Diet, Nutrition, and Cancer (1982) / Chapter Skim
Currently Skimming:
13 Mutagens in Food
13 Mutagens in Food
Pages 277-303
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 277... ...
Of course, most of these chemicals are present in relatively low concentrations, but if potent carcinogens exist, even at low concentrations in commonly consumed foods, they may warrant concern. The problem, therefore, is how to test the very large number of chemicals present in the complex mixtures we call food to determine whether or not they may be contributing to our risk for cancer.
|
From page 278... ...
The fact that simple mutagenicity tests correctly predicted the carcinogenic potential of these chemicals adds to our confidence that correctly interpreted mutagenicity data can assist us in identifying environmental carcinogens. The most widely used of the mutagenicity assays is the Salmonella plate incorporation test, commonly known as the Ames test.
|
From page 279... ...
typhimurium strain TADS, implying that the agent could induce frameshift mutations (Nagao et al., 1977a; Sugimura et al., 1977~. Positive results in these assays depended on the presence of an _ vitro metabolic activation system utilizing the postmitochondrial supernatant from homogenized livers of rats pretreated with polychlorinated biphenyls.
|
From page 280... ...
These investigators estimated that Glu-P-2 and Glu-P-1 accounted for approximately 10% of the total mutagenic activity of the pyrolysate. Analyses have confirmed that at least some of the mutagenic pyrolysis products of amino acids are present in cooked foods.
|
From page 281... ...
Mutagens in Food 2X1 From Amino Acids: CH3 NH2 HCH3 Trp-P-1 4NH2 CH3 Glu-P-1 Lysine pyrolysate NJ0N W H Lys-P-1 From Proteins: N>lN~ NH2 H ARC Tryptophan pyrolysates Glutamic acid pyrolysates Soybean globulin pyrolysates CH3 ~NH2 H Trp-P 2 O ~r NH2 Glu-P-2 Phenylalanine pyrolysate JJ tN1NH2 Phe-P-1 ~N~N4NH2 H MeAaC FIGURE 13-1. Some mutagens from pyrolysates and from cooked foods.
|
From page 282... ...
From Broiled Sardines: N=( 1 / N CH3 NH2 IQ From Broiled Beef: Protein pyrolysate NH2 N=< H3C~,N`~N CH3 MeIQx Protein pyrolysates NH2 NJ4` cH3 MeIQ Two previously unknown mutagens were isolated from broiled sardines (Kasai et al., 1979~. These were 2-amino-3-methylimidazo[4,5-fiquinoline (IQ)
|
From page 283... ...
GO o o o o o 4o u' 4o oD cd is a)
|
From page 284... ...
However, the presence of a carcinogenic chemical in a pyrolyzed amino acid or protein mixture does not necessarily imply that the carcinogen will also be present in normally cooked, uncharred food. Mutagens Fo~u~ed from Meat at Lower Temperatures In the experiments concerning the formation of mutagenic pyrolysis products from amino acids and proteins, temperatures of 250°C or greater were used (Matsumoto et al., 1977; 1978; Uyeta et al., 1979~.
|
From page 285... ...
The significance of their induction in cells _ vitro is not clear, particularly for chemicals unable to induce heritable mutations or _ vivo chromosome aberrations. Pyrazine and four of its alkyl derivatives -- compounds formed by heating mixtures of sugars and amino acids (Koehler et al., 1969~-were found to be nonmutagenic to S
|
From page 286... ...
In some mutagenic plant products consumed by humans, the mutagenic substances isolated were identified as flavonoids. For example, most of the mutagenic activity of an acid hydrolysate of green tea could be accounted for by three flavonoids: kaempferol, quercetin, and myricetin (Uyeta et al., 1981~.
|
From page 287... ...
When extracts of Aspergillus niger or human feces containing enzymes capable of hydrolyzing glycosides were added, tea became mutagenic to S typhimurium strain TA98 (Nagao et al., 1979; Tamura et al., 1980~.
|
From page 288... ...
Grape juice was also found to be mutagenic to strain TA98, although only when tested with fecal extracts containing glycosidases (Tamura et al., 1980~. Mutagenic activity has also been detected in concentrates of 17 out of 27 commonly consumed Chinese alcoholic beverages, mostly fermented from rice, glutinous rice, and barley (Lee and Fong, 1979~.
|
From page 289... ...
, 2-acetylaminofluorene, 2-aminofluorene, and N-hydroxy-2-acetylaminofluorene (Umezawa et al., 1978~. These chemicals all require an in vitro mammalian metabolic activation system for mutagenic activity.
|
From page 290... ...
typhimurium in the absence of a mammalian metabolic activation system. Therefore, at least some of the antimutagenic activity of hemin must be unrelated to such activation.
|
From page 291... ...
were antimutagenic in the presence of a series of mutagens that require in vitro metabolic activation, but not in the presence of mutagens that are directly mutagenic to S typhimurium without an added metabolic activation system.
|
From page 292... ...
It is not yet clear to what extent the mutagens produced by pyrolyzing proteins or amino acids are found in normally cooked foods. The finding that some constituents of food can enhance or inhibit the _ vitro mutagenicity of other compounds should not be interpreted as meaning that these compounds would produce the same effects in living animals or humans.
|
From page 293... ...
1980b. Inhibition of the mutagenicity of amino acid pyrolysis products by hemin and other biological pyrrole pigments.
|
From page 294... ...
1981a. Inhibitory effect of the ether extract of human feces on activities of mutagens: Inhibition by oleic and linoleic acids.
|
From page 295... ...
1980. Induction of 8-azaguanine or ouabain resistant somatic mutation of Chinese hamster lung cells by treatment with tryptophan pyrolysis products.
|
From page 296... ...
1980c. Chemical synthesis of 2-amino-3-methylimidazo[4,5-fJquinoline (IQj, a potent mutagen isolated from broiled fish.
|
From page 297... ...
1977. Mutagenic activity of amino acid pyrolyzates in Salmonella typhimurium TA 98.
|
From page 298... ...
1978. Studies on natural desmutagens: Screening for vegetable and fruit factors active in inactivation of mutagenic pyrolysis products from amino acids.
|
From page 299... ...
1978. An evaluation of 6 shortterm tests for detecting organic chemical carcinogens.
|
From page 300... ...
1979. In vitro mutagenicity assays of chemical carcinogens and related compounds with Salmonella typhimurium.
|
From page 301... ...
1977. In vitro transformation of hamster embryo cells with tryptophan pyrolysis products.
|
From page 302... ...
1979. Assaying mutagenicity of food pyrolysis products using the Ames test.
|
From page 303... ...
1980. Formation of mutagens by heating the aqueous solution of amino acids and some nitrogenous compounds with addition of glucose.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.