Short-chain dehydrogenase/reductase; part of the gene cluster that mediates the biosynthesis of eupenifeldin, a bistropolone meroterpenoid that acts as an antitumor agent. The first step of eupenifeldin biosynthesis is the biosynthesis of 3-methylorcinaldehyde performed by the non-reducing polyketide synthase eupA. Oxidative dearomatization of 3-methylorcinaldehyde likely catalyzed by the FAD-dependent monooxygenase eupB is followed by oxidative ring expansion by the 2-oxoglutarate-dependent dioxygenase eupC to provide the first tropolone metabolite, tropolone stipitaldehyde (Probable). In parallel, generation of sesquiterpene alpha-humulene from farnesylpyrophosphate (FPP) is catalyzed by the terpene cyclase eupE. The cytochrome P450 monooxygenase eupD then hydroxylates humulene to humulenol. The putative Diels-Alderase eupF probably catalyzes the formation of the tropolone-humulene skeleton by linking humulenol and the polyketide moiety (Probable). The short-chain dehydrogenase/reductase eupG and the flavin-dependent monooxygenase eupH are also essential for eupenifeldin biosynthesis and are likely the additional decorating enzymes of the tropolone-humulene skeleton to produce final eupenifeldin or derivatives (Probable)