Yaping Shen

The antineoplastic ether lipid, s-phosphonate, selectively induces apoptosis in human leukemic cells and exhibits antiangiogenic and apoptotic activity on the chorioallantoic membrane of the chick embryo.

Introduction: We investigated the cytotoxic and antiangiogenic activity of the ether lipid, 2′-(trimethylammonio)ethyl 4-(hexadecyloxy)-3(S)-methoxybutane-phosphonate (termed s-phosphonate). Method: Cytotoxicity was determined using an XTT bioassay. Apoptosis was measured by either DNA fragmentation or immunolabelling techniques. Angiogenesis was measured using the in vivo chorioallantoic membrane (CAM) of the chick embryo. Results: s-phosphonate was selectively cytotoxic towards the human leukemic cell lines, HL-60 and AML-14, whereas leukemic K-562 cells and the murine mast cell line, MC-9, were resistant to this agent at concentrations as high as 50 μM. This selectivity resulted from the induction of apoptosis (or programmed cell death) by s-phosphonate in HL-60 and AML-14 cells but not in resistant K-562 or MC-9 cells. S-phosphonate induced localized antiangiogenic effects and membrane thinning in the CAM. This concentration-dependent antiangiogenic effect was associated with apoptosis in the CAM as measured by DNA fragmentation in extracted CAM tissue. The localized areas of membrane thinning and antiangiogenesis on the CAM caused by s-phosphonate were also the only areas of the membrane in which apoptosis occurred. Conclusion: We conclude that s-phosphonate selectively induces apoptosis in human leukemic cells and exhibits antiangiogenic and apoptotic activity on the CAM.

STUDIES TOWARD THE SYNTHESIS OF CONTIGNASTEROL: FUNCTIONALIZATION OF THE STEROIDAL A,B RING SYSTEM

ABSTRACT The synthesis of androstane-3α,4β,6α,7β-tetrol-17-one (2), a potentially key intermediate for the preparation of contignasterol (1), was achieved by functionalization of the A,B-ring portion of the readily available androst-4-ene-3,17-dione (3).