Two new tryptamine-derived alkaloids, named as leptoclinidamide ( 1) and (-)-leptoclinidamine B ( 2), were isolated from an Indonesian ascidian Leptoclinides dubius together with C 2-α-D-mannosylpyranosyl-L-tryptophan ( 3). The structure of 1 was assigned on the basis of spectroscopic data for 1 and its N-acetyl derivative ( 4). Compound 1 was an amide of tryptamine with two β-alanine units. Although the planar structure of 2 is identical to that of the known compound (+)-leptoclinidamine B ( 5), compound 2 was determined to be the enantiomer of 5 based on amino acid analysis using HPLC methods. Compounds 1 to 4 were evaluated for cytotoxicity against two human cancer cell lines, HCT-15 (colon) and Jurkat (T-cell lymphoma) cells, but none of the compounds showed activity.
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