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The aim of this 28 d experiment was to examine the physiological response of growing rats to a dietary combination of prebiotic chicory fructans, with polyphenols originating from different parts of the chicory plant, i.e. roots, root peels, seeds and leaves. A total of forty rats were assigned to groups fed the following diets characterised by a similar content of oligofructose and inulin: control, with 10 % of a root extract (a low level of dietary polyphenols, 0·05 %), with 6·5 % of a root peel extract (a medium level of dietary polyphenols, 0·107 %), with a combination of 8 % of a peel extract and 0·8 % of a seed extract (a high level of dietary polyphenols, 0·208 %) and with 2·5 % of a leaf extract (a medium level of dietary polyphenols, 0·106 %, with chicoric acid constituting half of them). Chicory seeds are the richest source of polyphenols, especially abundant in dicaffeoylquinic acids. When applied as a dietary supplement, the mixture of monocaffeoylquinic and dicaffeoylquinic acids, from the extracts made of roots, root peels and seeds, elicited more favourable changes in parameters of the antioxidative status of the body and in the activity of bacterial b-glucuronidase in the faeces and caecal digesta. In turn, the extract from chicory leaves, containing considerable quantities of chicoric acid and polyphenolic glycosides, apart from chlorogenic acids, also triggered desirable changes in the lipid profile of the blood serum. The high concentration of polyphenols in the extracts examined enables their application as dietary supplements to be administered in low doses.Key words: Chicory: Polyphenols: Fructans: Caecum: RatsIn the last two decades, an increasing interest has been observed in the health-promoting properties of particular food constituents, including dietary fibre-polyphenolic complexes. Chicory belongs to plants of the Compositae family, accumulating energy in the form of the fructan inulin, the physiological (i.e. prebiotic) properties of which have been described in numerous studies. The available literature lacks comprehensive reports on the contents of individual active substances in the leaves and roots of chicory, particularly polyphenolic compounds. In the case of artichoke (Cynara scolymus L.), the leaves of which contain a similar array of biologically active substances as in chicory, the data are more compendious and more easily available (1) . The main components of chicory roots and leaves belonging to a group of phenolic compounds include monocaffeoylquinic acids (MCQA, e.g. chlorogenic acid being an ester of quinic and caffeic acids), dicaffeoylquinic acids (DCQA, e.g. cynarine, i.e. 1,5-DCQA) and chicoric acid. It has been reported that a high percentage of dietary chlorogenic and caffeic acids is not absorbed from the gastrointestinal tract of humans and may exhibit a variety of intestinal effects (2) . In vitro investigations have demonstrated that chlorogenic acid inhibits the process of DNA damage and the synthesis of mutagenic and carcinogenic N-nitroso compoun...

Forty-eight male Wistar rats were fed diets containing low (0.051% of diet) or high (0.153% of diet) levels of an ellagitannin-rich (ET) strawberry extract with dietary fructooligosaccharides (FOS) or cellulose (CEL) for 4 weeks. The in vivo study demonstrated that some positive changes in the cecal metabolism resulting from the ingestion of a diet enriched only with FOS were completely or slightly suppressed by the dietary ET. In particular, the pH value (7.21 vs 7.36), short-chain fatty acid production (41.2 vs 30.0 μmol/100g BW), and β-glucuronidase activity (20.2 vs 15.7 μmol/h/g) in the cecum of rats fed with FOS were affected upon the addition of the ET extract. Dietary FOS caused higher metabolism of the tested ET strawberry extract in the gastrointestinal tract of rats. Moreover, the systemic effect of the supplements when consumed together showed undesired serum HDL-cholesterol decrease (0.78 vs 1.02 mmol/L in the treatment with FOS only).

PurposeWe investigated the effects of dietary supplementation with strawberry extracts rich in ETs and fructo-oligosaccharides (FOS) on the intestinal microbiota and the formation of bacterial metabolites in the distal intestine, as well as the absorption of ET metabolites and antioxidant status in rats.MethodsRats were allocated into six groups of eight animals each and fed for 4 weeks with a control diet (group C), a control diet supplemented with FOS (group C + FOS) or modifications of these diets, in which a monomeric or dimeric ET-rich extract was added (groups ME and ME + FOS or DE and DE + FOS, respectively).ResultsThe extract addition, the FOS addition and their interaction significantly affected the total and selected bacterial counts in the caecal digesta (all P < 0.005). The total bacterial count was the highest in group C + FOS, lower in group DE and the lowest in group ME + FOS (10.6, 10.3 and 8.52 log cells/g, respectively; P ≤ 0.05). The total caecal content of ET metabolites was higher in the ME and ME + FOS group than in the DE and DE + FOS group, respectively (67.8 and 89.5 vs. 13.0 and 18.0 µg/g, respectively; P < 0.001). The total plasma concentration of ET metabolites was higher in the ME + FOS and DE + FOS group than in the ME group (248 and 281 vs. 8.13 ng/mL, respectively; P < 0.001).ConclusionsETs of the monomeric ET-rich extract are more prone to intestinal breakdown than those of the dimeric ET-rich extract, and absorption of their metabolites can be increased by dietary FOS; however, together, they evoke strong antibacterial activity.

The administration of fructooligosaccharides (FOS) beneficially modulates gastrointestinal functions and may enhance the metabolism of polyphenols. However, different polyphenolic components in the diet may have different influences on the activities of the digestive enzymes and microbiota in the gastrointestinal tract. Therefore, a 4-week study of forty-eight male Wistar rats was conducted to investigate the physiological response of the rat cecal environment to diets without and with FOS that contained two different strawberry polyphenolic extracts, specifically EP (polyphenolic profile 60, 35, 5, and 0% ellagitannins, proanthocyanidins, flavonols, anthocyanins, respectively) and EPA (polyphenolic profile: 50, 35, 6, and 9%, respectively). When combined with FOS, both extracts beneficially enhanced the acidification of the cecal digesta (P≤0.05 vs the groups without extracts), but the dietary combination of EPA and FOS elicited the greatest reduction in putrefactive short-chain fatty acid production and the lowest fecal β-glucuronidase activity in the cecum (P≤0.05 vs group EP). Moreover, the addition of dietary FOS elevated the metabolism of the examined strawberry extracts in the cecum and thereby increased the concentrations of the metabolites in the cecal digesta and urine (P≤0.05 vs the group with cellulose). Overall, both strawberry extracts modulated the effects of FOS in the gastrointestinal tract; however, the combination with EPA extract that contained anthocyanins exhibited greater beneficial effects in the lower gut environment than the EP extract.

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