New oxindole alkaloids with selective osteoclast inhibitory activity fromGelsemium elegans

A new alkaloid 14-hydroxygelseziridine (1), along with four known oxindoles (2-5), was isolated and characterized from the well-known toxic medicineGelsemium elegans. Their structures were elucidated by means of spectroscopic techniques and quantum chemistry calculations. Structurally, new compound1 has a three membered oxygen ring atN-4/C-20. All compounds were tested for osteoclast (MOC-1) inhibitory activityin vitro. Compound2 exhibited the selective osteoclast inhibitory activity. Flow cytometry revealed that the apoptosis of osteoclasts induced by2. Furthermore, the PCR bioassay suggested that compound2 may activate the apoptotic pathway of osteoclasts by reducing the expression of IL-6 and c-Jun, and increasing caspase 9. This work provided the evidence for the rationality as the traditional treatment for bone related diseases ofG. elegans, and shed a new light on its further research.