Antidiabetic Activity and in silico Molecular Docking of GC-MS- Identified Compounds in Chromatographic Fractions of Tephrosia bracteolata Guill. & Perr. (Fabaceae) Leaves

Recent efforts for the complementary treatment of diabetes have focused on medicinal plants and their bioactive compounds. This study evaluated the antidiabetic activity of chromatographic subfractions of ethylacetate fraction (EAF) of Tephrosia bracteolata leaves. Also, to carry out molecular docking of some GC-MS-identified compounds in the subfraction with the highest antidiabetic activity against key targets in the pathophysiology of diabetes. The EAF (5 g) was subjected to silica gel column chromatography using gradient elution with hexane, chloroform, ethyl acetate, methanol and water. Approximately 100 fractions (100 mL each) were collected and monitored via TLC, resulting in 7 major sub-fractions (SF1-SF7). The antidiabetic activity of the sub-fractions was evaluated (at doses of 200 and 400 mg/kg) against alloxan-induced diabetes in mice. GC-MS analysis was carried out on the subfraction with the highest activity. Subsequently, some of the identified active compounds were docked against key targets in the pathology of diabetes using AutoDock Vina. Phytochemical analysis revealed the presence of several phytochemicals in varying proportions in the subfractions.  SF5 (400 mg/kg) produced the most significant (p< 0.05) decrease in FBS (35.29 and 38.37 %) at 12 h and 24 h- post-treatment respectively. GC-MS analysis of SF5 revealed the presence of 36 compounds among which are Mome inositol, 2-methoxy-4-vinylphenol, 1-D-thio-glucitol and 4-Piperidinone. Molecular docking showed that Mome inositol and 1-D-thio-glucitol have a strong affinity for alpha-glucosidase and sodium-glucose co-transporter 2 (SGLT 2). These findings suggest that the antidiabetic activity of the extract maybe attributed to the bioactive compounds identified in SF5.