Phytochemical Analysis, Biological Activity And Molecular Docking Studies Of Root Extracts Of Rhynchosia Ferruginea A.Rich.

Abstract

Rhynchosia ferruginea (Udusalim, Afan Oromo) has been used by local community and traditional healers to treat various diseases like skin infection, wound, intestinal problems, and amoebiasis. Considering the absence of prior scientific report that supports ethno-medicinal uses of the roots of the plant, this study focused on isolation of chemical constituents, evaluation of the anti-bacterial and radical scavenging activities of the roots of R. ferruginea. The roots of R. ferruginea (500 g) were extracted by dichloromethane/methanol (1:1) and methanol to give 24.48 g (4.89%) and 17.55 g (3.51%) yield, respectively. Phytochemical screening of the roots extracts of R. ferruginea showed the presence of alkaloid, tannins, flavonoids, steroids, saponins, terpenoids, and phytosterol. The dichloromethane/methanol (1:1) extract was subjected to silica gel column chromatography to afford three compounds identified as isoflavan (55), isoflavene (56) and 1, 3-dilinoleoyl-2-Stearoylglycerol (57) reported here in for the first time from the genus. The structures of these compounds were characterized using spectroscopic methods (1H NMR, 13C NMR and DEPT-135).The extracts and isolated compounds were evaluated in vitro for their antibacterial activity using disc diffusion method against E. coli, S. aureus. P. aeruginosa and S. pyogenes. Compound 55 displayed 9.67±0.58 mm and 10.67±0.58 mm whereas compound 56 showed 10.33 ± 1.15 mm and 10 ± 1.00 mm zone of inhibition diameters against E. coli and S. aureus, respectively, compared to ciprofloxacin which showed inhibition zone of 15.67±0.58 for both strains. The extracts and isolated compounds were also assessed for their radical scavenging activity using DPPH assay. The dichloromethane/methanol (1:1) extract and compound 55 exhibited better radical scavenging activity with IC50 value of 17.7 and 32, respectively. Autodock vina software was used to perform molecular docking analysis of isolated compounds. Among the investigated ligands, compounds 55 and 56 exhibited similar binding affinity of -7.4 (kcal/mol) compared to ciprofloxacin -7.3 (kcal/mol) suggesting the compounds may act as potential inhibitors of DNA gyrase enzyme. Therefore, the in vitro antibacterial, radical scavenging activity and molecular docking analysis suggest the potential use of these compounds as potential drug lead candidates and gives hope for further investigation.