New antitumoral cyclic astin analogues containing uncoded amino acid residues:synthesis,structural and biological studies

摘要

The antitumor chlorine-and allo Thr-containing cyclic pentapeptides named astins A,B,and C,were isolated often the roots of A.Tataricus.Their structures,solved by a combination of X-ray,NMR,computational techniques [1] and chemical degradation,consist of a 16-membered ring system containing a unique beta,gmamma dichlorinated prline[Pro(Cl)_2],several uncoded aminoacid residues and a cis configuration in one of the amide bonds.