The potency of commercial blackcurrant juices to induce relaxations in porcine coronary artery rings is not correlated to their antioxidant capacity but to their anthocyanin content

Objective: Polyphenol-rich products such as fruit juices have been shown to have strong antioxidant capacities and to induce potent endothelium-dependent relaxations. We have evaluated whether the commercial blackcurrant juices induced endothelium-dependent relaxation of isolated coronary arteries can be related to their antioxidant capacity and/or phenolic content.
Research Methods & Procedures: Six different commercial blackcurrant juices were selected. Their main phenolic compounds were measured by UPLC and antioxidant capacity was evaluated by spectrometric methods. Vascular reactivity studies with these juices were done using isolated porcine coronary arteries.
Results: The six different commercial blackcurrant juices induced relaxations ranging from 21 to 100 % at the concentration of 0.5% v/v. The relaxation induced at 0.5 % v/v was not correlated to their antioxidant capacity measured by either ORAC or DPPH assays, and also not to the ascorbic acid, total polyphenols, total flavonols and total phenolic acid contents. In contrast, the amplitude of the relaxation was correlated to the total anthocyanins content and the individual anthocyanin concentration.
Conclusions: Correlations between relaxation amplitude and total anthocyanin or individual anthocyanin contents are of interest for the development of functional blackcurrant beverages with the potential to promote vascular protection.