Comparative Phytochemical and Antibacterial Evaluation of Methanol and Ethanol Extracts of Senna occidentalis Leaves against Uropathogenic Bacteria

Abstract

Urinary tract infections (UTIs) remain among the most common bacterial infections worldwide and are increasingly complicated by multidrug resistance among uropathogens. This study evaluated the phytochemical composition and antibacterial activities of methanol and ethanol leaf extracts of Senna occidentalis against clinical UTI-associated isolates, including Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Proteus vulgaris and Proteus mirabilis. Antibacterial efficacy was assessed using the agar well diffusion method, while minimum inhibitory concentrations (MICs) and minimum bactericidal concentrations (MBCs) were determined by the agar dilution method. Phytochemical screening was conducted to identify bioactive constituents. Both extracts exhibited notable antibacterial effects, with the methanol extract demonstrating superior inhibition zones (16–24 mm) compared to the ethanol extract (12–18 mm). The MIC values for methanol extract ranged from 6.25 to 25 mg/mL and 12.5 to 25 mg/mL for ethanol extract. Minimum bactericidal concentration values were lower for the methanol extract (12.5–25 mg/mL) than for the ethanol extract (25–50 mg/mL). Phytochemical analysis revealed tannins, alkaloids, flavonoids, saponins, steroids, phenols and terpenoids, with flavonoids absent in the ethanol extract. These secondary metabolites are well-documented for antimicrobial mechanisms, including protein precipitation, enzyme inhibition and membrane disruption. The findings highlight the strong antibacterial potential of S. occidentalis, particularly its methanol extract and support its traditional use in the treatment of urinary tract infections. Further investigations are needed to isolate, characterize and evaluate the bioactive compounds in vivo for potential development of novel plant-derived therapeutics.