Exploring the beneficial effects of curcumin-based hydrogel beads in rats with rheumatoid arthritis induced by Freund's complete adjuvant.

The aim of this study was to examine the potential antioxidant activity of curcumin in therapeutic and preventive condition and its potential role as adjuvant to conventional drug methotrexate in treatment of rheumatoid arthritis (RA). The study included 104 female Wistar albino rats, 6 weeks old, body weight of 200-250 g, which were divided into 8 groups (n=13 in each group): 1. CTRL: negative control, 2. CUR: positive control 1 (curcumin 200 mg/kg three times a week for 4 weeks per os), 3. MTX: positive control 2 (methotrexate 0,75 mg/kg i.p. two times a week for 4 weeks), 4. RA: positive control 3 (induced RA), 5. RA+pCUR: rats with induced RA + preventive administration of curcumin (curcumin 200 mg/kg three times a week for 4 weeks per os before the induction of RA), 6. RA+tCUR: rats with induced RA + curcumin therapy, 7. RA+MTX+pCUR; rats with induced RA + preventive administration of curcumin + methotrexate 0.75 mg/kg i.p. twice weekly for 4 weeks, 8. RA+MTX+tCUR: rats with induced RA + therapeutic administration of curcumin + methotrexate 0.75 mg/kg i.p. twice weekly for 4 weeks. Potential therapeutic effect of curcumin (200 mg/kg three times a week for 4 weeks orally) and RA induction were initiated on the same day; for preventive protocol, curcumin was administered 4 weeks before the start of RA induction at a dose of 200 mg/kg orally three times a week. Rheumatoid arthritis was triggered by administering 0.1 ml of Complete Freund's Adjuvant (CFA) subcutaneously at the base of the rat tail. Rats were sacrificed 28 days after immunization. During the experimental period, we collected data for arthritis score, radiography testing, and blood sample collecting for specific biochemical analysis for prooxidative and antioxidative parameters (superoxide anion radical, hydrogen peroxide, nitric oxide, index of lipid peroxidation, superoxide dismutase, catalase, and reduced glutathione). Our experimental study confirmed that the therapeutic administration of curcumin reduced disease activity and significantly increased the activities of antioxidative enzymes and reduced prooxidants. Also, preventive administration, especially in combination with methotrexate, offers superior protection by limiting the onset and development of oxidative stress. These findings support the claim that curcumin as turmeric can effectively inhibit inflammatory reactions and reduces symptoms through changing the redox status. Future large randomized controlled trials on the effects of turmeric substance are needed.