Antibacterial Activity, Phytochemical Composition, and Cytotoxicity Evaluation of Select Medicinal Plants from...

Bangladesh's rich plant diversity offers an underexplored source of plant-based antibacterials with the potential to strengthen sustainable aquaculture. This study evaluated the in vitro antibacterial efficacy of 55 Bangladeshi plants against five key fish pathogens, including Aeromonas hydrophila, Pseudomonas fluorescens, Pseudomonas aeruginosa, Flavobacterium columnare, and Streptococcus iniae. The findings revealed numerous plant extracts with potential antibacterial activity against test pathogens. Among pathogens, S. iniae and F. columnare were found to be the most susceptible to the majority of plants. Several plants exhibited promising broad-spectrum antibacterial activity, including Terminalia arjuna, Terminalia bellirica, Mikania micrantha, Peperomia pellucida, Lawsonia inermis, Phyllanthus emblica, Eryngium foetidum, Amaranthus spinosus, and Alstonia scholaris. Novel antibacterial activity was reported for Ipomoea quamoclit, Erythrina serrata, Cressa europaea, and Dillenia indica against all tested pathogens, along with first-time screenings of the majority of plants against F. columnare and S. iniae. Phytochemical analysis revealed diverse bioactive groups in potent active extracts, including flavonoids, terpenoids, phenolics, glycosides, alkaloids, and steroids. While a few potent extracts showed moderate cytotoxicity on the human embryonic kidney (HEK293) cell line, the majority were found to be safe. These findings highlight the significant potential of Bangladeshi flora as a source of novel, eco-friendly therapeutics for sustainable aquaculture disease management. This work provides a critical foundation for the future exploration of these plants, including the isolation of active compounds and subsequent in vivo studies, which could ultimately contribute to reducing reliance on conventional antibiotics.