Biosynthetic studies of novel polyketides from the marine sponge-derived fungusStachylidiumsp. 293K04

The marilones and marilines are a new family of polyketide metabolites recently isolated from the marine-derived fungus Stachylidium sp. 293K04. They are characterized by a phthalide and phthalimidine skeleton, respectively. From a series of feeding experiments using 13C-labeled precursors we could outline the biogenetic origin of the basic carbon skeleton of marilone A and mariline B. Results established the tetraketide nature of the phthalide/phthalimidine nucleus including the involvement of a methylated acetate starter unit in polyketide biosynthesis, which is unique amongst fungal metabolites.