Science and Education Publishing American Journal of Pharmacological Sciences 2327-672X 2 3 2014 05 12 Silibinin Improves the Anti-arthritic Activity of Methotrexate in Zymosan-Induced Arthritis in Rats 47 51 EN Ahmed Hashem Mortada Saad Abdulrahman Hussain Department of Pharmacology and Toxicology, College of Pharmacy, University of Baghdad, Baghdad, Iraq AJPS2014231 10.12691/ajps-2-3-1 2014 04 25 2014 05 12 2014 05 12 Because of low toxic effects of plant-derived drugs, it has become a research focus in disease prevention and treatment, especially those chronic diseases requiring long-term treatment. The present study was designed to evaluate the effects of silibinin (SIL) when administered with methotrexate (MTX) in animal model of zymosan-induced arthritis in rats. Male Wistar rats are used for induction and arthritic inflammation in the knee joint and hind paw using zymosan. The animals are treated with MTX alone (10 mg/kg), SIL (10mg/kg) or their combination. The effect was followed through edema formation, tissue cytokines release (IL-1β, IL-8, TNF-α) and infiltration of leukocytes in synovial fluid. The results showed that SIL has weak antiarthritic activity when used alone, and improves the antiarthitic activity of MTX when both are concomitantly administered before challenge with zymosan. In conclusion, although SIL has a relatively weak anti-arthritic activity, it strongly augments the effect of MTX in animal model of zymosan-induced arthritis.