Analysis of the free radical scavenging products of vitamin E in biological systems using a high-sensitive HPLC method

点击翻译按钮获取中文摘要

The high-sensitive method using a high-performance liquid chromatography with electrochemical detection (ECD-HPLC) has been applied for the analysis of the oxidation products of vitamin E (α-tocopherol, α-TH), including 8α-(phosphatidylcholine-dioxy)-α-tocopherones (TOO-PC), α-tocopherylquinone (α-TQ), and epoxy-α-tocopherylquinones (epoxy-α-TQ) during the peroxidation of rat tissue homogenates (liver, heart, lung, and kidney). When each tissue homogenate was peroxidized by the addition of a free radical initiator at 37℃, the endogenous α-TH could scavenge peroxyl radicals of phosphatidylcholines (PC) to suppress the formation of PC hydroperoxides (PC-OOH). The main products of α-TH in each tissue were α-TQ and the addition products of α-TH with PC-peroxyl radicals (TOO-PC). The structure of TOO-PC was characterized as 1-palmitoyl-2-[(8α-dioxy-α-tocopherone)-epoxyoctadecenoyl]-3-sn-phosphatidylcholine by the LC-ESIMS analysis. The results indicate that endogenous α-TH in rat tissue hom … More ogenates can react with lipid-peroxyl radicals to form α-TQ and TOO-PC as the reaction products.Oxidative stress has been implicated in the pathogenesis of diabetes mellitus, and α-TH might prevent the development of diabetic complications in some tissues by reducing lipid peroxidation and oxidative damage. Therefore, the oxidation products of α-TH in the tissues, serum, heart, liver, kidney, and lung, of storeptozotocin (STZ)-induced diabetic rats have been studied using the high-sensitive ECD-HPLC method. The amounts of endogenous α-TH and its oxidation products were measured in these tissues at different time points after STZ injection, in addition to the measurement of PC-OOH, a marker of oxidative stress. The PC-OOH was increased in plasma, liver, and kidney of diabetic rats 4 weeks after STZ injection. Therefore, oxidative stress occurred in these tissues. Although the level of α-TH in the tissues of diabetic rats was the same, the oxidation product α-TQ in the plasma, heart, liver, and lung was high compared with the control rats. Furthermore, TOO-PC has been detected in some tissues of diabetic rats using the ECD-HPLC method. The results suggest that α-TH in the tissues of diabetic rats may scavenge lipid-peroxyl radicals to form α-TQ as the oxidation product. In conclusion, the oxidation products of α-TH have been detected ex vivo and in vivo systems. Less