Evaluation of the antibacterial properties of methanolic pomegranate peel extract against standard strains of Staphylococcus aureus, Bacillus cereus, Pseudomonas aeruginosa, and Escherichia coli: An in Vitro Study

Background: The increasing prevalence of antimicrobial resistance has intensified the search for effective natural alternatives to synthetic antibiotics. Pomegranate (Punica granatum) peel, a widely available agricultural by-product, is known for its rich phytochemical composition. We aimed to quantify the in vitro antibacterial activity of pomegranate peel methanolic extract (PPME) against selected Gram-positive and Gram-negative bacteria and analyze their differential susceptibility. Methods: Here, PPME was prepared using a Soxhlet apparatus, and its antibacterial efficacy was tested against Staphylococcus aureus, Bacillus cereus, Escherichia coli, and Pseudomonas aeruginosa via the agar well-diffusion method at the concentrations of 50, 100, 200, and 400 mg/mL. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined using the broth dilution technique. Data were analyzed employing one-way ANOVA. Results: The PPME demonstrated notable dose-dependent antibacterial activity (p < 0.0001), especially against Gram-negative bacteria. Escherichia coli was the most sensitive bacterial strain, with the largest inhibition zone (27 mm) at 400 mg/mL and the lowest MIC (12.5 mg/mL) and MBC (25 mg/mL). Gram-positive bacteria were more resistant to PPME, for which Bacillus cereus showed the highest MIC (100 mg/mL) and MBC (200 mg/mL). Conclusion: Pomegranate peel extract possesses potent antibacterial activity, exhibiting relatively stronger efficacy against Gram-negative pathogens, offering it a promising sustainable candidate for developing novel antibacterial agents, especially against resistant Gram-negative pathogenic strains. Further research is warranted to identify the active compounds of PPME and their mechanisms of action.