A proposed biosynthesis pathway of drosopterins in Drosophila melanogaster

Some ommochrome-deficient mutants of Drosophila melanogaster (v, cn, cd, and st) the xanthine NAD-oxidoreductase-deficient mal mutant, and the double mutants mal v, mal cn, mal cd, and mal st, were analysed for their drosopterin content. Results indicate that xanthommatin and NAD⁺ are involved as cofactors in the transformation process of 7,8-dihydrobiopterin into sepiapterin. A metabolic pathway model for drosopterin biosynthesis that explains the different pterin contents of the mutants studied is now proposed.