New Monoterpenoid Indole Hybrids from Gelsemium elegans with Anti‐Inflammatory and Osteoclast Inhibitory Activities

Abstract

Gelsegansymines A (1) and B (2), two new indole alkaloids along with six known analogues (3‐8) were isolated from the aerial parts of Gelsemium elegans. Their structures were elucidated by means of spectroscopic techniques. Structurally, compounds 1 and 2 possessed the rare cage‐like gelsedine skeleton hybrid with bicyclic monoterpenoid. The anti‐inflammatory activities of isolated compounds (1‐3) were tested on LPS induced RAW264.7 cells. Under the treated concentration without toxicity for cells, the cytokines levels of nitric oxide (NO), tumor necrosis factor‐α (TNF‐α) and interleukin‐6 (IL‐6) were evaluated by Griess method and enzyme‐linked immunosorbent assay (ELISA). The results showed that compounds 1‐3 exhibited anti‐inflammatory activities with dose‐dependent manner range from 12.5 to 50 µmol/L. Furthermore, the inhibitory activities of compounds 1 and 2 on receptor activator of NF‐κB ligand (RANKL) induced osteoclast formation were tested in vitro. Compounds 1 and 2 at 5 µmol/L exhibited the significant inhibitory effect on the osteoclastogenesis induced by RANKL. This work reported the anti‐inflammatory and osteoclast inhibitory activities of new monoterpenoid indole hybrids, which may inspire the further light on the related traditional application research of G. elegans.