曲酸的抗氧化作用与辐射损伤防护效应的关系

Study on the relationship between the radioprotective effect and the anti-oxidation of kojic acid

目的 探究曲酸的抗氧化作用与辐射防护效应的关系.方法 将C57小鼠按随机数字表法随机分为健康对照组、模型照射组、曲酸低浓度组及高浓度组.健康对照组不做任何处理,其他组在照前27 h分别皮下单次给予无菌蒸馏水、75及300 mg/kg的曲酸,经4 Gy60Co γ射线单次全身照射,并于照后第3、4、7天处死小鼠,分别测定小鼠血清及肝肾组织中的总超氧化物歧化酶（T-SOD）活力、丙二醛（MDA）含量、股骨骨髓细胞DNA含量及骨髓细胞微核率,并体外测定曲酸对DPPH·自由基的清除作用.结果 曲酸300 mg/kg给药组小鼠血清及肝肾组织中总SOD活力、骨髓细胞DNA含量明显高于模型照射组（F =22.63、7.29、67.58、57.32,P＜0.05）,而其血清及肝肾组织中MDA含量、骨髓细胞微核率明显低于模型照射组（F =26.22、27.06、4.51、14.28,P＜0.05）,体外检测显示曲酸对DPPH·自由基具有明显的清除作用,曲酸、丁基羟基甲苯（BHT）清除DPPH·自由基的IC50值分别为（4.55±0.26）和（1.83±0.10） mg/ml,其浓度同为20 mg/ml时DPPH·自由基清除率分别为（82.38±3.51）％和（96.41±0.45）％.结论 曲酸可清除体内自由基,保护小鼠遗传物质免受射线损伤,从而实现其抗辐射作用.

Objective To evaluate the relationship between the radioprotective effect and the antioxidation of kojic acid and provide experimental evidence for using kojic acid as a potential radioprotective medicine.Methods Male C57BL/6 mice were divided into 4 groups （normal group,irradiation group,low/high doses of kojic acid pretreated groups） by the random digits table method.Mice in normal group without any treatment,and mice in other groups were s.c.injected with a single dose of sterile distilled water,kojic acid （75 and 300 mg/kg,respectively） 27 h prior to a sublethal dose （4 Gy） of whole body gamma-irradiation.20 mice were sacrificed at 3,4,and 7 d post-irradiation,respectively.The activities of total superoxide dismutase （T-SOD） in serums and tissues （liver and kidney）,the level of malondialdehyde （MDA）,and the DNA contents and the frequency of micronuclei in femur bone marrow were assessed,and the radical-scavenging activity of kojic acid against stable DPPH· （2,2-diphenyl-1-picrylhydrazyl） was also determined.Results The activities of T-SOD in serums and tissues （liver and kidney） and the DNA content in bone marrow of mice pretreated with 300 mg/kg body weight of kojic acid were increased significantly （F =22.63,7.29,67.58,57.32,P ＜ 0.05） compared with the irradiation group,while the levels of MDA in serums and tissues （liver and kidney） and the frequency of micronuclei in bone marrow of mice pretreated with 300 mg/kg body weight of kojic acid decreased significantly （F =26.22,27.06,4.51,14.28,P ＜ 0.05） compared with the irradiation group.There was a marked radical-scavenging activity for kojic acid,and the IC50 values （which was defined as the concentration of kojic acid or BHT （2,6-di-tert-butyl-4-methylphenol） causing 50％ inhibition of absorbance） for kojic acid and BHT were （4.55 ± 0.26） mg/ml and （1.83 ± 0.10） mg/ml,respectively,and the results of DPPH· inhibition for kojic acid （20 mg/ml） and BHT （20 mg/ml） were （82.38 ± 3.51）％ and （96.41 ± 0.45） ％,respectively.Conclusions Kojic acid protects the hereditary substances of mice from radiation damage by scavenging free radicals in mice and exerts marked radioprotective effect.