Antioxidant Effect of Silymarin on Cisplatin-Induced Renal Oxidative Stress in Rats

Silymarin (SIL) is a natural occurring antioxidant and has a free radical scavenging property. Cisplatin (CDDP) is a chemotherapeutic agent associated with nephrotoxicity. This study aims at investigating the antioxidant effect of SIL against CDDP-induced oxidative stress and renal toxicity in rat kidney. Thirty rats were divided into 5 groups of 6 animals each. The first group (G1) received no chemical treatment, G2 injected with 0.15 mL vehicle (propylene glycol and saline) intraperitoneally (i.p.), G3 injected with a single dose of CDDP 5 mg kgG1, i.p. only at the first day, G4 received SIL (50 mg kgG1 dayG1, i.p.) 2 h after a single dose of CDDP (5 mg kgG1; i.p.) and G5 received SIL (50 mg kgG1 dayG1, i.p.) 2 h before a single dose of CDDP (5 mg kgG1; i.p.). On day fifteen, animals sacrificed, serum and/or kidney tissues were used to determine renal functional markers (serum urea, creatinine), oxidative stress index (lipid peroxidation: Malondialdehyde), antioxidant enzyme activities (superoxide dismutase, SOD; glutathione peroxidase, GPx) and light microscopical analysis. The CDDP-induced oxidative stress was indicated by a marked increase in: Serum urea and creatinine concentration and tissue MDA and a significant reduction in SOD and GPx activities. The CDDP also caused severe histopahtological changes and histochemical depletion of total protein contents in kidney cells. Results suggest that pretreatment with SIL protect kidney tissues fully against CDDP toxicity, since renal markers, MDA levels; activities of antioxidant enzymes, histological and histochemical features were restored to normal levels. Hence, SIL could be a promising nephroprotective and antioxidant agent for reducing CDDP-induced renal oxidative stress and toxicity.