Lignans from the flowers of Osmanthus fragrans var. aurantiacus and their inhibition effect on NO production.

A new lignan, (7R,7'R,8R,8'R)-8-hydroxypinoresinol 8-O-β-D-glucopyranoside 4'-methyl ether (7), was isolated from the flowers of Osmanthus fragrans var. aurantiacus along with six known lignans: (+)-phillygenin (1), phillyrin (2), (-)-phillygenin (3), (-)-epipinoresinol-β-D-glucoside (4), taxiresinol (5), and (-)-olivil (6). The structure of the new compound was elucidated on the basis of 1D- and 2D-NMR spectroscopic analysis and specific rotation data. The compounds isolated from the flowers of O. fragrans var. aurantiacus were evaluated for inhibitory activities on nitric oxide production in lipopolysaccharide-stimulated macrophage RAW 264.7 cells. (+)-Phillygenin (1), phillyrin (2), and (-)-phillygenin (3) exerted the strongest inhibitory activities on NO production with IC(50) values of 25.5, 18.9, and 25.5 μM, respectively. These compounds may prove beneficial in the development of natural agents for prevention and treatment of inflammatory diseases.