Oxidation effects in antiaggregogenic properties of Epigallocatechingallate

Epigallocatechin-gallate (EGCG), the most abundant flavonoid in green tea, has been extensively studied for its potential in the treatment of amyloid related disorders. This molecule was found to modulate abnormal protein self-assembly, reducing resulting cellular toxicity. EGCG is known to suppress or to slow down the aggregation processes of several proteins, thus supporting the idea that general mechanisms regulate its anti-aggregogenic effects and, interestingly, in the oxidised form it demonstrated an higher efficiency in reducing protein aggregation with respect to intact molecule. We here investigate the effects of intact and oxidized EGCG the thermal aggregation pathway of Bovine Serum Albumin (BSA), a well-known model protein whose aggregation processes are known in details. By means of different spectroscopic methods, we evaluate similarities and differences of the two molecules during protein aggregation. Different solution conditions are investigated, close and away from the isoelectric point of the protein, with the aim of eliciting the role of electrostatics in the observed EGCG-Protein interaction and in the supramolecular assembly which are dramatically dependent on solution conditions.