Exploring Sonneratia caseolaris: A mangrove plant source for novel antibacterial compounds targeting quorum sensing and biofilm inhibition

Antibacterial resistance, fueled by the overuse and misuse of antibiotics, has become a global health concern, undermining the effectiveness of standard treatments against resistant bacterial strains. Pathogenic bacteria utilize mechanisms such as quorum sensing (QS) and biofilm formation to evade antimicrobial treatments, making these processes attractive therapeutic targets. This study investigates Sonneratia caseolaris, a mangrove plant, as a source of bioactive compounds to combat multidrug-resistant bacteria. Phytochemical analysis of the crude extract and its ethyl acetate and water fractions revealed the presence of carbohydrates, saponins, tannins, alkaloids, terpenoids, flavonoids, and steroids. Notably, significant antibiofilm activity (76.82 %, 78.84 %, and 76.06 %), pyocyanin inhibition (77.32 %, 70.73 %, and 67.28 %), and swarming motility inhibition (77.42 %, 78.74 %, and 77.18 %) were observed in the bioactive crude extract, ethyl acetate, and water fractions, respectively, at a concentration of 4 mg/mL. The compound Bis(2-Ethylhexyl) phthalate, isolated from the bioactive ethyl acetate fraction, was identified and characterized through GC-MS analysis. Microbiological assays revealed its potent antibiofilm (62.83 %), pyocyanin inhibition (52.18 %), and swarming motility inhibition (72.5 %) activities. Molecular docking further confirmed its QS inhibitory potential, with strong binding affinities to QS-regulatory proteins. These findings underscore the therapeutic potential of S. caseolaris as a source of novel QS and biofilm inhibitors. By targeting bacterial virulence rather than viability, this study offers a promising and sustainable strategy to address the growing threat of antibacterial resistance, laying the foundation for developing next-generation antimicrobial agents.