Table 1.
Occurrence, mutagenicity, carcinogenic properties and metabolism of test compounds
| Chemical (abbreviation), occurrence | Chemical group | Mutagenic and carcinogenic properties | Metabolism | References |
|---|---|---|---|---|
| Aflatoxin B1 (AFB1), produced by A. flavus and A. parasiticus; in peanuts, maize and cottonseeds | Mycotoxins | Causes formation of epoxide induce risk for HCC in humans and animals, clear evidence for carcinogenicity IARC: Group 1 |
Activation by CYP1A2, 2B6, 3A4, 3A5, 3A7; inhibition of DNA-adduct formation by GSTs | (IARC 1993) |
| Benzo(a)pyrene (B(a)P), tobacco smoke, ambient air, grilled/broiled and smoke-cured meats, vegetables grown in contaminated soils | Polycyclic aromatic hydrocarbons (PAH) | Causes guanine adducts and tumors in many animal species, local and systemic carcinogenic effects IARC: Group 1 |
Epoxide formation via CYP1A1, 1A2 and 1B1, conjugation of metabolites with GSTs, UGTs and SULTs | (IARC 2010) |
| 2-Amino-3-methyl-3H-imidazo[4,5-f]quinolone (IQ), grilled/boiled meat and fish | Heterocyclic aromatic amines (HAA) | Causes guanine adducts, clear evidence for carcinogenicity in experiments with rodents IARC: Group 2A |
Activation to DNA reactive species by CYP1A2 and NAT detoxification via GSTs and SULTs | (IARC 1993) |
| 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), cooked beef, pork, chicken and fish products | HAA | Causes guanine adducts that induces tumors at multiple sites in animal models IARC: Group 2B |
Activation through CYP1A2 and further metabolism by SULTs, detoxification via UGTs | (IARC 1993) |
| N-Nitroso-dimethylamine (NDMA), tobacco smoke, meat and fish products, endogenous formation (stomach) | Nitrosamines | Causes DNA methylation and induction of cancer in liver, lungs and kidneys of mice and of HCC in rats IARC: Group 2A |
Activation by CYP2E1, unstable metabolite dissociates to DNA reactive compound | (IARC 1978) |
| Hydrogen peroxide (H2O2) | Peroxides | Causes oxidation, directly acting mutagen IARC: Group 3 |
No activation required; decomposition leads to formation OH· and O·2 radicals | (Menghini 1988) |
HCC, human hepatoma cell carcinoma; GST, Glutathione S-transferases; NAT, N-acetyltransferase; SULTs, sulfotransferase; UGT glucuronyltransferase