In vitro antibacterial and antifungal activities of extracts and compounds from Uvaria scheffleri

Petroleum ether, dichloromethane, and ethanolic extracts of the stem bark and leaves of Uvaria scheffleri Diels (Annonaceae) exhibited antifungal activity against Aspergillus niger (wild strain), Aspergillus fumigatus (wild strain), and a Penicillium species (wild strain). The ethanol extract of the stem bark was also active against Candida albicans (Strain H6392). The dichloromethane extract of the leaves showed the highest antifungal activity and in addition it showed antibacterial activity against Staphylococcus aureus (NCTC 6571). Fractionation of the dichloromethane extract of the leaves yielded nine known compounds. They included a 1 : 1 mixture of stigmasterol (1) and -sitosterol (2), which showed antifungal activity against Candida albicans. Others were 3-farnesylindole (3), 2′,6′-dihydroxy-3′,4′-dimethoxy-chalcone (4), 2′-hydroxy-3′,4′,6′-trimethoxychalcone (5), 5-hydroxy-7,8-dimethoxyflavanone (6), 5,7,8-trimethoxyflavanone (7), and a 3 : 2 mixture of 2′,6′-dihydroxy-4′-methoxychalcone (8) and 5,7-dihydroxyflavone (9). Compound 7 and the mixture of compounds 8 and 9 showed antibacterial activity against Escherichia coli (NCTC 10418, MIC 125 µg/ml) and Staphylococcus aureus (MIC 125 µg/ml), respectively. The mixture of compounds 8 and 9 was also active against Candida albicans (MIC 31.25 µg/ml), Aspergillus niger, Aspergillus fumigatus, and the Penicillium species (MIC 1000 µg/ml). We conclude that Uvaria scheffleri extracts contain compounds with antifungal and antibacterial activity. The activities observed in this study are weak. Based on previous studies, it is being speculated that, possibly, the most active compounds were lost during fractionation. Further work to isolate more antifungal and antibacterial compounds is suggested.