The Metabolic Fate and Bioactivity of Anthocyanins in Humans

De Ferrars, Rachel (2014) The Metabolic Fate and Bioactivity of Anthocyanins in Humans. Doctoral thesis, University of East Anglia.

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Abstract

Anthocyanins, the class of flavonoid responsible for giving a red hue to many berries, have
been associated with a decreased risk of cardiovascular disease. However, numerous
intervention studies feeding anthocyanin-rich foods report limited (<1%) bioavailability of
the parent anthocyanins in vivo. Due to the instability of anthocyanins at neutral pH, it is
postulated that degradation products and metabolites of anthocyanins may be responsible for
the perceived bioactive effects. The aims of the present thesis were: (1) To model and
establish analytical methods for the extraction and quantification of putative anthocyanin
metabolites in urine, serum and faecal samples. (2) To identify and explore the
pharmacokinetics of anthocyanin metabolites via the analysis of urine, serum and faecal
samples from two human interventions, feeding either (a) 500 mg of isotopically (13C5)
labelled anthocyanin or (b) 500 mg elderberry anthocyanins for 12 wks. (3) To explore the
impact of acute (500 mg) versus chronic (500 mg/day for 12 wks) anthocyanin consumption
on their metabolism and (4) To investigate the anti-inflammatory activity of six anthocyanin
metabolites at physiologically relevant concentrations (0.01 μM to 10 μM) using human
umbilical vein endothelial cells (HUVECs). Following the consumption of 500 mg
elderberry anthocyanins, 28 anthocyanin metabolites were identified in urine and 21 in
plasma, with the phenolic metabolites within plasma identified at 45 fold higher levels than
their parent compounds. Similar results were observed within the 13C-labelled anthocyanin
intervention, where 17 13C-labelled compounds were identified in serum and 31 in urine.
However, chronic consumption of anthocyanins had no impact on the formation of the
metabolites. The cardiovascular bioactivity of anthocyanins may be linked to the antiinflammatory
activity of their metabolites. IL-6 and VCAM-1 are cytokines and adhesion
molecules integral to the initiation and progression of inflammation. In vitro, anthocyanin
metabolites reduced CD40L and TNF-α stimulated expression of the inflammatory markers,
sVCAM-1 and IL-6, indicating that the anti-inflammatory effects of anthocyanins are likely
attributed to their metabolites. In conclusion, the present thesis provides a new
understanding into the metabolism and bioactivity of anthocyanins, which should provide an
informative insight into how the consumption of higher intakes of anthocyanins may
contribute to optimising human health.

Item Type: Thesis (Doctoral)
Faculty \ School: Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User: Mia Reeves
Date Deposited: 09 Jul 2014 12:17
Last Modified: 09 Jul 2014 12:17
URI: https://ueaeprints.uea.ac.uk/id/eprint/49475
DOI:

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