THERMAL DEGRADATION OF QUERCETIN IN AQUEOUS SOLUTION

Quercetin is the most abundant dietary flavonol with the right structural features for free radical scavenging activity and due to its positive impact on human health it can be used as nutraceutical or food supplement. It has been shown that quercetin degrades at ambient temperatures in aqueous solutions and is susceptible to oxidation. Named degradation can be accelerated upon heating and/or the addition of metal catalysts. Except proton abstraction, the oxidative degradative mechanism involves C-ring opening, which leads to the formation of lower molecular weight phenolic carboxylic acids. In this study, we investigated the thermal degradation of quercetin at 100 °C and at different times (2, 30, 60, 90, 120 min). The thermal degradation of quercetin was monitored by LC-MS/MS. The results showed that quercetin degraded at 100 °C and that longer heating times accelerated the degradation. Furthermore the longest heating time studied yielded higher amounts of byproducts. The main thermal by-product is 3, 4-hydroxybenzoic acid, followed by 3, 5-dihydroxybenzoic acid and 2, 4, 6-trihydroxybenzoic acid. According to the obtained results we confirmed the thermal degradation reaction of quercetin in aqueous solution.