Quercetin derivatives regulate melanosome transportation via EPI64 inhibition and elongate the cell shape of B16 melanoma cells

4′-O-β-d-glucopyranosyl-quercetin-3-O-β-d-glucopyranosyl-(1→4)-β-d-glucopyranoside (3C4′GQ), first isolated from Helminthostachys zeylanica root extract, was synthesized as a compound that stimulates intracellular melanogenesis. 3-O-methylquercetin (3MQ) and 3,4′,7-O-trimethylquercetin (34′7TMQ) were synthesized as compounds that enhance extracellular melanin formation. The formation of dendrites and the expression of EBP50-PDZ interactor of 64 kDa (EPI64) relating to melanin transportation were investigated using B16 melanoma cells treated with 3C4′GQ, 3MQ, or 34′7TMQ in order to understand the mechanism underlying the observed activities. The influence of 3C4′GQ on the increase of intracellular melanin contents enhanced the expression of EPI64, exhibited no dendrite elongation activity, and inhibited melanin transportation. On the other hand, the increase of extracellular melanin content by 3MQ and 34′7TMQ inhibited the expression of EPI64 and formed elongated cells to stimulate melanin transportation.