Metabolism of the Olive Oil Phenols Hydroxytyrosol, Tyrosol, and Hydroxytyrosyl Acetate by Human Hepatoma HepG2 Cells

Abstract

To study the potential hepatic metabolism of olive oil phenols, human hepatoma HepG2 cells were incubated for 2 and 18 h with hydroxytyrosol, tyrosol, and hydroxytyrosyl acetate, three phenolic constituents of olive oil. After incubation, culture media and cell lysates were hydrolyzed with β-glucuronidase and sulfatase and analyzed by LC-MS. In vitro methylation, glucuronidation, and sulfation of pure phenols were also performed. Methylated and glucuronidated forms of hydroxytyrosol were detected at 18 h of incubation, together with methylglucuronidated metabolites. Hydroxytyrosyl acetate was largely converted into free hydroxytyrosol and subsequently metabolized, yet small amounts of glucuronidated hydroxytyrosyl acetate were detected. Tyrosol was poorly metabolized, with <10% of the phenol glucuronidated after 18 h. Minor amounts of free or conjugated phenols were detected in cell lysates. No sulfated metabolites were found. In conclusion, olive oil phenols can be metabolized by the liver as suggested by the results obtained using HepG2 cells as a hepatic model system. Keywords: Phenols; virgin olive oil; metabolism; in vitro conjugation; HepG2 cells; LC-MS analysis

Metabolism and Bioavailability of Olive Oil Polyphenols

“…To study the potential hepatic metabolism of olive oil phenols, human hepatoma HepG2 cells were incubated for 2 and 18 h with Ty, Hyty and Hyty acetate (Mateos et al, 2005 glucurono-and methyl-, but no sulfo-conjugates, were found. Olive oil phenols are metabolized by the liver as well, as suggested by these results.…”

Protective effects of papaya extracts on tert-butyl hydroperoxide mediated oxidative injury to human liver cells (An in-vitro study)

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Safety evaluation of subchronic oral administration of Oleuropein and its semisynthetic peracetylated derivative

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