ABSTRACT
Rheumatoid arthritis （RA） is a chronic and systemic autoimmune disease with aggressive and symmetrical polyarthritis as the main clinical manifestations. The exact pathogenesis is unknown. Its basic pathological changes include chronic inflammation of the joint synovium， increased joint cavity effusion， pannus formation， gradual cartilage damage and bone erosion， eventually leading to joint deformity and loss of function. It has been found that the onset and development of RA are related to heredity， environment and other factors. The drugs for RA mainly include non-steroidal anti-inflammatory drugs （NSAIDs）， corticosteroids， disease-modifying anti-rheumatic drugs （DMARDs） and biological agents. However， long-term use of these drugs can cause a variety of side effects and adverse reactions， such as myocardial infarction， peptic ulcer， poor wound healing， and liver and kidney dysfunction. In addition， natural medicines have a good application prospect because of their various pharmacological activities and few side effects. Quercetin is a flavonoid found in Morus alba and tetrandrine， with diverse pharmacological activities， including cardiovascular diseases， joint movement， tumor immunology and so on. Not only have the clinical trials shown good efficacy of quercetin， but the experimental studies have also proven that quercetin can improve RA by reducing inflammatory response， inhibiting the formation of synovial pannus， synovial hyperplasia， neutrophil NETs formation， osteoclast function， regulating Th17/Treg balance and other mechanism. In this article， we will briefly summarize the regulatory mechanism of quercetin and discuss the complexed effect of quercetin on rheumatoid arthritis.