Protective effects of synthetic hydroxytyrosol acetyl derivatives against oxidative stress in human cells.
Journal of Agricultural and Food Chemistry. 2005 November 30;53(24):9602-7
This study investigated the activity of di- and triacetyl derivatives of hydroxytyrosol. The acetyl groups modify the o-diphenolic ring of hyrdoxytyrosol, thereby removing the antioxidant capacity of the acetyl derivates. The loss of antioxidant capacity was confirmed with the ferric reducing antioxidant power test. However, after metabolization of the acetyl derivates by esterases they protected human cells from oxidative stress. This study suggested that chemically stable di- and triacetyl derivatives of hydroxytyrosol could be used as nutritional, cosmetic and pharmaceutical applications.
Olive oil hydroxytyrosol protects human erythrocytes against oxidative damages.
The Journal of Nutritional Biochemistry. 1999 March;10(3):159-65
Hydroxytyrosol is the main active phytochemical of olive oil. The aim of this in vivo study was to investigate the effect of hydroxytyrosol on the oxidative action of hydrogen peroxide in erythrocytes. A culture of human erythrocytes was treated with hydroxytyrosol and hydrogen peroxide. The cells were then analyzed for oxidative damage. The researchers found that hydroxytyrosol prevented oxidation in the erythrocytes. Treatment of the cells with low hydrogen peroxide levels showed a decrease in the transport of the amino acids methionine and leucine, but not glucose, through the cell membranes. This reduced transport was prevented when the cells were first exposed to hydroxytyrosol.
Antioxidant effect of hydroxytyrosol, a polyphenol from olive oil: scavenging of hydrogen peroxide but not superoxide anion produced by human neutrophils.
Biochemical Pharmacology. 2004 November 15;68(10):2003-8
Hydroxytyrosol, the main polyphenol in virgin olive oil, is a strong antioxidant. The mechanism of antioxidant action of hydroxytyrosol is still unclear. The aim of this study was to identify the targeted reactive oxygen molecules. The researchers found that hydroxytyrosol exerts its antioxidant effect by scavenging hydrogen peroxide but not superoxide anions.
Antioxidant activity of hydroxytyrosol acetate compared with that of other olive oil polyphenols.
Journal of Agricultural and Food Chemistry. 2001 May;49(5):2480-5
The aim of this study was to compare the antioxidant activity of the natural phytochemicals hydroxytyrosol, oleuropein, 3,4-DHPEA-EA and vitamin E with that of chemically produced hydroxytyrosol acetate. The antioxidant activity was determined with scavenging of 1,1-diphenyl-2-picrylhydrazyl radicals. They found that hydroxytyrosol acetate had a weaker scavenging activity than hydroxytyrosol, oleuropein or 3,4-DHPEA-EA, but the activity was similar to that of vitamin E. In oil, hydroxytyrosol had the strongest antioxidant activity but in an emulsion 3,4-DHPEA-EA and vitamin E were more active than hydroxytyrosol.
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