This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Tsuda, M. Articles by Sugimura, T. Search for Related Content PubMed PubMed Citation Articles by Tsuda, M. Articles by Sugimura, T.

Marked Increase in the Urinary Level of N-Nitrosothioproline after Ingestion of Cod with Vegetables¹

Biochemistry Division, National Cancer Center Research Institute, 1-1, Tsukiji 5-chome, Chuo-ku, Tokyo 104, Japan

When five volunteers were given food containing cod and vegetables (a traditional Japanese food, called tara-chiri), their urinary excretion of N-nitrosothioproline increased from 7.9 ± 4.2 (SD) µg/day to 110 ± 64.5 µg/day. This increase was accounted for by in vivo nitrosation of thioproline by nitrite formed from nitrate in the vegetables. This finding was confirmed by results on a volunteer who ate boiled cod and Japanese radish (daikon) (a simple version of the food containing cod and vegetables). Boiled cod was found to contain 300–500 µg/100 g of thioproline, and the level nearly doubled when the cod was boiled with Japanese radish. This increase occurred during the cooking of cod with Japanese radish by the reaction of formaldehyde in the cod with cysteine in the Japanese radish. The nitrosation of thioproline was estimated to be 1000-fold that of proline in the human body. Thus thioproline is a very sensitive probe of in vivo nitrosation. Thioproline formation either in vivo or in vitro may have the following two roles in reducing tumorigenesis in humans: (a) detoxication of formaldehyde, which is genotoxic; and (b) blocking the formation of carcinogenic N-nitroso compounds by trapping nitrite and then being excreted in the urine.

¹ This work was supported in part by a Grant from the Princess Takamatsu Cancer Research Fund; a grant from the Ito Memorial Foundation; Grants-in-Aid for Cancer Research from the Ministry of Education, Science and Culture of Japan; and a Comprehensive 10-Year Strategy for Cancer Control from the Ministry of Health and Welfare of Japan.

² To whom requests for reprints should be addressed, at Biochemistry Division, National Cancer Center Research Institute, 1-1, Tsukiji 5-chome, Chuo-ku, Tokyo 104, Japan.

³ Foreign Research Fellow of the Foundation for Promotion of Cancer Research, Tokyo, Japan. Present address: Institute of Toxicology and Chemotherapy, German Cancer Research Center, Im Neuenheimer Feld 280, 6900 Heidelberg, Federal Republic of Germany.

Received 1/15/88. Revised 4/18/88. Accepted 4/20/88.