Impact of Unsaturated Fatty Acids on β-Amyloid Aggregation Mediated by Cholesterol-Rich Membranes and Acetylcholinesterase

Abstract

Alzheimer’s disease (AD) involves a progressive deterioration of neuronal connectivity and synaptic function, driven by multiple interrelated pathological mechanisms. Among these, the aberrant aggregation of β-amyloid (Aβ) peptides and the decline of cholinergic transmission represent two converging hallmarks. Beyond its catalytic role in acetylcholine hydrolysis, acetylcholinesterase (AChE) can also promote Aβ assembly through peripheral binding interactions, thereby amplifying neurotoxic effects. Increasing evidence highlights the critical influence of membrane lipid composition, particularly cholesterol (chol), in modulating these processes. Changes with aging and Alzheimer’s risk factors in chol distribution across membrane leaflets promote lipid environments that enhance Aβ–membrane interactions and facilitate peptide aggregation. Building upon our previous studies in which model membranes with defined chol levels were shown to influence Aβ aggregation, the present work investigates how natural fatty acids (FA) affect peptide aggregation in chol-enriched systems. Using a combination of fluorescence spectroscopy, microscopy, and molecular docking, we evaluated the ability of various FA to inhibit AChE activity and additionally prevent Aβ aggregation. Notably, oleic acid and docosahexaenoic acid (DHA) exhibited the strongest capacity to interfere with Aβ aggregation and AChE catalytic activity, consistent with their predicted interactions at the catalytic anionic site revealed by molecular docking. These effects showed a clear dependence on FA chain length and degree of unsaturation. These findings indicate that specific unsaturated FA modulate membrane topology and alter the lateral distribution of chol, thereby attenuating the membrane-mediated enhancement of Aβ oligomerization and fibrillation, while also targeting AChE activity. Altogether, our results support the potential of FA-based molecules as multifunctional therapeutic candidates for AD.