FORMATION OF BURST CHEMILUMINESCENCE, EXCITED ALDEHYDES, AND SINGLET OXYGEN IN MODEL REACTIONS AND FROM CARCINOGENIC COMPOUNDS IN RAT LIVER S9 FRACTIONS

Abstract

It is shown that in physiological circumstances (T=298 K, pH=7.4) various aldehydes (formaldehyde, acetaldehyde, glyoxal, methyl-glyoxal, etc.) can be activated by hydrogen peroxide (H202) in the presence of the ε-amino group of L-lysine, with simultaneous formation of singlet oxygen (1O2 ) and chemiluminescence. The activated aldehydes are in an excited state and have radical structure causing extremely high reactivity and a possible attack of cellular components like proteins, amino acids, RNA and DNA. In the reactions methylated, formylated, acetylated, etc. compounds are formed as well. Activated aldehydes can also be formed during the biological oxidation of different nitrosamines (DMN, DEN, N-nitroso-morpholine) and formaldehyde-hydrazine adduct. It is proved that in rat liver S9 fractions these activated (excited) aldehydes, especially formaldehyde, have been formed with a simultaneous burst chemiluminescence emission and appearance of singlet oxygen. In rat liver S9 fractions excited formaldehyde can be liberated only after 30 min preincubation time from dimethyl-nitrosamine (DMN) and monomethyl-hydrazine (MMH). On the other hand, excited formaldehyde is liberated immediately from hydrazine-formaldehyde-adduct (HZ/FORM) and isonicotinic acid-hydrazide-formaldehyde adduct (INH/FORM), i.e. no preincubation is necessary.