Two new metabolites from a marine-derived fungus Penicillium ochrochloron

Co-culturing of fungi and bacteria proved to be an efficient tool for inducing the expression of silent biosynthetic gene clusters (BGCs). This study reports the isolation of a new meroterpenoid derivative, andrastin I (1), from a marine-derived fungus Penicillium ochrochloron. Co-cultivation of the fungus with Bacillus subtilis yielded another new natural product, a butyrolactone congener, ochrochloronic acid (2) and the known fungal metabolite striatisporolide A. Chemical structures of all isolated compounds were confirmed based on HRESIMS as well as, extensive 1D and 2D NMR spectral analyses. Absolute configuration of 1 was established by comparing the experimental ECD with those of known analogues. Results of this study highlight the potential of marine fungi as sources of new natural products and demonstrates the efficiency of fungal-bacterial co-cultivation as a promising tool to induce the immense biosynthetic capabilities of silent BGCs.