In vitro Evaluation of Antibacterial Activity of Persea americana Seed Extract against Pseudomonas aeruginosa

Abstract

Antimicrobial resistance among Gram-negative bacteria, particularly Pseudomonas aeruginosa, remains a major public health concern and has prompted increased interest in alternative antimicrobial agents derived from medicinal plants. Persea americana (avocado) seed contains phytochemical constituents with reported antimicrobial properties. This study evaluated the in vitro antibacterial activity of ethanolic Persea americana seed extract against Pseudomonas aeruginosa ATCC 27853 using the Kirby-Bauer disc diffusion method. Ethanolic seed extract was prepared by Soxhlet extraction and tested at concentrations of 50 mg/mL, 100 mg/mL, 200 mg/mL, and 400 mg/mL. Antibacterial activity was determined by measuring zones of inhibition on Mueller-Hinton agar after incubation at 35 ± 2°C for 16-18 hours. Ceftazidime was used as the positive control, while distilled water served as the negative control. All treatments were performed in triplicate, and data were analysed using one-way analysis of variance (ANOVA). All tested concentrations showed inhibitory activity against P. aeruginosa. The 400 mg/mL concentration produced the largest mean zone of inhibition (37.3 ± 0.6 mm), whereas the 50 mg/mL concentration produced the smallest mean zone (13.3 ± 1.5 mm). One-way ANOVA showed a statistically significant difference in antibacterial activity among the tested extract concentrations (F = 276.56, p < 0.001). A concentration-dependent increase in antibacterial activity was observed. These findings indicate that ethanolic Persea americana seed extract has in vitro antibacterial activity against Pseudomonas aeruginosa and may contain bioactive compounds of antimicrobial interest. Further studies involving phytochemical characterisation, minimum inhibitory concentration testing, cytotoxicity evaluation, and multidrug-resistant clinical isolates are recommended to strengthen the evidence generated by this preliminary investigation.