Short chain dehydrogenase; part of the gene cluster that mediates the biosynthesis of penigequinolones, potent insecticidal alkaloids that contain a highly modified 10-carbon prenyl group (PubMed:25859931, PubMed:28114276). The first stage is catalyzed by the nonribosomal pepdide synthetase penN that condenses anthranilic acid and O-methyl-L-tyrosine to produce 4'-methoxycyclopeptin (By similarity). 4'-methoxycyclopeptin is then converted to 4'-methoxydehydrocyclopeptin by the ketoglutarate-dependent dioxygenase penM through dehydrogenation to form a double bond between C-alpha and C-beta of the O-methyltyrosine side chain (By similarity). PenM also converts its first product methoxydehydrocyclopeptin to 4'-methoxycyclopenin (By similarity). The following conversion of 4'methoxycyclopenin into 4'-methoxyviridicatin is catalyzed by the cyclopenase penL (By similarity). 4'-methoxyviridicatin is the precursor of quinolone natural products, and is further converted to quinolinone B (Probable). The prenyltransferase penI then catalyzes the canonical Friedel-Crafts alkylation of quinolinone B with dimethylallyl cation to yield dimethylallyl quinolone, which is subjected to FAD-dependent dehydrogenation by the FAD-linked oxidoreductase penH to yield conjugated aryl diene (PubMed:25859931). The delta(3') double bond then serves as the site of the second alkylation with DMAPP catalyzed by the prenyltransferase penG to yield a carbenium ion intermediate, which can be attacked by H(2)O to yield a styrenyl quinolone containing a C3'-hydroxyprenyl chain, or undergo cyclization to yield yaequinolones J1 and J2 (PubMed:25859931). The conversion of the styrenyl quinolone into the tetrahydrofuran-containing yaequinolone C is performed by the FAD-dependent monooxygenase penE and involves epoxidation of the terminal C7'-C8' olefin, followed by epoxide ring opening initiated by the C3' hydroxyl group (PubMed:25859931). The predicted cysteine hydrolase penJ acts as an epoxide hydrolase that enhances the rate of the 5-exo-tet cyclization step, increasing the yield of yaequinolone C (PubMed:25859931, PubMed:28114276). PenF catalyzes the cationic rearrangement of the epoxide formed by penE (before ring opening to produce yaequinolone C) into yaequinolone D (PubMed:28114276). Finally, the short-chain dehydrogenase/reductase (SDR)-like reductase penD, catalyzes both the dehydration of yaequinolone D and the reduction of the resulting oxonium to yield penigequinolone (PubMed:28114276). Secondary metabolite biosynthesis. Alkaloid biosynthesis. Mycotoxin biosynthesis. Belongs to the short-chain dehydrogenases/reductases (SDR) family.