Abstract

Kasim Mahmood Juma'a, Zheen Aorahman Ahmed, Intesar Tariq Numan and Saad Abdul Rehman Hussain*

Silymarin is a polyphenolic flavonoid derived from milk thistle (Silybum marianum) that has anti-inflammatory, cytoprotective, and anticarcinogenic effects. It has been used medicinally to treat liver disorders including acute and chronic viral hepatitis, toxin/drug induced hepatitis and alcoholic liver disease. The efficacy and dose-response effect of silymarin (125, 250 and 500 mg/kg) were assessed against negative and positive control using formalininduced paw edema in rats as a model of chronic inflammation. In this model, all doses of silymarin were given intraperitonealy (IP) 30 min before induction of inflammation and continued for 7 consecutive days. Paw edema was measured before and 6 days after induction of inflammation using vernier caliper method and balance method. Silymarin in 250 and 500 mg/kg significantly lowered paw edema (P < 0.05) in both methods and found to be comparable with that produced by the reference drug dexamethazone and significantly different from that produced by acetyl salicylic acid and silymarin 125 mg/kg (P < 0.05). Therefore, silymarin exerts anti-inflammatory activity in rat model of chronic inflammation which was significantly increased as the dose increased up to 500 mg/kg.