L' acide 5-O-caféoylquinique, un polyphénol alimentaire et ses métabolites produits par des bactéries intestinales : études électrochimiques, analyses LC-MS/MS, biotransformation et études biologiques

Polyphenols are known for their antioxidant properties and as modulators of redox signalling pathways, which have a positive effect on human health. Given their superiority in terms of presence in systemic circulation and their often higher bioactivity than parent polyphenols, there is now more interest in the gut microbiota`s pivotal role in the production of low molecular weight metabolites. Thus, we have focused our study on 5-O-caffeoylquinic acid (5-CQA), a dietary polyphenol, subjected to a resting cell biotransformation study using Lactobacillus reuteri, Bacteroides fragilis and Bifidobacterium longum. Our study highlighted the ability of only L. reuteri to bioconverse 5-CQA into several metabolites, including a known natural compound esculetin. This biotransformation capacity was also evaluated in co-culture. This study put in the spotlight, for the first time, an interesting oxidative pathway carried out by gut bacteria. Electrochemical and enzymatic studies led to identify, after LC-MS/MS analysis, the oxidized compounds of 5-CQA and caffeic acid. In addition, esculetin has shown a beneficial effect on the integrity of the epithelial barrier using an original in vitro quadruple intestinal model.