MUTAGENIC ACTIVITY OF HETEROCYCLIC AMINES IN COOKED FOODS

Mutagenic heterocyclic amines are generated in foods when they are coo ked at temperatures over 150 degrees C. These compounds are present fr om 0.1 to 50 ppb, depending on the food and cooking conditions. These heterocyclic amines are not only present in cooked red meat, fish, and chicken, but are also present at lower levels in baked and fried food s derived from grain. Mutagenicity of fried beef hamburgers cooked at 230 degrees C is 800 +/- 37 TA98 revertants per gram cooked weight. We measured 2-amino-3,8-dimethylimidazo[4,5-f]quinox (MeIQx), 2-amino-3, 4,8-trimethylimidazo[4,5-f]quinoxaline (DiMeIQx), and 2-amino-3-methyl imidazo[4,5-f]quinoline (IQ) formation at this temperature and found 3 .0 +/- 2.0, 1.0 +/- 0.18, and 0.06 +/- 0.03 ng/g, respectively. 2-amin o-1 -methyl-6-phenylimidazo[4,5-6] pyridine (PhIP) was found al a high er concentration of 9.6 ng/g. In our laboratory we have shown these he terocyclic amines are capable of producing both reverse and forward mu tations in Salmonella bacteria and forward mutations in Chinese hamste r ovary cells (CHO). We have also been able to show a statistically si gnificant increase in mutations in the pancreas of the ''mutamouse'' f ollowing PhIP exposure. The pancreas also shows relatively high DNA bi nding compared to other organs in the mouse, The number and type of mu tations depend on the repair capacity of the cells for both Salmonella and CHO. In Salmonella the mutations are primarily 2-base deletions w hen the cells lack uvrB repair, but mutations are more complex (larger deletions and insertions) but lower in frequency when repair is funct ional. Efforts are now under way to assess specific sequence changes i n the aprt gene in mutant CHO cells.