Phytochemical Evaluation and Antibiogram of Aqueous and Ethanolic Leaf Extracts of Mormodica charantia against Clinical Bacterial Isolates

Abstract

The ever-increasing incidence of antimicrobial-resistant (AMR) pathogens necessitates the exploration of alternative therapeutic agents, particularly those sourced from medicinal plants. Among the numerous medicinal plants under investigation, Momordica charantia, commonly known as bitter melon or bitter gourd, stands out due to its rich ethnomedicinal heritage and diverse phytochemical profile. M. charantia has been used traditionally to treat a range of ailments, including diabetes, malaria, skin diseases, and infections. This study presents a comparative evaluation of the phytochemical composition and antibacterial efficacy of aqueous and ethanolic leaf extracts of Momordica charantia against clinical isolates of Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, and Klebsiella pneumoniae. Aqueous and ethanolic leaf extracts of M. charantia were prepared as cold macerations. Phytochemical analyses revealed the prominent presence of flavonoids, saponins, and steroids, with the ethanolic extract exhibiting markedly higher concentrations: flavonoids (52.92%), saponins (17.11%), and steroids (12.64%). Antibacterial activity, assessed using the agar well diffusion method, indicated that the ethanolic extract demonstrated broader and more potent inhibition, with K. pneumoniae showing the greatest susceptibility (16 mm zone of inhibition at 100 mg/mL). Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) assays corroborated these findings, revealing bactericidal effects of the ethanolic extract against S. aureus and P. aeruginosa, and inhibitory activity against E. coli and K. pneumoniae. Conversely, the aqueous extract exhibited only inhibitory effects and limited efficacy at lower concentrations. These results validate the ethnopharmacological relevance of M. charantia and emphasise the critical role of solvent polarity in optimising bioactive compound extraction. The findings support the potential of M. charantia as a source of novel antimicrobial agents and warrant further investigation through in vivo models and clinical studies.