Phenylethanoid and phenylpropanoid glycosides with melanogenesis inhibitory activity from the flowers of Narcissus tazetta var. chinensis.

A methanol extract of the flowers of Narcissus tazetta var. chinensis Roem. (Amaryllidaceae) demonstrated inhibitory effects on melanogenesis in theophylline-stimulated murine B16 melanoma 4A5 cells. From the extract, four new phenylethanoid glycosides, tazettosides A–D (1–4), and a new phenylpropanoid glycoside, tazettoside E (5), were isolated along with 23 known compounds (6–28). Of the isolates, 1 (IC50 = 22.0 μM) and 4 (82.5 μM), 3-methoxy-8,9-methylenedioxy-3,4-dihydrophenanthridine (13, IC50 = 28.5 μM), 5,6-dihydrobicolorine (14, 23.7 μM), tazettine (16, 60.8 μM), benzyl β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside (18, 27.8 μM), 2-(3,4-dimethoxyphenyl)ethyl β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside (21, 74.6 μM), 3-phenylpropyl β-D-glucopyranoside (22, 59.0 μM), and cinnamyl β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside (24, 88.0 μM) showed inhibitory effects without notable cytotoxicity at the effective concentrations.