Antimicrobial activity of compounds isolated from the leaves of Aspilia africana (Pers.) C. D. Adams (Asteraceae)

Background: Incidences of serious failures in the treatment of infectious disease by antibiotics caused by the emergence and spread of drug resistant strains of the microorganisms/multiple drug resistant bacteria have led to new global search for more effective anti-infective microbial agents from natural sources. This study intends to examine the anti-microbial potentials of the leaves of Aspilia africana, which is employed in the treatment of wounds and sores by traditional medical practitioners in Nigeria. Objective: To evaluate the anti-microbial potentials of the isolates from leaves of Aspilia africana (Pers.) C. D. Adams (Aristeraceae), using isolated clinical strains of pathogens such as Staphylococcus aureus, Methicillin Resistant Staphylococcus aureus (MRSA), Streptococcus pyogenes, Bacillus substilis, Proteus vulgaris, Salmonella typhi, Shigella dysenteriae, Escherichia coli, Klebsiella pneumonia, Candida albicans and Candida stellafoidea. Methodology: Three compounds isolated from butanol fraction of the methanol extract of the dried powdered leaves of Aspilia africana through repeated silica gel column-chromatography and sephadex gel filtration, were evaluated for anti-microbial potentials using Agar-well diffusion method. Results: The isolated compounds identified as oleanolic acid, ursolic acid, and corosolic acid by 1D, 2D-NMR and FITR spectroscopic analyses inhibited the growth of all the pathogens with inhibition diameters ranging between 25 – 33 mm compared with the standard drugs used. The MIC, MBC/MFC of the plant extracts ranged from between 5.00 and 10.00 mg/mL while that of the isolated compounds ranged between 0.0125 and 0.0500mg/mL Discussion: From the results, we conclude that isolated compounds namely oleanolic acid, ursolic acid and corosolic acid are the bioactive constituents responsible for the anti-microbial activity of Aspilia africana. Key words: Aspilia africana, Anti-microbial, Oleanolic acid, Ursolic acid, Corosolic aci