Impact of Phenolic Compounds on Fibrillogenesis of Human Lysozyme under Physiological Conditions: Inhibition or Promotion?

Numerous compounds have been studied in the search for a potential drug to interrupt the process of formation of the amyloid fibers. Human lysozyme is a good model for studying the formation of amyloid fibers. In this research, the effect of phenolic compounds (caffeic acid, l-tyrosine, pyrogallol, guaiacol, 6-(-toluidino)-2-naphthalenesulfonic, epicatechin, chrysin, quercetin) during the formation of amyloid fibers at physiological conditions (37 °C and pH 7.5) was studied, resulting in inhibition with certain compounds; on the contrary, the formation of fibers was favored by others. Fluorescence experiments were carried out, like thioflavin T and 8-anilino-1-naphthalenesulfonic acid, where the signal change indicates an increase or a decrease of the amyloid fibers. Circular dichroism was made to understand the changes in the second structure produced for the interaction of the phenolic compounds with the lysozyme. Additionally, molecular docking experiments indicate that the interaction of the compounds with specific amino acids of lysozyme is crucial for inhibiting or exerting a higher effect on fiber formation.