Cladobotric Acids: Metabolites from Cultures of sp., Semisynthetic Analogues and Antibacterial Activity.

Three new polyketide-derived natural products, cladobotric acids G-I (-), and six known metabolites (, , -) were isolated from fermentation of the fungus sp. grown on rice. Their structures were elucidated by extensive spectroscopic methods. Two metabolites, cladobotric acid A () and pyrenulic acid A (), were converted to a series of new products (-) by semisynthesis. The antibacterial activities of all these compounds were investigated against the Gram-positive pathogen including methicillin-susceptible (MSSA), methicillin-resistant and vancomycin-intermediate (MRSA/VISA), and heterogeneous vancomycin-intermediate (hVISA) strains. Results of these antibacterial assays revealed structural features of the unsaturated decalins important for biological activity.