Myricetin Prevents Fibrillogenesis of Hen Egg White Lysozyme

Myricetin is a natural flavonol found in many grapes, berries, fruits, vegetables, and herbs as well as other plants. Recent studies have identified potential antiamyloidogenic activity for this compound. In this study, the kinetics of amyloid fibril formation by hen egg white lysozyme (HEWL) and the antifibril-forming activity of myricetin were investigated. We demonstrate that myricetin significantly inhibits the fibrillation of HEWL and the inhibitory effect is dose-dependent. Interestingly, the inhibitory effect toward HEWL fibrillation was stronger than that exerted by the previously characterized fibril-forming inhibitor quercetin, which has high structural similarity with myricetin. Spectrofluorometric and computational studies suggest that the mechanism underlying the inhibitory action of myricetin at a molecular level is to reduce the population of partially unfolded HEWL intermediates. This action is achieved by the tight binding of myricetin to the aggregation-prone region of the beta-domain of HEWL and linking to the relatively stable a-domain, thus resulting in the inhibition of amyloid fibril formation.