Chromatographic Examinations of Tea's Protection Against Lipid Oxidative Modifications

Ethanol metabolism is accompanied by generation of free radicals that damage cell components, especially lipids. The present study was designed to investigate the efficacy of the preventive effect of black tea on the lipid oxidative modifications in different tissues (plasma, liver, brain, kidney, stomach, lung, intestine, and spleen) of 12-month-old rats chronically intoxicated with ethanol. Ethanol intoxication caused changes in the level/activity of antioxidants that led to the significant increase in the level of lipid oxidative modification products. Oxidative modifications were estimated by measuring lipid hydroperoxides, malondialdehyde, and 4-hydroxynonenal by high-performance liquid chromatography (HPLC) and by spectrophotometric determination of conjugated dienes. These lipid-modification marker levels were increased in almost all examined tissues (3%–71%) after ethanol intoxication. Described changes were in accordance with the liver level of the most often used marker of arachidonic acid oxidation, isoprostane (8-isoPGF(2α)), determined by the LC/MS system. Administration of black tea to ethanol-intoxicated rats remarkably prevents the significant increase (by about 15%–42%) in concentrations of all measured parameters regarding all examined tissues, but especially the plasma, liver, brain, stomach, and spleen. The preventive effect of black tea in the other organs (kidney, lung, intestine) caused a decrease in examined markers in a smaller degree (by about 7%–28%). To determine in the liver the major constituents of black tea mainly responsible for antioxidative action such as catechins and theaflavins, which were absorbed in organism, the present study indicates their protective effect against ethanol-induced oxidative modifications of lipids.