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

Eur J Nutr. 2014 Jun;53(4):1015-27. doi: 10.1007/s00394-013-0604-9. Epub 2013 Oct 26.

Abstract

Purpose: 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.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Aged
  • Antioxidants / metabolism*
  • Biological Availability
  • Chromatography, High Pressure Liquid
  • Female
  • Humans
  • Iridoids / administration & dosage
  • Iridoids / blood
  • Iridoids / pharmacokinetics*
  • Iridoids / urine
  • Malondialdehyde / blood
  • Middle Aged
  • Olea / chemistry*
  • Oxidative Stress / drug effects
  • Phenols / blood
  • Phenols / pharmacokinetics*
  • Phenols / urine
  • Plant Extracts / administration & dosage
  • Plant Extracts / pharmacokinetics*
  • Plant Leaves / chemistry*
  • Postmenopause / blood
  • Postmenopause / urine
  • Premenopause / blood
  • Premenopause / urine
  • Young Adult

Substances

  • Antioxidants
  • Iridoids
  • Phenols
  • Plant Extracts
  • oleuropein
  • Malondialdehyde