Multi-Technique Approach to Identify Potent Antimicrobial Agents from Calotropis procera: Insight into Pharmacophore Modeling, Molecular docking, MD simulation, and DFT Approaches

In this research, natural compounds from Calotropisprocera were screened according to their antimicrobial activity against the pathogenic microbes selected as E. coli, S. aureus, Traypanosomabrucei, Moraxella catarrhalis, and Leishmaniaamazonensis. A 3D-QSAR study was performed that evaluated the correlation of the structural parameters for the antimicrobial activity of the natural compounds which were selected based on their antimicrobial in-vivo and in-vitro studies previously. The screened active compounds were further studied by molecular docking to analyze the various interactions between the ligands and target proteins. Molecular docking was also performed with the three FDA-approved antibiotics Cephalexin, Dicloxacillin, and Levofloxacin, having antimicrobial potential, and their results were compared with the docking results of the hit compounds. Results of ADME/T study of the compounds revealed that the two compounds stigmasterol and caryophyllene oxide are the hit compounds having no toxicity, best values of TPSA and average molecular weight. Validation of the docking results was also carried out by re-docking as well as by molecular dynamic simulation. DFT study was also carried out to explore the stability and chemical properties of active compounds. Results showed that caryophyllene oxide is the hit compound because of the highest Moldock score with 3VOB protein, better than standard drugs and according to dynamic simulation analysis. Therefore, the derived results in these studies provide crucial information for designing antimicrobial drugs by using natural compounds that have better antimicrobial activity.