Phenolic compounds from the leaves of Breynia officinalis and their tyrosinase and melanogenesis inhibitory activities.

From the EtOAc-soluble fraction of a MeOH extract of the leaves of Breynia officinalis, five new compounds (1-5) along with 11 known compounds (6-16) were isolated. The structures of the new compounds were elucidated by spectroscopic methods and compounds 1-3 were found to be acylated hydroquinone apiofuranosylglucopyranosides, while compound 4 was an acylated hydroquinone glucopyranoside. Compound 5 was shown to be butyl p-coumarate and this seems to be its first isolation from a natural source. The tyrosinase inhibitory activity of all of the isolated compounds was assayed, and the activity was significant in p-coumarate derivatives. The most active compound, compound 3, also inhibited melanogenesis in an in vivo whole animal model, zebrafish.