Isolation and Structural Elucidation of Novel Antidiabetic Compounds from Leaves of Momordica balsamina Linn and Leptadenia hastata (Pers) Decne.

The antihyperglycemic effect of the polyherbal combination of the leaves of Momordica balsamina Linn (MB) and Leptadenia hastata (pers) Decne (LH) have been reported in our previous study in addition to its documented dietary usages. However, the bioactive principles are yet to be fully elucidated. In the present study, bioactive antidiabetic compounds from the leaf extracts of Momordica balsamina Linn and Leptadenia hastata (pers) Decne were isolated and characterized. The plant leaves were fractionated with solvents in ascending order of polarity (hexane-chloroform-ethylacetate-methanol) using microwave assisted extraction method. The ethylacetate (MBE) and methanolic (LHM) leaf extracts of MB and LH, having the highest antihyperglycemic effects were purified by column chromatography and preparative thin layer chromatography. The antihyperglycemic activity of the isolated compounds was evaluated in streptozotocin (STZ)-induced diabetic rats and the structures of the most bioactive compounds were elucidated by 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy in comparison with reported literature. A pentacyclic triterpenoid (H3) and an isoflavone (LH2b) isolated from MBE and LHM with significant (p < 0.05) antihyperglycemic effects were identified as betulinic acid and 5-methyl genistein respectively. Our study isolated for the first time a triterpenoid and an isoflavone with potential antidiabetic effects from these indigenous antidiabetic plants. This further validates the traditional multi-therapeutic usage of the combination for the management of Diabetes Mellitus (DM) and its complications.