Formation of mutagens in cooked foods. V. The mutagen reducing effect of soy protein concentrates and antioxidants during frying of beef.

Cooking beef patties results in the formation of mutagens detectable by Salmonella typhimurium TA98 with metabolic activation. Decreased mutagenic activity results when frying beef with added soy protein concentrates (SPC). The reduction in mutagenicity takes place during the cooking process. Whereas fried beef hamburgers show high mutagenic activity, by comparison, similarly fried soy-hamburgers have much less mutagenic activity. Volumetric effects are responsible partly for the reduction on mutagenicity by SPC. Naturally occurring antioxidants in SPC, such as chlorogenic acid, also play a role. Also, a commonly used antioxidant, butylated hydroxyanisole (BHA), has been found effective in reducing the mutagenicity of fried beef. Thus, the addition of SPC or BHA in beef patties may provide a practical way of reducing mutagen formation during frying of beef.

Formation of mutagens in cooked foods. IV. Effect of fat content in fried beef patties.

Cooking beef patties results in the formation of mutagens detectable by Salmonella typhimurium TA98 with metabolic activation. We now show that the amount of fat in beef affects the quantity of mutagens formed. While char increases with increasing fat, over the range of 5-309% of added fat content, mutagenicity reaches a peak at 10% added fat and subsequently decreases. Thus, char formation is not an accurate measure of mutagenicity. These results suggest that fat plays an important role in mutagen formation in fried beef.

Formation of mutagens in cooked foods. III. Isolation of a potent mutagen from beef.

The major mutagenic component of fried beef has been isolated using a series of chromatographic steps. The pure compound has been analyzed by low and high resolution mass spectroscopy and nuclear magnetic resonance spectroscopy. The results indicate that the molecular weight of this extremely mutagenic compound is 198, with an elemental composition of C11H10N4. The compound is different from the known mutagenic pyrolysis products of amino acids or proteins.

Formation of mutagens in cooked foods. II. Foods with high starch content.

Mutagens, detectable Salmonella typhimurium TA98 and TA100 after activation by liver S-9 fraction, are formed when starchy foods are cooked. Potatoes were fried and breads were toasted, baked and fried to produce mutagenically active substances. While toasting both white bread and dark bread produce the mutagens at the same initial rate, dark bread products much higher levels of mutagenicity when toasted for long times. Significant mutagenic activity is produced when starchy foods are prepared by common cooking procedures.

Synthesis and evaluation of the thiosemicarbazone, dithiocarbazonate, and 2'-pyrazinylhydrazone of pyrazinecarboxaldehyde as agents for the treatment of iron overload.

Three prototype tridentate ligands (i.e., pyrazinecarboxaldehyde thiosemicarbazone, sodium pyrazinecarboxaldehyde dithiocarbazonate, and pyrazinecarboxaldehyde 2'-pyrazinylhydrazone) were prepared and evaluated for their relative abilities to remove iron from model systems designed to mimic particular aspects of chronic transfusional iron overload. These compounds were synthesized by condensation of pyrazinecarboxaldehyde with the appropriate substituted hydrazide. Iron-binding properties were determined, and the ability to remove iron from the proteins transferrin and ferritin was ascertained. An in vivo model system employing iron-loaded mice was used to demonstrate that all three compounds were effective at reducing tissue iron levels.

Formation of mutagens in cooked foods. I. Beef.

Mutagens detectable by Salmonella typhimurium TA98, after activation by liver S-9 fraction, are formed when meat is cooked by frying, broiling and boiling. High levels of mutagenic activity are formed rapidly when frying, or more slowly during broiling. Formation of mutagens in boiled beef stock requires several days under reflux, but shows a strong concentration dependence. Time curves suggest that a period exists during which mutagens are not readily formed; however, after this period mutagen production is rapid. Hamburgers from commercial franchises were frequently mutagenically active.

Detection of carcinogens as mutagens: bacterial tester strains with R factor plasmids.

We described previously a simple test on petri plates for detecting chemical carcinogens as mutagens, using an especially sensitive set of bacterial strains to detect mutagenic acitivty and a mammalian liver extract for carcinogen activity. We now extend the utility of the method by introducing two new bacterial strains which can detect with great sensitivity many carcinogens which we did not detect before or detected with less sensitivity. Among these carcinogens are aflatoxin B-1, sterigmatocystin, benzyl chloride, benzo[a]-pyrene, 7,12-dimethylbenzanthracene, 1'-acetoxysafrole, and the nitrofuran food additive furylfuramide (AF-2). The new strains TA100 and TA98 contain an R factor plasmid, pKM101, in our standard tester strains TA1535 and TA1538. The R factor increases mutagenesis with certain mutagens, but not others. We present evidence that the mutagens that become more effective work through an error-prone recombinational repair.