Antiproliferative Terpenes Isolated from Euonymus and Celastrus Species

As part of an ongoing investigation focused on the discovery of anticancer compounds from natural sources found in the southern Appalachian region of the United States, whole plant and root bark extracts of species from the genera Euonymus and Celastrus have been subjected to bioactivity-guided fractionation. Terpenes with antiproliferative activity against mammalian cell lines have been isolated. Most active have been a series of triterpenes including the known compounds celastrol and pristimerin. These compounds exhibit IC₅₀ values against JEG-3 choriocarcinoma cells ranging from 2.2 to 80 µg/mL. The same compounds have lesser activity against a non-tumor cell line (Vero) with IC₅₀ values ranging from 25 to 150 µg/mL, suggesting some selectivity towards diseased cells. A subset of these compounds has displayed activity against gram positive bacteria. Bioactivities and structure elucidation of these terpenes will be presented.