Guaiane‐Type Sesquiterpenes from the Stems of Fissistigma oldhamii

Abstract Two new guaiane‐type sesquiterpenes dysodensiols J and L, one new natural product dysodensiol K together with four known biogenetically related guaiane‐type sesquiterpenes were isolated from the stems of Fissistigma oldhamii . Their structures were elucidated by detailed analysis of NMR, HR‐ESI‐MS, IR and Optical rotations data. Compound 1 contains an uncommon five‐membered ether ring. The inhibitory effect of all compounds on the proliferation of primary synovial cells was evaluated. Compound 3 showed inhibitory activity with an IC 50 value of 6.8 μM. Compounds 5–7 exhibited moderate inhibitory activity with IC 50 values of 23.8, 26.6, and 27.1 μM, respectively.