l-Carnitine in the lipid and protein protection against ethanol-induced oxidative stress

Chronic ethanol intoxication induces oxidative stress participating in the development of many diseases. Nutrition and the interaction of food nutrients with ethanol metabolism may modulate alcohol toxicity. One such compound is l-carnitine (l-3-hydroxy-4-N,N,N-trimethylaminobutyrate), which also reveals antioxidant abilities. The present study has been designed to investigate the effect of l-carnitine as an antioxidant on the serum and liver of rats chronically intoxicated with ethanol. Rats received l-carnitine solution (1.5 g/1L) for 5 weeks and/or were treated intragastrically with ethanol for 4 weeks. In the serum and liver, the level of nonenzymatic antioxidants and lipid and protein oxidation markers were determined. It was shown that alcohol caused the increase in the level of lipid peroxidation products—conjugated dienes (by about 70% and 60% in the liver and blood serum, respectively), malondialdehyde (MDA) (by about 60% and 30% in the liver and blood serum, respectively), 4-hydroxynonenal (4-HNE) (by about 35% and 25% in the liver and blood serum, respectively), and changes in the level of protein oxidative markers—increase in dityrosine and decrease in tryptophan (by about 40%) in the serum and liver of rats. Moreover, the decrease in vitamin E level (by about 30%) and the level of glutathione (GSH) (by about 20% in the liver and blood serum) was also observed. Administration of l-carnitine to rats intoxicated with ethanol significantly protects lipids and proteins against oxidative modifications in the serum and liver. The level of conjugated dienes, MDA, and 4-HNE was decreased by about 30%, 30%, and 20% in the liver, respectively, and by about 20%, 10%, and 10% in the blood serum in comparison to the ethanol group. Moreover, the level of tryptophan was increased and dityrosine decreased by about 10% and 20% in the liver, respectively, and by about 30% and 10% in the blood serum in comparison to the ethanol group. l-carnitine partially protects nonenzymatic antioxidants against oxidative stress. The level of vitamin E was increased by about 20% and the level of GSH was increased by about 25% in the liver and blood serum in comparison to the ethanol group. It is possible that beneficial effect of l-carnitine is connected with its abilities to scavenge free radicals and to chelate metal ions.