Semax, a Synthetic Regulatory Peptide, Affects Copper-Induced Abeta Aggregation and Amyloid Formation in Artificial Membrane Models

Alzheimer's disease, the most common form of dementia, is characterized by the aggregation of amyloid beta protein (A?). The aggregation and toxicity of A? are strongly modulated by metal ions and phospholipidic membranes. In particular, Cu2+ ions play a pivotal role in modulating A? aggregation. Although in the last decades several natural or synthetic compounds were evaluated as candidate drugs, to date, no treatments are available for the pathology. Multifunctional compounds able to both inhibit fibrillogenesis, and in particular the formation of oligomeric species, and prevent the formation of the A?:Cu2+ complex are of particular interest. Here we tested the anti-aggregating properties of a heptapeptide, Semax, an ACTH-like peptide, which is known to form a stable complex with Cu2+ ions and has been proven to have neuroprotective and nootropic effects. We demonstrated through a combination of spectrofluorometric, calorimetric, and MTT assays that Semax not only is able to prevent the formation of A?:Cu2+ complexes but also has anti-aggregating and protective properties especially in the presence of Cu2+. The results suggest that Semax inhibits fiber formation by interfering with the fibrillogenesis of A?:Cu2+ complexes.