Monooxygenase that converts norsolorinic acid anthrone to norsolorinic acid during aflatoxin biosynthesis. noranthrone + O2 = H2O + norsolorinic acid Mycotoxin biosynthesis; aflatoxin biosynthesis. Cells accumulate excess amounts of norsolorinic acid (NA) and a small amount of norsolorinic acid anthrone (NAA). Belongs to the anthrone oxygenase family.