New dibenzocyclooctadiene lignans from Kadsura induta with their anti-inflammatory activity

Five new dibenzocyclooctadiene lignans, named kadsuindutains A-E (1-5), and three known ones schizanrin F (6), schizanrin O (7), and schisantherin J (8) were isolated from the stems of Kadsura induta. Their structures were determined by analyses of HR-ESI-MS, NMR, and ECD spectra. Compounds 1-5 contain a 2',4'-dioxygenated-2',3'-dimethylbutyryl moiety which is rarely reported for dibenzocyclooctadiene lignans. Molecular docking predicted that compounds 1-8 displayed good binding affinity to the active site of iNOS and TNF-α proteins but unstable binding to the active site of COX-2 protein. Additionally, in vitro experiments showed that compounds 1-8 inhibited NO production in LPS-activated RAW264.7 cells with IC₅₀ values from 10.7 μM to 34.0 μM, compared to the positive control L-NMMA (IC₅₀ = 31.2 μM).