Antimicrobial action of methanolic seed extracts of Syzygium cumini Linn. on Bacillus subtilis

Phytochemicals of Syzygium cumini are used for the treatment of various diseases as a traditional medicine but the mechanism behind their action is not well reported. Antimicrobial activity of methanolic seed extract of S. cumini was done by agar well diffusion assay on Bacillus subtilis and its zone of inhibition was found to be 20.06 mm in comparison to control having no zone of inhibition. MIC of S. cumini was found to be 0.3 mg/ml. Genomic DNA degradation of B. subtilis reveals apoptosis and FE-scanning electron microscope indicates cell wall cracking on several intervals of time. Results of propidium iodide staining showed few bacterial cells were stained in control; however population of stained cells increased after exposing them for varying period of time. Flow cytometric kinetic data analysis on the membrane permeabilization in bacterial cell showed the significant contribution of antimicrobial potential of the seed extract on antimicrobial-induced permeabilization. In silico analysis revealed two components of S. cumini methanolic extract to be active against four enzymes (PDB ID—1W5D, 4OX3, 3MFD and 5E2F) which are crucial for plasma membrane synthesis in B. subtilis. Moreover lupeol showed highest binding energy for macromolecule 1W5D and 4OX3 forming one hydrogen bond each whereas stigmasterol showed the highest binding energy for macromolecule 3MFD and 5E2F forming four hydrogen bonds and alkyl bonds respectively. It demonstrates that methanolic seed extracts of S. cumini could be used for inhibition of food born infection caused by B. subtilis and also an alternative of prevalent antibiotics.