A new melanin biosynthesis inhibitor, melanoxadin from fungal metabolite by using the larval haemolymph of the silkworm, Bombyx mori.

Melanin biosynthesis in insects involves the following three key steps: oxidation of tyrosine to dopa by monophenoloxidase (tyrosinase), conversion of dopa to dopachrome by diphenoloxidase and formation of melanin by polymerization of dopachrome.1] Whenthe larval haemolymphof Bombyxmori is exposed to air, it changes from pale yellow to black. This color change is based on melanin formation, by which tyrosine in the haemolymph is oxidized by tyrosinase. We have devised a screening system to search for melanin biosynthesis inhibitors from fungal metabolite using the larval haemolymph of the silkworm, Bombyx mori as an experimental animal model and demonstrated that this screening is an useful method to find the inhibitor.2) We found that a strain of Trichoderma sp. ATF-606 isolated from a soil sample collected at Nikko city, Tochigi Prefecture, Japan produced a new melanin biosynthesis inhibitor, melanoxadin. In this communication we report the production, isolation, structure elucidation and