Skeletocutins A-L: Antibacterial Agents from the Kenyan Wood-Inhabiting Basidiomycete, sp.

Fermentation of the fungal strain sp. originating from Mount Elgon Natural Reserve in Kenya, followed by bioassay guided fractionation led to the isolation of 12 previously undescribed metabolites named skeletocutins A-L (- and -) together with the known tyromycin A (). Their structures were assigned by NMR spectroscopy complemented by HR-ESIMS. Compounds - and - exhibited selective activities against Gram-positive bacteria, while compound weakly inhibited the formation of biofilm of . The isolated metabolites were also evaluated for inhibition of -leucine aminopeptidase, since tyromycin A had previously been reported to possess such activities but only showed weak effects. Furthermore, all compounds were tested for antiviral activity against Hepatitis C virus (HCV), and compound moderately inhibited HCV infectivity with an IC of 6.6 μM.