Effect of Aliphatic Aldehydes on the Lipid Peroxidation and Chemiluminescence of Biological Systems under Oxidative Stress L. A. Videla, 1 V. Ferrer 2 and E. A. Lissi 2 * 1 Department of Biochemistry, Faculty of Medicine, University of Chile 2 Department of Chemistry, Faculty of Chemistry and Biology, University of Santiago, Santiago, Chile The effect of several aliphatic aldehydes on lipid peroxidation w as evaluated by measuring the oxygen uptake rate, thiobarbituric acid-reactive products formation and the emitted visible chemiluminescence intensity. Measurements were carried out in brain homogenates and erythrocyte plasma membrane and liver microsomal fractions. In all systems studied, aldehydes (25 mmol/ L) (e.g. acetaldehyde, 2,2-dimethylpropanal), increased the intensity of the lumines- cence associated with the oxidation process. In contrast, aldehyde incorporation decreased TBARS production and the rate of oxygen uptake. The increased luminescence intensity is explained in terms of secondary reactions of aldehyde derived free radicals. These results clearly indicate that extreme care must be exercized in the intepretation of chemiluminescence data in the presence of aldehydes. © 1997 John Wiley & Sons, Ltd. J Biolumin Chemilumin 1997: 12: 141–148 No. of Figures: 8 No. of Tables: 0 No. of References: 22 Keywords: lipid peroxidation; aldehydes; chemiluminescence, oxidative stress Received 14 March 1996; accepted 16 March 1997 INTRODUCTION Aldehydes are both reactive and cytotoxic agents, which can be directly incorporated by inhalation in polluted atmospheres, produced by the oxidation of alcohols and monoamines, or by the breakdown of oxidized polyunsaturated fatty acids. Aldehyde- induced cytotoxicity has been linked to lipid peroxidation promotion, but different indicators of the process have produced conflicting results (1,2). In fact, alkane production and chemiluminescence (CL) were reported to increase following aldehyde addition to perfused livers (1), whereas malondialdehyde and conjugated diene formation by isolated hepatocytes was unaltered (2). Both CL and alkane production induced by aldehydes are decreased by free radical scavengers such as vitamin E and are absent in anaerobiosis, suggesting the involvment of reactive oxygen species in the process (2). Enhancement of low level CL by aldehydes is a general event elicited by either aliphatic and aromatic aldehydes not related to lipid peroxidation (3–8) or by substances formed in the process, namely, 4-hydroxy alkenals (1,2). This effect has been observed for bilirubin in alkaline and aerobic conditions upon addition of different aliphatic aldehydes and benz- aldehyde (4,5), in yeast cells supplemented with formaldehyde (7), and after acetaldehyde addition to mitochondrial fractions (8). The weak CL emitted by soybean seedlings is significantly enhanced by the addition of aldehydes (3,6) in a process considered to involve the formation of radical species derived from hydroperoxide intermediates. Aldehydes also enhance CL elicited by the interaction of hydroxyl radicals with aromatic compounds (9). Under physiological conditions, aldehydes can be activated by hydrogen J BIOLUMIN CHEMILUMIN 1997; 12: 141–148 © 1997 John Wiley & Sons, Ltd. CCC 0884–3996/97/030141–08 $17.50