Antibacterial Activity Against Clinical Isolates from a Tertiary Hospital in Nigeria Exhibited by Methanol and Aqueous Extracts of Root and Stem Bark of Persea Americana (Laureaceae)

Ching F.P, Josephs GC, Nwaeze N


Introduction: Various parts of Persia americana are used in ethnomedicine in Nigeria to treat microbial infections. We investigated the antibacterial activities of its aqueous and methanol stem bark and roots extracts against clinical bacterial isolates.

Materials and methods: The minimum inhibition concentration (MIC) assay was employed using the agar dilution method. Final nutrient agar extracts concentrations of 25, 50, 75 and 100mg/ml were used. In the zones of inhibition assay 0.2ml of the MIC exhibited by each extract against each bacterium and ciprofloxacin (20µg) was used.

Results: The MICs of the aqueous and methanol extracts of the stem bark against Staphylococcus aureus and Escherichia coli were 75mg/ml and 50mg/ml respectively with 100mg/ml of either the
aqueous or methanol extract against the other isolates. The MIC of the aqueous and methanol extracts of the root against the bacteria tested was 100mg/ml except Staphylococcus aureus in which the MIC of the methanol extract was 50mg/ml. The zones of inhibition ranged from 15.0 ± 0.12 mm to 21.0 ± 0.02 mm for the extracts and 10.5 ± 0.21 mm to 44.0 ± 0.03 mm for
ciprofloxacin. The extracts produced the largest zone of inhibition (21.0 ± 0.02 mm) against Staph. aureus and relatively comparable zones of inhibition against Escherichia Coli, Pseudomonas aeruginosa, Serratia marcescens, Enterobacter aerogenes and Klebseilla pneumoniae . Comparatively, the
methanol extracts exhibited a better antibacterial activity than the aqueous extracts.

Conclusion: The results have shown that Persia americanan root and stem bark extracts possess antibacterial activity against pathogenic bacteria.


Persia americana, stem bark, roots, microbal infections, antibacterial activity.

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