Ten New Lignans with Anti-inflammatory Activities from the Leaves of Illicium dunnianum

The anti-inflammatory phytochemical investigation of the leaves of Illicium dunnianum led to the isolation of five pairs of new lignans (1-5), and 7 known analogues (6-12). Separation of the enantiomer mixtures 1-5 to 1a/1b-5a/5b were respectively achieved on a chiral column using acetonitrile-water mixtures as eluents. Among them, the planar structures of 1-2 were undescribed previously, and the chiral separation and absolute configurations of 3-5 were firstly reported. Their structures were elucidated by comprehensive spectroscopic data analysis (NMR, HR-ESI-MS, IR, UV) and quantum chemistry calculations (ECD). Moreover, the new isolates were evaluated by measuring their inhibitory effect on NO in LPS-stimulated BV-2 cells. As a result, compounds 1a, 3a, 3b and 5a could partially inhibit NO production in a concentration-dependent manner. Furthermore, Western blot and real-time PCR assays indicated that 1a could down-regulate the mRNA levels of TNF-α, IL-6, COX-2, iNOS and the protein expressions of COX-2 and iNOS. This study could provide some guidance and evidence to the further development and utilization of I. dunnianum.