/kg per oral after 24 h as compared to diabetic control. In order to assess the role of polyphenolic components in the relevant activity, polyphenolic and flavonoid contents were determined. The polyphenolic and flavonoid content of methanol extract and its ethyl acetate soluble fraction were found to be 15.8 +/- 1.2 mg and 18.55 +/- 0.34 mg (gallic acid equivalent/g extract) and flavonoid content 2.92 +/- 0.03 mg and 1.534 +/- 0.30 mg (rutin equivalent/g extract) respectively. Conclusion: The increased antidiabetic potential of ethyl acetate fraction over methanol extract is due to its partial purification achieved by fractionation which resulted in increase in degree of polymerization and segregation of secondary metabolites. (C) 2011 Published by Elsevier Ireland Ltd.