MELANOXAZAL, NEW MELANIN BIOSYNTHESIS INHIBITOR DISCOVERED BY USING THE LARVAL HEMOLYMPH OF THE SILKWORM, BOMBYX-MORI - PRODUCTION, ISOLATION, STRUCTURAL ELUCIDATION, AND BIOLOGICAL PROPERTIES

A new melanin biosynthesis inhibitor, melanoxazal, was isolated from t he fermentation broth of Trichoderma sp. ATF-451 by successive purific ation procedures of carbon adsorption, ethyl acetate extraction and si lica gel column chromatography. The inhibitor possesses a novel oxazol e-containing structure with molecular formula, C8H9NO3. The structure was determined by means of NMR analyses to be (E)-4-(2'-formyl-3'-hydr oxybuten-1'-yl) oxazole, which is related to melanoxadin. Melanoxazal inhibited melanin formation in the larval haemolymph of the silkworm, Bombyx moil; IC50 value = 30.1 mu g/ml. Melanoxazal also showed a stro ng inhibitory activity against mushroom tyrosinase with IC50 value = 4 .2 mu g/ml.