Antioxidant Lignans and Chromone Glycosides from Eurya japonica

Four new 8,8',7,2'-lignans, (+)-ovafolinin B-9'-O-beta-D-glucopyranoside (1), (-)-ovafolinin B-9'-O-beta-D-glucopyranoside (2), (+)-ovafolinin E-9'-O-beta-D-glucopyranoside (3), and (-)-ovafolinin E-9'-0-13-o-glucopyranoside (4), two neolignans, eusiderin N (5) and (7S,8R)-3,5,5'-trimethoxy4',7-epoxy-8,3'-neolignan-9,9'-diol-4-O-beta-D-xylopyranoside (6), and two new chromone glycosides, 5,7-dihydroxy-4Hchromen-4-one-3-O-beta-D-glucopyranoside (7) and 5,7-dihydroicy-4H-chromen-4-one-3-0-fl-o-xylopyranoside (8), together with 25 known compounds, were isolated from the stems of Eurya japonica. Structural elucidation of compounds 1-8 was established by spectroscopic methods, especially 2D NMR techniques, electronic circular dichroism data, and comparison with reported data. The isolates were evaluated for antioxidant and anti-NO production activities. Compounds 1, 2, 12-20, and 29 (ED50 23.40 mu M for 1) demonstrated potent antioxidant activity compared to the positive control a-tocopherol (ED50 27.21 yM). On the other hand, compounds 1, 2, 7-9, 12-20, and 32 showed only weak anti-NO production activity when compared to the positive control quercetin.