Antimicrobial activity, phytochemical characterization and molecular docking studies of Nyctanthes arbor-tristis L. extracts

Antimicrobial resistance among nosocomial pathogens reduces the efficacy of antibiotics and lead to treatment failure among susceptible patients, which necessitates the identification of novel antimicrobial agents. Nyctanthes arbor-tristis L. is a valuable medicinal plant with numerous bioactive phytochemicals, which could be explored for their antimicrobial potential. This study evaluated the antimicrobial activity of hexane fractions of ethanolic extracts of Nyctanthes arbor-tristis L. against nosocomial bacteria Escherichia coli, Bacillus subtilis, Pseudomonas florescens, Aeromonas hydrophila, Enterococcus faecalis and Kleibsella pneumonia, determined the phytochemical composition and predicted potential antimicrobial compounds through in-silico method. The hexane fractions of ethanolic extracts of Nyctanthes arbor-tristis L. were obtained by maceration and solvent partitioning, and further characterized through gas chromatography–mass spectrometry. The hexane fractions were examined in-vitro for antibacterial activity by the disc diffusion method and minimal inhibitory concentration (MIC) was determined on the basis of optical density. Molecular docking was done using AutoDockTools 1.5.7 and Pyrx. The leaf and stem samples exhibited significant antimicrobial activity against E. coli, B. subtilis, P. florescens and A. hydrophilla. The major compounds identified through GC-MS phytol, 1,2-benzenedicarboxylic acid and dioctyl phthalate were docked; the docking scores were -6.4, -6.6 and -7.2 respectively against 6KVP, while -6.2, -6.7 and -7.6 respectively against 4FS3. This study gives the first report of the antimicrobial activity of non-polar fractions of ethanolic extracts of Nyctanthes arbor-tristis L. against nosocomial bacteria and lead to the identification of phytol, 1,2-benzenedicarboxylic acid and dioctyl phthalate as novel potential antimicrobial agents.