Anti-rheumatoid arthritis sesquiterpenoids from the roots of Lindera glauca

Lindera glauca (Siebold et Zucc.) Blume, a traditional medicinal plant used to treat rheumatoid arthritis (RA) in China, requires the effective characterization of its active components. Chemical investigation on the roots of L. glauca led to the discovery of 14 undescribed sesquiterpenoids, linderglandins A-N (1-14), and 15 known analogs (15-29). The structures of these compounds were elucidated by NMR spectroscopic data, HRESIMS, ECD calculations and single-crystal X-ray diffraction analyses. Structurally, a series of undescribed guaiane-type, cadinane-type and eudemane-type sesquiterpenoids were isolated. Linderglandins A and B (1 and 2) were unusual guaiane-type norsesquiterpenoids and linderglandin M (13) was the first cadinane-type dinorsesquiterpenoid. Compounds 1-8, 10-12, 14-18, 20-29 were tested for anti-RA activity on TNF-α-induced MH7A cells, and compounds 6, 7, 16 and 17 exhibited potential activity with IC₅₀ values of 11.56, 12.54, 8.61, and 15.78 μM, respectively. The above results suggest that sesquiterpenoids were the potential active components of L. glauca for treating RA.