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

Abstract

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-β-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.