PTGS2 and Arthritis: Quercetin is a flavonoid with chemopreventive and therapeutic effects in a variety of diseases, including inhibition of oxidative stress, cytokines and COX2 production.[10] Previous studies have shown that quercetin can reduce pain and inflammation related to arthritis, and inhibit mechanical hyperalgesia, edema, and leukocyte aggregation of the knee joint in mice in a dose-dependent manner.[11] Its mechanisms include inhibition of proinflammatory cytokines (TNF) in human peripheral blood monocytes-α).