Bergenin from Cissus javana DC. (Vitaceae) root extract enhances glucose uptake by rat L6 myotubes

Purpose: To examine the glucose uptake stimulatory activity of the root extract of Cissus javana DC. (Vitaceae) in L6 myotubes of rat, and also to identify the extract's active principles. Methods: The methanol extract was prepared from Cissus javana tuberous roots and evaluated for glucose uptake stimulatory effects on L6 rat muscle cells and inhibitory activity against alpha-glucosidase. The chemical components were isolated using several chromatographic techniques, and their structures characterized by spectroscopic methods. Each isolate was then assayed for glucose uptake stimulatory and alpha-glucosidase inhibitory activities. Results: The extract (100 mu g/ml) exhibited glucose uptake stimulatory effect (70.9 % enhancement) and alpha-glucosidase enzyme inhibitory activity (100 % inhibition). Through chromatographic separation, bergenin, stigmast-4-en-3-one and beta-sitosterol were isolated and identified. Bergenin, at 100 mu g/ml (0.3046 mM), increased glucose uptake by L6 myotubes by 50.5 % without toxicity. At the same concentration, bergenin showed no inhibition on alpha-glucosidase enzyme, while stigmast-4-en-3-one and beta-sitosterol exhibited 98.6 and 40.6 %, inhibition, respectively. Conclusion: This study is the first report on the chemical constituents, and the glucose uptake stimulatory and alpha-glucosidase inhibitory activities of Cissus javana DC. roots. The findings reveal the antidiabetic potential of the plant and the glucose-uptake enhancing activity of bergenin.