FAD-dependent monooxygenase; part of the gene cluster that mediates the biosynthesis of diterpenoid pyrones (PubMed:32286350). The first step of the pathway is the synthesis of the alpha-pyrone moiety by the polyketide synthase dpmpA via condensation of one acetyl-CoA starter unit with 3 malonyl-CoA units and 2 methylations (Probable). The alpha-pyrone is then combined with geranylgeranyl pyrophosphate (GGPP) formed by the GGPP synthase dpmpD through the action of the prenyltransferase dpmpC to yield a linear alpha-pyrone diterpenoid (Probable). Subsequent steps in the diterpenoid pyrone biosynthetic pathway involve the decalin core formation, which is initiated by the epoxidation of the C10-C11 olefin by the FAD-dependent oxidoreductase dpmpE, and is followed by a cyclization cascade catalyzed by the terpene cyclase dpmpB (Probable). The short chain dehydrogenase/reductase dpmpG then oxidizes the 8S hydroxy group to a ketone and the short chain dehydrogenase/reductase dpmpH reduces the ketone to the 8R hydroxy group to yield higginsianin B (PubMed:32286350). Higginsianin B is further methylated by the methyltransferase dpmpI to produce the intermediate named FDDP B (PubMed:32286350). The cytochrome P450 monooxygenase dpmpJ then oxidizes the C-26 methyl to primary alcohol, producing the final diterpenoid pyrone with a C-26 primary alcohol on the gamma-pyrone moiety named FDDP C (PubMed:32286350). Secondary metabolite biosynthesis; terpenoid biosynthesis. Diterpenoid pyrones display various biological activities and FDDP C shows anti-cancer and anti-HIV activities (PubMed:32286350). FDDP C shows also inhibitory activity of 42-mer-amyloid beta aggregation that is involved in the pathogenesis of Alzheimer's disease (PubMed:32286350). Belongs to the paxM FAD-dependent monooxygenase family.