Dihydromonacolin L monooxygenase; part of the gene cluster that mediates the biosynthesis of lovastatin (also known as mevinolin, mevacor or monacolin K), a hypolipidemic inhibitor of (3S)-hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase (HMGR) (PubMed:10334994, PubMed:12929390, PubMed:21495633). The first step in the biosynthesis of lovastatin is the production of dihydromonacolin L acid by the lovastatin nonaketide synthase lovB and the trans-acting enoyl reductase lovC via condensation of one acetyl-CoA unit and 8 malonyl-CoA units (PubMed:10334994, PubMed:10381407, PubMed:19900898, PubMed:22733743). Dihydromonacolin L acid is released from lovB by the thioesterase lovG (PubMed:23653178). Next, dihydromonacolin L acid is oxidized by the dihydromonacolin L monooxygenase lovA twice to form monacolin J acid (PubMed:12929390, PubMed:21495633). The 2-methylbutyrate moiety of lovastatin is synthesized by the lovastatin diketide synthase lovF via condensation of one acetyl-CoA unit and one malonyl-CoA unit (PubMed:19530726, PubMed:21069965). Finally, the covalent attachment of this moiety to monacolin J acid is catalyzed by the transesterase lovD to yield lovastatin (PubMed:10334994, PubMed:17113998, PubMed:18988191, PubMed:19875080, PubMed:24727900). LovD has broad substrate specificity and can also convert monacolin J to simvastatin using alpha-dimethylbutanoyl-S-methyl-3-mercaptopropionate (DMB-S-MMP) as the thioester acyl donor, and can also catalyze the reverse reaction and function as hydrolase in vitro (PubMed:19875080). LovD has much higher activity with LovF-bound 2-methylbutanoate than with free diketide substrates (PubMed:21069965). dihydromonacolin L carboxylate + O2 + reduced [NADPH--hemoprotein reductase] = H(+) + 2 H2O + monacolin L carboxylate + oxidized [NADPH--hemoprotein reductase] monacolin L carboxylate + O2 + reduced [NADPH--hemoprotein reductase] = H(+) + H2O + monacolin J carboxylate + oxidized [NADPH--hemoprotein reductase] Binds 1 heme group per subunit. Polyketide biosynthesis; lovastatin biosynthesis. Loss of lovastatin biosynthesis. Accelerates degradation of lovastatin precursors. Lovastatin acts as a hypolipidemic agent that works as inhibitor of (3S)-hydroxymethylglutaryl-coenzyme A (HMG-CoA) reductase (HMGR) which reduces HMG-CoA to mevalonate and is the key step in cholesterol biosynthesis (PubMed:6933445). Lovastatin, simvastatin and related compounds are widely used to treat hypercholesteremia and reduce the risk of cardiovascular disease (PubMed:6933445). Furthermore, statins such as lovastatin were found to be anticancer agents (PubMed:29236027, PubMed:29932104). Belongs to the cytochrome P450 family.