3-amino-1-4-dimethyl-5h-pyrido(4-3-b)indole and norharman

Topics: Animals; Breast Neoplasms; Carbolines; Carcinogens, Environmental; Cattle; Colonic Neoplasms; Cooking; Food; Harmine; Head and Neck Neoplasms; Humans; Imidazoles; Male; Meat; Mutagens; Neoplasms; Nitrates; Nitrites; Nitrosamines; Prostatic Neoplasms

Topics: Amines; Animals; Antioxidants; Carbolines; Carcinogens; Chromatography, High Pressure Liquid; Garlic; Harmine; Hot Temperature; Humans; Meat; Meat Products; Mutagens; Onions; Swine

Heterocyclic aromatic amines (HAAs) are process-induced food contaminants with high mutagenic and/or carcinogenic potential. Although the human gut microbiota is known to affect the metabolism of dietary constituents, its impact on HAA metabolism and toxicity has been little studied. Here, the glycerol-dependent metabolism of seven foodborne HAAs (AαC, Trp-P-1, harman, norharman, PhIP, MeIQx, and MeIQ) by the human fecal microbiota is investigated.. As analyzed by HPLC-DAD/FLD, the extent of conversion is strongly dependent on glycerol supplementation and HAA structure. AαC (60-100%) and the 2-aminoimidazoazarenes (up to 58%) are especially prone to microbial conversion. Based on high-resolution MS and/or NMR spectroscopy data, 70 fecal metabolites are identified in total, mainly formed by chemical reactions with one or two molecules of microbially derived reuterin. Moreover, it has been demonstrated that the human fecal microbiota can further transform reuterin adducts by reduction and/or hydroxylation reactions. Upon isolation, some reuterin-induced HAA metabolites appear to be partially unstable, complicating structural identification.. The formation of microbial metabolites needs to be incorporated into risk assessment considerations for HAAs in human health. In this study, several HAA metabolites, mainly reuterin-dependent, are identified in vitro, providing the basis for future human studies investigating microbial HAA metabolism.

Topics: Adult; Amines; Animals; Carbolines; Feces; Female; Food Contamination; Gastrointestinal Microbiome; Glyceraldehyde; Harmine; Heterocyclic Compounds, Fused-Ring; Humans; Male; Microsomes, Liver; Middle Aged; Propane; Quinolines; Quinoxalines; Rats, Wistar

Heat processing of muscle foods gives rise to the formation of mutagenic and carcinogenic heterocyclic amines, often at ng/g levels. A gas chromatographic-mass spectrometric (GC-MS) technique was introduced for the analysis of nonpolar heterocyclic amines in common cooked meats, pan residues, and meat extracts after solid-phase extraction. The mutagenic heterocyclic amines 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), 2-amino-9H-pyrido[2,3-b]indole (A alpha C) and 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeA alpha C) were identified in several samples in amounts up to 8 ng/g. Also the comutagenic substances 1-methyl-9H-pyrido [3,4-b]indole (harman) and 9H-pyrido[3,4-b]indole (norharman) were detected in the samples in amounts up to almost 200 ng/g. The GC-MS method can be applied without derivatisation of the sample. The technique offers high chromatographic efficiency, yielding detection limits for pure references in the range 0.1-2 ng per injection.

Topics: Amines; Animals; Carbolines; Carcinogens; Cooking; Gas Chromatography-Mass Spectrometry; Harmine; Heterocyclic Compounds; Hot Temperature; Meat; Meat Products; Mutagens; Reindeer; Surface Properties; Swine

beta-Carbolines, harman (1-methyl-9H-pyrido[3,4-b]indole) and norharman (9H-pyrido[3,4-b]indole) and gamma-carbolines, 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1) and 3-amino-4-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), are present in cooked foods and cigarette smoke. We studied the effects of these heterocyclic amines on the activity of DNA topoisomerases. Trp-P-1 and Trp-P-2 inhibited topoisomerase I (topo I) activity with ED50 values of 1.48 and 1.55 micrograms/ml, respectively, in a relaxation assay. Harman and norharman inhibited topo I activity but with much higher ED50 values, 23.8 and 34.4 micrograms/ml, respectively. Trp-P-1 and Trp-P-2 also inhibited topoisomerase II (topo II) activity at about 50 micrograms/ml, in a decatenation assay. Harman and norharman showed a much lower inhibitory effect on topo II activity. None of these compounds stabilized the cleavable complex mediated by topo II. Trp-P-1 and Trp-P-2 intercalated into DNA at concentrations inhibitory to topoisomerases. We considered that the intercalation with DNA and the inhibition of DNA topoisomerases by heterocyclic amines might be partly related to their inhibition of DNA excision repair and their enhancing effect on UV- or chemically induced mutagenic activity.

Topics: Breast Neoplasms; Carbolines; Carcinoma, Small Cell; Cell Line; Enzyme Inhibitors; Female; Harmine; Humans; Kinetics; Mutagens; Topoisomerase I Inhibitors; Topoisomerase II Inhibitors; Tumor Cells, Cultured

Electrospray ionization mass spectrometry was applied to the study of the amines IQ, Trp-P-1, Trp-P-2, PhIP and A alpha C and the co-mutagens harman and norharman. The results obtained on a triple quadrupole mass spectrometer equipped with a pneumatically assisted electrospray source are reported. The chromatographic conditions were optimized with a reversed-phase column (1 mm I.D.) using acetonitrile-5 mM ammonium acetate (pH 6.7) (50:50) as the mobile phase at a flow-rate of 50 microliters min-1. Different parameters influencing the mass spectra were investigated. For these compounds [M + H]+ in the positive-ion mode and also some fragments produced through collisionally activated decomposition in the interface were observed. Detection limits of 5.4-44 pg were obtained for standard solutions of these amines. Analysis of a meat extract was performed by HPLC-MS using single-ion monitoring after a solid-phase extraction clean-up.

Topics: Amines; Animals; Calibration; Carbolines; Cattle; Chromatography, High Pressure Liquid; Harmine; Heterocyclic Compounds; Mass Spectrometry; Meat; Mutagens

Three recent topics related to possible exposure of humans to mutagenic and carcinogenic aromatic amines and related compounds in foods are reviewed. A food additive, AF-2,2-(2-furyl)-3-(5-nitro-2-furyl) acrylamide, was first demonstrated to be mutagenic in Escherichia coli WP-2 and then proved to be carcinogenic in experimental animals. This is an example of prediction of the carcinogenicity of a compound from results of short-term microbial tests. Pyrolysates of amino acids, proteins, and foods high in a protein contain many heterocyclic aromatic amine compounds. For example, a tryptophan pyrolysate contains two derivatives ofamino-gamma-carboline(pyridoindole), and a glutamicd acid pyrolysate contains two derivatives of djipyridoimidazole. These compounds are strong frameshift mutagens in Salmonella typhimurium. Some of them were carcinogenic in an in vitro transformation test and were also carcinogenic when injected sc into hamsters and rats and when given orally to mice. Carcinogenic aromatic amines, such as aniline, and o-toluidine and yellow OB were demonstrated to be mutagenic in the presence of the beta-carboline, norharman, with S-9 mix. Diphenylnitrosamine was also mutagenic in the presence of norharman, which is present in tobacco tar and broiled food. These mutagenicities of aniline, o-toluidine, yellow OB, and diphenylnitrosamine are discussed in relation to an evaluation of compounds as environmental carcinogens from the results of short-term microbial tests.

Topics: Animals; Azo Compounds; Carbolines; Carcinogens; Cooking; Drug Synergism; Food Additives; Furylfuramide; Harmine; Humans; Mutagenicity Tests; Mutagens; Nitrofurans; Nitrosamines