Ten new lignans with anti-inflammatory activities from the leaves of Illicium dunnianum.

The anti-inflammatory phytochemical investigation of the leaves of Illicium dunnianum (I. dunnianum) resulted in the isolation of five pairs of new lignans (1-5), and 7 known analogs (6-12). The separation of enantiomer mixtures 1-5 to 1a/1b-5a/5b was achieved using a chiral column with acetonitrile-water mixtures as eluents. The planar structures of 1-2 were previously undescribed, and the chiral separation and absolute configurations of 3-5 were reported for the first time. Their structures were determined through comprehensive spectroscopic data analysis [nuclear magnetic resonance (NMR), high-resolution electrospray ionization mass (HR-ESI-MS), infrared (IR), and ultraviolet (UV)] and quantum chemistry calculations (ECD). The new isolates were evaluated by measuring their inhibitory effect on NO in lipopolysaccharide (LPS)-stimulated BV-2 cells. Compounds 1a, 3a, 3b, and 5a demonstrated partial inhibition of NO production in a concentration-dependent manner. Western blot and real-time polymerase chain reaction (PCR) assays revealed that 1a down-regulated the messenger ribonucleic acid (mRNA) levels of tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), COX-2, and iNOS and the protein expressions of COX-2 and iNOS. This research provides guidance and evidence for the further development and utilization of I. dunnianum.