Isolation and structure of hemibastadinols 1-3 from the Papua New Guinea marine sponge Ianthella basta

Further investigation of the Bismarck Archipelago (Papua New Guinea) marine sponge Ianthella basta for biologically active constituents has led to the isolation of hemibastadins 1 (2), 2 (3), and 3 (4) and the new brominated tyrosine derivatives hemibastadinols 1-3 (9, 13, and 14). Isolation and structure elucidation of the monomethyl ether derivatives (7 and 8) of hemibastadins 1 and 2 and the 3-bromotyramine amide of oxalic acid amide (1a) concluded our chemical investigation of I. basta. The hemibastadins and hemibastadinols represent important biosynthetic links to a series of bromotyrosine tetramers collectively known as the bastadins. The antimicrobial activity of the bastadins, hemibastadins, and hemibastadinols is summarized.