Cytotoxic oxasqualenoids from the red alga Laurencia viridis.

Three new polyether squalene derivatives 15-dehydroxythyrsenol A (2), prethyrsenol A (3) and 13-hydroxyprethyrsenol A (4) have been isolated from the red alga Laurencia viridis. Their structures were determined through the interpretation of NMR spectroscopic data and chemical correlations. In addition, four semi-synthetic compounds modulating the solubility of the lead compound dehydrothyrsiferol (1) were prepared without loss of activity. The cytotoxicity of the new compounds exhibited low μM activities. In order to explain their biological properties, docking simulations of the natural and synthetic compounds onto the αvβ3 integrin binding region were carried out.