A new and 23 known cardenolide glycosides from Thevetia neriifolia seeds and their cytotoxic activities against human oral carcinoma cell lines.

Phytochemical analysis of Thevetia neriifolia seeds resulted in the isolation of one new (1) and 23 known (2－24) cardenolide glycosides. The structure of 1 was determined based on one- and two-dimensional NMR spectroscopic analysis and acid hydrolytic cleavage reaction. The effect of the cytotoxic activity of 1－24 on three human oral carcinoma cell lines was assessed. The cell lines included Ca9-22 human gingival carcinoma cells, HSC-2 human mouth carcinoma cells, HSC-4 human tongue carcinoma cells, and HGF human gingival fibroblast cells. The isolated compounds had a cytotoxic effect on the carcinoma cells with IC₅₀ values ranging from 0.004 μM to 64.9 μM. The structure-activity relationship is also discussed.