Quercetin, a secondary metabolite present in methanolic extract of Calendula officinalis, is a potent inhibitor of peptide deformylase, undecaprenyl pyrophosphate synthase and DNA primase enzymes of Staphylococcus aureus: an in vitro and in silico result analysis

Plant based naturally occurring phytochemicals have great inhibitory potential against various pathogenic bacteria but the mechanism of inhibition and the essential cell molecules to which they bind and inhibit remain unclear and unexplored so far In the present study we examined the effect of secondary metabolites from C officinalis both in vitro and in silico to decrypt the probable pathway of inhibition In in vitro experiments Staphylococcus aureus was used to evaluate the antibacterial potential of secondary metabolites present in different organic extracts of C officinalis using agar well diffusion and XTT colorimetric methods In in silico experiments important C officinalis secondary metabolites viz Alpha cadinol Scopoletin Esculetin and Quercetin were docked against essential enzymes of bacteria like Peptide deformylase Gamma hemolysins Undecaprenyl pyrophosphate synthase and DNA primases to assess their antibacterial potential using AutoDock Vina The enzyme ligand interaction of docked complexes was further analyzed by Molecular Dynamics Simulation technique using GROMACS As per in vitro results methanolic extract was found to be the most promising extract having highest antibacterial potential where the mg ml concentration of the extract was found to completely inhibit the bacterial growth whereas for pure Quercetin the complete inhibition was achieved at mg ml concentration MIC was observed to be and mg ml with methanolic and pure Quercetin extracts respectively Whereas MBC values were found to be and mg ml for methanolic extract and Quercetin respectively As per in silico results Quercetin was found to be the only secondary metabolite which strongly inhibited three essential enzymes of S aureus like Peptide deformylase Undecaprenyl pyrophosphate synthase and DNA primases enzymes which resulted in the inhibition of post translation cell wall biosynthesis and initiation of replication pathways respectively As Quercetin was found in methanolic extract of C officinalis we have successfully demonstrated that C officinalis has great potential to inhibit the growth of S aureus