title: Bioavailability of phenolics from an oleuropein-rich olive (Olea europaea) leaf extract and its acute effect on plasma antioxidant status: comparison between pre- and postmenopausal women.
abstract: OBJECTIVE
  Preclinical studies suggest a potential protective effect of oleuropein in osteoporosis, and one of the proposed mechanisms is the modulation of the oxidative stress. Oleuropein bioavailability and its effect on antioxidant status in pre- and postmenopausal women are unknown. The aim of the present study was to investigate the oral bioavailability of an olive leaf extract rich in oleuropein (40 %) and its effect on antioxidant status in postmenopausal women compared to premenopausal women.
  
  
  METHODS
  Premenopausal (n = 8) and postmenopausal women (n = 8) received 250 mg of olive leaf extract, blood samples (t = 0, 1, 2, 3, 4, 6, 8, 12, 16 and 24 h) were taken, and 24-h urine divided into five fractions was collected. Olive-leaf-extract-derived metabolites were analyzed in plasma and urine by HPLC-ESI-QTOF and UPLC-ESI-QqQ, and pharmacokinetics parameters were determined. Ferric reducing antioxidant ability and malondialdehyde levels were measured in plasma.
  
  
  RESULTS
  Plasma levels of hydroxytyrosol glucuronide, hydroxytyrosol sulfate, oleuropein aglycon glucuronide and oleuropein aglycon derivative 1 were higher in postmenopausal women. MDA levels were significantly decreased (32%) in postmenopausal women and inversely correlated with hydroxytyrosol sulfate levels. Postmenopausal women excreted less sulfated metabolites in urine than premenopausal women.
  
  
  CONCLUSIONS
  Our results suggest that postmenopausal women could be a target population for the intake of olive phenolics in order to prevent age-related and oxidative stress-related processes such as osteoporosis.
authors.affiliation: Department of Food Science and Technology, Research Group on Quality, Safety and Bioactivity of Plant Foods CEBAS-CSIC, 30100 Campus de Espinardo, Murcia, Spain.
authors.forename: R
authors.initials: R
authors.lastname: García-Villalba
authors.forename: M
authors.initials: M
authors.lastname: Larrosa
authors.forename: S
authors.initials: S
authors.lastname: Possemiers
authors.forename: F A
authors.initials: FA
authors.lastname: Tomás-Barberán
authors.forename: J C
authors.initials: JC
authors.lastname: Espín
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000975:Antioxidants / Q000378:metabolism*; D001682:Biological Availability; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006801:Humans; D057888:Iridoid Glucosides; D039823:Iridoids / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D008315:Malondialdehyde / Q000097:blood; D008875:Middle Aged; D031658:Olea / Q000737:chemistry*; D018384:Oxidative Stress / Q000187:drug effects; D010636:Phenols / Q000097:blood / Q000493:pharmacokinetics* / Q000652:urine; D010936:Plant Extracts / Q000008:administration & dosage / Q000493:pharmacokinetics*; D018515:Plant Leaves / Q000737:chemistry*; D017698:Postmenopause / Q000097:blood / Q000652:urine; D017697:Premenopause / Q000097:blood / Q000652:urine; D055815:Young Adult
chemical_list: D000975:Antioxidants; D057888:Iridoid Glucosides; D039823:Iridoids; D010636:Phenols; D010936:Plant Extracts; C002769:oleuropein; D008315:Malondialdehyde