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The preparation of aflatoxins labeled with tritium

✍ Scribed by William Lijinsky

Publisher: John Wiley and Sons
Year: 1970
Tongue: French
Weight: 343 KB
Volume: 6
Category: Article
ISSN: 0022-2135
DOI: 10.1002/jlcr.2590060109

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✦ Synopsis

Aflatoxins BI and G1 were labeled with tritium by reaction with tritiated water in the presence of a catalyst. Although considerable decomposition occurred, it was possible to purify the products by thin layer chromatography and crystallization following addition of unlabeled compound. The products were chemically homogeneous and the radiochemical purity was above 82 x,. When the exchange was carried out with a natural aflatoxin mixture, the specific activity of the purified GI was only one-tenth that of the BI. When the aflatoxin GI was tritiated alone, the specific activity after dilution was 194 pCilmg. Similarly, the specific activity of purified tritium labeled aflatoxin B1 was 300 pCilmg. The problems encountered in labeling with tritium such unstable molecules as the aJatoxins are discussed.

Aflatoxin B, is a naturally occurring carcinogen of a very high order of potency (as little as 1 mg has given rise to liver tumors in rats), produced, along with other aflatoxins of similar structure, by several strains of Aspergillus. Because of their unique chemical structure, studies of the metabolism of aflatoxins and of their interaction with the constituents of cells might provide some new insight into the mechanism of carcinogenesis. To enable such studies to be carried out, radioactively labeled compounds were needed and it was decided to attempt to label these compounds with tritium by an exchange procedure (the chemical synthesis being long and complex (l)). Some of the problems encountered in the attempt to prepare these compounds with fairly

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