Anti-inflammatory neolignans from the roots of Magnolia officinalis

Nine neolignan derivatives (1-9) were characterized from the roots of Magnolia officinalis, and their structures were elucidated based on spectroscopic and physicochemical analyses. Among them, houpulins E (1) and M (9) possess novel homo- and trinor-neolignan skeletons. In addition, 15 known compounds (10-24) were identified by comparison of their spectroscopic and physical data with those reported in the literature. Some of the purified constituents were examined for anti-inflammatory activity and, among the tested compounds, houpulins G (3), I (5), J (6), and 2,2'-dihydroxy-3-methoxy-5,5'-di-(2-propenylbiphenyl) (19) significantly inhibited superoxide anion generation and elastase release with IC₅₀ values ranging from 3.54 to 5.48 μM and 2.16 to 3.39 μM, respectively. Therefore, these neolignan derivatives have tremendous potential to be explored as anti-inflammatory agents.