Botryllamides E-H, four new tyrosine derivatives from the ascidian Botrylloides tyreum.

A specimen of the ascidian Botrylloides tyreum from Palau contained the known metabolites botryllamides A (5) and C (7) together with four new tyrosine derivatives, botryllamides E-H (1-4), the structures of which were elucidated by interpretation of spectroscopic data. The botryllamides exhibited weak cytotoxicity against the HCT-116 cell line.