Antibacterial Effects of Two Banana Varieties: A Comparative Study of Methanolic and Ethanolic Leaf Extracts of Banana Varieties against Selective Pathogenic Bacteria

Abstract

Background: Increasing antimicrobial resistance has encouraged the investigation of plant-derived antibacterial agents. Banana leaves, traditionally used for food preparation and serving, may contain constituents with antimicrobial activity, although comparative evidence for different cultivars remains limited. Aim: To compare the antibacterial effects of methanolic and ethanolic extracts of dried leaves from the grand naine and agnishwar banana cultivars against selected pathogenic bacteria. Method: Dried banana leaves were extracted separately using methanol and ethanol, and the resulting extracts were prepared at 100 mg/mL. Antibacterial activity was assessed using the disc diffusion method against Staphylococcus aureus (ATCC 25953), Escherichia coli (ATCC 25922) and Salmonella typhi (ATCC 14028). Gentamicin and the corresponding solvents served as positive and negative controls, respectively. Assays were performed in triplicate, and inhibition zones were expressed as mean ± standard deviation. Results: Grand naine methanolic extract inhibited all three organisms, producing inhibition zones of 8 ± 0.50, 7 ± 0.30 and 9 ± 0.57 mm, respectively. Its ethanolic extract inhibited only S. typhi (8 ± 0.40 mm). Agnishwar methanolic and ethanolic extracts inhibited only S. aureus, producing inhibition zones of 7 ± 0.35 and 7 ± 0.30 mm, respectively. Gentamicin produced larger inhibition zones (19–24 mm), whereas negative controls showed no inhibition. Conclusion: Antibacterial activity varied according to banana cultivar, extraction solvent and bacterial species. Grand naine methanolic extract exhibited the broadest antibacterial activity, although all active extracts were less effective than gentamicin under the experimental conditions.