Pharmacokinetic Evaluation of Oleuropein from the Olive Tree (Olea europaea)

In this study, the pharmacokinetic (PK) characteristics of oleuropein present in the olive tree (Olea europaea) were determined. We developed and validated a highly sensitive ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) method to quantify oleuropein and its aglycone derivative, thereby establishing their pharmacokinetic properties in vitro and in vivo. Quantification of oleuropein and oleuropein aglycone was performed using selected reaction monitoring (SRM) with heated electrospray ionization in negative ion mode, employing mass transitions of m/z 275.06 and 307.137 for the respective analytes, and methylparaben as the internal standard. The calibration curve for both exhibited a range from 1 ng/mL to 1000 ng/mL, utilizing a total of 10 calibrator standards. The method demonstrated superior sensitivity, precision, and reproducibility, facilitating accurate quantification of analytes over a wide concentration range in biological matrices. To develop a pharmacokinetic profile, C57BL/6 male mice were administered oleuropein at a dose of 100 mg/kg body weight via oral gavage, and plasma levels were examined by LC-MS/MS. Oleuropein pharmacokinetics were evaluated exclusively, as plasma levels of oleuropein aglycone remained below the limit of quantification throughout the 24 h sampling period. Mass analysis of plasma samples identified multiple glucuronidated and sulfated metabolites, establishing Phase II metabolism as the dominant pathway governing the systemic disposition of oleuropein. In addition, the metabolic stability of the compounds was also investigated in mouse liver microsomes and S9 fractions to define the in vivo stability of oleuropein and oleuropein aglycone.