Lemon-Peel extract ameliorates rheumatoid arthritis by reducing xanthine oxidase and inflammatory cytokine levels

Abstract

Abstract We investigated the effect of a lemon-peel extract in a rat model of rheumatoid arthritis and SW1353 chondrocytes. The rats were divided into control (sham), rheumatoid arthritis (control), extract (150 mg/kg bwt) and extract (300 mg/kg bwt) groups. Pyrogallic acid, caffeic acid, eugenol, p-coumaric acid, p‑hydroxyl benzoic acid, resorcinol, salicylic acid, luteoline, quercetin, chrysin, and luteolin-3‑methoxy‑7-rutinoside were noted in the extracts. The extract was administered orally for five consecutive weeks, and antioxidant and inflammatory markers were investigated. Extracts markedly increased the plasma levels of catalase, superoxide dismutase, reduced glutathione, glutathione peroxidase and zinc, and reduced those of lipid peroxidation, nitric oxide, uric acid, ceruloplasmin, copper, matrix metalloproteinase-3 and prostaglandin E2. Moreover, the extracts reduced the serum levels of interleukin-1 beta, tumor necrosis factor-alpha and interleukin-6. Extracts at 50, 100 and 150 mg/L reduced chondrocyte proliferation by 20.9, 38.8, and 52.1%, respectively, and reduced the reactive oxygen species and NF-κB levels by > 40%. Furthermore, the lemon-peel extract at 50, 100 and 150 mg/L reduced the xanthine oxidase level by 0.26-, 0.55- and 0.89-fold, respectively. Taking all these data together, it is suggested the lemon peel extract ameliorated rheumatoid arthritis, reduced the SW1353 chondrocyte proliferation, ROS, inflammatory cytokines, and xanthine oxidase levels.