Advances in studies on C21 steroidal glycosides of plants in Asclepiadaceae Current situation of research on Cynanchi Bungei Radix Study on C21 steroidal glycosides of Cynanchum atratum by LC-MS New C21 Steroidal Glycosides from Marsdenia tenacissima A NOVEL C21 STEROIDAL GLYCOSIDE FROM MARSDENIA INCISA Optimization of the hydrolysis process for C21 steroidal glycoside of Bai Shou Wu by acetic acid with multi-target orthogonal design Determination of C21 steroidal glycosides in total glycosides H from Marsdenia tenaccima Determination of C21 steroidal glycosides in total glycosides H from Marsdenia tenaccima Effect of C21 teroidal glycoside from root of Cynanchum auriculatum on D-galactose induced aging model mice