Cranberry is associated with multiple health benefits, which are mostly attributed to its high content of (poly)phenols, particularly flavan-3-ols. However, clinical trials attempting to demonstrate these positive effects have yielded heterogeneous results, partly due to the high inter-individual variability associated with gut microbiota interaction with these molecules. In fact, several studies have demonstrated the ability of these molecules to modulate the gut microbiota in animal and in vitro models, but there is a scarcity of information in human subjects. In addition, it has been recently reported that cranberry also contains high concentrations of oligosaccharides, which could contribute to its bioactivity. Hence, the aim of this study was to fully characterize the (poly)phenolic and oligosaccharidic contents of a commercially available cranberry extract and evaluate its capacity to positively modulate the gut microbiota of 28 human subjects. After only four days, the (poly)phenols and oligosaccharides-rich cranberry extract, induced a strong bifidogenic effect, along with an increase in the abundance of several butyrate-producing bacteria, such as Clostridium and Anaerobutyricum. Plasmatic and fecal short-chain fatty acids profiles were also altered by the cranberry extract with a decrease in acetate ratio and an increase in butyrate ratio. Finally, to characterize the inter-individual variability, we stratified the participants according to the alterations observed in the fecal microbiota following supplementation. Interestingly, individuals having a microbiota characterized by the presence of Prevotella benefited from an increase in Faecalibacterium with the cranberry extract supplementation.

Oxidative stress and chronic inflammation contribute to some chronic diseases. Aronia berries are rich in polyphenols. The aim of the present study was to characterize the cellular antioxidant effect of an aronia extract to reflect the potential physiological in vivo effect. Cellular in vitro assays in three cell lines (Caco-2, HepG2, and SH-SY5Y) were used to measure the antioxidant effect of AE, in three enriched polyphenolic fractions (A1: anthocyanins and phenolic acids; A2: oligomeric proanthocyanidins; A3: polymeric proanthocyanidins), pure polyphenols and microbial metabolites. Both direct (intracellular and membrane radical scavenging, catalase-like effect) and indirect (NRF2/ARE) antioxidant effects were assessed. AE exerted an intracellular free radical scavenging activity in the three cell lines, and A2 and A3 fractions showed a higher effect in HepG2 and Caco-2 cells. AE also exhibited a catalase-like activity, with the A3 fraction having a significant higher activity. Only A1 fraction activated the NRF2/ARE pathway. Quercetin and caffeic acid are the most potent antioxidant polyphenols, whereas cyanidin and 5-(3′,4′-dihydroxyphenyl)-γ-valerolactone showed the highest antioxidant effect among polyphenol metabolites. AE rich in polyphenols possesses broad cellular antioxidant effects, and proanthocyanidins are major contributors. Polyphenol metabolites may contribute to the overall antioxidant effect of such extract in vivo.

Although the relationship between gut microbiota and flavan-3-ol metabolism differs greatly between individuals, the specific metabolic profiles, known as metabotypes, have not yet been clearly defined. In this study, fecal batch fermentations of 34 healthy donors inoculated with (-)-epicatechin were stratified into groups based on their conversion rate of (-)-epicatechin and their quali-quantitative metabolic profile. Fast and slow converters of (-)-epicatechin, high producers of 1-(3'-hydroxyphenyl)-3-(2″,4″,6″-trihydroxyphenyl)-propan-2-ol (3-HPP-2-ol) and 5-(3',4'-dihydroxyphenyl)-γ-valerolactone (3,4-DHPVL) were identified. Fecal microbiota analysis revealed that fast conversion of (-)-epicatechin was associated with short-chain fatty acid (SCFA)-producing bacteria, such as Faecalibacterium spp. and Bacteroides spp., and higher levels of acetate, propionate, butyrate, and valerate were observed for fast converters. Other bacteria were associated with the conversion of 1-(3',4'-dihydroxyphenyl)-3-(2″,4″,6″-trihydroxyphenyl)-propan-2-ol into 3-HPP-2-ol (Lachnospiraceae UCG-010 spp.) and 3,4-DHPVL (Adlercreutzia equolifaciens). Such stratification sheds light on the mechanisms of action underlying the high interindividual variability associated with the health benefits of flavan-3-ols.

Extracellular tannase Lactiplantibacillus plantarum-producing strains (TanA+) release bioactive metabolites from dietary tannins. However, there is a paucity of knowledge of TanA+ strains and their hydrolyzing capacities. This study aimed to shed light on the metabolic and genomic features of TanA+ L. plantarum strains and to develop a screening technique. The established spectrophotometric was validated by UPLC-UV-QToF. Eight of 115 screened strains harbored the tanA gene, and six presented TanA activity (PROBI S126, PROBI S204, RKG 1-473, RKG 1-500, RKG 2-219, and RKG 2-690). When cultured with tannic acid (a gallotannin), TanA+ strains released 3.2−11 times more gallic acid than a lacking strain (WCFS1) (p < 0.05). TanA+ strains with gallate decarboxylase (n = 5) transformed this latter metabolite, producing 2.2–4.8 times more pyrogallol than the TanA lacking strain (p < 0.05). However, TanA+ strains could not transform punicalagin (an ellagitannin). Genomic analysis revealed high similarity between TanA+ strains, as only two variable regions of phage and polysaccharide synthesis were distinguished. A phylogenetic analysis of 149 additional genome sequences showed that tanA harboring strains form a cluster and present two bacteriocin coding sequences profile. In conclusion, TanA+ L. plantarum strains are closely related and possess the ability to resist and transform gallotannins. TanA can be screened by the method proposed herein.

Flavan-3-ols intake is associated with numerous health benefits, but these are influenced by their conversion into smaller phenolic metabolites by the gut microbiota. Thus, the identification of bacteria that metabolize flavan-3-ols could lead to targeted interventions to enhance their benefits. To this end, we screened 47 Lactiplantibacillus plantarum strains for their ability to metabolize (+)-catechin, a flavan-3-ol. Then, we assessed these strains for their capacity to convert various flavan-3-ol structures. Out of the 47 isolates, 12 released 3-(3',4'-dihydroxyphenyl)-1-(2,4,6-trihydroxyphenyl)-propan-2-ol (a form of diphenylpropan-2-ol) from (+)-catechin. All strains metabolized (+)-catechin, (-)-epicatechin, (-)-epigallocatechin, but only a subset transformed (-)-gallocatechin. Among these simple flavan-3-ol structures, (-)-epicatechin was metabolized the most. A hierarchical cluster analysis identified two groups of flavan-3-ol-metabolizing strains categorized as having "high" and "low" production of diphenylpropan-2-ols. Notably, the strains that produced higher levels of diphenylpropan-2-ol from (+)-gallocatechin and (+)-catechin also performed better with a camu-camu extract, which was studied as a complex source of flavan-3-ols and predominantly contained these two flavan-3-ols. These results demonstrate the interstrain variability in L. plantarum metabolism, which may be useful for developing tailored formulations to enhance the production of flavan-3-ols bioactive metabolites.

Many strategies are used to quantify microbial (poly)phenol metabolites (MPMs) in urine. Currently, to obtain accurate results, the use of phase II conjugate analytical standards is deemed to be the gold standard. However, these standards are expensive or commercially unavailable. Quantification using an affordable and commercially available unconjugated analytical standard following hydrolysis with the crude preparation from Helix pomatia containing arylsulfatase and β-glucuronidase was once considered to be an alternative, but previous studies have shown poor hydrolysis efficiency for conjugated MPMs. In this work, we evaluated the efficiency of purified recombinant enzymes and compared them with the preparation from H. pomatia using 75 urine samples. 38 conjugated MPMs were identified before hydrolysis, associated with 17 unconjugated MPMs. Rapid chemical synthesis of sulfated compounds was carried out to increase the confidence level for the identification of 13 sulfated MPMs. Recombinant enzymes had a mean hydrolysis efficiency of over 95% for 36 out of 38 conjugated MPMs with a hydrolysis time of 30 min. In comparison, the preparation from H. pomatia achieved similar efficiency for only 28 conjugated MPMs after 6 h of hydrolysis. When comparing the concentration of unconjugated MPMs released after enzymatic hydrolysis, recombinant enzymes were more or as effective for almost every MPM. These results demonstrate that accurate quantification of MPMs in urine can be quickly achieved using purified recombinant enzymes and represent an affordable alternative to the use of conjugated analytical standards, improving access to the analysis of the metabolism of (poly)phenols by the gut microbiota.