Periploca sepium is a decidious plant with simple leaves. The leaves are arranged alternately along the stems. They are ovate with entire margins. The flowers are five-petaled and purple. The plants bloom from June to July. The flowers are arranged in corymbs.  Periploca sepium is native to north China. Periploca sepium Bung, Shrubs deciduous, to 4 m. Petiole to 5 mm; leaf blade ovate-oblong, 5-9 × 1.5-2.5 cm, membranous, base cuneate, apex attenuate; lateral veins 20-25 pairs. Cymes on lateral branchlets, often paired, few flowered. Pedicel ca. 2 cm. Five new C21 steroidal glycosides, named periseosides A–E (1–5), along with six known analogues, were isolated from the root barks of Periplocasepium. Their structures were elucidated on the basis of spectroscopic analysis and chemical evidence. All compounds were evaluated for their immunosuppressive activities.