Lipid peroxidation and antioxidant system of the animal organism under the influence of toxic factors

Abstract

In the course of evolution, animals have developed mechanisms for neutralising (detoxifying) toxic substances, mainly in the liver, where about 2/3 of their total amount is metabolised. These mechanisms consist of metabolic transformations of xenobiotics that make them more water-soluble, which accelerates their excretion with bile through the intestines or urine through the kidneys. The process of neutralising toxic substances is divided into two phases. In the first phase of biological transformation, xenobiotics undergo oxidation, reduction, hydrolysis, and other reactions catalysed mainly by enzymes of the liver endoplasmic reticulum (microsomal oxidation and reduction enzymes). The microsomal oxidation system, which includes cytochrome P-450 and the flavin enzyme NADPH cytochrome P-450 reductase, catalyses the hydroxylation of substrates. In the second phase, the functional group of the xenobiotic (-OH, -COOH, -SH, -NH2) is joined to glucuronic or sulfuric acids, amino acids, methyl or acetyl groups, and the tripeptide glutathione.