New Amino Acid Derivatives from the Marine Ascidian Leptoclinides dubius

From the cytotoxic extracts of the marine ascidian Leptoclinides dubius, N -( p -hydroxybenzoyl)- l -arginine ( 1 ), N -(1 H -indolyl-3-carbonyl)- d -arginine ( 2 ), and N -(6-bromo-1 H -indolyl-3-carbonyl)-R, where R is l -Arg ( 4 ), l -His ( 5 ), and the very rare amino acid l -enduracididine ( 3 ), have been isolated and identified by spectroscopic data, hydrolysis, and comparison with authentic samples.