Hypoglycaemic activity of saponin fraction extracted from Momordica charantia in PEG/salt aqueous two-phase systems.

Momordica charantia (family, Cucurbitaceae), commonly known as karela or bitter melon (Japanese name 'Tsurureishi'), is used as a folk medicine in China, the Indian subcontinent and South America. In Chinese traditional medicine, the plant is usually used as a hypoglycaemic and anti-diabetic agent. The hypoglycaemic activity of saponin fraction (SF) extracted from M. charantia in PEG/salt aqueous two-phase systems was studied in this article. Alloxan-induced hyperglycaemic mice were used in the study. The blood glucose, insulin secretion, glycogen synthesis and the body weight of the mice were analysed. At the same time, the sugar tolerance of the normal mice was also determined. After the mice were administered (i.g.) with SF (500 mg kg(-1)), the blood glucose of alloxan-induced hyperglycaemic mice decreased (p < 0.05), the level of insulin secretion and glycogen synthesis of alloxan-induced hyperglycaemic mice elevated (p < 0.05, p < 0.01) and the sugar tolerance of the normal mice was improved. Also, the body weight of the alloxan-induced hyperglycaemic mice was increased gradually. The saponin constituents extracted from M. charantia in an aqueous two-phase extraction system induced significant hypoglycaemic activity in hyperglycaemic and normal mice.