Lignans and neolignans from the stems of Vibrunum erosum and their neuroprotective and anti-inflammatory activity.

A new lignan, (7'S,8S,8'S)-3,5'-dimethoxy-3',4,9'-trihydroxy-7',9-epoxy-8,8'-lignan, named vibruresinol (1), was isolated from the stems of Viburnum erosum by silica gel, ODS, and Sephadex LH-20 column chromatography. In addition, four other known lignans, (7'R,8S,8'S)-3,5'-dimethoxy-3',4,8',9'-tetrahydroxy-7',9-epoxy-8,8'-lignan (2), (+)-syringaresinol (3), (+)-pinoresinol (4), and (+)-pinoresinol-4-O-ß-D-glucopyranoside (5), and five known neolignans, herpetol (6), vibsanol (7), (-)-dehydrodiconiferyl alcohol (8), icariside E4 (9), and dihydrodehydrodiconiferyl alcohol (10), were isolated in the same manner. The chemical structures of the compounds were determined based on spectroscopic data including NMR, MS, and IR. All of the compounds described above were isolated from V. erosum for the first time. The isolated compounds 3, 4, and 6 were evaluated for neuroprotective activity on glutamate-induced cell death in HT22 cells and had EC50 values of 6.33 ± 1.22, 6.96 ± 0.65, and 9.15 ± 0.36 µM, respectively. Likewise, the same compounds had inhibitory activity on NO production in LPS-induced RAW 264.7 cells with IC50 values of 8.30 ± 1.56, 7.89 ± 1.22, and 9.32 ± 0.36 µM, respectively.

Re-evaluation of physicochemical and NMR data of triol ginsenosides Re, Rf, Rg2, and 20-gluco-Rf from Panax ginseng roots.

Ginseng roots were extracted with aqueous methanol, and extracts were suspended in water and extracted successively with ethyl acetate and n-butanol. Column chromatography using the n-butanol fraction yielded four purified triol ginseng saponins: the ginsenosides Re, Rf, Rg2, and 20-gluco-Rf. The physicochemical, spectroscopic, and chromatographic characteristics of the ginsenosides were measured and compared with reports from the literature. For spectroscopic analysis, two-dimensional nuclear magnetic resonance (NMR) methods such as (1)H-(1)H correlation spectroscopy, nuclear Overhauser effect spectroscopy, heteronuclear single quantum correlation, and heteronuclear multiple bond connectivity were employed to identify exact peak assignments. Some peak assignments for previously published (1)H- and (13)C-NMR spectra were found to be inaccurate. This study reports the complete NMR assignment of 20-gluco-Rf for the first time.