Abstract: Three plants,Cynanchum wilfordii,Cynanchum auriculatum and Cynanchum bungei,have been used for traditional Chinese medicine as "Bai-Shou-Wu" or "Ge-Shan-Xiao" for a long time,in which the one of main bioactive components are C₂₁-steroids.Since all of three plants contain caudatin,deacymetaplexigenin,kidjolanin,gagamine and their glycosides,which can be used as the standard components for qualitative and quantitative controls of these plants.In this study,HPLC analytic technology was used to detect the contents of the four C₂₁-steroids,providing the method of qualitative and quantitative controls guiding the scientific usage of these medicinal herbs.The average content of C₂₁-steroids in each gram of crude drug (mg/g) was investigated.As the results,the content of caudatin in C.wilfordii (before hydrolysis/after hydrolysis=0.3542/9.7142) was highest than other two species (before hydrolysis/after hydrolysis=0.2577/4.0825 for C.auriculatum,and before hydrolysis/after hydrolysis=0.0734/0.1895 for C.bungei ),while the content of kidjolanin in C.auriculatum (before hydrolysis/after hydrolysis=0.1102/0.6094) was highest one among three species (before hydrolysis/after hydrolysis=0.0751/0.3225 for C.bungei,and before hydrolysis/after hydrolysis=0.0736/0.2813 for C.wilfordii).However,the contents of gagamine and deacymetaplexigenin in the three species were not obvious difference.

Key words: Cynanchum wilfordii, Cynanchum auriculatum, Cynanchum bungei, caudatin, kidjolanin