Simultaneous quantification of oleuropein and its metabolites in rat plasma by liquid chromatography electrospray ionization tandem mass spectrometry

Abstract

Oleuropein (OE) is the cardinal bioactive compound derived from Olea europaea and possesses numerous beneficial properties for human health. However, despite the plethora of analytical methods that have studied the biological fate of olive oil-derived bioactive compounds, no validated methodology has been published to date for the simultaneous determination of OE, along with all its major metabolites. In this study, a liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI MS/MS) method has been developed and validated for the quantification of OE, simultaneously with its main metabolites hydroxytyrosol, 2-(3,4-dihydroxyphenyl)acetic acid, 4-(2-hydroxyethyl)-2-methoxy-phenol or homovanillyl alcohol, 2-(4-hydroxy-3-methoxyphenyl)acetic acid or homovanillic acid, and elenolic acid in rat plasma matrix. Samples were analyzed by LC-ESI MS/MS prior to and after enzymatic treatment. A solid-phase extraction step with high mean recovery for all compounds was performed as sample pretreatment. Calibration curves were linear for all bioactive compounds over the range studied, while the method exhibited good accuracy, intra- and inter-day precision. The limit of detection was in the picogram range (per milliliterof plasma) for HT and OE and in the nanogram range (per milliliter of plasma) for the other analytes, and the method was simple and rapid. The developed methodology was successfully applied for the simultaneous quantification of OE and its aforementioned metabolites in rat plasma samples, thus demonstrating its suitability for pharmacokinetics, as well as bioavailability and metabolism studies.

Human absorption and metabolism of oleuropein and hydroxytyrosol ingested as olive (Olea europaeaL.) leaf extract

“…Thus, we aimed to quantitatively determine the absorption and metabolism of oleuropein and hydroxytyrosol in humans, following acute ingestion of different doses and formulations of OLE. We used a previously validated technique , specifically looking for oleuropein, hydroxytyrosol, and homovanillic acid. Further, we also adopted β‐glucuronidase hydrolysis to determine conjugated (sulfated and glucuronidated) metabolites of hydroxytyrosol.…”

“…Concentrations of oleuropein and its metabolites in plasma and urine were quantified by LC‐ESI‐MS/MS (Supporting Information). Data were analyzed using linear mixed models with repeated measures (SAS Institute, Cary, NC, USA).…”

Metabolism and Bioavailability of Olive Oil Polyphenols

“…A notable metabolic pathway for Hyty is the methylation, giving rise to the formation of HVAlc Bazoti et al, 2010;Manna et al, 2000;Visioli et al, 2003). Oxidation and methylation-oxidation, rendering 3,4-dihydroxyphenilacetic acid (DOPAC) and HVA, respectively, have been also proposed (D'Angelo et al, 2001).…”

“…Recently (Bazoti et al, 2010), the simultaneous quantification of Ol and its major metabolites in rat plasma was carried out after a control diet of 80 days supplemented with Ol or with EVOO. Basal levels of HVAlc were detected in the blood stream after the enzymatic treatment of the samples with β-glucuronidase.…”

Development and Validation of a Combined Methodology for Assessing the Total Quality Control of Herbal Medicinal Products – Application to Oleuropein Preparations

“…Many analytical methods have been developed for the determination of OE in various matrices such as olive oil [21], table olives [22], byproducts [23] and biological fluids [24]. Thus, OE has been analysed employing HPLC-UV [25], HPLC-fluorescence [26] and HPLC-MS/MS [23,27].…”