Evaluation of 3,4-dihydroquinazoline-2(1H)-thiones as inhibitors of alpha-MSH-induced melanin production in melanoma B16 cells.

Novel 3,4-dihydroquinazoline-2(1H)-thiones (QNTs) 1 were found to be potent inhibitors of alpha-MSH-induced melanin production. The effect of QNTs to inhibit melanin formation in B16 melanoma cells was screened in the presence of alpha-MSH. In defining the mechanism of activity, the effects on tyrosinase activity, on tyrosinase synthesis and on the depigmentation of melanin were evaluated. QNTs did not affect the catalytic activity of tyrosinase, but rather acted as an inhibitor of tyrosinase synthesis.