Protective effect of hydroxytyrosol and its metabolite homovanillic alcohol on H2O2 induced lipid peroxidation in renal tubular epithelial cells

We investigated the capacity of hydroxytyrosol (HT), 3,4-dihydroxyphenylethanol, and homovanillic alcohol (HVA), 4-hydroxy-3-methoxy-phenylethanol, to inhibit H2O2 induced oxidative damage in LLC-PK1, a porcine kidney epithelial cell line, studying the effect of H2O2 on specific cell membrane lipid targets, unsaturated fatty acids and cholesterol. Exposure to H2O2 induced a significant increase of the level of MDA together with a disruption of the membrane structure, with the loss of unsaturated fatty acids, cholesterol and α-tocopherol, and the formation of fatty acids hydroperoxides and 7-ketocholesterol. Pretreatment with HT protected renal cells from oxidative damage: the level of membrane lipids was preserved and there was no significant detection of oxidation products. HVA exerted a comparable activity, thus both HT and HVA were able to prevent in renal cells the lipid peroxidation process that plays a central role in tubular cell injury.