ABSTRACT
Aims: To investigate the antimicrobial activity of ethyl acetate and residual aqueous fractions of the methanol extract of Alchornea cordifolia leaf against Pseudomonas aeruginosa ATCC 10145, Staphylococcus aureus ATCC 12600, Escherichia coli ATCC 11775 and Candida albicans ATCC 18804 in comparison to standard antibiotics. Study design: Extraction of Alchornea cordifolia leaf, partitioning of the extract, susceptibility tests (Zones of inhibition) and Minimum Inhibitory and Bactericidal Concentrations determination. Place and Duration of Study: Department of Medicinal Plant Research and Department of Pharmaceutical Microbiology and Biotechnology, National Institute for Pharmaceutical Research and Development, Idu – Abuja, Nigeria and Department of Pharmaceutics and Pharmaceutical Microbiology, Ahmadu Bello University, Zaria, Nigeria, July and October. Methodology: The leaves of Alchornea cordifolia (Schum. & Thonn.) Muell. Arg. were collected, dried at room temperature and extracted with methanol using a soxhlet extractor. The methanol extract was partitioned between ethyl acetate and distilled water to obtain an ethyl acetate sub-fraction (EAF) and an aqueous residual fraction (AF). Agar well diffusion and agar dilution methods according to Clinical Laboratory Standards Institute (CLSI) were used to test the antimicrobial activity of the ethyl acetate and aqueous fractions of Alchornea cordifolia against the above mentioned microbial species. Results: Both fractions; ethyl acetate and residual aqueous fractions of the methanol extract showed antimicrobial activity against the standard organisms viz: Pseudomonas aeruginosa ATCC 10145, Staphylococcus aureus ATCC 12600, Escherichia coli ATCC 11775 and Candida albicans ATCC 18804. The highest activity was observed for the ethyl acetate fraction against Staphylococcus aureus ATCC 12600 with zone of inhibition of 27 mm, Minimum Inhibitory Concentration (M.I.C) of 1.25 mg/ml and Minimum Bactericidal Concentration (M. B. C) of 2.5mg/ml. Conclusion: Pseudomonas aeruginosa ATCC 10145, Staphylococcus aureus ATCC 12600, Escherichia coli ATCC 11775 and Candida albicans ATCC 18804 were susceptible to the ethyl acetate sub-fraction and residual aqueous fractions of the methanol extract of Alchornea cordifolia leaf.