Antibacterial activity and phytochemical components of leaf extracts of agave Americana

Abstract

Background: Ethiopian flora is a source of innumerable cures for several infections. The medicinal potential of A. americana has been evaluated in some studies. The current study aimed to investigate the antimicrobial effect of A. americana leaf extracts on selected bacterial strains and to determine the phytochemical components. Purpose: To determine the phytochemical constituents and in vitro antibacterial activity of leaf extracts of Agave americana against Staphylococcus aureus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Salmonella species, and Eshercia coli. Methods: The macerated and Soxhlet crude extracts of Agave americana were further fractionated to petroleum ether, chloroform, acetone, and methanol fractions. The agar well diffusion method and disc diffusion methods were used to test the antibacterial effect and determine the minimum inhibitory concentration (MIC) of the plant extract. Standard methods of determination were used to determine the phytochemical components of Agave americana. Results: The percentage yield of crude extracts of A. americana was 15.11%. Alkaloids, saponins, tannins, polyphenols, and flavonoids were identified as phytochemical constituents of A. americana. The crude and solvent fractions of A. americana have an antibacterial activity comparable to gentamycin, with zones of inhibition ranging from 17 to 40mm and minimum inhibitory concentration (MIC) of 2.5 mg mL for S. aureus, P. aeruginosa, and S. typhi strains and 10 mg mL for E. coli strains. S. aureus and E. coli were the most and least susceptible bacteria among the four bacterial test strains tested. Conclusion: The crude and solvent fractions of A. americana have antibacterial activity against S. aureus, P. aeruginosa, and S. thyphi, comparable to gentamycin.