Antimicrobial, anti-inflammatory activity and cytotoxicity of Funtumia africana leaf extracts, fractions and the isolated methyl ursolate

Abstract

Funtumia africana is used to treat and manage diverse ailments including fever, inflammation, malaria, cancer and urinary incontinence in South Africa. In this study, the antibacterial, antifungal, anti-inflammatory activities and cytotoxicity of the crude extracts, fractions and an isolated compound were determined. Serial microplate dilution and bioautography methods were used to determine the antimicrobial activities. The bacteria tested were ATCC reference strains of Escherichia coli, Enterococcus faecalis, Pseudomonas aeruginosa and Staphylococcus aureus. The fungal test organisms used were three clinical isolates (Aspergillus fumigatus, Cryptococcus neoformans and Candida albicans), C. albicans ATCC 10231 and three phytopathogenic fungi (Fusarium oxysporum, Penicillium janthinellum and Rhizoctonia solani). The anti-inflammatory activity was determined using cyclooxygenase (COX) enzymes and the MTT assay was used to determine cellular toxicity against Vero and human liver (C3A) cells. The crude extract had MICs as low as 80μg/ml against both bacteria and fungi. The chloroform fraction had the lowest MIC of 20μg/ml against P. aeruginosa. The hexane and chloroform fractions had MIC of 40μg/ml against C. albicans ATCC 10231. The crude extract, hexane and chloroform fractions had moderate activity against both COX-1 and COX-2. The chloroform fraction was more active than the crude extract (59.7%) with an inhibition of 68.2% against COX-1. Bioassay-guided fractionation using column chromatography led to the isolation of methyl ursolate (MU) with an MIC of 62.5μg/ml against F. oxysporum. It was relatively toxic against Vero cells with an IC50 of 10.4μg/ml. The antimicrobial and anti-inflammatory activities of the crude extract provide some support for the traditional use of the plant.