Novel Benzo[d]imidazole-2(3H)-thiones as Potent Inhibitors of the α-Melanocyte Stimulating Hormone Induced Melanogenesis in Melanoma B16 Cells

Abstract

In order to determine the optimum size of heterocycle of lead compound 1 (6-methyl-3-phenethyl-3,4-dihydro-1H-quinoline-2-thione; IC₅₀=0.8 μM) for inhibition of melanogenesis, we have synthesized and evaluated some benzimdazole-2(3H)-thiones 5a—e. The preliminary bioassay has shown that the benzimdazole-2(3H)-thione motif of 5 is essential structural unit for their inhibitory activity. Among all thiones 5a—e, the compound 5d strongly inhibited the formation of melanin with IC₅₀ value of 1.3 μM.