Differential inhibition of metabolite amyloid formation by generic fibrillation-modifying polyphenols

The formation of ordered amyloid fibrils by proteins and polypeptides is associated with human disorders. A recent extension of the amyloidogenic building block family includes several small metabolites, which form assemblies with structural and functional similarities to well-established amyloids. Here we investigate whether generic amyloid polyphenolic inhibitors can also restrict the formation of metabolite fibrils. We reveal that epigallocatechin gallate and tannic acid inhibit amyloid-like fibrillation of adenine, phenylalanine, and tyrosine. Moreover, the compounds reduce the cytotoxicity triggered by these assemblies. In contrast, acetylsalicylic acid, used as a control does not have an inhibitory effect. The compounds’ differential effects at various time points is consistent with molecular dynamics simulations, providing information about the inhibition mechanisms and inhibitors’ key interactions with the monomeric and subsequent crystalline fibril states. Taken together, we provide additional evidence for the fundamental similarities between protein- and metabolite-based amyloids, the inhibition process and dynamics of association. Small-molecule metabolites can form amyloid fibrils associated with human disease, similar to those formed by proteins. Here the authors show that generic polyphenol inhibitors of protein amyloid formation also inhibit the aggregation of metabolite fibrils and reduce their cytotoxicity.