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.