Cardenolide Glycosides of Thevetia peruviana and Triterpenoid Saponins of Sapindus emarginatus as TRAIL Resistance-Overcoming Compounds

A screening study for TRAIL resistance-overcoming activity was carried out, and activity-guided fractionations of Thevetia peruviana and Sapindus emarginatus led to the isolation of four cardenolide glycosides (1-4) and four triterpenoid saponins (5-8), respectively. In particular, cardenolide glycosides (1 and 2) from T peruviana were shown to have a significant reversal effect on TRAIL resistance in human gastric adenocarcinoma cells, and real-time PCR showed that thevefolin (2) enhanced mRNA expression of death receptor 4 (DR4) and DR5. In addition, H-1 and C-13 NMR characterizations are shown for thevefolin (2) for the first time.