Molecular Docking Study of Bioactive Compounds of Withania somnifera Extract Against Topoisomerase IV Type B

Abstract

The rapid emergence of multi-drug resistant bacteria and reduced susceptibility of bacteria to antibiotics adds urgency to search for new compounds having noticeable action on new and re-emerging infectious diseases. Withania somnifera is a remarkable source of new therapeutic agents for antimicrobial activity as well as antioxidant activity. The root powder of Withania somnifera was extracted sequentially with hexane, chloroform and methanol, by both hot and cold extraction method. In vitro antibacterial activity of extract was screened against both gram-negative and gram-positive bacteria. The chloroform extract of Withania somnifera root showed significant antibacterial activity against Staphylococcus aureus and Salmonella typhi. The methanol extract showed comparable antioxidant potential with ascorbic acid (standard compound). These extracts were analyzed structurally and qualitatively, to identify the phytocompounds responsible for the activity. The antimicrobial potential of major phytoconstituents was screened using docking software AutoDock 4 against a target protein topoisomerase IV type B. It was found that withasomnine was an efficient antibacterial compound which showed significant inhibition with minimum docking energy − 6.22 kJ mol−1, binding energy − 10.07 kJ mol−1 and inhibition constant 4.14e−008. This was the first report on the antimicrobial docking studies on withasomnine by proving its antimicrobial activity.