Antidiabetic Activity, Molecular Identification and In silico Docking of Compounds in Chromatographic Fractions of Tephrosia bracteolata Guill. & Perr. (Fabaceae) Leaves

Abstract

Background Recent efforts for the complementary treatment of diabetes have focused on medicinal plants and their bioactive compounds. Tephrosia bracteolata is one of such plants used in the management of diabetes but its anti-diabetic principles are yet to be identified. This study was aimed at identifying the compounds responsible for the antidiabetic activity of the ethylacetate fraction of Tephrosia bracteolata leaves and subsequently, carryout an in silico molecular docking of these compounds against key targets in the pathophysiology of diabetes. Methods The ethylacetate fraction (EAF) of T. bracteolata leaves was fractionated using Silica gel column chromatography to yield 100 fractions. Pooling together of fractions with similar thin layer chromatographic (TLC) mobility profile afforded seven major fractions (SF1- SF7). Preliminary phytochemical studies were carried out on the fractions using standard methods. The antidiabetic activity of the fractions was subsequently evaluated (at a dose of 200 mg/kg) against alloxan- induced diabetes in adult mice. GC-MS analysis was carried out on the fraction with the highest activity. Subsequently, some of the identified active compounds were docked against key targets in the pathology of diabetes using Auto Dock tool. Results Preliminary phytochemical analysis revealed the presence of terpenoids, saponins, steroids, glycosides, flavonoids, tannins and alkaloids in varying proportions in the fractions. The sub-fractions produced varying degrees of significant (p < 0.05) decrease in FBS at 12h and 24h- post-treatment. GC-MS analysis of the most active fraction (SF5) revealed the presence of thirty- six compounds among which are some that have been reported to possess direct or indirect antidiabetic properties. These are Mome-inositol, 2-methoxy-4-vinylphenol, 1-D-thio-glucitol, 4-Piperidinone, Hexadecanoic acid, 9- octadecanoic acid, n- hexadecanoic acid and D- allose. Molecular docking studies (Auto Dock tool) between Mome inositol, 1-D-thio-glucitol and alpha-glucosidase showed that Mome inositol (− 6.7 kcal/mol) had a stronger affinity to the enzyme. Similarly, for sodium glucose co-transporter 2 (SGLT 2), Mome inositol (− 6.5 kcal/mol) had a stronger affinity than 1-D-thio-glucitol. Conclusions The identified compounds in the fraction could be responsible for the observed antidiabetic properties of the fraction of T. bracteolata.