Volume 88, Issue 3, September (2002), pp. 225-235 © The Author 2002
doi:10.1079/BJN2002620

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Olive oil phenolics: effects on DNA oxidation and redox enzyme mRNA in prostate cells

José L. Quiles^1*, Andrew J. Farquharson², David K. Simpson², Ian Grant², Klaus W. J. Wahle^2
1Institute of Nutrition and Food Technology, Department of Physiology, University of Granada, C/Ramón y Cajal 4, 18071 Granada, Spain
²Rowett Research Institute, Greenburn Road North, Bucksburn, Aberdeen, AB21 9SB, UK

 (Received 17 July 2001–Revised 4 February 2002–Accepted 8 April 2002)

Hydroxytyrosol, tyrosol and caffeic acid effects on hydrogen peroxide-induced DNA damage, hydroperoxide generation and redox enzyme gene expression were studied in oxidative-stress-sensitive human prostate cells (PC3). Hydroxytyrosol led to lower levels of hydroperoxides, DNA damage, and mRNA levels of classic glutathione peroxidase (GPx) for all the studied concentrations. Only hydroxytyrosol was effective at low concentrations (10 μM). Tyrosol reduced DNA oxidation only at high (>50 μM) concentrations and increased hydroperoxides, GPx and phospholipid hydroperoxide GPx mRNA levels. Caffeic acid elicited effects between those of the other two phenolics. Results indicate that hydroxytyrosol is the only significant antioxidant phenolic in olive oil and may be the major component accounting for its beneficial properties. Tyrosol appeared to exhibit pro-oxidant effects (only at high concentrations) and caffeic acid was neutral. Both number and position of hydroxyl groups appear to play a role in the cellular effects of hydroxytyrosol.

Keywords:
Olive oil: Phenolic compounds: DNA damage: Gene expression