Therapeutic effects of Caesalpinia minax Hance on complete Freund's adjuvant (CFA)-induced arthritis and the anti-inflammatory activity of cassane diterpenes as main active components

Ethnopharmacological relevance: Seeds of Caesalpinia minax Hance called 'Ku-Shi-Lian' (KSL) in China have been used as Zhuang or Dai folk medicines for treatment of common cold, fever, rheumatoid arthritis and dysentery for hundred years.

Aim of the study: This study aimed to investigate therapeutic efficacy of KSL extract using complete Freund's adjuvant (CFA) induced arthritis in a rat model and the anti-inflammatory activity of cassane diterpenes as the main active material basis of this herb.

Materials and methods: Arthritis was induced in male Wistar rats (200-220 g) by immunization with CFA. Dexamethasone (DXMS) and Tripterygium glycosides (TG) were chosen as the positive drugs. Water soluble fraction (CMW, 1000 and 2000 mg/kg) and chloroform soluble fraction (CMC, 400 and 800 mg/kg) of KSL were orally administered from day 1 and continued for 21 days. Change of paw swelling perimeter, arthritics score, body weight growth, were observed, and the production of TNF-α, IL-1β and IL-6 in serum were measured by enzyme-linked immunosorbent assay (ELISA). The histological changes in the ankle joint were analyzed in adjuvant induced arthritis rats. Moreover, the inhibitory effect on mRNA expression of proinflammatory cytokine IL-1β, IL-6 and TNF-α of fourteen cassane diterpenes obtained from CMC extract were valued using the RAW 264.7 macrophages cell stimulated by lipopolysaccharide (LPS) assay.

Results: The chloroform soluble fraction (CMC) showed the significantly suppressed change of paw swelling perimeter, arthritics score and increased body weight loss. The overproduction of TNF-α, IL-1β and IL-6 were remarkably suppressed in the serum. Fourteen cassane derivatives as the main constituents of CMC extract showed the promising activity on the expression mRNA of cytokine IL-1β, IL-6 and TNF-α produced by macrophages cells.

Conclusions: In this study, the chloroform soluble fraction of 'KSL' (seeds of C. minax) was found to exert an anti-RA activity significantly in vivo for the first time, which indicted this fraction might be used as a powerful therapeutic agent for arthritis treatments. Cassane diterpenes, as the main constituents in this fraction, showed the anti-inflammation activity through the regulation of cytokine expression, which might be developed as target-agents for this national herb further developing.