Effect of ethanol and aqueous extracts of seed pod of Copaifera salikounda (Heckel) on complete Freund's adjuvant‐induced rheumatoid arthritis in rats

The antirheumatoid arthritis potential of ethanol and aqueous extracts of seed pod of Copaifera salikounda (SPCS) was evaluated using the chicken collagen/complete Freund's adjuvant‐induced arthritic rats model. Adjuvat‐induced rats were treated with varied doses of the extracts (400, 600, and 800 mg/kg body weight) and with reference drug, indomethacin for 21 days. Antiarthritic evaluation was done through measurement of body weight, paw size, inflammatory makers, hematological parameters, cytokines, antioxidant enzymes, reduced glutathione, lipid peroxidation as well as histopathological examinations. Treatment with the ethanol and aqueous extracts of SPCS markedly inhibited the paw size and caused weight gain. The extracts considerably modulated the hematological as well as the antioxidant parameters. Likewise, the extract restored the altered lipid peroxidation, pro‐inflammatory mediators, and inflammatory factors which further accentuate the implication in adjuvant‐induced arthritis. Thus, the ethanol and aqueous extracts of SPCS showed a significant antiarthritic activity that was statistically analogous to that of indomethacin. Practical applications Copaifera salikounda (Heckel) has been used in treatment of different ailments including rheumatoid arthritis in folklore medicine. This is the first reported proof of the antiarthritic potential of the seed pod. Oxidative stress has been implicated in rheumatoid arthritis. Ethanol extract of SPCS has been shown to be predominantly rich in phenols, terpenoids, alkaloids, and flavonoids which are natural antioxidant. The present study has demonstrated that ethanol and aqueous extracts of SPCS can exert antioxidative and antiinflammatory effects, thus strengthening its antiarthritic potentials.