Stereocontrolled total syntheses of isodomoic acids G and H via a unified strategy.

Marine neuroexcitatory compounds isodomoic acids G and H were efficiently synthesized from a common intermediate using a silicon-based cross-coupling reaction. Dividing each target compound into the core fragment and the side-chain fragment enabled the synthesis to be convergent. The trans-2,3-disubstituted pyrrolidine core fragment was accessed through a diastereoselective rhodium-catalyzed carbonylative silylcarbocyclization reaction of a vinylglycine-derived 1,6-enyne. A stereochemically divergent desilylative iodination reaction was developed to convert the cyclization product to both E- and Z-alkenyl iodides, which would eventually lead to isodomoic acid G and isodomoic acid H, respectively. The late-stage alkenyl-alkenyl silicon-based cross-coupling reaction uniting the core alkenyl iodides and the side-chain alkenylsilanol was achieved under mild conditions. Finally, two mild deprotections afforded the target molecules.

Class-specific pro-apoptotic effect of statins on human vascular endothelial cells.

Neonangiogenesis represents an important step in tumor development and propagation. Statins may have anticancerogenic potential by blocking vascular endothelial cell growth. The antiproliferative effect of four statins on human endothelial cells was compared, concomitantly delineating a possible pro-apoptotic process. All four statins tested, i. e. atorvastatin, fluvastatin, lovastatin, and simvastatin inhibited cell proliferation. Nearly complete blocking of cell proliferation was achieved at a concentration of 10 microM. We were able to demonstrate that the antiproliferative effect of the statins is not due to cytotoxicity but rather to an apoptotic effect as demonstrated by comparison of cytotoxicity assay and apoptosis assay. The apoptotic mechanism seems to involve caspases, since the statins significantly enhanced caspase activity at dosages of 10 and 20 microM. Further experiments revealed a downregulation of the pro-apoptotic protein Bcl-2. Our data indicate that statins may class-specific inhibit angiogenesis at high dosages which can contribute to prevention of tumor development and progression.