Dose-Related Regulatory Effect of Raspberry Polyphenolic Extract on Cecal Microbiota Activity, Lipid Metabolism and Inflammation in Rats Fed a Diet Rich in Saturated Fats.

The amount of berry polyphenols required to exert health-promoting effects seems to be difficult to achieve by fresh fruit ingestion, so polyphenol-rich extracts could be considered a dietary alternative. In the present study, laboratory rats were fed high-fat diets supplemented with 0.1 or 0.3% raspberry polyphenols from pomace, with the former dose reflecting the amount of polyphenols consumed with a glass of fresh raspberries. It was hypothesized that beneficial changes in blood and hepatic tissue related to lipid metabolism would accompany both treatments, but the health-promoting effect would be more noticeable with the higher dose of extract. This hypothesis was confirmed, and the high dose of raspberry polyphenols was better than the low dose extract in terms of decreased epididymal white adipose tissue weight, hepatic triglyceride content, PPARγ and SREBP-1c expression in the liver, and plasma IL-6 concentration, as well as increased acetic acid concentration in the cecal digesta. These effects might be partially associated with the enhanced content of ellagitannin and anthocyanin metabolites found in the blood plasma of rats administered the high dose of the extract. The results showed that this extract could be considered a dietary vehicle to provide an amount of raspberry polyphenols that could promote health.

Rosa spp. Extracts as a Factor That Limits the Growth of Staphylococcus spp. Bacteria, a Food Contaminant.

Due to their richness of bioactive substances, rose hips are a valuable raw material for obtaining extracts with potential antimicrobial activity. The aim of the study was to determine the antagonistic potential of whole pseudo-fruit and flesh extracts of three Rosa sp. varieties against Staphylococcus spp. bacteria isolated as food contaminants. The biological material in this study consisted of seven strains of bacteria from the genus Staphylococcus. Two strains-Staphylococcus aureus ATCC 25923 and Staphylococcus epidermidis DSMZ 3270-were used as reference strains. The other five strains were food-derived isolates-S. epidermidis A5, S. xylosus M5, S. haemolyticus M6, S. capitis KR6, and S. warneri KR2A. The material was the pseudo-fruits of Rosa canina, Rosa pomifera Karpatia, and Rosa rugosa. The polyphenols were extracted from the fleshy part and the whole pseudo-fruit for all rose varieties. The tested preparations differed significantly in their polyphenol composition. The sum of polyphenols ranged from 28 862 to 35 358 mg/100 g of lyophilisate. The main groups of polyphenols found in the preparations were flavanols and ellagitannins. All of the tested extracts inhibited the growth of staphylococci at a concentration of 500 mg/mL. Rosa rugosa fruit extract showed the strongest antimicrobial properties among the studied extracts. For all the strains, the growth inhibition had a diameter of 20.3-29.0 mm. Moreover, six out of the seven tested strains showed the highest inhibition with the use of this extract. The MIC of rose extracts was in the range of 3.125-500 mg/mL and was strictly dependent on the bacterial species, the species of the rose, and the part of the fruit from which the extract was obtained. Correlations were assessed between the main groups of polyphenols in the extracts and their inhibition of bacterial growth. In the case of pseudo-fruit extracts, the inhibitory effect on bacterial growth positively correlated with the content of ellagitannins, and this effect was observed for almost all the tested strains. The results presented herein follow the current trend of minimising the use of chemical preservatives in food; from this point of view, rose extracts are very promising.

Strawberry phenolic extracts effectively mitigated metabolic disturbances associated with high-fat ingestion in rats depending on the ellagitannin polymerization degree.

In the present experiment it was hypothesised that dietary strawberry ellagitannin-rich extracts would mitigate negative consequences associated with consumption. Therefore, two extracts rich in dimeric (D-ET) or monomeric (M-ET) ellagitannins (ETs) were added to a standard or high-fat diet fed to rats for four weeks. The D-ET-rich extract contained 82.3% polyphenols, and the M-ET/D-ET ratio was 40 : 60, while the M-ET-rich extract contained 88.0% and 96 : 4, respectively. The experimental feeding with high-fat diets containing extracts resulted in beneficial mitigating effects in the lipid profile, redox status of the rat's liver and blood plasma. According to the accepted hypothesis, the obtained results pointed at increased desired hepatic and plasma modifications when the extract was rich in M-ET, as indicated by favourable changes in the hepatic fat content, GSH and GSSG concentrations and GSH/GSSG ratio as well as blood plasma FRAP, ACL, HDL-cholesterol, and atherogenic coefficient values. These changes were partly connected to the fact that M-ET was more prone vs. D-ET to intestinal microbial conversion into respective metabolites. The urinary daily excretion of ET metabolites and their blood plasma concentrations were higher in rats fed with M-ET vs. D-ET-rich diets. To conclude, the metabolic action of the M-ET-rich extract in the normalization of high-fat-induced disturbances was more pronounced.

Protective Effects of a Strawberry Ellagitannin-Rich Extract against Pro-Oxidative and Pro-Inflammatory Dysfunctions Induced by a High-Fat Diet in a Rat Model.

Due to the demonstrated intestinal microbial transformation of strawberry ellagitannins (ET) into bioactive metabolites, in the current study on rats, we hypothesised that the dietary addition of a strawberry ET-rich extract (S-ET) to a high-fat diet (HFD) would attenuate disturbances in the redox and lipid status as well as in the inflammatory response. We randomly distributed 48 Wistar rats into six groups and used two-way analysis of variance (ANOVA) to assess the effects of two main factors-diet type (standard and high-fat) and ET dosage (without, low, and 3× higher)-applied to rats for 4 weeks. In relation to the hypothesis, irrespective of the dosage, the dietary application of ET resulted in the desired attenuating effects in rats fed a HFD as manifested by decreased body weight gain, relative mass of the epididymal pad, hepatic fat, oxidized glutathione (GSSG), triglycerides (TG), total cholesterol (TC), and thiobarbituric acid-reactive substances (TBARS) concentrations as well as desired modifications in the blood plasma parameters. These beneficial changes were enhanced by the high dietary addition of ET, which was associated with considerably higher concentrations of ET metabolites in the urine and plasma of rats. The results indicated that S-ET could be effectively used for the prevention and treatment of metabolic disturbances associated with obesity, dyslipidaemia, redox status imbalance, and inflammation.

Protocatechuic acid and quercetin glucosides in onions attenuate changes induced by high fat diet in rats.

Yellow onion waste from industrial peeling was used to obtain three pure preparations: protocatechuic acid (PA), quercetin diglycosides (QD) and quercetin monoglycosides (QM). PA contained 61% protocatechuic acid, QD contained 35% quercetin diglucosides, mainly quercetin-3,4'-diglucoside, and QM contained 41% monoglucosides, mainly quercetin-4'-glucoside. The highest antioxidant activity was shown by PA. The effects of preparations on the digestive functions of the gastrointestinal tract of rats as well as the biochemical parameters and antioxidant capacity of the blood in model research on Wistar rats sustained by a high-fat diet were assessed (5 groups per 8 animals). The results of the present experiment showed that different onion phenolic preparations differently modulated the enzymatic activity of faecal (P < 0.001) and caecal (P < 0.001) microbiota. For instance, the QD preparation but not QM efficiently reduced the faecal and caecal bacterial ß-glucuronidase activity. Both protocatechuic acid and quercetin monoglycosides showed a beneficial effect by regulating blood lipids (reduction of TC (P < 0.001) and TG (P < 0.001), non-HDL increase in HDL (P < 0.001)), thereby lowering the risk factors for atherosclerotic lesions AI (P = 0.038) and AII (P = 0.013). In addition, onion phenols showed a strong antioxidant effect, however, with a different mechanism: protocatechuic acid via serum ACL (P = 0.033) increase and hepatic GSSG (P = 0.070) decrease, QM via ACW (P < 0.001) increase and hepatic TBARS (P = 0.002) decrease, and QD via serum ACW increase and hepatic GSSG decrease. It can be concluded that onion polyphenols with a lower molar weight, i.e. QM more preferably affect the blood lipid profile than QD. However QD more efficiently reduced the faecal and caecal bacterial ß-glucuronidase activity.

Protective Effects of Ellagitannin-Rich Strawberry Extracts on Biochemical and Metabolic Disturbances in Rats Fed a Diet High in Fructose.

The present study compares the effects of two dietary strawberry extracts rich in monomeric (ME) or dimeric (DE) ellagitannins (ETs) on gastrointestinal, blood and tissue biomarkers in Wistar rats fed high-fructose diets. Both strawberry extracts beneficially affect the antioxidant status and lipid profile of the liver and serum. The ME extract shows a greater ability to inhibit lipid peroxidation in kidneys, more effectively decreases serum and liver triglycerides, and exerts greater anti-inflammatory effects in blood serum than the DE extract. The DE extract significantly reduces the activity of microbial enzymes in the cecum. These effects might be associated with higher cecum and urine levels of ET metabolites in rats fed with ME than in rats fed with DE. In conclusion, the diet-induced fructose-related disturbances observed in biochemical parameters are regulated by both extracts; nevertheless, the beneficial effects of the ME extract are mostly associated with systemic parameters, while those of the DE extracts are associated with local microbial activity.

Onion quercetin monoglycosides alter microbial activity and increase antioxidant capacity.

The effects on fermentation processes in the digestive tract, the biochemical parameters and antioxidant capacity of blood in rats fed high-fat diets with quercetin (Q) and quercetin with quercetin monoglycosides (Q+MQ) preparations obtained from onion waste were evaluated. Four groups of eight animals were fed for 4 weeks with a control diet (C), a high-fat diet (HF) and high-fat diets with 0.15% addition of Q and Q+MQ preparations. HF caused an increase in alanine transaminase (ALT), non-high-density lipoprotein (non-HDL) and the atherogenic index AII vs. C and a decrease in the proportion of HDL in total cholesterol (TC). Q and Q+MQ showed a tendency to moderate the values aspartate transaminase (P=.087), ALT (P<.05), TC (P=.068), non-HDL cholesterol (P<.05), triglycerides (P=.064) and the atherogenic index AII (P<.05). Q+MQ significantly increased the activity of α-glucosidase (P<.05 vs. HF), ß-glucosidase (P<.05) and ß-galactosidase (P<.05 vs. C and Q). Q increased activity of ß-glucosidase (P<.001 vs. C and HF). Both increased the activity of ß-glucuronidase (P<.05 vs. C and HF). Both increased the antioxidant capacity of the hydrophilic fraction in serum (P<.05 vs. C and HF), and Q enhanced that of the lipid fraction (P<.001). Q preparation contained 70% quercetin, and Q+MQ preparation contained 29% quercetin and 13% quercetin monoglycosides, mainly quercetin-4'-glucoside. Both exhibited high antioxidant capacity. Supplementation with Q and Q+MQ increased the enzymatic activity of the intestinal microbiota and the antioxidant capacity of blood and revealed a tendency to improve the blood lipid profile. MQ were particularly effective in stimulating the bacterial enzymatic activity.

Ellagitannins from Strawberries with Different Degrees of Polymerization Showed Different Metabolism through Gastrointestinal Tract of Rats.

The present paper describes a comparative study of the metabolism of (1) ellagic acid, (2) monomeric ellagitannins (a mixture of α- and ß-bis-hexahydroxydiphenoyl-d-glucose), and (3) dimeric ellagitannins (mainly agrimoniin with both glucose residues being esterified with hexahydroxydiphenoyl) in rats fed polyphenol-rich diets. Their metabolites were identified and quantified in selected parts of the gastrointestinal tract, i.e., the stomach, small intestine, and cecum, on the second, fourth, and seventh days of the experiment, as well as in the rats' feces, blood serum, and urine. Significant differences between the metabolites of strawberry ellagitannins and ellagic acid were observed in all parts of the gastrointestinal tract. Urolithin A was the predominant polyphenolic metabolite of rats fed a diet supplemented with ellagic acid. On the other hand, in rats fed low degree of polymerization (DP) ellagitannins, the main metabolite was nasutin followed by urolithin A, while ellagitannins with a higher DP led to nasutin only.

Nutritional and Health-Related Effects of a Diet Containing Apple Seed Meal in Rats: The Case of Amygdalin.

Apple pomace includes seeds that are rich in protein, fiber, and oil, which can be extracted from them. However, they can also contain a significant amount of toxigenic amygdalin. We hypothesized that amygdalin is a compound that significantly reduces the nutritional and health quality of defatted apple seeds. An experiment was conducted on rats that were distributed into three groups and fed with high-fructose diets. In the control (C) and amygdalin (AMG) groups, cellulose and casein were the source of dietary fiber and protein, respectively; in the apple seed meal (ASM) group, dietary fiber and protein originated from the endosperm of apple seeds, which were previously defatted and ground. A diet fed to the ASM group also contained 0.24% of amygdalin from the meal, whereas the AMG diet was supplemented with the same amount of synthetic amygdalin. After 14 days of experimental feeding, the body weight of rats was decreased in the ASM group. When compared to the C group, apparent protein digestibility and nitrogen retention were increased in the AMG group, while both were decreased in the ASM group. In the small intestine, mucosal maltase activity was decreased in the AMG and ASM groups, whereas lactase activity was only decreased by dietary amygdalin. The caecal SCFA pool and butyrate concentration were significantly increased in the ASM group compared to the other groups. Moreover, the ASM diet increased plasma concentration of high density lipoprotein (HDL) cholesterol and plasma antioxidant capacity of water-soluble substances (ACW). It also decreased the liver content of thiobarbituric acid-reactive substances (TBARS). In contrast, dietary amygdalin did not affect these indices. Dietary supplementation with apple seed meal can exert beneficial effects on the intestinal tract, blood lipid profile and antioxidant status of rats. In most cases, these effects are not limited by the presence of amygdalin. However, the nutritional value of protein from apple seed meal is relatively low.

Metabolism of strawberry mono- and dimeric ellagitannins in rats fed a diet containing fructo-oligosaccharides.

PURPOSE: We 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. METHODS: Rats 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). RESULTS: The 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). CONCLUSIONS: ETs 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.

Anthocyanins in Strawberry Polyphenolic Extract Enhance the Beneficial Effects of Diets with Fructooligosaccharides in the Rat Cecal Environment.

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 ß-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.

Strawberry ellagitannins thwarted the positive effects of dietary fructooligosaccharides in rat cecum.

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 ß-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).

Effect of the dietary polyphenolic fraction of chicory root, peel, seed and leaf extracts on caecal fermentation and blood parameters in rats fed diets containing prebiotic fructans.

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 ß-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.

Consumption of polyphenol concentrate with dietary fructo-oligosaccharides enhances cecal metabolism of quercetin glycosides in rats.

OBJECTIVE: We verified the hypothesis that the consumption of polyphenol concentrate (PC), rich in quercetin and its glycosides (36 g/100 g), in association with different dietary fiber matrices, that is, an easily fermentable fructo-oligosaccharides (FOS) or non-fermentable cellulose (CEL), causes a disparate adaptive response of the cecal microbial activity in rats. This in turn facilitates further utilization of biologically active polyphenolic compounds, which are not, as usual, digested in the foregut. METHODS: Four-week experimental feeding of male Wistar rats consisted of diets containing 5% FOS or CEL, as a source of dietary fiber, with or without 0.3% addition of PC. RESULTS: Positive changes in rat cecum were observed resulting from the ingestion of an FOS-containing diet, such as decreased pH and increased the production of short-chain fatty acids in the digesta, compared with a CEL-containing diet. The addition of PC to the FOS diet did not eliminate the positive effects of the latter, except for a slight increase in cecal pH and a decrease in microbial glycolytic activity. However, a simultaneous increase in the cecal butyrate pool was also observed. An adaptation process of the microflora enzymatic system to dieting with PC and FOS was proven in further enhanced susceptibility of rutin (quercetin 3-O-glucorhamnoside), hyperoside (quercetin 3-O-galactoside), and quercitrin (quercetin 3-O-rhamnoside) to hydrolysis by the cecal digesta solution. CONCLUSION: Especially when consumed together, PC and FOS are important dietary factors affecting the susceptibility of quercetin glycosides to microbial metabolism in the cecum. The intensification of the hydrolysis of quercetin glycosides by dietary treatments leads also to the increased metabolism of quercetin itself.

Characterization of cell wall polysaccharides of cherry (Prunus cerasus var. Schattenmorelle) fruit and pomace.

The polysaccharide composition of cell wall of sour cherry (Prunus cerasus var. Schattenmorelle) fruit and pomace was investigated. Furthermore, the alcohol insoluble solids composition of 'Kelleriis' and 'Dobreczyn Botermo' varieties were studied too. Yield of alcohol insoluble solids for fruits was lower than 10%, and for pomaces circa 50%. Uronic acid was the main pectin component of alcohol insoluble solids. Enzymes used as juice processing aids decreased the content of uronic acid. Araban and galactan side chains bonded tightly to cellulose presence was suggested by high content of arabinose and galactose in hemicellulose fraction. The process of drying at below 70 degrees C did not influence polysaccharide composition of sour cherry pomaces. Alcohol insoluble solids of fruits expressed higher hydration properties than of pomaces.