We have designed and evaluated 45 linear analogues of the natural constrained cyclopeptide TMC-95A. These synthetically less demanding molecules are based on the tripeptide sequence Y-N-W of TMC-95A. Structural variations in the amino acid side chains and termini greatly influenced both the efficiency and selectivity of action on a given type of active site. Inhibition constants were submicromolar (K-i approximate to 300 nM) despite the absence of the entropically favorable constrained conformation that is characteristic of TMC-95A and its cyclic analogues. These linear compounds were readily prepared and reasonably stable in culture medium and could be optimized to inhibit one, two, or all three proteasome catalytic sites. Cytotoxicity assays performed on a series of human tumor cell lines identified the most potent inhibitors in cells.
We have designed and evaluated 45 linear analogues of the natural constrained cyclopeptide TMC-95A. These synthetically less demanding molecules are based on the tripeptide sequence Y-N-W of TMC-95A. Structural variations in the amino acid side chains and termini greatly influenced both the efficiency and selectivity of action on a given type of active site. Inhibition constants were submicromolar (K-i approximate to 300 nM) despite the absence of the entropically favorable constrained conformation that is characteristic of TMC-95A and its cyclic analogues. These linear compounds were readily prepared and reasonably stable in culture medium and could be optimized to inhibit one, two, or all three proteasome catalytic sites. Cytotoxicity assays performed on a series of human tumor cell lines identified the most potent inhibitors in cells.
Synthesis of Macrocyclic Peptide Analogues of Proteasome Inhibitor TMC-95A
作者:Alexandra Berthelot、Sandrine Piguel、Gwennaël Le Dour、Joëlle Vidal
DOI:10.1021/jo035256c
日期:2003.12.1
The synthesis of three constrained macrocyclic peptide analogues 1 of TMC-95A as potential proteasome inhibitors is described. The key step involves a Ni(0)-mediated macrocyclization of tripeptides 2 bearing halogenated aromatic side chains for the formation of the biaryl junction. In addition, an enantioselective preparation of l-7-bromotryptophan methyl ester 3 using a Corey-O'Donnell alkylation