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Abstract

The effects of the polyphenolic compounds from virgin olive oil: tyrosol, hydroxytyrosol and oleuropein on the non-enzymatic lipid peroxidation induced by ascorbate-Fe2+ of rat liver microsomes were examined. The inhibition of light emission (maximal induced chemiluminescence) by oleuropein was concentration dependent. Hydroxytyrosol showed a substantial degree of inhibition against ascorbate-Fe2+ induced lipid peroxidation in rat liver microsomes that was at least 6 times higher than that observed in the presence of oleuropein. Inhibition of lipid peroxidation by tyrosol was not observed. In rat liver microsomes incubated alone or in the presence of tyrosol, the fatty acid composition was profoundly modified when subjected to in vitro peroxidation mediated by ascorbate-Fe2+, with a considerable decrease of 18:2n6 and 20:4n6; however, changes in fatty acid composition were not observed when microsomes were incubated with hydroxytyrosol. When oleuropein was used at low concentration (5, 15 microM) a considerable decrease of 20:4n6 was observed, but 18:2n6 was not modified; at higher concentration (30, 60 microM) changes in fatty acid composition were not observed. There was a very good correlation between the presence of oxidized phospholipids and the changes in polyunsaturated fatty acids previously observed. Thus, hydroxytyrosol showed the highest protection again oxidized phospholipid formation. The presence of oleuropein at low concentration (5, 15 microM) does not prevent the formation of oxidized phospholipids (8.02 +/- 1.22 and 1.22 +/- 1.22) but concentration higher than 30 microM avoids completely the formation of this molecules whereas tyrosol at any concentration assayed was found to be ineffective and allows the formation not only of oxidized phospholipids but also of oxidized cholesterol.

Caffeic acid and hydroxytyrosol have anti-obesogenic properties in zebrafish and rainbow trout models

“…Moreover, a slight decrease was also observed in plasma glucose following treatment, in agreement with mammal studies where CA and HT have been proposed as potential hypoglycemic antidiabetic treatments [76,77]. Within this in vivo scenario it is important to notice that CA and HT are antioxidants, with proven effects upon cell viability (S2 Fig), which may have an implication in modulating fatty acid oxidation [78]. In this sense, HT administration upregulated acsl1 mRNA levels in WAT while slightly decreased its expression in liver, indicating a tissue-specific regulation as previously reported [79].…”

Nutraceutical Properties of Olive Oil Polyphenols. An Itinerary from Cultured Cells through Animal Models to Humans

“…The strong antioxidant properties of these substances, particularly HT and OLE [ 74 ], could explain, at least in part, these effects. In fact, OLE, HT and tyrosol are able to reduce the kinetics and the extent of lipid peroxidation [ 77 ] and protect against ischemia/reperfusion-induced oxidative stress provided to isolated rat hearts at doses corresponding to the average intake in a normal MD [ 78 ]. Moreover, OLE has been reported to reduce the extent of infarcted tissue, total cholesterol and triglyceride levels in both normal and hypercholesterolemic rabbits, thus providing cardioprotection even before the ischemic event [ 79 ].…”

Hydroxytyrosol in the Prevention of the Metabolic Syndrome and Related Disorders

“…Moreover, it can inhibit superoxide anion burst from macrophages but not from neutrophils where it can only scavenge hydrogen peroxide (1 to 50 µM) [116]. It also protects erythrocytes from hemolysis (50 to 200 µM) [117], endothelial cells from monocytes adhesion (0.5 to 2.5 µM) [118] and hepatocytes (10 to 40 µM) [119], and protects from lipid peroxidation in rat livers (5 to 60 µM) [120] as well as from lipid oxidation (10 µM) [91]. …”