ubiquinone and thiobarbituric-acid

The ability of ubiquinone-3, a short chain ubiquinone homologue, to prevent Cu2+ induced oxidation of human low density lipoprotein was investigated. The results are as follows: in the presence of ubiquinone-3 the extent of peroxidation, as determined by the formation of thiobarbituric acid reactive substances, was only one third of that found in its absence; the quinone can also prevent the fragmentation of apolipoprotein B-100 and the increase of the net negative surface charge of the particle.

Topics: Apolipoprotein B-100; Apolipoproteins B; Chemical Phenomena; Chemistry, Physical; Copper; Copper Sulfate; Edetic Acid; Humans; Lipid Peroxidation; Lipoproteins, LDL; Liposomes; Oxidation-Reduction; Phosphatidylcholines; Surface Properties; Thiobarbiturates; Ubiquinone

Five groups of five weanling rats were each fed a Torula yeast-based diet either unsupplemented or supplemented with 30 mg beta-carotene/kg, 30 IU vitamin E/kg, 1 mg selenium/kg or 30 mg coenzyme Q10/kg. Elevated levels of plasma aspartate aminotransferase and alanine aminotransferase are sensitive indicators of liver damage. The former enzyme was lower (P less than 0.01) in the vitamin E-, selenium- and beta-carotene-supplemented groups than in the unsupplemented control group, and the latter enzyme was lower in the vitamin E- and selenium-supplemented groups, suggesting a relatively equal effectiveness of these three antioxidants against liver damage. Erythrocytes were tested for protection against uninduced oxidative damage or that induced by 1 mmol/L bromotrichloromethane (BrCl3C) by measuring thiobarbituric acid-reactive substances (TBARS), hemoglobin, hemolysis, protein precipitation, alanine release and several enzyme activities. In untreated erythrocytes, selenium, beta-carotene and coenzyme Q10 exhibited protection by lowering (P less than 0.05) TBARS and alanine release, but only vitamin E protected against hemolysis. In BrCl3C-treated erythrocytes, vitamin E, selenium and beta-carotene protected by decreasing (P less than 0.05) protein precipitation, whereas selenium and beta-carotene decreased alanine release. The results of this study suggested that, in a manner analogous to vitamin E and selenium, beta-carotene and coenzyme Q10 function as antioxygenic nutrients.

Topics: Alanine Transaminase; Animals; Antioxidants; Aspartate Aminotransferases; beta Carotene; Bromotrichloromethane; Carotenoids; Coenzymes; Diet; Erythrocytes; Glutathione Peroxidase; Male; Rats; Rats, Inbred Strains; Selenium; Thiobarbiturates; Ubiquinone; Vitamin E

The question has been addressed whether the side chain contributes to the antioxidant activity of Ubiquinones. The length, the chemical composition and structure of the chain have been considered. The effect of the actual concentration of the quinone in egg lecithin vesicles has been investigated by means of both UV spectroscopy and time resolved fluorescence quenching experiments of 12-AS. The results indicate that the antioxidant properties of the quinone do not seem to depend on the side chain.

Topics: Antioxidants; Chromatography, Gel; Fluorescence; Fluorescent Dyes; Lipid Peroxidation; Liposomes; Spectrophotometry, Ultraviolet; Stearic Acids; Structure-Activity Relationship; Thiobarbiturates; Ubiquinone