Synthesis of d -amino acid peptides and their effect on beta-amyloid aggregation and toxicity in transgenic Caenorhabditis elegans

Genetic, biochemical, and pathological evidence supports that aggregation of amyloid-beta (Aβ) peptide into fibrillar structures rich in beta-sheets is implicated as the cause of Alzheimer’s disease. Therefore, an attractive therapeutic strategy is to prevent or alter amyloid-beta aggregation. In this work we examine the effects of the short d -peptides pgklvya, kklvffarrrra, and kklvffa on Aβ aggregation in vitro and toxicity in vivo. These peptides are based on the central hydrophobic region of Aβ (residues 16–20), which is believed to be crucial in Aβ self-association. The effect of peptides on Aβ aggregation was examined by circular dichroism spectroscopy, Thioflavin T fluorescence, and ANS binding assay. Transgenic Caenorhabditis elegans model was used to evaluate the pharmacological effect of d -peptides on Aβ-initiated toxicity. The data suggested that d -peptides are very effective at inhibiting fibrillogenesis of Aβ. Among the three peptides tested, only pgklvya and kklvffa improved survival in the transgenic C. elegans . The activity of these peptides correlates with their ability to inhibit Aβ oligomerization. These suggest that d -peptides should be considered during future design of peptide-based inhibitors of amyloid deposition and toxicity.