Fusapyrone and deoxyfusapyrone, two antifungal alpha-pyrones from Fusarium semitectum

A strain of Fusarium semitectum Berk. and Rav. from maize stalk rot in southern Italy produced bioactive metabolites when cultured on autoclaved rice kernels at room temperature for 4 weeks. The organic extracts of fungal culture showed a strong antibiotic activity towards Geotrichum candidum in disk diffusion assays, but they were not toxic to Artemia salina larvae. Two antifungal metabolites were isolated and characterized by chemical and spectroscopic methods as two 3-substituted-4-hydroxy-6-alkyl-2-pyrones, in particular, the 3-(4-deoxy-beta-xylo-hexopyranosyl)-4-hydroxy-6-(2-hydroxy-7-hydroxymethyl-1,1,5,9,11-penta- methyl-3,5,8-heptadecatrienyl)-2H-pyran-2-one and its 6-(2-hydroxy-1,1,5,7,9,11-hexamethyl) analog, which were named fusapyrone and deoxyfusapyrone, respectively.