The mechanistic insights into the role of pH and solvent on antiradical and prooxidant properties of polyphenols - Nine compounds case study

Polyphenols are the most widely intake exogenous antioxidants. Their properties prevent the accumulation of radicals in the body and the development of oxidative stress, a recognized trigger for some diseases and a manifestation of others. Nonetheless, apart from their beneficial effects, polyphenols might also exhibit proox-idant potential, often observed as the oxidation of transition state metals, resulting in amplified radical pro-duction. DFT studies at the B3LYP/6-311++G(d,p) level of theory were conducted on nine common polyphenolic compounds to assess both activities in physiologically relevant media. It has been found that there is a fine line between antioxidant and prooxidant character, and increasing pH values promote the occurrence of the latter. Anthocyanidins proved to be the most potent radical scavengers, particularly under slightly alkaline conditions, followed by flavonoids and phenolic acids last. Antiradical activity is better in a polar solvent than in apolar one, due to the possibility of dissociation.

Automated summary

Polyphenols are widely consumed exogenous antioxidants that can prevent the accumulation of radicals and oxidative stress. However, they may also have prooxidant potential, resulting in increased radical production. DFT studies on nine common polyphenolic compounds showed that there is a fine line between antioxidant and prooxidant activities and that higher pH values promote prooxidant behavior. Anthocyanidins were found to be the most potent radical scavengers, followed by flavonoids and phenolic acids. The antiradical activity is higher in polar solvents due to the possibility of dissociation.