ISOLATION OF ANTIDIABETIC AND OTHER BIOACTIVE COMPONENTS FROM SOME MEDICINAL PLANTS AVAILABLE IN NORTHERN PART OF BANGLADESH

Abstract

Aqueous, chloroform and 80% ethanol extracts of both Clerodindrum infortuntum (CI) leaves and Tinospora cordifolia (TC) stems were prepared by usual method and their antidiabetic effect were studied in the type 2 diabetic model rats. Male Long—Evans rats bred at BIRDEM animal house were used in the study. Type 2 diabetes was induced by a single intraperitoneal injection of streptozotocin to 48 hours old pups and three months later after confirming with an IPGTT, type 2 rats were selected for experiment. The rats were divided into seven groups. Glibenclamide (5 mg/kg body weight) and extracts (1.25 g/kg body weight) were administered orally for 28 consecutive days with single feeding. The body weights of the rats were measured weekly. Serum glucose (glucose-oxidase), serum lipids and serum creatinine were measured by the enzymatic colorimetric method. At the beginning, the fasting serum glucose level (8.77-11.67 mmol/l) raised in all the STZ induced type 2 rats. There was no significant difference in blood glucose level among the groups (p=ns). Ethanol extract of C infortunatum leaves (ETCI) when compared to control showed a significant antidiabetic effect on the 29" day(Fasting blood glucose, mmol/L, M+SD,9.25+1.41 in control group vs 6.37+40.93 in ETCI treated group p<0.009). As expected glibenclamide also significantly (p<0.023) reduced the blood glucose level on the 29" day. The aqueous extract of C infortunatum leaves (AqCI), aqueous extract of T cordifolia stem (AqTC), ethanol extract of T cordifolia stem (ETTC) and chloroform extract of T cordifolia stem (CHTC) also reduced blood glucose levels by 18.16, 23.24, 4.41 and 14.9%, respectively but the reduction was not significant. Except CHTC all the groups showed significant antidiabetiic effect on the final day (p<0.04-0.001). Atherogenic lipids (cholesterol, triglycerides and LDL cholesterol) were found to decline by glibenclamide and 80% ETCI but the decrease was not statistically significant. HDL cholesterol was found to rise by 80% ETCI, but no significant change was found in the serum creatinine level in any group on the last day. The body weights of the rats in all the groups increased compared to their initial weights. In the second part of the study, chemical analyses of C infortunatum and T cordifolia were done. The study revealed that the ethanol extract of CI exerts had better hypoglycemic effect in comparison to TC extract in type-2 diabetic model rats. This effect was at least partly mediated by pancreatic action of CI. Chemical investigation of ETCI showed five different compounds at different Rr values, which were purified by column chromatography, preparative TLC and finally by HPLC. Very interestingly, the fraction-1 of Clerodendrum infortunatum (ETCI) showed significant insulin tropic effect compared to other fractions. Structural study of the fraction 1 by spectroscopic studies (like 1 H-NMR, '3 C-NMR, and Mass Spectroscopy study) indicated that it was the chlorophillic compound Phaeophytin.