Immunosuppressive pregnane glycosides from Periploca sepium and Periploca forrestii

Five pregnane glycosides, periperoxide A–E ( 1– 5) with T cell proliferation inhibitory activity and three oligosaccharides, perisaccharide A–C ( 6– 8) were identified from Periploca sepium and Periploca forrestti. Nine pregnane glycosides containing peroxy functions in their sugar moieties ( 1– 5 and 11– 14), five oligosaccharides ( 6– 10), six pregnane glycosides ( 15– 20), and five cardiac glycosides ( 21– 25) were isolated from the root barks of Periploca sepium Bge. (Asclepiadaceae) and the roots of Periploca forrestii Schltr. (Asclepiadaceae), two traditional Chinese medicines used for the treatment of rheumatoid arthritis. Among them, 1– 8 are hitherto unknown. Their structures were characterized on the basis of spectroscopic analyses. In pharmacological testing, compounds 1– 5 and 11– 14 were found to exhibit inhibitory activity against the proliferation of T lymphocyte in vitro with IC 50 values ranging from 0.29 μM to 1.97 μM, while the other components showed no significant inhibitory activity.