Evaluation of Potential Antimicrobial Activity of Stem Barks Extract of Persea americana (Mill) and its Solvent Fractions against Randomly Selected Pathogenic Bacteria and Fungi

Abstract

Persea americana stem barks are used locally in parts of Nigeria in treating bacterial infections. This study aims to determine the antimicrobial potential of the methanol extract and fractions against S. aureus, B. substilis, E. coli, P. aeruginosa, C. albicans and Aspergilus species. The plant material was extracted with 80% methanol and partitioned into chloroform and aqueous phases which were evaluated for antimicrobial activities using agar well diffusion method. The methanol extract inhibited the growth of the test organisms; P. aeruginosa showed the most activity at 100mg/mL. The CHCl₃ fraction of the plant extract was ineffective against gram negative bacteria (E. coli and P. aeruginosa) at low concentrations. The CHCl₃ fraction was most effective against S. aureus at 50mg/mL but ineffective against gram-negative organisms at lower concentrations. The extract's H₂O fraction had the most antimicrobial activity. The H₂O fraction inhibited B. substilis at 50mg/mL (8.50±1.08mm).Alkaloids, saponins, tannins, steroids, among others were observed in the extract and fractions. Owing to the higher antimicrobial activity in the H₂O fraction, the active antimicrobial compounds could be polar in nature. The higher inhibitory activity recorded by the H₂O fraction supports the folkloric use of P. Americana.