Research Article

In Vitro Antimicrobial Activities of Leaf Extracts of Mangifera indica Dehnh. and Psidium guajava F. Muell. Against Selected Antibiotic-Resistant Bacteria Strains

Julius Oluwatosin AYOADE^1*; Oluwarotimi John JOSEPH¹; Habeebat Eniola AROYEHUN¹; Oluwadamiloju Mofeoluwa ADEKUNLE¹; Abdullahi Adeyemi ADEGOKE²

¹Department of Microbiology, Faculty of Science, University of Ibadan, Ibadan, Nigeria

²Department of Pharmacognosy and Drug Development, Faculty of Pharmaceutical Science, Mercy Medical University, Iwara, Iwo, Osun State, Nigeria

*Corresponding author e-mail: ayoadejulius8@gmail.com

(Received: 05/03/2026; Revised: 19/05/2026; Accepted: 10/06/2026; Published: 20/06/2026)

ABSTRACT

The global rise of antibiotic-resistant bacteria necessitates the discovery of new antimicrobial agents. This study investigated the antibacterial potential of Mangifera indica and Psidium guajava leaf extracts against multidrug-resistant pathogens, including Escherichia coli, Klebsiella pneumoniae, Staphylococcus aureus, Staphylococcus epidermidis, and Pseudomonas aeruginosa. Leaves were extracted using methanol, ethanol, and aqueous solvents. Phytochemical analysis confirmed the presence of alkaloids, flavonoids, saponins, and other bioactive compounds, with methanol extracts yielding the most comprehensive profile. Alkaloids were the most abundant phytochemical. Antimicrobial testing revealed that methanol extracts were the most effective, demonstrating the largest zones of inhibition against S. aureus and P. aeruginosa at a concentration of 100 g/mL. Ethanol extracts also showed significant activity, while aqueous extracts were moderately effective. Determination of the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) confirmed that methanol extracts had the lowest inhibitory values, indicating superior bactericidal potential. Furthermore, Gram-positive bacteria (S. aureus and S. epidermidis) were more susceptible to the extracts than Gram-negative strains, likely due to differences in cell wall structure. The results highlight the efficacy of M. indica and P. guajava extracts, particularly methanol-based ones, against resistant bacteria. The study concludes that the bioactive compounds in these plants are promising candidates for development as alternative antimicrobial agents.

Keywords: Mangifera indica, Psidium guajava, Antibiotic resistance, Phytochemicals, Antibacterial activity

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