para-Sulfonatocalix[n]arenes Inhibit Amyloid β-Peptide Fibrillation and Reduce Amyloid Cytotoxicity.

Amyloid β-peptide (Aβ) fibrillation is a major hallmark of Alzheimer's disease (AD). Inhibition of Aβ fibrillation is thus considered to be an effective strategy for AD prevention and treatment. Here we show that para-sulfonatocalix[n]arenes (SC[n]A, n=4, 6, 8), a class of amphiphilic calixarene derivatives, can bind to Aβ42 through nonspecific and multipoint hydrophobic interactions. Their binding leads to a pronounced delay in β-sheet adoption and formation of multiple secondary structures of the peptide, accompanied by changes at the level of the fibrillary architecture. Furthermore, the ζ-potential value of Aβ42 incubated with SC[6/8]A decreased, which correlated with the reduction of amyloid cytotoxicity. Overall, the SC[n]A effectively inhibits Aβ42 fibrillation and reduces amyloid cytotoxicity, and SC[8]A showed the best performance among the three macrocycles, possibly owing to its having the strongest interactions with Aβ42 .