Cytotoxic effect of [glycated albumin-transition metal ion] on rat hepatocyte suspension

Combination of glycation and oxidation is associated with diabetes mellitus. The aim of this study was to clarify the effect of glycated proteins in presence of transition metal ions on production of reactive oxygen species [ROS] in rat hepatocyte suspension. Glycated albumin was prepared by incubation of bovine serum albumin with 100 mM glucose in 0.3 M phosphate buffer at 37°C for 2, 4, and 6 weeks. The prepared rat liver cell suspension was treated with glycated albumin in presence of either Fe[+++] or Cu[++] ions. Produced malone-dialdehyde was measured as an indicator of ROS and of cell injury. The results showed Fe[+++] and Cu[++] ions increase the ROS production in presence of glycated albumin [p<0.01]. All prepared glycated albumin showed cytotoxicity in rat hepatocytes suspension in the presence of cupric and ferric ions, and this injury was dependent to metal ion concentration. Higher degree of glycation showed higher effect on ROS production [P<0.01] Comparing the effect of Fe[+++] and Cu[++], cupric ion had higher cytotoxic effect [p<0.01]. Conclusion: These results indicated that hepatocytes may be damaged by ROS which are produced by the interaction of the glycated albumin and transition metal ion

Effects of ubiquinol-10 and beta-carotene on the in vitro susceptibility of low-density lipoprotein to copper-induced oxidation

Dietary antioxidant intake has been reported to be inversely associated with coronary artery disease. To clarify the possible role of lipophilic antioxidants in the prevention of atherosclerosis, we investigated the effects of ubiquinol-10 and beta-carotene on the susceptibility of low-density lipoprotem [LDL] to oxidative modification. In this study, first "ubiquinol-10 and beta-carotene" were added to plasma and incubated for 3hr at 37°C. Then, the LDL fraction was separated by ultracentrifugation. The oxidizability of LDL was estimated by measuring conjugated diene[CD], lipid peroxides and thiobarbituric acid-reactive substances [TEARS] after cupric sulfate solution was added. We showed that ubiquinone-10 and P-carotene significantly [p<0.01 by ANOVA] and dose-dependently prolonged the lag time before initiation of oxidation reaction. Also, these two compounds suppressed the formation of lipid peroxides and TEARS more markedly than others. The ability of them to prolong lag time and suppression of lipid peroxides and TEARS formation resulted to be in the following order: ubiquinol-10> p-carotene.LDL exposed to the lipophilic antioxidants in vitro reduced oxidizability. These findings suggest that ubiquinol-10 and p-carotene have a role in ameliorating atherosclerosis

Effects of vitamin E volatile oils on the susceptility of low - denssity lipoprotien to oxidative modification

Antioxidant consumption has been reported to be inversely associated with the incidence of coronary artery disease. To clarify the possible role of vitamin E and volatile oils in the prevention of atherosclerosis, the effects of these compounds on the susceptibility of low-density lipoprotein [LDL] to oxidative modification were investigated. In this study, vitamin E and seven volatile oils "anethol, eugenol, geraniol, limonene, linalool, pulegone and thymol" were added to plasma and incubated at 37°C for 3 h. The LDL fraction was separated by ultracentrifugation and the oxidizability of LDL was estimated by measuring conjugated diene [CD], lipid peroxides and thiobarbituric acid-reactive substances [TBARS] after cupric sulfate solution was added. The data show that vitamin E, thymol and eugenol significantly and dose-dependently prolonged the lag time before initiation of oxidation reaction [P<0.01 by ANOVA]. Also, vitamin E and thymol suppressed the formation of lipid peroxides and TBARS more markedly than other volatile oils. The ability to prolong lag time, suppression of lipid peroxides and TBARS formation was in the following order: vitamin E > thymol > eugenol > geraniol > linalool > limonene > anethol > pulegone. These data clearly show that LDL exposed to vitamin E and volatile oils in vitro reduces oxidizability; therefore have favorable effects in ameliorating atherosclerosis

effects of lipophilic antioxidants on the affinity of LDL to its receptor: a model for prevention of atherogenesis

The affinity of low density lipoprotein [LDL] to its receptor is very important, because most of LDL-uptake pathway is done by the LDL receptor and the change in size of LDL particle and the modification in its components may affects the LDL affinity for its receptor. In this study, the effects of lipophilic agents such as vitamin E and seven volatile oils: anethol, eugenol, geraniol, limonene, linalool, pulegone and thymol have been investigated on the affinity of LDL to its receptor. LDL receptor was purified of bovine adrenal tissue. LDL was isolated by sequential density ultracentrifugation from normolipidemic human plasma. Then, LDL was labeled with fluoresein isothiocyanate [FITC] at 4°C for 24 h. Native LDL was incubated with various concentrations of each of the volatile oils and vitamin E for 2 h. Finally, the native LDL treated with volatile oils and vitamin E was incubatd with the LDL receptor in the presence of labeled-LDL at 37°C for 30 min. After incubation, the medium was centrifuged at 4000 'g for 20 min and the fluorescence intensity [FI] of supernatant from each sample was determined at excitation 495 nm and emission 515 nm. The elevation of FI in each fraction demonstrates increasing the affinity of non-labeled-LDL to its receptor. We showed that vitamin E and volatile oils increased the affinity of LDL to its receptor, and among these compounds, vitamin E and thymol are the best agents that increase the affinity of native LDL to its receptor. The effects of these compounds are as follows: vitamin E > thymol > eugenol > anethol > geraniol > linalool > limonene > pulegone. These findings raise the possibility that vitamin E and some of the volatile oils may decrease the effect of LDL in formation of atherosclerotic lesions