Shimoi K, Masuda S, Shen B, Furugori M, Kinae N
Laboratory of Food Hygiene, School of Food and Nutritional Sciences, University of Shizuoka, Japan.
Mutat Res. 1996 Feb 19;350(1):153-61. doi: 10.1016/0027-5107(95)00116-6.
Radioprotective effects of tea infusions and plant flavonoids were investigated by using the micronucleus test for anticlastogenic activity and the thiobarbituric acid assay for antioxidative activity. A single gastric intubation of rooibos tea (Aspalathus linearis) infusion at 1 ml per mouse 2 h prior to gama-ray irradiation (1.5 Gy) reduced the frequency of micronucleated reticulocytes (MNRETs). After the fractionation of rooibos tea infusion, the flavonoid fraction was found to be most anticlastogenic and antioxidative. From this fraction, luteolin was isolated as an effective component. Then, anticlastogenic effects of 12 flavonoids containing luteolin and their antioxidative activities against lipid peroxidation by Fenton's reagent were examined. A good correlation (r=0.717) was observed between both activities. Luteolin showed the most effective potency. A gastric intubation of luteolin (10 micromoles/kg) 2 h prior to gamma-ray irradiation (6 Gy) suppressed lipid peroxidation in mouse bone marrow and spleen and a trend of protective effect of luteolin against the decrease of endogenous ascorbic acid in mouse bone marrow after gamma-ray irradiation (3 Gy) was observed. These results suggest that plant flavonoids, which show antioxidative potency in vitro, work as antioxidants in vivo and their radioprotective effects may be attributed to their scavenging potency towards free radicals such as hydroxyl radicals. Therefore, the flavonoids contained in tea, vegetables and fruits seem to be important as antioxidants in the human diet.
通过微核试验检测抗断裂活性以及用硫代巴比妥酸法检测抗氧化活性，对茶浸液和植物类黄酮的辐射防护作用进行了研究。在γ射线照射（1.5 Gy）前2小时，给每只小鼠经胃插管1 ml的路易波士茶（Aspalathus linearis）浸液，可降低微核网织红细胞（MNRETs）的频率。对路易波士茶浸液进行分级分离后，发现类黄酮级分具有最强的抗断裂和抗氧化作用。从该级分中分离出木犀草素作为有效成分。然后，检测了含木犀草素的12种类黄酮的抗断裂作用及其对芬顿试剂诱导的脂质过氧化的抗氧化活性。观察到这两种活性之间具有良好的相关性（r = 0.717）。木犀草素表现出最有效的效力。在γ射线照射（6 Gy）前2小时经胃插管给予木犀草素（10微摩尔/千克），可抑制小鼠骨髓和脾脏中的脂质过氧化，并且观察到木犀草素对γ射线照射（3 Gy）后小鼠骨髓中内源性抗坏血酸减少具有保护作用的趋势。这些结果表明，在体外具有抗氧化能力的植物类黄酮在体内可作为抗氧化剂发挥作用，其辐射防护作用可能归因于它们对羟基自由基等自由基的清除能力。因此，茶、蔬菜和水果中所含的类黄酮作为人类饮食中的抗氧化剂似乎很重要。
