The flavonolignan-silymarin protects enzymatic, hematological, and immune system against γ-radiation-induced toxicity

Abstract

The main focus of this study is evaluation of radioprotective efficacy of silymarin, a flavonolignan, against γ-radiation-induced damage to hematological, vital organs (liver and intestine), and immune system. Survival studies revealed that silymarin (administered orally for 3 days) provided maximum protection (67%) at 70 mg/kg body weight (b.wt.) against lethal 9 Gy γ-irradiation (dose reduction factor=1.27). The study revealed significant (p < 0.05) changes in levels of catalase (12.57±2.58 to 30.24±4.89 units), glutathione peroxidase (6.23±2.95 to 13.26±1.36 μg of reduced glutathione consumed/min/mg protein), glutathione reductase (0.25±5.6 to 11.65±2.83 pM NADPH consumed/min/mg protein), and superoxide dismutase (11.74±0.2 to 16.09±3.47 SOD U/mg of protein) activity at 30th day. Silymarin pretreated irradiated group exhibited increased proliferation in erythrocyte count (1.76±0.41 × 106 to 9.25±0.24 × 106), hemoglobin (2.15±0.48g/dL to 14.77±0.25g/dL), hematocrit (4.55±0.24% to 37.22±0.21%), and total leucocyte count (1.4±0.15 × 106 to 8.31±0.47 × 106) as compared with radiation control group on 15th day. An increase in CD4:CD8 ratio was witnessed (0.2-1%) at 30th day time interval using flow cytometry. Silymarin also countered radiation-induced decrease (p < 0.05) in regulatory T-cells (Tregs) (11.23% in radiation group at 7th day versus 0.1% in pretreated silymarin irradiated group at 15th day). The results of this study indicate that flavonolignan-silymarin protects enzymatic, hematological, and immune system against γ-radiation-induced toxicity and might prove useful in management of nuclear and radiological emergencies.