Kápolna Emese, Fodor Péter
Department of Applied Chemistry, Corvinus University of Budapest, Budapest, Hungary.
Int J Food Sci Nutr. 2007 Jun;58(4):282-96. doi: 10.1080/09637480601154335.
Three sample preparation methods--proteolysis to determine the initial species distribution, and an in vitro gastric and gastrointestinal digestion to assess the bioavailability of selenium--were applied to extract the selenium from selenized green onion and chive samples. Ion exchange chromatography was coupled to a high-performance liquid chromatography-ICP-MS system to analyze the selenium species of Allium samples. The difference in the selenium accumulation capability of green onions and chives was significant. Chive accumulated a one order of magnitude higher amount of selenium than did green onion. After proteolysis of both types of Allium plants, high amounts of organic selenium species such as MeSeCys, SeCys2 and SeMet became accessible. In the case of Se(VI)-enrichment, selenate was the main species in the proteolytic extract. After simulating the human digestion, the organic species were just slightly bioavailable compared with the results from proteolysis. The inorganic selenium content of the selenized samples increased significantly and SeOMet could be detected from the extracts. As an effect of the significant pH change between the gastric and the intestinal tracts, two oxidation processes took place: selenite oxidized to selenate, while SeMet oxidized to SeOMet.
采用三种样品制备方法——蛋白水解以确定初始物种分布，以及体外胃和胃肠道消化以评估硒的生物利用度——从富硒葱和韭菜样品中提取硒。离子交换色谱与高效液相色谱-电感耦合等离子体质谱系统联用，分析葱属样品中的硒物种。葱和韭菜在硒积累能力上存在显著差异。韭菜积累的硒量比葱高一个数量级。对这两种葱属植物进行蛋白水解后，大量的有机硒物种如甲基硒代半胱氨酸、硒代半胱氨酸和硒代蛋氨酸变得可及。在富硒（VI）的情况下，硒酸盐是蛋白水解提取物中的主要物种。模拟人体消化后，与蛋白水解结果相比，有机物种的生物利用度仅略有提高。富硒样品中的无机硒含量显著增加，并且可以从提取物中检测到硒代蛋氨酸。由于胃和肠道之间显著的pH变化，发生了两个氧化过程：亚硒酸盐氧化为硒酸盐，而硒代蛋氨酸氧化为硒代蛋氨酸砜。
