Oxidized quercetin has stronger anti-amyloid activity and anti-aging effect than native form

Quercetin (QUE) is one of the most widely distributed and used flavonoid. It has many biological activities and pharmacological effect. As a polyhydroxy phenol, QUE is easily oxidized. However, it is unclear how its biology efficacy changes after oxidation. In this study, we prepared QUE oxidation product (QUE-ox) through enzymatic oxidation of QUE. We found the oxidation reduced the antioxidant activity of QUE but increased its anti-amyloid activity in vitro. In C. elegans, oxidation increased the anti-aging effects of QUE. Further experiments showed that both QUE and QUE-ox delayed aging by improving stress resistance, but they have different molecular mechanisms. QUE mainly increased the transcriptional activities of DAF-16 and SKN-1, resulting in the enhancement of expression of oxidative stress resistance genes, and further increased the oxidative resistance in C. elegans. QUE-ox increased the transcriptional activities of DAF-16 and HSF-1 transcription factors to enhance the heat stress resistance. In summary, our study indicated oxidized QUE has stronger anti-amyloid activity and anti-aging effect than native form. This study provides a theoretical basis for the safe and rational application of QUE, especially for its antioxidant, anti-amyloid and anti-aging effects.