DMOA-based meroterpenoids with diverse scaffolds from the sponge-associated fungus Penicillium brasilianum

Bioinformatics analysis of the synthetic gene clusters in association with the qRT-PCR detection led to speculate a marine derived fungus, Penicillium brasilianum WZXY-m122-9, to be potential to produce meroterpenoids. Chromatographic separation of the EtOAc extract of this fungal strain on a large-scale fermentation resulted in the isolation of six new DMOA-related meroterpenoids, namely brasilianoids G‒L (1–6), together with nine known meroterpenes. Their structures were determined by extensive analyses of spectroscopic data, including the X-ray diffraction and the ECD data for configurational assignment. Brasilianoid G is characterized by the presence of an unprecedented scaffold bearing a 6/6/5/5/5 pentacyclic nucleus, while brasilianoid K possessing a 7/6/6/6/5 pentacyclic system is uncommonly found from nature. The biogenetic relationship among the isolated compounds was postulated based on the comparative analyses of gene clusters. Brasilianoid L (6), austinol (12), and dehydroaustin (14) exhibited significant inhibition against bacteria invasion into host cells, that was suggested to be mediated by preventing the polymerization of actin in the host cells.