Nitrite-trapping capacity of thioproline in the human body.
Nitrite-trapping capacity of thioproline in the human body.
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硫代脯氨酸在人体内的亚硝酸盐捕获能力。
DOI：
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发表时间：
1991
期刊：
影响因子：
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通讯作者：
Y. Kurashima
中科院分区：
文献类型：
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作者：
M. Tsuda;Y. Kurashima
已使用脯氨酸监测人体亚硝化能力;然而，N-亚硝基噻唑烷4-羧酸（NTCA; N-亚硝基硫代脯氨酸）是人体尿液中主要的N-亚硝基化合物之一，也无致突变性，并且可能无致癌性。在体外，硫代脯氨酸的亚硝化速度比脯氨酸快约1000倍，NTCA不经代谢就排泄到尿液中。因此，我们提出硫代脯氨酸作为一种有效的亚硝酸盐捕获剂在人体内。最近，我们在各种熟食中发现了硫代脯氨酸，包括鳕鱼和干香菇。在这里报道的研究中，我们评估了硫代脯氨酸的亚硝酸盐捕获能力的男性非吸烟志愿者摄入NO3-和饮食控制。NTCA排泄的最高水平为5.89 μ mol，在受试者摄入6 mmol NO3-后测量，然后摄入0.45 mmol（60 mg）硫代脯氨酸。我们估计亚硝酸盐的有效量，定义为亚硝酸盐在胃中参与亚硝化的实际量，为NO3摄入量的0.3%。因此，对于6 mmol NO3-摄入的NO2-的有效量计算为18 μ mol，并且通过摄入0.45 mmol硫代脯氨酸捕获了33%的亚硝酸盐。因此，硫代脯氨酸是评价人体亚硝化能力最敏感的探针，也是一种有效的亚硝酸盐捕获剂。
Human nitrosating capacity has been monitored using proline; however, N-nitrosothiazolidine 4-carboxylic acid (NTCA; N-nitrosothioproline), one of the predominant N-nitroso compounds in human urine, is also nonmutagenic and, presumably, noncarcinogenic. Thioproline is nitrosated about 1000 times faster than proline in vitro, and NTCA is excreted into the urine without being metabolized. We have therefore proposed thioproline as an effective nitrite-trapping agent in the human body. Recently, we found thioproline in various cooked foods, including cod and dried shiitake mushrooms. In the study reported here, we evaluate the nitrite trapping capacity of thioproline in a male nonsmoking volunteer ingesting NO3- and eating a controlled diet. The highest level of NTCA excreted, 5.89 mumol, was measured after the subject ingested 6 mmol NO3- followed by 0.45 mmol (60 mg) thioproline. We estimated the effective amount of nitrite, defined as the actual amount of nitrite participating in nitrosation in the stomach, to be 0.3% of the NO3- ingested. Thus, the effective amount of NO2- for 6 mmol NO3- ingested was calculated to be 18 mumol, and 33% of this nitrite was trapped by ingestion of 0.45 mmol thioproline. We conclude that thioproline is a most sensitive probe for evaluating human nitrosating capacity and an effective nitrite-trapping agent.