Detection of the Free Radicals Produced by β‐amyloid and its Effects on the Acetylcholinesterase Activity

Abstract

One of the most common neurodegenerative diseases, among people older than 65 years, is Alzheimer's disease (AD). The involved neurotransmitter is acetylcholine (ACh), which in turn is hydrolyzed by acetylcholinesterase (AChE). Therefore, evaluate the AChE catalytic activity is very important; which result gives out the alterations in the concentration of the neurotransmitter. The production of the amyloid β‐42 (Aβ‐42) peptide is another process involved in the AD. Aβ form senile plaques which are producers of hydrogen peroxide (H2O2), which reacts with a transition metal (Fe) via Fenton Reaction. That reaction originates some reactive oxygen species (ROS), such as the hydroxyl radical (·OH). Therefore, it is possible that production of ROS modifies the AChE catalytic activity. In this work the catalytic activity of the enzyme was assessed in presence of H2O2 and FeCl2. Later on, H2O2 was replacing by the βA. The presence of the free radical ·OH was determined using electron paramagnetic resonance spectroscopy (EPR) through the presence of spin adduct which is formed by N‐tert‐butyl‐α‐phenylnitrone (PBN) spin‐trap and the ·OH. No modification on AChE catalytic activity were found for high concentrations both H2O2 and de FeCl2. Likewise, the activity of the enzyme was not affected by βA, which could be due to βA did not produce H2O2. This last fact was corroborated by evaluating the catalytic activity of peroxidase and EPR spectroscopy.