Chemical constituents of Rhododendron lepidotum.

An unusual natural product named 2,4,6-trihydroxacetophenone-3, 5-di-C-beta-D-glucoside (18) were isolated from aerial parts of Rhododendron lepidotum grows in Tibet, along with other 17 known compounds: hopenol-B (1), lupeol (2), ursolic acid (3), avicularin (4), quercetin (5), myricetin (6), hyperoside (7), myricetin-3'-O-beta-D-xyloside (8), (+)-taxifolin-3-O-alpha-L-arabinopyranoside (9), (+)-taxifolin-3-O-beta-D-glucopyranoside (10), lyoniside (11), confluentin (12), 2-(4-hydroxyphenyl)-ethyltriacontanoate (13), 2, 6-dimethoxy-4-hydroxyphenyl-1-O-beta-D-glucopyranoside (14), (-)-2-hydroxy-5-(2-hydroxyethyl) phenyl-O-beta-D-glucopyranoside (15), (-)-isola-riciresinol (16) and isofraxoside (17). All the compounds were firstly isolated from this plant as well as compounds 1, 13-18 were reported occurrence in R. spp. for the first time. The structures were identified based on analyses of spectroscopic data and physico-chemical evidences.