Cytochrome P450 monooxygenase; part of the gene cluster that mediates the biosynthesis of ilicicolin H, a 4-hydroxy-2-pyridonealkaloid that has potent and broad antifungal activities by inhibiting the mitochondrial respiration chain (PubMed:30905148). IccC catalyzes the ring expansion of the tetramate intermediate to the acyclic 2-pyridone intermediate that contains the trans bis-diene chain (PubMed:30905148). The biosynthesis of ilicicolin H starts with formation of the tetramic acid by the hybrid PKS-NRPS synthetase iccA with the partnering trans-enoyl reductase iccB since iccA lacks a designated enoylreductase (ER) domain. The cytochrome P450 monooxygenase iccC then catalyzes the ring expansion of the tetramate to the acyclic 2-pyridone. The pericyclase iccD further converts the acyclic 2-pyridone into 8-epi-ilicicolin H. Finally, the epimerase iccE converts 8-epi-ilicicolin H into ilicicolin H via epimerization. IccA to iccE are sufficient for ilicicolin H biosynthesis and the roles of the remaining enzymes, iccF, iccG and iccH within the pathway have still to be determined (PubMed:30905148) (Probable). (3E,5S)-3-[(2E,4E,8S,10E,12Z)-1-hydroxy-4,8-dimethyltetradeca-2,4,10,12-tetraen-1-ylidene]-5-[(4-hydroxyphenyl)methyl]pyrrolidine-2,4-dione + O2 + reduced [NADPH--hemoprotein reductase] = 3-[(2E,4E,8S,10E,12Z)-4,8-dimethyltetradeca-2,4,10,12-tetraenoyl]-4-hydroxy-5-(4-hydroxyphenyl)-1,2-dihydropyridin-2-one + 2 H2O + oxidized [NADPH--hemoprotein reductase] Mycotoxin biosynthesis. Belongs to the cytochrome P450 family.