Obtaining and characterizing peptides with neuroprotective activity

Abstract

The Alzheimer's Disease (AD) is a progressive and irreversible neuropathology that has been affected more and more people, especially over 65 years old. The progression of the disease results from the aggregation of amyloid-² peptide, their assembly into amyloid fibrils and the consequent formation of senile plaques. In parallel, activation of the resident immune cells of the central nervous system (microglia) can occur, with the release of inflammatory cytokines. Thus, in the last years, several studies have been targeted on new antifibrillar and anti-inflammatory agents for therapeutic applications. Based on current knowledge, some metallic ions, such as copper, iron, and zinc, are considered to trigger the ²-amyloid peptide aggregation. Therefore, our hypothesis is that mineral chelating agents, as bioactive peptides of food origin, may promote the reduction of fibrils formation, as well as act in the inhibition of neuroinflammation. This study aims to obtain and characterize new whey peptides with neuroprotective activity, acting in some factors closely related to the establishment and development of the AD. For this purpose, it will be evaluated the peptides from bovine whey protein. Whey protein isolate (WPI) will be hydrolyzed with Alcalase® and ultrafiltered to obtain peptides with low molecular mass (MM < 5 kDa). The peptides with metal-binding ability (Cu, Fe, and Zn) will be isolated by immobilized metal affinity chromatography (IMAC), in an FPLC system, and sequenced by mass spectrometry (MALDI-TOF/TOF). The peptides will be evaluated by in vitro assays of aggregation of amyloid-ß peptides inhibition, in the presence or absence of metal ions, and microglia activation assays using cell culture model. The peptides will be also evaluated by their antioxidant (ORAC and DNA protection) and anticholinesterase activities, related to the decrease in oxidative stress and the decrease of the acetylcholine degradation, respectively. The peptides whose show positive results can be synthesized and evaluated for their neuroprotection potential using the same techniques described. This project proposes to identify bioactivities not yet studied to whey peptides, providing a subsidy for future studies in the treatment of neurodegenerative diseases with food-derived peptides.