Metabolites of Avena sativa with Blood Cholesterol Lowering Properties

Research output: ThesisDoctoral Thesis (monograph)

Abstract

Cardiovascular diseases are among the most important causes of death in the
developed countries. These diseases are partly caused by too high cholesterol
concentrations in the blood. Avena sativa, oat, is the most common spieces of the genus Avena, and produced in huge amounts worldwide. Oats have been shown to have cholesterol-lowering properties since the 1960s. This property was originally attributed to the ß-glucans, however, it has also been observed that other compounds, which are soluble in organic solvents (not ß-glucans), are able to lower the cholesterol concentration in the blood in rats as well as in humans.

The aim of this thesis has been to obtain a better understanding about the
relationship between the cholesterol lowering effect (CLE) and compounds
naturally present in oats (besides ß-glucans).

Initially, avenanthramides (AVAs), which is a major group of phenolic compounds present in oats, were detected and quantified in order to search for any relationship between the contents of AVAs in oats and a CLE. However, there
was no obvious relationship, and it seems unlikely that the AVAs contribute
significantly to the CLE. During this study, it was necessary to prepare AVAs by
synthesis, as their isolation from oats as pure compounds in larger amounts is
rather complicated. Fourteen AVAs, whereof six are natural products, were
synthesized, and used as standards for the analytical work as well as for in vitro
assays. The three most prevalent AVAs in oat, avenanthramides (1), (2), and (3)
were evaluated in vitro for their ability to prevent oxLDL-induced lipid
accumulation in murine macrophages. However, the pre-incubation of
the macrophages with the three AVAs (1), (2), and (3) did not alter the mRNAexpression of scavenger receptors or lipid transporters of the macrophages.

Bio-assay guided fractionation was used to find the fraction of oat with the
strongest CLE. Oat extracts were fractionated and the fractions were tested in vivo. The fraction rich in phytosterols showed the best CLE. However, another
compound, 13-HODE, was also present in the fractions showing CLE. Thus, it
was not possible to link the CLE to a specific compound or compounds.

Details

Authors
  • Narda Thuresson
Organisations
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Natural Sciences

Keywords

  • Cholesterol lowering effect, Avena sativa, phytosterols, avenanthramides, 13-HODE
Original languageEnglish
QualificationDoctor
Awarding Institution
Supervisors/Assistant supervisor
Thesis sponsors
  • VINNOVA Industrial Excellence Centre: System on Silicon (SoS)
Award date2017 Nov 10
Place of PublicationLund
Publisher
  • Lund University, Faculty of Science, Department of Chemistry, Centre for Analysis and Synthesis
Print ISBNs978-91-7422-549-5
Electronic ISBNs978-91-7422-549-1
StatePublished - 2017 Oct

Bibliographic note

Defence details Date: 2017-11-10 Time: 10:00 Place: Lecture hall B, Center for chemistry and chemical engineering, Naturvetarvägen 14, Lund. External reviewer(s) Name: Horsfelt Skibsted, Leif Title: Professor Affiliation: University of Copenhagen, Denmark ---