Comparative antidiabetic activity of different fractions of Enicostemma littorale Blume in streptozotocin induced NIDDM rats

Abstract

Aqueous extract of Enicostemma littorale is reported to have antidiabetic activity. In the present investigation, we studied the effect of aqueous extract of E. littorale and its different fractions i.e., toluene, chloroform, ethyl acetate, n-butanol fractions and remaining residual fraction in streptozotocin (STZ)-induced neonatal type 2 diabetic rats. Fasting glucose and insulin levels in NIDDM were significantly (P<0.05) higher than control rats and they were significantly decreased by treatment with aqueous extract of E. littorale and its n-butanol and ethyl acetate fractions. Results of oral glucose tolerance test (OGTT) showed that aqueous extract and its n-butanol and ethyl acetate fractions significantly (P<0.05) decrease both <TEX>$AUC_{glucose}$</TEX> and <TEX>$AUC_{insulin}$</TEX> values in NIDDM treated groups. Insulin sensitivity <TEX>$(K_{ITT})$</TEX> index of NIDDM control was significantly lower as compared to normal control and this was significantly (P<0.05) increased after treatment with aqueous extract, its n-butanol and ethyl acetate fractions. Treatment with aqueous extract of E. littorale and its n-butanol and ethyl acetate fractions lowered the elevated cholesterol and triglyceride levels observed in NIDDM rats. Treatment with aqueous extract of E. littorale and its n-butanol fraction showed significant decrease in creatinine, urea, SGPT and SGOT levels as compared to NIDDM control rats. However ethyl acetate fraction showed significant changes only in creatinine and SGOT levels, and not in the levels of urea, and SGPT as compared to NIDDM control rats. Treatment with toluene, chloroform and residual fractions of E. littorale did not produce any effect on glucose, insulin, triglyceride, cholesterol, creatinine, urea, SGPT or SGOT levels as compared to NIDDM control rats. Our data suggest that n-butanol and ethyl acetate fractions contain the active compounds which may be responsible for the above activity and associated complications in NIDDM diabetes mellitus.