Journal of Organic Chemistry
Journal of Organic Chemistry
5 years ago

Cyclic Hexapeptide Dimers, Antatollamides A and B, from the Ascidian Didemnum molle. A Tryptophan-Derived Auxiliary for l- and d-Amino Acid Assignments

Cyclic Hexapeptide Dimers, Antatollamides A and B, from the Ascidian Didemnum molle. A Tryptophan-Derived Auxiliary for l- and d-Amino Acid Assignments
Mariam N. Salib, Tadeusz F. Molinski
Two dimerized cyclic hexapeptides, antatollamides A (1) and B (2), were isolated from the colonial ascidian Didemnum molle collected in Pohnpei. The amino acid compositions and sequences were determined by interpretation of MS and 1D and 2D NMR data. Raney Ni reduction of antatollamide A cleaved the dimer to the corresponding monomeric cyclic hexapeptide with replacement of Cys by Ala. The amino acid configuration of 1 was established, after total hydrolysis, by derivatization with a new chiral reagent, (5-fluoro-2,4-dinitrophenyl)-Nα-l-tryptophanamide (FDTA), prepared from l-Trp, followed by LCMS analysis; all amino acids were found to be l-configured except for d-Ala.

Publisher URL: http://dx.doi.org/10.1021/acs.joc.7b01659

DOI: 10.1021/acs.joc.7b01659

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