Essential oil of Syzygium boisianum (Gagnep.) Merr. & LMPerry: Chemical compositions, antimicrobial activity, and molecular docking

Essential oil obtained from hydrodistillation of the Vietnamese Syzygium boisanum leaves was analyzed by the GC/FID-MS (gas chromatography/flame ionization detection-mass spectrometry). Forty-five compounds (90.08%) were namely identified, in which sesquiterpene hydrocarbons (73.07%) were the major chemical class. Among identified compounds, beta-caryophyllene (18.21%) and bicyclogermacrene (25.47%) were the principal compounds. This essential oil was comparable with the positive control streptomycin in an antimicrobial assay against three Gram-positive bacteria Enterococcus faecalis ATCC299212, Staphylococcus aureus ATCC25923, and Bacillus cereus ATCC14579. Docking study of two major sesquiterpene hydrocarbons beta-caryophyllene and bicyclogermacrene against bacterial DNA gyrase B showed that these two compounds mainly interacted with hydrophobic residues at the rim of the pocket, thereby they are possible inhibitors.