Periplocin, the most anti-proliferative constituent of Periploca sepium, specifically kills liposarcoma cells by death receptor mediated apoptosis

Background: During a screening of Chinese plants traditionally used for the treatment of cancer and related diseases, extracts of the root bark of Periploca sepium Bunge showed strong cytotoxic activity. Purpose: Isolate and identify cytotoxic compounds from P. sepium and investigate the effects and mechanism of action on different cancer cell lines. Methods: Extracts obtained with solvents of different polarities of the root bark of P. sepium were tested for their anti-proliferative effects. The most active extract was subjected to activity-guided fractionation using different chromatographic methods. The most active compound was further investigated on sarcoma cell lines regarding its effects concerning apoptosis, DNA damage and death receptor expression. Results: We isolated the cardiac glycosides periplocin, glucosyl divostroside, periplogenin, periplocymarin and periplocoside M with periplocin exhibiting the lowest IC50 value against leukemia and liposarcoma cells. Liposarcomas are rare tumors within the heterogeneous group of soft tissue sarcomas and respond poorly to conventional treatments. Periplocin led to growth inhibition and apoptosis induction by changing the expression of death receptors and inducing DNA double strand breaks in SW-872 cells. Conclusion: Periplocin displays a promising mechanism of action in sarcoma cells because altering the death receptor expression is an interesting target in sarcoma treatment especially to overcome TRAIL resistance.