Metabolism of the olive oil phenols hydroxytyrosol, tyrosol, and hydroxytyrosyl acetate by human hepatoma HepG2 cells.
Journal of Agricultural and Food Chemistry. 2005 December 28;53(26):9897-905
This in vitro study investigated the metabolism of the polyphenols hydroxytyrosol, tyrosol and hydroxytyrosyl acetate by liver cells. The liver cells were incubated for 2 and 18 hours in a culture media with HepG2 liver cells. After 18 hours methylated, glucuronidated and methylglucuronidated forms of hydroxytyrosol were detected. Hydroxytyrosyl acetate was mainly hydrolyzed to free hydroxytyrosol.
Hydroxytyrosol, a natural antioxidant from olive oil, prevents protein damage induced by long-wave ultraviolet radiation in melanoma cells.
Free Radical Biology and Medicine. 2005 April 1;38(7):908-19
In is known that UV-A radiation results in damage to skin cells caused by an increased production of free radicals and depletion of antioxidants. The damage results in increased levels of lipid peroxidation products (TBARS) and abnormal L-isoaspartyl residues. The aim of this in vivo study was to investigate the protective effect of hydroxytyrosol on human melanoma cells exposed to UV-B radiation. The researchers found that hydroxytyrosol reduced lipid peroxidation and other markers of oxidative stress. However, at higher levels of hydoxytyrosol, cell differentiation was stopped. The study concluded that the effect of hydroxytyrosol on melanoma cells depends on the used dosage.
The in vivo fate of hydroxytyrosol and tyrosol, antioxidant phenolic constituents of olive oil, after intravenous and oral dosing of labeled compounds to rats.
The Journal of Nutrition. 2001 July;131(7):1993-6
This study used radiolabeling of polyphenols to study the in vivo bioavailability of hydroxytyrosol and tyrosol. The rats were fed with hydroxytyrosol and tyrosol, either dissolved in water or oil. The polyphenols were also injected. The researchers found that the oral bioavailability of hydroxytyrosol was higher when given in olive oil (99 percent) then when dosed as aqueous solution (75 percent). For tyrosol the bioavailability was 98 percent in olive oil and 71 percent in aqueous solution.
Hydroxytyrosol, a phenolic compound from virgin olive oil, prevents macrophage activation.
Naunyn Schmiedebergs Archives of Pharmacology. 2005 June;371(6):457-65
The aim of this study was to determine the effect of hydroxytyrosol on inducible nitric oxide synthase and cyclooxygenase-2 expression in macrophages, which were stimulated with lipopolysaccharide. The researchers found that incubation of macrophages with hydroxytyrosol reduced the inducible nitric oxide synthase and expression of cyclooxygenase-2 mRNA. Hydroxytyrosol also reduced inflammatory indicators. The study concluded that hydroxytyrosol may represent a natural agent for the control of inflammatory genes.