Searching for antihyperglycemic phytomolecules through bioassay-guided solvent fractionation and subfractionation from hydro-methanolic (2:3) extract of Tamarindus indica Linn. seeds in streptozotocin-induced diabetic rat

The study identified the most effective fraction and subfraction of hydro-methanolic extract (2:3) of the seed of Tamarindus indica Linn. (T. indica) having antidiabetic activity in rats with diabetes induced by streptozotocin (STZ). The effective fraction and subfraction of T. indica were subjected to an antidiabetic study in STZ-induced diabetic rats at two dose levels, 100 mg/kg and 25 mg/kg body weight twice a day. Serum insulin, glycosylated hemoglobin, carbohydrate metabolic enzymes, and transaminases were assessed and the histopathology of the pancreas was examined after 8 weeks of treatment and compared to the vehicle control. Treatment of n-hexane fraction at a dose of 100 mg/kg twice a day for 56 days in STZ-induced diabetic rat resulted in a significant reduction in fasting blood glucose and glycosylated hemoglobin levels along with a rise in serum insulin and glycogen contents in hepatic and skeletal muscle in comparison to chloroform, ethyl acetate, or n-butanol fraction treated groups as well as the untreated diabetic group. The most antidiabetic activity of n-hexane fraction had been highlighted by the activities of hexokinase, glucose-6-phosphate dehydrogenase, glucose-6-phosphatase, and lactate dehydrogenase in the liver, kidney, cardiac, and skeletal muscle in respect with groups treated with other fractions. Two subfractions, A and B, were obtained from the n-hexane fraction using petroleum ether, of which subfraction B was more bioactive considering the above biosensors and was comparable with glibenclamide, a standard antihyperglycemic drug. Chromatographic study by high performance thin layer chromatography focused on two components of subfraction B, P₁ and P₂ where P₁ is predominant, conformed by high performance liquid chromatography. The dose of subfraction B was 25 mg/kg twice a day i.e., 1/4 dose of the n-hexane fraction. The n-hexane fraction and subfraction B of T. indica are free from hepatic and renotoxicity according to the study of serum transaminase.