Bioactivity Study of Tricyclic and Tetracyclic Genipin Derivatives as Anti-inflammatory Agents

A series of genipin derivatives included tricyclic cyclopentaimidazopyridine, cyclopentapyridopyrimidine, octahydrocyclopentapyridodiazepine, and tetracyclic decahydrobenzoimidazocyclopentapyridine were synthesized and developed as anti-inflammatory agents. All of them were tested against NO production in LPS-induced RAW264.7 cells. Based on IC₅₀ data and the SAR study, we found that tricyclic cyclopentaimidazopyridines 3d-f and 7-9 presented the better inhibitory activities (≦ 28.1 μM) in comparison with the reference standard Indomethacin (166 μM). On the other hand, all of them showed inactivity for in vitro cyclooxygenase COX-2 inhibition assays and compounds 8 and 9 possessed the cell toxity. To explore the further anti-inflammatory mechanism, Western blot analysis was carried out. Furthermore, compound 3d shown better bioactivity than Indomethacin. The suppression of NF-κB signal pathway by compound 3d was also determined. To sum-up, compound 3d would be the potential anti-inflammatory lead compound.