'Clickable' 2,5-diketopiperazines as scaffolds for ligation of biomolecules: their use in Aβ inhibitor assembly

Org Biomol Chem. 2014 Jul 21;12(27):4964-74. doi: 10.1039/c4ob00541d.

Abstract

The synthesis of 1,3,6-trisubstituted-2,5-diketopiperazine scaffolds bearing up to three 'clickable' sites for further oxime bond or alkyne-azide cycloaddition ligations is described. The orthogonally Boc/Alloc protected DKP precursors prepared from L-lysine residues and an aminohexyl arm are efficiently prepared on a gram scale by sequentially using Fukuyama-Mitsunobu alkylation, dipeptide coupling and diketopiperazine ring formation as key steps. These scaffolds, with their glyoxylyl, aminooxy, alkynyl or azido functions, are "ready-to-use" platforms for biomolecular assembly. Their potentiality in this field was proved through the chemoselective ligation of Aβ-binding motifs, the KLVFFA peptide and the curcumin molecule. The inhibitory effect of these conjugates on Aβ amyloid fibril formation is reported using thioflavin T fluorescence assays and AFM observation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amyloid beta-Peptides / antagonists & inhibitors*
  • Benzothiazoles
  • Curcumin / analogs & derivatives
  • Curcumin / pharmacology
  • Diketopiperazines / chemical synthesis*
  • Diketopiperazines / pharmacology
  • Ligation
  • Thiazoles / chemistry

Substances

  • Amyloid beta-Peptides
  • Benzothiazoles
  • Diketopiperazines
  • Thiazoles
  • thioflavin T
  • Curcumin