Four Undescribed Oxygenated Cardiac Glycosides From the Fruits of <i>Thevetia peruviana</i> With Their Anticancer Activities

Phytochemical investigation of the extract from Thevetia peruviana fruits resulted in the isolation of 20 cardiac glycosides (1-20), including four previously undescribed compounds (1-4). Their chemical structures were elucidated through comprehensive spectroscopic analyses and quantum chemical calculations. Structurally, compounds 1-4 are neriifolin derivatives featuring an additional hydroxyl group at C-7 (1 and 2), C-17 (3), and C-4 (4) on the aglycone structure, respectively, were identified for the first time in the genus Thevetia. All the isolates were tested for their cytotoxic activities against four human cancer cell lines (MCF-7, HCT-116, HeLa, and HepG2), and their structure-activity relationships were investigated. Of the four previously undescribed compounds, compound 1 demonstrated the strongest cytotoxic effects, with IC₅₀ values ranging from 0.096 to 0.410 µM. Furthermore, compound 1 was found to induce both apoptosis and G2/M phase arrest in a dose-dependent manner toward HepG2 cells.