Inhibition of quorum sensing in microbial escherichia coli and pseudomonas sp. biofilms using yellow bell (allamanda cathartica) leaf extract

Background: Antimicrobial resistance is an escalating global health threat, necessitating alternative strategies such as quorum sensing (QS) inhibition. Quorum sensing governs bacterial virulence and biofilm formation, making its inhibition a promising therapeutic target. Objective: To evaluate the anti-quorum sensing and antibiofilm activity of ethanol extract from Allamanda cathartica leaves against Escherichia coli and Pseudomonas sp. Methods: Allamanda cathartica leaves were collected, processed, and extracted using ethanol. Multiple concentrations of the extract were tested alongside positive and negative controls. Anti-QS susceptibility assays and biofilm formation experiments were conducted under laboratory conditions. Inhibition zones were measured and analyzed using one-way Analysis of Variance (ANOVA). Results: A statistically significant difference in inhibition zones was observed across treatment concentrations for both E. coli and Pseudomonas sp. (p < 0.05, one-way ANOVA). Higher extract concentrations produced greater inhibition, demonstrating dose-dependent anti-QS activity and suppression of biofilm formation. Conclusion: Allamanda cathartica leaf extract demonstrates potential as a natural, accessible, and cost-effective quorum sensing inhibitor. Further research testing the extract against additional bacterial strains is recommended to fully characterize its antibacterial scope.