Bastadins, cyclic tetramers of brominated-tyrosine derivatives, selectively inhibit the proliferation of endothelial cells.

Eight bastadins, tetramers of brominated-tyrosine derivatives, were isolated from the marine sponge Ianthella basta, and their anti-proliferative activities against endothelial cells were examined. A structure-activity relationship study of these compounds revealed that a macrocyclic structure was crucial, and a bastarane-type skeleton was important for the selective activity of these bastadins against endothelial cells. A conformational analysis of the bastadins was also carried out by molecular mechanics calculation.