Isolation of flavonoids from the flowers of Rhynchosia beddomei Baker as prominent antimicrobial agents and molecular docking.

Rhynchosia beddomei Baker (R. beddomei) is a viscous hairy under shrub, belongs to the family of Fabaceae and widely distributed in Deccan and Carnatic regions of South India. In the present investigation, four flavonoids such as an isoflavone, 5,7-dihydroxy-4'-methoxyisoflavone (RB-1), a flavonol, quercetin-7-O-methylether (RB-2), two flavone C-glycosides, isovitexin (RB-3) and 5,7,3',4'-tetrahydroxy-6-C-β-d-glucopyranosyl flavone (RB-4) were isolated from the flowers of R. beddomei Baker through bioassay guided fractionation. Subsequently, antimicrobial activity of compounds against drug resistant gram positive and negative bacteria and fungi revealed RB-2 and RB-4 have shown highest minimal inhibition concentrations against Pseudomonas aeruginosa and Candida albicans. RB-2 and RB-4 enclosed OH groups at 5th position on the ring A, 3' and 4' ortho dihydroxyl groups positioned on the ring B and accomplished efficacious antibacterial activity. In addition, Docking studies perceptible that RB-4 conferred highest binding energy of -10.5 kcal/mol and exhibited eloquent polar and non-polar interactions with active site residues of N-Myristoyltransferase (Nmt) of Candida albicans while binding energy of -7.5 kcal/mol was recorded for peptidyldeformylase (PaPDF) of Pseudomonas aeruginosa. Moreover, these compounds obey Lipinski's rule of five and exerts good drug likeness properties and might be ratified as lead molecules for further investigations to prevent panicking microbial infections.