Effects of cichoric acid extract from Echinacea purpurea on collagen-induced arthritis in rats

Cichoric acid extract (CAE) from Echinacea purpurea L. was used to investigate the anti-arthritic effect by using collagen-induced arthritis (CIA) rat model. The hind paw swelling volume and the body weight were measured and recorded. All the drug solutions were administered orally to rats for a total of 28 days. On day 28, the rats were anaesthetized and decapitated. The thymus and spleen were weighed for the determination of the organ index. The concentration of tumor necrosis factor alpha (TNFα), interleukin-1 beta (IL-1β) and prostaglandin E2 (PGE-2) in the serum was measured using commercially available ELISA kits. Total and phosphor-NF-κB and Cox-2 protein expression in synovial tissues were determined by histological slides quantification and western blot analysis. Our data showed that administration of all doses of CAE (8, 16, and 32 mg/kg) significantly decreased the paw swelling, restored body weight gain and decreased the organ index of the thymus and spleen compared with that of the CIA group. CAE (8, 16, and 32 mg/kg) treatment significantly reduced the levels of TNFα, IL-1β and PGE-2 in serum compared with the CIA group. Histopathological analysis demonstrated that CAE has obvious anti-arthritic activity. In addition, CAE (32 mg/kg) significantly decreased the levels of nuclear factor-κB (NF-κB), TNFα and cyclooxygenase 2 (Cox-2) in synovium tissues of the ankle joint compared with the CIA group. Furthermore, CAE administration significantly decreased the protein expression of phosphor-NF-κB and Cox-2 in synovium tissues of the knee joint compared with the CIA group. The results suggest that the anti-inflammatory activity of CAE may account for its anti-arthritic effect, and CAE could be a potential therapeutic drug for the treatment of rheumatoid arthritis (RA).