Effects of Naringenin on Experimentally Induced Rheumatoid Arthritis in Wistar Rats

Naringenin is one of the most important and abundant known flavonoids found in grapefruit and other citrus fruits. This experimental study aimed to assess the clinical effects and immune responses of naringenin in the animal model of rheumatoid arthritis (RA) according to various reports on its anti-inflammatory effects and modulation of the immune system. To this end, 40 Wistar rats in the weight range of 160-180g were randomly assigned to four groups (n=10) including healthy, control, naringenin, and methotrexate orally treated groups. To induce RA disease, a compound of 200 μl of Freund's adjuvant and collagen type II was injected subcutaneously into the rear footpads of rats. The severity of RA clinical signs was assessed based on a standard scoring method. The treatment lasted for three weeks (days7-28 after induction). The obtained data pointed out that the levels of C-reactive protein (CRP), myeloperoxidase, nitric oxide, IL-17, and IFN-γ cytokines significantly increased in the RA rats, while the level of their serum antioxidants significantly reduced, compared to the healthy rats. The inflammation of the paws and the level of CRP decreased similarly in both methotrexate and naringenin-treated groups. In the naringenin-treated group, a further decrease was detected in serum myeloperoxidase, nitric oxide, and the total antioxidant capacity occurred, as compared to the methotrexate-treated rats. Nonetheless, IL-17 and IFN-γ cytokines levels were further decreased in the methotrexate-treated group. Accordingly, it can be concluded that naringenin can be effectively used for the reduction of inflammatory effects and control of RA disease.