RESUMO
Flavonoids are polyphenol compounds abundantly found in plants and reported to have an inhibitory effect on amyloidfibrillation. The number and position of hydroxyl groups, as well as the arrangement of flavonoids rings, may influencetheir inhibitory effects. In this study, we investigate the effect of structural characteristics of flavonoids on amyloid fibrilformation. For this purpose, five compounds (i.e., biochanin A, daidzein, quercetin, chrysin and fisetin) were selected thatrepresent a variety in the number and position of their hydroxyl groups. The inhibitory effect of these flavonoids on theamyloid fibril formation of apo-carbonic anhydrase (apo-BCA), as a model protein, was evaluated using thioflavin T andtransmission electron microscopy. The results showed that fisetin possessed the most significant inhibitory effect. Interestingly, upon apo-BCA acetylation, none of the tested flavonoids could inhibit the fibrillation process, which indicates thatthe interactions of these compounds with the amine groups of lysine residues could be somewhat important