Potential neurotrophic activity and cytotoxicity of selected C21 steroidal glycosides from Cynanchum otophyllum

Cynanchum otophyllum was traditionally used for treating muscle and skeletal pain, epilepsy, abdominal pain, and tightness. Four known C21 steroidal glycosides, namely caudatin 3-O- β -cymaropyranoside ( 1 ), caudatin 3-O- β -D-cymaropyranosyl-(1 → 4)- β- D-cymaropyranoside ( 2 ), otophylloside B ( 3 ), and otophylloside A ( 4 ) were isolated from the roots of this plant and their neurotrophic activities were examined in rat neuronal PC12 cell model, while their cytotoxicities were evaluated in human cancer cells and normal fibroblasts. Differential promoting effects on neurite-bearing cells were found among testing compounds, with 2 the most potent. On the other hand, selective cytotoxicity against human colon cancer cells HCT-116 of 2 was firstly demonstrated here. Besides, 2 induced inhibitory activities on cancer cell proliferation, sphere formation and interfered the cell cycle. The new potential pharmacological activities of 2 on colon cancer cells were revealed in the present study.