Phytochemical and Antimicrobial Properties of Crude n-Hexane and Methanol Extracts of Cola acuminata Nuts

Aim: To determine the phytochemical and antimicrobial properties of crude n-hexane and methanol extracts of Cola acuminata nuts against standard and clinical strains of pathogenic bacteria and fungi species implicated in various infections.
Place and Duration of study: Department of Pharmaceutical Microbiology, Faculty of Pharmacy, University of Ibadan, Nigeria, between February 2009 and September 2009.
Methodology: All the microorganisms were tested for their susceptibilities to the plant extracts by means of agar diffusion (Kirby-Bauer) method according to the National Committee for Clinical Laboratory Standard guidelines. Minimum Inhibitory Concentrations were determined using the broth dilution method.
Results: The methanol extract showed activity on all 16 isolates tested with zones of inhibition in the range of 10 to 19 mm for fungi and 13 to 20 mm for bacteria while that of n-hexane was completely inactive. The minimum inhibitory concentration (MIC) of the methanol extract was between 62.5 and 500 µg/ml with the fungi species having higher values. Phytochemical analysis of Cola acuminata nuts reveals the presence of saponins, tannins, alkaloids and sugar. Griseofulvin, tioconazole and nystatin resistant Candida sp were sensitive to the methanolic extracts of C. acuminata. The kinetics of bactericidal and fungicidal studies show that 90% of Staphylococcus aureus and 99% of Candida albicans were killed within 3 h of contact time at a concentration of 250 µg/ml of the crude methanol extract of Cola acuminata.
Conclusion: In comparison with these antibiotics, the test plant extracts fared better in their antifungal activity and are capable of being a good replacement as alternatives if processed.