FAD-dependent monooxygenase; part of the gene cluster that mediates the biosynthesis of elsinochrome C, a perelyenequinone phytotoxin structurally similar to cercosporin (PubMed:28251756, PubMed:30809363). The first step of elsinochrome C biosynthesis is performed by the polyketide synthase elcA which catalyzes the formation of nor-toralactone (PubMed:28251756, PubMed:30809363). The starter unit acyltransferase (SAT) domain of elcA initiates polyketide extension by the selective utilization of acetyl-CoA, which is elongated to the heptaketide in the beta-ketoacyl synthase (KS) domain by successive condensations with six malonyl units introduced by the malonyl acyltransferase (MAT) domain (By similarity). The product template (PT) domain catalyzes C4-C9 and C2-C11 aldol cyclizations and dehydrations to a trihydroxynaphthalene, which is thought to be delivered to the thioesterase (TE) domain for product release (By similarity). The bifunctional enzyme elcB then methylates nor-toralactone to toralactone before conducting an unusual oxidative aromatic ring opening (PubMed:28251756, PubMed:30809363). The next step in perylenequinone biosynthesis is an O-methylation at the nascent OH-6 of the elcB product performed by the O-methyltransferase elcD (PubMed:30809363). The oxidative coupling of the two monomeric naphthol units in perylenequinone biosynthesis is catalyzed by the FAD-dependent monooxygenase elcE and the multicopper oxidase elcG (PubMed:30809363). ElcG might catalyze the first intermolecular coupling in a regio- and stereo-selective manner via a phenol radical coupling mechanism and the elcE could forge the second C-C bond intramolecularly via a hydride transfer mechanism (PubMed:30809363). The fasciclin domain-containing protein elcF might also play a role duting this step (Probable). The last piece of the puzzle in the biosynthesis of elsinochrome C is the additional annulation by enolate coupling to afford the dihydrobenzo(ghi)perylenequinone system, catalyzed by the FAD-dependent monooxygenase elcH (PubMed:30809363). Secondary metabolite biosynthesis. Belongs to the paxM FAD-dependent monooxygenase family.