Isolation and structure elucidation of 34-sulfatobastadin 13, an inhibitor of the endothelin A receptor, from a marine sponge of the genus Ianthella.

34-Sulfatobastadin 13 [1] was isolated from the sponge Ianthella sp. Its structure was elucidated by nmr techniques and chemical transformation to bastadin 13 [2]. Compound 1 weakly inhibited binding to the endothelin A receptor (ETA), while compound 2 inhibited growth of Bacillus subtilis.