Anti-arthritic activities of ethanol extracts of Circaea mollis Sieb. & Zucc. (whole plant) in rodents.

ETHNOPHARMACOLOGICAL RELEVANCE: Circaea mollis Sieb. & Zucc., a genus of Circaea that follows Onagraceae, has been used for centuries as a folk herb in traditional Chinese medicine (TCM) and Hani Ethnopharmacy for the treatment of joint swelling and pain in rheumatoid arthritis.

AIM OF THE STUDY: This study was designed to confirm anti-arthritic effects and its underlying mechanism of ethanol extracts of Circaea mollis Sieb. & Zucc. (EEC), which may contribute to provide the pharmacological basis in the treatment of rheumatoid disease.

MATERIALS AND METHODS: Dimethylbenzene (DMB)-induced inflammatory swelling model, hot-plate pain model in mice and Freund's complete adjuvant (FCA)-induced arthritis model in rats were used to evaluate the anti-arthritis effect of EEC. Arthritis severity was done by measuring inflammatory swelling, pain threshol, paw swelling, arthritis index, body weight, spleen index and thymus index. The levels of TNF-α, IL-1β and IL-10 in sera were measured using ELISA. The pathological change of the ankle joint was also done. Phenolic composition of EEC was analyzed.

RESULTS: EEC inhibited inflammatory swelling and increased heat-induced pain threshold in mice. Furthermore, EEC significantly alleviated paw swelling and arthritis index, decreasing the spleen index and thymus index. Besides, EEC down-regulated the serum TNF-α and IL-1β, and increased the production of serum IL-10 in FCA-induced rats. Histopathological examination demonstrated that EEC can effectively relieve synovial hyperplasia, control the infiltration of the inflammatory and protect cartilage from destruction.

CONCLUSION: Our work demonstrated that EEC possessed the potential therapeutic effect against arthritis in rodents which was attributed to modulating proinflammatory cytokines TNF-α, IL-1β and anti-inflammatory factors IL-10. Flavonoids and polyphenols may contribute to the therapeutic effect of EEC on arthritis.