A new lignan glucoside from stems and branches of Rhododendron ovatum / 中国中药杂志

Ten lignans were isolated from the ethanol extract of stems and branches of Rhododendron ovatum through column chromatography over silica gel, ODS, Sephadex LH-20, and MCI-gel resin and semi-preparative RP-HPLC. The structures of all compounds were elucidated by extensive spectroscopic data analysis(UV, IR, HR-ESI-MS, ECD and NMR) as(-)-4-epi-lyoniresinol-9'-O-α-L-rhamnopyranoside(1),(+)-lyoniresinol-3α-O-α-L-rhamnopyranoside(2),(+)-5'-methoxyisolariciresinol-9'-O-α-L-rhamnopyranoside(3),(-)-lyoniresinol-3α-O-β-D-glucopyranoside(4),(+)-lyoniresinol-3α-O-β-D-glucopyranoside(5),(-)-4-epi-lyoniresinol-9'-O-β-D-glucopyransoide(6), racemiside(7), neociwujiaphenol(8),(+)-syringaresinol(9), and homohesperitin(10). Among them, compound 1 was a new aryltetralin-type lignan. All the isolated lignans were tested for antioxidant activities in Fe~(2+)-cysteine induced rat liver microsomal lipid peroxidation in vitro, and compounds 8 and 9 showed antioxidant activities on the formation of malondiadehyde(MDA) in rat liver microsomes at 1×10~(-5) mol·L~(-1), with significant inhibitory rates of 75.20% and 91.12%, respectively.

The chemical constituents of Rhododendron ovatum Planch / 药学学报

Aim To study the chemical constituents of Rhododendron ovatum Planch. Methods The chemical constituents were isolated and purified by silica gel column chromatography and identified on the basis of their physiochemical and spectral data. Results Seven compounds were isolated and identified. Their structures were established as 3,5,7-trihydroxylchromone 3-O-β-D-xylopyranoside (I), taraxerol (II), β-sitosterol (III), betulinic acid (IV), quercetin (V), quercetin-3-O-α-L-rhamnopyranoside (VI), and D-glucose (VII). Conclusion Compound I is a new compound. Compounds II-VII were isolated from this plant for the first time.