4'-O-beta-D-Glucopyranosyl-quercetin-3-O-beta-D-glucopyranosyl-(1 -> 4)-beta-D-glucopyra-noside (3) was isolated from Helminthostachys zeylanica root extract as a melanogenesis acceleration compound and was synthesized using rutin as the starting material. Related compounds were also synthesized to understand the structure-activity relationships in melanin biosynthesis.
Melanogenesis activities of the glycosides were determined by measuring intracellular melanin content in B16 melanoma cells. Among the synthesized quercetin glycosides, quercetin-3-O-beta-D-glucopyranoside (1), quercetin-3-O-beta-D-glucopyranosyl-(1 -> 4)-beta-D-glucopyranoside (2), and 3 showed more potent intracellular melanogenesis acceleration activities than theophyline used as positive control in a dose-dependent manner with no cytotoxic effect. (C) 2014 Elsevier Ltd. All rights reserved.