Abstract

• The present study investigates some biological effects: in vitro antioxidant, in vitro -amylase inhibitory activity, in vivo acute toxicity, in vivo anti-diabetic activity of the crude extracts and isolated compounds of Stemona tuberosa Lour. root. In vitro antioxidant activity using DPPH radical scavenging assay, with ascorbic acid as positive control, showed the ethanolic extract possessed excellent antioxidant property (IC50=1.56 g/mL). No toxic behaviour was observed up to 5000 mg/ kg oral dose of water and ethanol extracts on mice for two weeks treatment following the in vivo acute toxicity OECD guideline. The in vivo antidiabetic activity, with metformin, oral hypoglycemic agent, as a positive control, against alloxan-induced diabetic mice; and the in vitro antidiabetic activity, with acarbose, antihyperglycemic agent, as a positive control, for the inhibitory effect on -amylase enzyme, was employed to determine the antidiabetic activity. The ethanolic extract of S. tuberosa root was found to be exhibited potent antidiabetic activity in vitro (IC50 values; 80.98 g/mL for -amylase activity) as well as in vivo (41.290.05 % maximum reduction (R)) in blood glucose level. By column and thin layer chromatography, tuberostemonine J (1) was isolated from active ethanol fraction and identified by modern spectroscopy. Moreover, tuberostemonine J (1) (41.62  0.01 % R in vivo) exhibited similar antidiabetic activity (p < 0.01) but good proliferation of beta islet cells of Langerhans and acinar cells in pancreas of diabetic mice when compared to the positive control, metformin (41.87  0.05 % R in vivo).