Studies On Chemical Constituents Of Rhododendron Phaeochrysum Var. Agglutinatum

This paper consists of two chapters. The first one introduces the chemical constituents of Rhododendron phaeochrysum var. agglutinatum, and the second chapter summarizes the progress in the chemistry and biological activity of the genus Rhododendron.R. phaeochrysum var. agglutinatum belongs to the genus Rhododendron which is a cosmopolitan genus of the Ericaceae family. It distributes in western Sichuan, northwestern Yunnan and southeastern Tibet. The plant has been applied in traditional Tibetan medicine to treat various diseases, such as rheumatism and scrofula.So far, there are a few investigations on the chemical constituents of the plant that only four flavonoids were reported. As a continuous research on the genus Rhododendron, phytochemical studies on R. phaeochrysum var. agglutinatum were carried out. Fractionation of an ethanol extract of this plant afforded fourteen compounds, including a new phenolic glycoside, (2R)-4-(4’-methoxyphenyl)-2-butanol-2-O-a-L-arabinofuranosyl-(1→6)-β-D-glucopyranoside (1), seven known phenolics, (2R)-4-(3’,4’-dihydroxyphenyl)-2-butanol (2), rhododendrol (3), rhododendrin (4), (+)-isolariciresinol (5), (-)-lyoniresinol (6), lyoniresnol-9’-O-β-D-xylopyranoside (7), (2S,3R)-2,3-dihydro-3-hydroxylmethyl-7-methoxy-2-(4’-hydroxyl-3’-methoxyphenyl)-5-benzofuranpropanol-3a-O-a-L-rhamnopyranoside(8), four known triterpenoids, a-amyrin (9), oleanolic acid (10), betulinic acid (11), ursolic aldehyde (12), and two other compounds,5β,6a-dihydroxy-3β-(β-D-glucopyranosyloxy)-7-megastigmen-9-one (13), and (3R,9S)-megastigman-5-en-3,9-diol-3-O-β-D-glucopyranoside (14). Their stuctures were identified by spectroscopic methods and by comparison of their spectroscopic data with those reported.