An Evaluation of the Antimicrobial Activities of Aloe barbadensis, A. chabaudii and A. arborescens Leaf Extracts Used in Folklore Veterinary Medicine in Zimbabwe

摘要

The antimicrobial activities of Aloe barbadensis Miller (Aloe vera), A. chabaudii and A. arborescens sap extracts on selected microorganisms were determined. Methanol as well as aqueous extracts of these plants were obtained and then tested for their antimicrobial activities using the disc diffusion assay. The extracts were assayed against gram positive bacteria (Staphylococcus aureus, Bacillus substilis), gram negative bacteria (Escherichia coli, Salmonella typhimurium, S. gallinarum, Klebsiella sp., Proteus sp.) and Candida albicans. The study showed that the sap extracts of the three Aloes had antimicrobial activity against all the tested microorganisms. The antimicrobial activity of the methanol extracts were significantly higher than those of the aqueous (warm and cold) extracts (one tailed t-test, p<0.05). There was no significant difference in the antimicrobial activities of the aqueous extracts (one tailed t-test, p<0.05). S. typhimurium and S. gallinarum were the least susceptible to the extracts tested. E. coli, Proteus sp., Klebsiella sp. and C. albicans were the most sensitive.