Year: 2014
Type: dissertation
Abstract: Anthocyanins, the class of flavonoid responsible for giving a red hue to many berries, have \nbeen associated with a decreased risk of cardiovascular disease. However, numerous \nintervention studies feeding anthocyanin-rich foods report limited (<1%) bioavailability of \nthe parent anthocyanins in vivo. Due to the instability of anthocyanins at neutral pH, it is \npostulated that degradation products and metabolites of anthocyanins may be responsible for \nthe perceived bioactive effects. The aims of the present thesis were: (1) To model and \nestablish analytical methods for the extraction and quantification of putative anthocyanin \nmetabolites in urine, serum and faecal samples. (2) To identify and explore the \npharmacokinetics of anthocyanin metabolites via the analysis of urine, serum and faecal \nsamples from two human interventions, feeding either (a) 500 mg of isotopically (13C5) \nlabelled anthocyanin or (b) 500 mg elderberry anthocyanins for 12 wks. (3) To explore the \nimpact of acute (500 mg) versus chronic (500 mg/day for 12 wks) anthocyanin consumption \non their metabolism and (4) To investigate the anti-inflammatory activity of six anthocyanin \nmetabolites at physiologically relevant concentrations (0.01 μM to 10 μM) using human \numbilical vein endothelial cells (HUVECs). Following the consumption of 500 mg \nelderberry anthocyanins, 28 anthocyanin metabolites were identified in urine and 21 in \nplasma, with the phenolic metabolites within plasma identified at 45 fold higher levels than \ntheir parent compounds. Similar results were observed within the 13C-labelled anthocyanin \nintervention, where 17 13C-labelled compounds were identified in serum and 31 in urine. \nHowever, chronic consumption of anthocyanins had no impact on the formation of the \nmetabolites. The cardiovascular bioactivity of anthocyanins may be linked to the antiinflammatory \nactivity of their metabolites. IL-6 and VCAM-1 are cytokines and adhesion \nmolecules integral to the initiation and progression of inflammation. In vitro, anthocyanin \nmetabolites reduced CD40L and TNF-α stimulated expression of the inflammatory markers, \nsVCAM-1 and IL-6, indicating that the anti-inflammatory effects of anthocyanins are likely \nattributed to their metabolites. In conclusion, the present thesis provides a new \nunderstanding into the metabolism and bioactivity of anthocyanins, which should provide an \ninformative insight into how the consumption of higher intakes of anthocyanins may \ncontribute to optimising human health.
Author: Rachel de Ferrars
Language: English
Subfield: Biochemistry (medical)
Field: Medicine
Domain: Health Sciences
Open Access status: green
OpenAlex ID: W1526905696