FEED ADDITIVES: METABOLIC STABILITY OF RADIOACTIVE ARSANILIC ACID IN CHICKENS

An investigation of its possible metabolic alterations showed that arsanilic acid is metabolically stable when used in medicated feeds of chickens. The ratio of C/sup 14/ to As/sup 74/ in a double-labeled molecule did not change. Unlike As/sup 74/ acid. Arsanilic acid was found unchanged in excreta. Neither arsenate metabolic products nor reduced forms of arsanilic acid were found in tissues. Residual arsanilic acid in edible tissues was handled like authentic arsanilic acid in second animals. This conclusion is based on experiments done with As/sup 74/ and C/sup 14/-labeled arsanilic acid. In double-labeled C/sup 14/ -, As/sup 74/-arsanilic acid, the two isotopes remained in constant proportions in all the various body compartments. Secondly, there wag no expired As/sup 74/ after administration of arsanilic-As/sup 74/ acid. Thirdly, arsanilic acid was excreted intact. Fourthly, arsenate metabolites were not detected in tissues of chickens given arsanilic acid. Finally, tissues containing arsanilic acid residues were handled like authentic arsanilic acid when fed to second test animals, including man. A rupture of the carbon-arsenic bond in arsanilic-l-C/ sup 14/, -As/sup 74/ acid would leave C/sup 14/-labeled aniline and As/sup 74/- labeled arsenate. Through normal differential metabolism the two isotopes would go their separate ways. Theymore » would not stay together in any consistent manner. But if the bond were not ruptured, the ratio of C/sup 14/ to As/sup 74/ would always remain constant, regardless of whatever happened to the rest of the molecule. Chicks were fed double-labeled arsanilic acid and the counting rates of the two isotopes were differentially determined in tissues taken 48 hours after the dose. The dose ratio, tissue ratio, and excretory ratio of C/sup 14/ to As/sup 74/ were the same, within the limits of experimental error. Thus, if the carbon-arsenic bond of arsanilic acid were ruptured by chicks at all, it was much less than 1% of the administered dose. Other experiments showed that the radioactivity in tissues cleared in a first-order reaction, very much the same as blood. The results were consistent with the idea that arsanilic acid was translocated in the body rather than transformed. (BBB)« less