Anthrone oxygenase; part of the gene cluster that mediates the biosynthesis of monodictyphenone, a prenyl xanthone derivative (PubMed:20139316, PubMed:21351751, PubMed:22730213). The pathway begins with the synthesis of atrochrysone thioester by the polyketide synthase (PKS) mdpG (PubMed:20139316). The atrochrysone carboxyl ACP thioesterase mdpF then breaks the thioester bond and releases the atrochrysone carboxylic acid from mdpG (PubMed:20139316). The atrochrysone carboxylic acid is then converted to atrochrysone which is further transformed into emodin anthrone by mdpH-1 and mdpH-2 (PubMed:20139316). Emodin is further modified to yield monodictyphenone via several steps involving mdpB, mdpC mdpJ, mdpK and mdpL (PubMed:20139316, PubMed:21351751). These enzymes with xptA, xptB and xptC are also proposed to be involved in the synthesis of shamixanthone from emodin (PubMed:22730213). Especially, direct reduction of emodin by the short chain dehydrogenase mdpC followed by dehydration catalyzed by the scytalone dehydratase-like protein mdpB gives loss of oxygen and formation of chrysophanol intermediate in two simple steps (PubMed:22730213). emodin anthrone + O2 = emodin + H(+) + H2O Secondary metabolite biosynthesis. Impairs the production of monodictyphenone, but leads to the accumulation of endocrocin (PubMed:20139316, PubMed:21351751). Belongs to the anthrone oxygenase family. The predicted gene ANIA_10022 has been split into 2 genes: mdpH-1 and mdpH-2. The predicted gene AN0151 has been split into 2 genes: ANIA_10022 and ANIA_10035. ANIA_10022 has been further split into mdpH-1 and mdpH-2.