Study of the Interaction Between the Amyloid Beta Peptide (1-40) and Antioxidant Compounds by Nuclear Magnetic Resonance Spectroscopy

Amyloid beta peptide (Aβ) aggregation leads to the senile plaque formation, a process that is strongly influenced by oxidative stress and is considered as the molecular basis of various neurodegenerative diseases, such as Alzheimer's Disease (AD). Endogenous antioxidants or dietary derived compounds may down-regulate this process. In this study, the interaction of two antioxidants, oleuropein (OE) and melatonin (M) with Aβ, is monitored through NMR spectroscopy and Mass Spectrometry. The concerted application of these two analytical techniques provides new experimental evidence and residue-specific insights into the interacting Aβ peptide amino acids that are implicated in this process. Both antioxidant compounds interact in a similar way with the peptide and cause chemical shift variations. The most pronounced resonance changes have been observed for the (1)H-(15)N signals of N-terminal region and Leu(17)-Phe(20) residues, as monitored by NMR titration studies.