Structure and absolute configuration of toxic polyketide pigments from the fruiting bodies of the fungus Cortinarius rufo-olivaceus.

Two new polyketide-derived pigments, named rufoolivacins B (), and D (), with a 4',10-coupled aryl linkage between polysubstituted 1-naphthol and 1,4- or 1,2-anthraquinone, together with nine known metabolites including rufoolivacins A () and C (), have been isolated from the fruiting bodies of the Chinese toadstool Cortinarius rufo-olivaceus (basidiomycetes). Their structures were characterized on the basis of spectroscopic methods, including 2D-NMR experiments (COSY, NOESY, HSQC, and HMBC). The axial chirality of and was assigned through analysis of their CD spectra and ZINDO and TDDFT calculations. Compounds and were found to be unusual natural products incorporating an ortho-anthraquinone chromophore. All the metabolites were shown to be toxic toward the brine shrimp.