Anti-diabetes activity of ethanol extract of Centella asiatica (L.) Urban (whole plant) in Streptozotocin-induced diabetic rats, isolation of an active fraction and toxicity evaluation of the extract

The study was carried out to evaluate the anti-diabetes activity of ethanol extract of Centella asiatica (L.) Urban in streptozotocin diabetic rats, to determine the acute and subacute toxicity of the extract in mice and to isolate most active anti-hyperglyceamic fraction of ethanol extract. Diabetes was induced in male Wistar rats by streptozotocin (50mg/kg) injection and anti-diabetes efficacy of various doses of ethanol extract was tested. Among the various doses tested, ethanol extract at a dose of 200 mg/kg showed significant anti-diabetes activity in streptozotocin diabetic rats as judged from body weight, serum glucose, lipids, cholesterol and urea, and liver glycogen levels. However, the extract did not significantly influence the levels of serum insulin in both diabetic and normoglycemic rats. In acute and sub-acute toxicity evaluation of the ethanol extract in all tested doses did not showed any conspicuous toxicity in mice. The active ethanol extract was suspended in water and sequentially fractionated with petroleum ether, chloroform, ethyl acetate and butanol and their anti-hyperglyceamic activity was determined in glucose loaded normal rats by glucose tolerance test. Among the fractions tested, anti-hyperglycemic activity was found predominantly in the chloroform fraction (12.5mg/kg) of alcohol extract. The active chloroform fraction when subjected to qualitative chemical analysis showed positive test to the presence of terpenoids, coumarins and saponins. Thus ethanol extract and its chloroform fraction of C. asiatica (L.) Urban open up a new vista for the discovery of new generations single or combinational safe oral hypoglycemic agents.