Characterization of bioactive compounds from Saraca asoca and their antibacterial activity against fish pathogens in Oreochromis niloticus

Saraca asoca, known for its therapeutic properties in Ayurveda, is the focus of this study, aiming to identify and quantify the bioactive compounds in its leaf extract using Gas Chromatography-Mass Spectrometry (GC-MS) and Fourier Transform Infrared Spectroscopy (FTIR). The study also investigates the antibacterial efficacy of methanol, ethanol and acetone extracts of S. asoca against fish pathogens in Oreochromis niloticus like Vibrio alginolyticus, Streptococcus pyogenes, Pseudomonas fluorescens and Aeromonas hydrophila through the well-diffusion method. GC-MS confirmed the presence of compounds such as 3- hydroxy biphenyl, n-hexa decanoic acid, oleic acid, octadecanoic acid, 4,5-diethyl octane and 9-tetradecen-1-ol. In contrast, FTIR spectra revealed several significant peaks, indicating the presence of specific functional groups in the S. asoca leaf fraction. The results exhibited high absorbance in the wavenumber ranges of 4000–3500 cm?1, 3000–2500 cm?1, 1800–1500 cm?1 and 1100–950 cm?1. The findings of the antibacterial assay suggest that the methanolic extract exhibited a strong inhibitory effect against bacterial pathogens, with zones of inhibition ranging from 6 ± 0.21 to 18 ± 0.57 mm in size. These results indicate that S. asoca leaf extract contains bioactive compounds effective against the pathogenic bacteria in O. niloticus, supporting the growing shift towards reducing antibiotic use in aquaculture.