Integrated Phytochemical and Bioactivity Evaluation of Ocimum tenuiflorum Linn. Essential Oil Against Multidrug‐Resistant Aeromonas spp.

ABSTRACT Plant essential oils extracted from various parts are known for their potential antimicrobial properties. The gas chromatography and mass spectrometry (GC–MS) of Ocimum tenuiflorum essential oil (TEO) revealed estragole and eugenol as major compounds. The FTIR profiling showed the presence of functional groups like O─H, C─H, C═O, C─C, which is in correspondence with the results of GC–MS analysis. In a similar way, UV–visible spectroscopy identified peaks within 315 nm that showed the presence of C═C and aromatic compounds. The disc diffusion results revealed Aeromonas hydrophila to be more sensitive, with 29.57 ± 0.32 mm zone of inhibition (ZoI) and Aeromonas jandaei with 28.07 ± 0.83 mm. The MIC and MBC values of A. hydrophila were 0.125% and 0.25%, while 0.25% and 0.5% for A. jandaei . DPPH and ABTS assay for antioxidant activity determined the IC 50 value to be 53.67 ± 0.16 µg/mL and 53.7 ± 0.2 µg/mL. Strong antibiofilm activity (%) was observed against both A. hydrophila and A. jandaei , with 94.3% and 90% respectively. The present study provides insight into the sustainable use of TEO against bacterial infections by Aeromonas spp. isolated from moribund Labeo rohita .