Cytotoxic activity and G2/M cell cycle arrest mediated by antofine, a phenanthroindolizidine alkaloid isolated from Cynanchum paniculatum.

Starting with an extract derived from the root of Cynanchum paniculatum Kitagawa (Asclepiadaceae) that was active in the process of inhibiting the growth of human cancer cells in culture, a phenanthroindolizidine alkaloid antofine was isolated and identified as an active principle (IC50 = 7.0 +/- 0.2 ng/ml for A549, human lung cancer cells; IC50 = 8.

Induction of apoptosis by 1,4-phenylenebis(methylene)selenocyanate in cultured human colon cancer cells.

Using a cultured human colon cancer cell line (Col 2), a structurally diverse group of chemopreventive agents was evaluated for their potential to induce apoptosis. As a result, 1,4-phenylenebis(methylene)selenocyanate (p-xylylselenocyanate; p-XSC) was found to be active in this process. p-XSC, a synthetic organoselenium compound, has been shown to inhibit tobacco-specific 4-(methylnitrosoamino)-(3-pyridyl)-1-butanone-induced tumorigenesis in A/J mouse lung, rat tongue carcinogenesis and colon cancer.