The recovery, catabolism and potential bioactivity of polyphenols from carrot subjected to in vitro simulated digestion and colonic fermentation

Functional properties of insoluble dietary fibers extracted from different grape pomaces during simulated digestion and in vitro fermentation

This study investigated insoluble dietary fibers (IDFs) extracted from the grape pomaces of Cabernet Sauvignon (CS-IDF), Marselan (MS-IDF), and Merlot (ML-IDF). It explored the release patterns and potential bioactivities of dietary fiber-bound polyphenols from these sources through simulated digestion and in vitro colonic fermentation. The results showed a higher polyphenol content in MS grape skins, which also yielded more IDF. Bound polyphenols were released more effectively during fermentation than during digestion. Caffeic acid and epicatechin disappeared during the fermentation stage, while compounds such as chlorogenic acid, catechin, and myricetin appeared. Gentisic acid was the most abundant monomeric phenolic compound in the fermentation fluid. The released polyphenols exhibited strong antioxidant properties and digestive enzyme inhibitory activity. Fermentation of the IDFs increased propionic acid and total short-chain fatty acid (SCFA) levels, particularly in the CS-IDF and MS-IDF groups. MS-IDF also elevated the relative abundance of Acidaminococcus fermentans, a key SCFA producer. Additionally, all IDFs promoted the growth of beneficial gut bacteria such as Bacteroides H uniformis and Phascolarctobacterium A faecium, while reducing harmful bacteria such as Escherichia. Correlation analysis revealed a positive relationship between released polyphenols and the relative abundance of beneficial gut bacteria, including Parabacteroides B 862006 distasonis and Mitsuokella multacida. These findings suggest that dietary fiber-bound polyphenols exhibit significant bioactivity in the gastrointestinal tract, with MS-IDF showing particular advantages in promoting gut health and bioactive compound release.

Formation of polyphenol-based nanoparticles in dried hawthorn with enhanced in vitro absorption over free polyphenols

Plant-derived nanoparticles are gaining attention for enhancing the delivery and bioavailability of bioactive compounds, though the mechanisms remain unclear. This study aims to investigate dried hawthorn-derived nanoparticles (DHNPs), focusing on their composition, molecular interactions and impact on polyphenol absorption. The results showed that DHNPs, averaging 275.7 nm, were primarily composed of polysaccharides and high content of polyphenolic compounds (~25 %), with covalent and non-covalent interactions forming between them. Saponification increased the polyphenol release, and metabolomics identified 252 polyphenolic compounds, with 195 showing a relative increase post-treatment, including caffeic acid and (-)-catechin. An in vitro intestinal absorption test using Caco-2 cell monolayer model demonstrated that DHNPs-bound polyphenols exhibited significantly higher permeability (27.90 %) compared to free polyphenols (12.38 %), indicating that endocytosis may serve as a potential pathway through which DHNPs enhance polyphenol absorption. This study provides new insights into the role of plant-derived nanoparticles contributing to bioactive compound delivery and bioavailability.

Metabolic outcomes of Cordyceps fungus and Goji plant polysaccharides during in vitro human fecal fermentation

This study was to assess the digestion and colonic fermentation of two bioactive polysaccharides, EPS-LM and LBPS, and the subsequent influences on human gut microbiota through simulated gastrointestinal systems. EPS-LM, an exopolysaccharide isolated from mycelial culture of a medicinal fungus Cordyceps sinensis Cs-HK1, was characterized as a heteropolysaccharide consisting of Man(108):Gal(52.7):Glc(29.2) (molar ratio) with an average molecular weight (MW) 5.513 × 106. LBPS was isolated from a well-known medicinal plant (Lycium barbarum L.) which was also characterized as a heteropolysaccharide (1.236 × 105 MW). Both polysaccharides were highly resistant to saliva, gastric and small-intestine digestion with negligible MW reduction and release of reducing sugars but were quickly degraded to lower MW during in vitro human fecal fermentation. They were consumed as a carbon source by the gut bacteria to produce short-chain fatty acids (SCFAs). In comparison, the carbohydrate content of EPS-LM was more completely consumed than LBPS and there were also notable differences in consumption of specific monosaccharides and production of specific SCFAs, propionic and butyric acid, and relative abundance of gut bacterial populations between EPS-LM and LBPS group. The results suggest that metabolic outcomes and modulating effects of EPS-LM and LBPS on the gut microbiota are highly dependent on their molecular composition.

The bioaccessibility and bioactivity of polyphenols from tsampa prepared from roasted highland barley flour solid-fermented by autochthonous lactic acid bacteria

Tsampa, which is abundant in polyphenols, demonstrates significant bioactivity and potential health benefit. However, the bioaccessibility and potential bioactivity of polyphenols derived from tsampa prepared from autochthonous lactic acid bacteria solid-fermented roasted highland barley flour (F-RHBF) have not been investigated. This study aimed to evaluate the bioaccessibility and bioactivity of polyphenols from tsampa prepared from F-RHBF through in vitro digestion model, and additionally, to explore the protective effects of digested tsampa extract against oxidative stress damage by establishing H2O2 -induced oxidative stress injury model of HepG2 cells. The results indicated that tsampa prepared from F-RHBF exhibited excellent bioaccessibility and bioactivity of polyphenols, including antioxidant and digestive enzymes inhibitory activity, compared to tsampa prepared from unfermented RHBF (UF-RHBF). Furthermore, the digested extract of tsampa prepared from F-RHBF was more effective in protecting HepG2 cells from oxidative damage by reducing the level of reactive oxygen species (ROS) and malondialdehyde (MDA), while enhancing the activity of superoxide dismutase (SOD), glutathione (GSH), catalase (CAT), glutathione peroxidase (GPx), and total antioxidant capacity (T-AOC). These findings suggested that fermentation and in vitro digestion can improve the bioaccessibility and bioactivity of polyphenols from tsampa. Present findings pave the way toward applying fermented highland barley flour to design tsampa and novel functional foods.

Modulation of Gut Microbiota Composition and Microbial Phenolic Catabolism of Phenolic Compounds from Achillea millefolium L. and Origanum majorana L

The impact of the nonbioaccessible fraction of two phenolic-rich extracts from Achillea millefolium L. (yarrow) and Origanum majorana L. (marjoram) on the modulation of the human gut microbiota was investigated in vitro. Microbial metabolism of the phenolic compounds was also addressed. In general, phenolic acids or O-glycosidic flavones quickly disappeared, in contrast to methoxy- or C-glycosidic flavonoids. This colonic metabolism yielded phloroglucinol, 3,4-dimethoxyphenylacetic acid, 3-(4-hydroxyphenyl)-propionic acid, and 4-hydroxybenzoic acid as the main metabolites of the microbial catabolism of rosmarinic acid or caffeoylquinic acids, among others. The 16S rRNA gene sequencing showed that the most promising modulatory effect was related to the increase in Bifidobacterium spp., Collinsella spp., Romboutsia, and Akkermansia muciniphila for both plant extracts, along with Blautia spp. and Dialister for yarrow extract. This beneficial modulation was accompanied by the increase in butyric acid production, highlighting the potential prebiotic-like effect on the gut microbiota of these two previously unstudied edible plants.

Structure identification of myricetin-phenylacetaldehyde adducts and their potential biological activities

Our previous research discovered that myricetin could effectively inhibit the formation of heterocyclic aromatic amines (HAAs) in cantonese baked foods by trapping phenylacetaldehyde to form adducts. However, the structure and biological activity of these adducts were still unknown. In this study, we identified two myricetin-phenylacetaldehyde adducts from cantonese mooncakes, BYQ-2 and BYQ-3, using pre-HPLC. These adducts were found to be the products of phenylacetaldehyde addition at the C-8 and C-6 positions of myricetin, followed by cyclization with hydroxyl groups at the C-7 and C-5 positions. Antioxidant assays revealed that BYQ-2 and BYQ-3 have stronger radical scavenging abilities than myricetin in the concentration range of 12.5 ∼ 800 μg/mL in the three samples. Additionally, both adducts showed potential health benefits by inhibiting α-glucosidase and CYP450 1A2, enzymes involved in blood sugar regulation and HAAs metabolism. BYQ-2 exhibited the highest inhibitory potency against α-glucosidase and CYP450 1A2 with IC50 values of 10.32 μg/mL and 5.44 μg/mL, respectively. Theoretical calculations suggested that hydrogen bonding and hydrophobic interactions are the primary forces driving enzyme binding, with BYQ-2 showing the highest binding energies (-7.75 kcal/mol for α-glucosidase and -9.31 kcal/mol for CYP450 1A2). Our findings suggested that myricetin inhibited HAAs in baked foods while also enhancing food safety and providing health benefits through its adduction with small molecule aldehydes. In future research, it is necessary to further evaluate the absorption and metabolic behavior as well as safety of myricetin-HAAs active intermediate adducts at the cellular and animal experimental level.

Fates of bioactive compounds and antioxidant activities of red pitaya pulp upon in vitro gastrointestinal digestion

Health benefit effects of bioactive compounds depend on their bioavailabilities, which could vary according to factors including food matrix and digestion environment. To understand the "bioaccessible" health benefit of red pitay pulp, the INFOGEST static in vitro simulation of gastrointestinal (GI) digestion model and targeted metabolomics method were applied to unravel the fates of bioactive compounds in the whole food of red pitaya pulp during GI digestion. The antioxidant activity as one of the health benefit indices was also assessed to compare the changes in bioactive properties of red pitaya pulp. Results showed that, after GI digestion, total phenolic and flavonoid content increased by 84% and 4.55 folds, respectively. But total betacyanin content decreased. All the detected phenolic acids increased during the GI process, and lots of new phenolic compounds were produced. The overall chemical antioxidant capacity of red pitaya pulp increased after GI digestion. Correlation analysis results indicated that flavonoids and ferulic acid were probably the primary sources of the antioxidant capacity of the red pitaya pulp and its digests. Moreover, the cytoprotective effects against H2O2-induced oxidative damage varied among gastric cell, enterocyte and hepatocyte. The GI digests of red pitaya pulp could better alleviate the H2O2-induced oxidative stress in cells by preventing the increase of reactive oxygen species (ROS), inhibiting the production of malondialdehyde (MDA), increasing the production of glutathione (GSH), and promoting the activities of catalase (CAT) and superoxide dismutase (SOD). These findings can be used as a basis for future studies in the design and production of functional ingredients/foods.

Analyzing the gut microbiota and microbial-associated metabolites of tomato-based sauces

Red Cooked Sauce (RCS) and Red Raw Sauce (RRS) are a mixture of natural crops that have a promising content of bioactive compounds (BC). The aim was to determine the effect of the indigestible fraction (IF) during the colonic fermentation in RCS and RRS by studying the two-way relationship between gut microbiota composition and microbial metabolites produced from BC fermented in the TNO in vitro dynamic model of the human colon (TIM-2). Total BC in undigested and predigested RRS, 957 and 715 mg/100 g DW, respectively, was significantly higher (p < 0.05) than in the RCS, 571 and 406 mg/100 g DW, respectively. Catenibacterium and Holdemanella increased during RCS fermentation, while 13 genera showed a clear positive correlation with most microbial phenolic metabolites. Our findings suggest that the mechanisms, pathways, and enzymes involved in producing microbial metabolites exhibited uniqueness among bacterial taxa, even within shared genus/family classifications.

Gastrointestinal digestion of yerba mate, rosemary and green tea extracts and their subsequent colonic fermentation by human, pig or rat inocula

Polyphenolic compounds are common constituents of human and animal diets and undergo extensive metabolism by the gut microbiota before entering circulation. In order to compare the transformations of polyphenols from yerba mate, rosemary, and green tea extracts in the gastrointestinal tract, simulated gastrointestinal digestion coupled with colonic fermentation were used. For enhancing the comparative character of the investigation, colonic fermentation was performed with human, pig and rat intestinal microbiota. Chemical analysis was performed using a HPLC system coupled to a diode-array detector and mass spectrometer. Gastrointestinal digestion diminished the total amount of phenolics in the rosemary and green tea extracts by 27.5 and 59.2 %, respectively. These reductions occurred mainly at the expense of the major constituents of these extracts, namely rosmarinic acid (-45.7 %) and epigalocatechin gallate (-60.6 %). The yerba mate extract was practically not affected in terms of total phenolics, but several conversions and isomerizations occurred (e.g., 30 % of trans-3-O-caffeoylquinic acid was converted into the cis form). The polyphenolics of the yerba mate extract were also the least decomposed by the microbiota of all three species, especially in the case of the human one (-10.8 %). In contrast, the human microbiota transformed the polyphenolics of the rosemary and green extracts by 95.9 and 88.2 %, respectively. The yerba mate-extract had its contents in cis 3-O-caffeoylquinic acid diminished by 78 % by the human microbiota relative to the gastrointestinal digestion, but the content of 5-O-caffeoylquinic acid (also a chlorogenic acid), was increased by 22.2 %. The latter phenomenon did not occur with the rat and pig microbiota. The pronounced interspecies differences indicate the need for considerable caution when translating the results of experiments on the effects of polyphenolics performed in rats, or even pigs, to humans.

Catabolism of phenolics from grape peel and its effects on gut microbiota during in vitro colonic fermentation

BACKGROUND

Grape peels, the main by-products of wine processing, are rich in bioactive ingredients of phenolics, including proanthocyanidins, flavonoids and anthocyanins. Phenolics have the function of regulating intestinal microbiota and promoting intestinal health. From the perspective of the dietary nutrition of grape peel phenolics (GPP), the present study aimed to investigate the influence of GPP on the composition and metabolism of human gut microbiota during in vitro fermentation.

RESULTS

The results indicated that GPP could decrease pH and promote the production of short-chain fatty acids. ACE and Chao1 indices in GPP group were lower than that of the Blank group. GPP enhanced the levels of Lachnospiraceae UCG-004, Bacteroidetes and Roseburia, but reduced the Firmicutes/Bacteroidetes ratio. Kyoto Encyclopedia of Proteins and Genome enrichment pathways related to phenolic acid metabolism mainly included flavonoid, anthocyanin, flavone and flavonol biosynthesis. Gut microbiota could accelerate the release and breakdown of phenolic compounds, resulting in a decrease in the content of hesperetin-7-O-glucoside, delphinidin-3-O-glucoside and cyanidin-3-rutinoside etc. In vitro antibacterial test found that GPP increased the diameters of the inhibition zones of Escherichia coli and Staphylococcus aureus in a dose-dependent manner.

CONCLUSION

The results of the present study revealed that GPP might be a potential prebiotic-like to prevent diseases by improving gut health. The findings could provide a theoretical basis for the potential to exploit GPP as dietary nutrition to maintain intestinal function. © 2024 Society of Chemical Industry.

In vitro digestion and colonic fermentation characteristics of media-milled purple sweet potato particle-stabilized Pickering emulsions

BACKGROUND

Pickering emulsions stabilized by multicomponent particles have attracted increasing attention. Research on characterizing the digestion and health benefit effects of these emulsions in the human gastrointestinal tract are quite limited. This work aims to reveal the digestive characteristics of media-milled purple sweet potato particle-stabilized Pickering emulsions (PSPP-Es) during in vitro digestion and colonic fermentation.

RESULTS

The media-milling process improved the in vitro digestibility and fermentability of PSPP-Es by reaching afree fatty acids release rate of 43.11 ± 4.61% after gastrointestinal digestion and total phenolic content release of 101.00 ± 1.44 μg gallic acid equivalents/mL after fermentation. In addition, PSPP-Es exhibited good antioxidative activity (2,2-diphenyl-1-picrylhydrazyl and ferric reducing antioxidant power assays), α-glucosidase inhibitory activity (half-maximal inhibitory concentration: 6.70%, v/v), and prebiotic effects, reaching a total short-chain fatty acids production of 9.90 ± 0.12 mol L-1, boosting the growth of Akkermansia, Bifidobacterium, and Blautia and inhibiting the growth of Escherichia-Shigella.

CONCLUSIONS

These findings indicate that the media-milling process enhances the potential health benefits of purple sweet potato particle-stabilized Pickering emulsions, which is beneficial for their application as a bioactive component delivery system in food and pharmaceutical products. © 2024 Society of Chemical Industry.

Exploring the Biogenic Transformation Mechanism of Polyphenols by Lactobacillus plantarum NCU137 Fermentation and Its Enhancement of Antioxidant Properties in Wolfberry Juice

This study investigated the transformation of polyphenols, including free and bound polyphenols during the fermentation of wolfberry juice by Lactobacillus plantarum NCU137. Results indicated that fermentation significantly increased the free polyphenols content and released bound polyphenols, enhancing the antioxidant activity. Analysis showed that there were 19 free polyphenols, mainly scopoletin, pyrogallol, and dihydroferulic acid, and 16 bound polyphenols, especially p-coumaric acid, feruloyl hexoside, and caffeic acid. A significant correlation was observed between the generation and degradation of polyphenols, and specific bound polyphenols peaked during the 24-48 h fermentation. Furthermore, reduced surface roughness and galacturonic acid content in wolfberry residue, along with increased pectinase activity, suggested substantial pectin degradation in the cell wall, which may be associated with the release of polyphenols, due to pectin serving as carriers for bound polyphenols. The fermentation also increased polyphenol oxidase and peroxidase activity, contributing to polyphenol breakdown. These findings provide insights for improving wolfberry juice production.

Metabolomic insights into the profile, bioaccessibility, and transepithelial transport of polyphenols from germinated quinoa during in vitro gastrointestinal digestion/Caco-2 cell transport, and their prebiotic effects during colonic fermentation

The health-promoting activities of polyphenols and their metabolites originating from germinated quinoa (GQ) are closely related to their digestive behavior, absorption, and colonic fermentation; however, limited knowledge regarding these properties hinder further development. The aim of this study was to provide metabolomic insights into the profile, bioaccessibility, and transepithelial transport of polyphenols from germinated quinoa during in vitro gastrointestinal digestion and Caco-2 cell transport, whilst also investigating the changes in the major polyphenol metabolites and the effects of prebiotics during colonic fermentation. It was found that germination treatment increased the polyphenol content of quinoa by 21.91%. Compared with RQ group, 23 phenolic differential metabolites were upregulated and 47 phenolic differential metabolites were downregulated in GQ group. Compared with RQ group after simulated digestion, 7 kinds of phenolic differential metabolites were upregulated and 17 kinds of phenolic differential metabolites were downregulated in GQ group. Compared with RQ group after cell transport, 7 kinds of phenolic differential metabolites were upregulated and 9 kinds of phenolic differential metabolites were downregulated in GQ group. In addition, GQ improved the bioaccessibilities and transport rates of various polyphenol metabolites. During colonic fermentation, GQ group can also increase the content of SCFAs, reduce pH value, and adjust gut microbial populations by increasing the abundance of Actinobacteria, Bacteroidetes, Verrucomicrobiota, and Spirochaeota at the phylum level, as well as Bifidobacterium, Megamonas, Bifidobacterium, Brevundimonas, and Bacteroides at the genus level. Furthermore, the GQ have significantly inhibited the activity of α-amylase and α-glucosidase. Based on these results, it was possible to elucidate the underlying mechanisms of polyphenol metabolism in GQ and highlight its beneficial effects on the gut microbiota.

Bioactivity and influence on colonic microbiota of polyphenols from noni (Morinda citrifolia L.) fruit under simulated gastrointestinal digestion

Noni (Morinda citrifolia L.) is a tropical fruit rich in bioactive compounds. Little is known about its polyphenol composition at different ripeness levels and digestive characteristics. Here, we studied changes in polyphenols and antioxidant activity as noni ripened. Rutin and kaempferol-3-O-rutinoside were found in high amounts in noni, with antioxidant capacity increasing as it ripened. Under simulated digestion, polyphenols were gradually released from the oral to gastrointestinal phases, partially decomposing in the small intestine due to their instability. Conversely, fiber-bound phenols were released during colonic fermentation, leading to high bioaccessible antioxidant activity. Additionally, noni consumption affected the intestinal microbiome by reducing the Firmicutes/Bacteroidetes ratio and increasing bacteria with prebiotic properties like Prevotella and Ruminococcus. These findings demonstrate that polyphenols significantly contribute to the health benefits of noni fruit by providing absorbable antioxidants and improving the structure of the intestinal microbiome.

Industrial and culinary treatments applied to Piquillo pepper (Capsicum annuum cv. Piquillo) impact positively on (poly)phenols' bioaccessibility and gut microbiota catabolism

Thermal treatments applied to plant-based foods prior to consumption might influence (poly)phenols' bioaccessibility and the metabolization of these compounds by the gut microbiota. In the present research, the impact of industrial (grilling and canning) and culinary (microwaving and frying) treatments on the bioaccessibility and colonic biotransformations of (poly)phenols from Piquillo pepper (Capsicum annum cv. Piquillo) were evaluated by in vitro gastrointestinal digestion and colonic fermentation models and HPLC-ESI-MS/MS. The application of industrial treatments impacted positively on (poly)phenols' bioaccessibility compared to raw pepper. Microwaving also exerted a positive effect on (poly)phenols' bioaccessibility compared to canning whereas the addition of oil for frying seemed to negatively affect (poly)phenols' release from the food matrix. Throughout the 48 hours of the colonic fermentation process (poly)phenolic compounds were catabolized into different (poly)phenol derivatives whose formation was also positively affected by industrial and culinary treatments. Based on the concentration and time of appearance of these derivatives, catabolic pathways of (poly)phenols from Piquillo pepper were proposed. The major (poly)phenol derivatives identified (3-(3'-hydroxyphenyl)propanoic acid, 4-hydroxy-3-methoxyphenylacetic acid and benzene-1,2-diol) are considered of great interest for the study of their bioactivity and the potential effect on human health.

Polyphenols Influence the Development of Endometrial Cancer by Modulating the Gut Microbiota

Dysbiosis of the microbiota in the gastrointestinal tract can induce the development of gynaecological tumours, particularly in postmenopausal women, by causing DNA damage and alterations in metabolite metabolism. Dysbiosis also complicates cancer treatment by influencing the body's immune response and disrupting the sensitivity to chemotherapy drugs. Therefore, it is crucial to maintain homeostasis in the gut microbiota through the effective use of food components that affect its structure. Recent studies have shown that polyphenols, which are likely to be the most important secondary metabolites produced by plants, exhibit prebiotic properties. They affect the structure of the gut microbiota and the synthesis of metabolites. In this review, we summarise the current state of knowledge, focusing on the impact of polyphenols on the development of gynaecological tumours, particularly endometrial cancer, and emphasising that polyphenol consumption leads to beneficial modifications in the structure of the gut microbiota.

The Effect of Opuntia ficus Mucilage Pectin and Citrus aurantium Extract Added to a Food Matrix on the Gut Microbiota of Lean Humans and Humans with Obesity

Experimental studies have provided evidence that physicochemical interactions in the food matrix can modify the biologically beneficial effects of bioactive compounds, including their effect on gut microbiota. This work aimed to evaluate the effect of a food gel matrix with Opuntia ficus cladodes mucilage pectin and Citrus Aurantium extract on the growth of four beneficial gut bacteria obtained from the fecal microbiota of people who are lean or who have obesity after digestion in the upper digestive system. To accomplish this, a base formulation of Opuntia ficus cladodes mucilage with or without C. aurantium extract was submitted to an ex vivo fecal fermentation in an automatic and robotic intestinal system. The changes in the intestinal microbiota were determined by means of plate culture and 16S sequencing, while short-chain fatty acids (SCFA) produced in the colon were determined via gas chromatography. In the presence of the extract in formulation, greater growth of Bifidobacterium spp. (+1.6 Log10 Colonic Forming Unit, UFC) and Lactobacillus spp. (+2 Log10 UFC) in the microbiota of lean people was observed. Only the growth in Salmonella spp. (-1 Log10 UFC) from both microbiota was affected in the presence of the extract, which decreased in the ascending colon. SCFA was mainly produced by the microbiota of people who were lean rather than those who had obesity in the presence of the extract, particularly in the ascending colon. The effect of sour orange extract seems to depend on the origin of the microbiota, whether in people who have obesity (25 mM/L) or are lean (39 mM/L).

In vitro gastrointestinal digestion and colonic fermentation of media-milled black rice particle-stabilized Pickering emulsion: Phenolic release, bioactivity and prebiotic potential

This is a pioneer study that investigated the digestive characteristics of Pickering emulsions stabilized by media-milled black rice particles during in vitro digestion and colonic fermentation. Free fatty acid release of the emulsions improved from 28.42 ± 3.13% to 33.68 ± 4.05% after media milling. The phenolics released from media-milled sample were close to those from unground sample. Media-milled sample exhibited higher DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging ability and α-glucosidase inhibition rate than unground sample. Media milling increased the generation of short-chain fatty acids (SCFAs) during colonic fermentation, especially acetic acid (23% improvement in media-milled sample over unground sample). It also inhibited the growth of harmful bacteria namely Escherichia Shigella and Streptococcus, and promoted the growth of beneficial bacteria including Bifidobacterium and Blautia. These findings revealed that media-milled black rice particle-stabilized Pickering emulsions possessed intrinsic bioactivity and prebiotic potentials in the gastrointestinal tract for the first time.

Effect of in vitro Digestion on the Bioaccessibility of Polyphenols and Potential Prebiotic Properties of Potato Peel

BACKGROUND

Potato peel is a byproduct of the potato processing industry and a potential source of functional ingredients such as dietary fiber, polyphenols, and prebiotics. However, the bioaccessibility of polyphenols and antioxidants during in vitro digestion as well as prebiotic potential after in vitro digestion of potato peel flour has not been reported.

OBJECTIVE

The study was designed to assess the bioaccessibility of polyphenols and the prebiotic potential of potato peel flour.

METHODS

In this study, the changes in polyphenol content and antioxidant capacity during different phases of in vitro digestion, including salivary, gastric and intestinal phases were studied. Additionally, an investigation was conducted to evaluate the prebiotic properties of potato peel flour by in vitro fermentation with Lactobacillus acidophilus.

RESULTS

The findings revealed a significant increase in the recovery index for total phenolic content during both gastric (106.90%) and intestinal (102.71%) digestive phases. Furthermore, polyphenols in potato peel flour exhibited high residual intestinal digestibility index values (>90%). The antioxidant capacity increased by >50% during various phases of in vitro digestion. Regarding prebiotic properties, potato peel flour significantly increased L. acidophilus counts and promoted the production of short-chain fatty acids, specifically propionate and butyrate.

CONCLUSION

This study suggests that potato peel flour has the potential to serve as a functional ingredient or nutraceutical that can enhance health and may help in reducing environmental problems.

Release characteristic of bound polyphenols from tea residues insoluble dietary fiber by mixed solid-state fermentation with cellulose degrading strains CZ-6 and CZ-7

The purpose of this work was to investigate the release characteristic of bound polyphenols (BP) from tea residues insoluble dietary fiber (IDF) by mixed solid-state fermentation (SSF) with cellulose degrading strains CZ-6 and CZ-7. The results implied that cellulase, β-glucosidase and filter paper lyase activities were strongly correlated with the BP content. The scanning electron microscop and fourier transform infrared spectroscopy manifested that the cellulose network of the IDF was decomposed and dissolve, forming more loose fibrous structure. Additionally, 28 polyphenols components were detected and their biotransformation pathways were preliminary speculated. Moreover, the BP obtained by mixed SSF produced prominent inhibitory activities against α-glucosidase and α-amylase, as well as exhibited significant scavenging effects on DPPH•, ABTS+• free radicals and ferric reducing antioxidant power. These findings could further promote the utilization of BP from agricultural by-products in a more natural and economical method, CZ-6 and CZ-7 strains provide a new approach to expound the release and conversion of BP.

Bioavailability and Antioxidant Activity of Rambutan (Nephelium lappaceum) Peel Polyphenols during in Vitro Simulated Gastrointestinal Digestion, Caco-2 Monolayer Cell Model Application, and Colonic Fermentation

The bioavailability of rambutan peel polyphenols (RPPs) was studied via in vitro simulated digestion, a Caco-2 monolayer cell model, and colonic fermentation. Total phenolic content of RPPs decreased with the progress of the simulated digestion. A total of 38 phenolic compounds were identified during the digestion and colonic fermentation, of which 12 new metabolites were found during colonic fermentation. The possible biotransformation pathways were inferred. Geraniin was transformed into corilagin, ellagic acid, and gallic acid during the digestion and colonic fermentation. Ellagic acid could be further transformed into urolithin under the action of intestinal microbiota. The transformation of ellagitannins could be beneficial to transport on Caco-2 monolayer cell. The antioxidant capacity of RPPs increased with the progress of gastrointestinal digestion. Furthermore, RPPs could increase the yield of short-chain fatty acids, decrease the pH value, promote the growth of beneficial bacteria, and inhibit the growth of pathogenic Escherichia coli/Shigella during colonic fermentation.

Probiotic Yoghurt Enriched with Mango Peel Powder: Biotransformation of Phenolics and Modulation of Metabolomic Outputs after In Vitro Digestion and Colonic Fermentation

This study investigated the health-promoting effects and prebiotic functions of mango peel powder (MPP) both as a plain individual ingredient and when incorporated in yoghurt during simulated digestion and fermentation. The treatments included plain MPP, plain yoghurt (YA), yoghurt fortified with MPP (YB), and yoghurt fortified with MPP and lactic acid bacteria (YC), along with a blank (BL). The identification of polyphenols in the extracts of insoluble digesta and phenolic metabolites after the in vitro colonic fermentation were performed employing LC-ESI-QTOF-MS². These extracts were also subjected to pH, microbial count, production of SCFA, and 16S rRNA analyses. The characterisation of phenolic profiles identified 62 phenolic compounds. Among these compounds, phenolic acids were the major compounds that underwent biotransformation via catabolic pathways such as ring fission, decarboxylation, and dehydroxylation. Changes in pH indicated that YC and MPP reduced the media pH from 6.27 and 6.33 to 4.50 and 4.53, respectively. This decline in pH was associated with significant increases in the LAB counts of these samples. The Bifidobacteria counts were 8.11 ± 0.89 and 8.02 ± 1.01 log CFU/g in YC and MPP, respectively, after 72 h of colonic fermentation. Results also showed that the presence of MPP imparted significant variations in the contents and profiles of individual short chain fatty acids (SCFA) with more predominant production of most SCFA in the MPP and YC treatments. The 16s rRNA sequencing data indicated a highly distinctive microbial population associated with YC in terms of relative abundance. These findings suggested MPP as a promising ingredient for utilisation in functional food formulations aiming to enhance gut health.

Beneficial effects of phenolic compounds: native phenolic compounds vs metabolites and catabolites

In the human body, the positive effects of phenolic compounds are increasingly observed through their presence in tissues and organs in their native form or in the form of metabolites or catabolites formed during digestion, microbial metabolism, and host biotransformation. The full extent of these effects is still unclear. The aim of this paper is to review the current knowledge of beneficial effects of native phenolic compounds or their metabolites and catabolites focusing on their role in the health of the digestive system, including disorders of the gastrointestinal and urinary tracts and liver. Studies are mostly connecting beneficial effects in the gastrointestinal and urinary tract to the whole food rich in phenolics, or to the amount of phenolic compounds/antioxidants in food. Indeed, the bioactivity of parent phenolic compounds should not be ignored due to their presence in the digestive tract, and the impact on the gut microbiota. However, the influence of their metabolites and catabolites might be more important for the liver and urinary tract. Distinguishing between the effects of parent phenolics vs metabolites and catabolites at the site of action are important for novel areas of food industry, nutrition and medicine.

Bioaccessibility and transport of lentil hull polyphenols in vitro, and their bioavailability and metabolism in rats

Polyphenol-rich lentil hulls are a valuable by-product. In this study, lentil hulls were subjected to simulated in vitro digestion and caco-2 cell monolayer models to assess the bioaccessibility, transmembrane transport, and a rat model to examine the bioavailability and metabolism in vivo. Polyphenols were increasingly released during the in vitro digestion, and were found to contribute to the increased antioxidant activity. Among the bioaccessible polyphenols, catechin glucoside, kaempferol tetraglucoside, procyanidin dimer and dihydroxybenzoic acid-O-dipentoside were most efficiently transported across the caco-2 membrane, and responsible for promoting intestinal integrity as a result of enhanced expression of tight junction proteins. When ingested by rats, lentil hull polyphenols underwent extensive I and II phase metabolic reactions in vivo, including hydroxylation, methylation, glucuronidation and sulfation. Overall, results of this study showed that lentil hull polyphenols are bioaccessible and bioavailable, and lentil hulls as a by-product can be a valuable ingredient for future functional foods.

Neuro-Nutraceutical Polyphenols: How Far Are We?

The brain, composed of billions of neurons, is a complex network of interacting dynamical systems controlling all body functions. Neurons are the building blocks of the nervous system and their impairment of their functions could result in neurodegenerative disorders. Accumulating evidence shows an increase of brain-affecting disorders, still today characterized by poor therapeutic options. There is a strong urgency to find new alternative strategies to prevent progressive neuronal loss. Polyphenols, a wide family of plant compounds with an equally wide range of biological activities, are suitable candidates to counteract chronic degenerative disease in the central nervous system. Herein, we will review their role in human healthcare and highlight their: antioxidant activities in reactive oxygen species-producing neurodegenerative pathologies; putative role as anti-acetylcholinesterase inhibitors; and protective activity in Alzheimer’s disease by preventing Aβ aggregation and tau hyperphosphorylation. Moreover, the pathology of these multifactorial diseases is also characterized by metal dyshomeostasis, specifically copper (Cu), zinc (Zn), and iron (Fe), most important for cellular function. In this scenario, polyphenols’ action as natural chelators is also discussed. Furthermore, the critical importance of the role exerted by polyphenols on microbiota is assumed, since there is a growing body of evidence for the role of the intestinal microbiota in the gut–brain axis, giving new opportunities to study molecular mechanisms and to find novel strategies in neurological diseases.

Effect of Processing and In Vitro Digestion on Bioactive Constituents of Powdered IV Range Carrot (Daucus carota, L.) Wastes

Daucus carota L. is an important food crop utilized worldwide and a rich source of bioactive compounds. Carrot processing generates residues which are discarded or underused, for which using them as a source for obtaining new ingredients or products is an opportunity for the development of healthier and more sustainable diets. In the present study, the impact of different milling and drying procedures and in vitro digestion on the functional properties of carrot waste powders was evaluated. Carrot waste was transformed into powders by disruption (grinding vs. chopping), drying (freeze-drying or air-drying at 60 or 70 °C) and final milling. Powders were characterized in terms of physicochemical properties (water activity, moisture content, total soluble solids and particle size) nutraceuticals (total phenol content, total flavonoid content antioxidant activity by DPPH and ABTS methods, as well as carotenoid content (α-carotene, β-carotene, lutein, lycopene). Antioxidants and carotenoid content during in vitro gastrointestinal digestion were also evaluated; the latter in different matrices (directly, in water, in oil, and in oil-in-water emulsion). Processing allowed to reduce water activity of samples and obtain powders rich in antioxidant compounds and carotenoids. Both disruption and drying had a significant impact on powders' properties freeze-drying led to finer powders with higher carotenoid content but lower antioxidant values, whereas air-drying implied chopped air-dried powders exhibited higher phenols content and improved antioxidant activity. Simulated in vitro digestion studies revealed that digestion helps release bioactive compounds which are bound to the powder structure. The solubilization of carotenoids in oil was low, but fat co-ingestion notably increased their recovery. According to the results, carrot waste powders containing bioactive compounds could be proposed as functional ingredients to increase the nutritional value of foods, thus contributing to the concepts of more sustainable food systems and sustainable healthy diets.

In Vitro Fermentation of Beechwood Lignin-Carbohydrate Complexes Provides Evidence for Utilization by Gut Bacteria

Lignin-carbohydrate complexes (LCCs) are emerging as a new and natural product with pharmacological and nutraceutical potential. It is uncertain, however, whether LCCs have a positive effect on the microbiota of the gut based on the current evidence. Here, the LCC extracted from beechwood (BW-LCC) was used as a substrate for in vitro fermentation. The lignin in BW-LCC consisted of guaiacyl (G) and syringyl (S) units, which are mainly linked by β-O-4 bonds. After 24 h of in vitro fermentation, the pH had evidently declined. The concentrations of acetic acid and propionic acid, the two main short-chain fatty acids (SCFAs), were significantly higher than in the control group (CK). In addition, BW-LCC altered the microbial diversity and composition of gut microbes, including a reduction in the relative abundance of Firmicutes and an increase in the relative abundance of Proteobacteria and Bacteroidetes. The relative abundance of Escherichia coli-Shigella and Bacteroides were the most variable at the genus level. The genes of carbohydrate-active enzymes (CAZymes) also changed significantly with the fermentation and were related to the changes in microbes. Notably, the auxiliary actives (AAs), especially AA1, AA2, and AA3_2, play important roles in lignin degradation and were significantly enriched and concentrated in Proteobacteria. From this study, we are able to provide new perspectives on how gut microbes utilize LCC.

The Sustainability of Sweet Potato Residues from Starch Processing By-Products: Preparation with Lacticaseibacillus rhamnosus and Pediococcus pentosaceus, Characterization, and Application

The effects of Lacticaseibacillus rhamnosus and Pediococcus pentosaceus on the nutritional-functional composition, structure, in vitro saliva-gastrointestinal digestion, and colonic fermentation behaviors of fermented sweet potato residues (FSPR) were investigated. The FSPR was obtained under the condition of a solid-to-liquid ratio of 1/10, inoculation quantity of 1.5%, mixed bacteria ratio 1:1, fermentation time of 48 h, and fermentation temperature of 37 °C. The FSPR showed higher contents of soluble dietary fiber (15.02 g/100 g), total polyphenols content (95.74 mg/100 g), lactic acid (58.01 mg/g), acetic acid (1.66 mg/g), volatile acids (34.26%), and antioxidant activities. As exhibited by FTIR and SEM, the higher peak intensity at 1741 cm^-1 and looser structure were observed in FSPR. Further, the FSPR group at colonic fermentation time of 48 h showed higher content of acetic acid (1366.88 µg/mL), propionic acid (40.98 µg/mL), and butyric acid (22.71 µg/mL), which were the metabolites produced by gut microbiota using dietary fiber. Meanwhile, the abundance of Bifidobacterium and Lacticaseibacillus in the FSPR group was also improved. These results indicated that FSPR potentially developed functional foods that contributed to colonic health.

In Vitro Gastrointestinal Bioaccessibility, Bioactivities and Colonic Fermentation of Phenolic Compounds in Different Vigna Beans

Beans are widely consumed throughout the world, rich in non-nutrient phenolic compounds and other bioactive constituents, including alkaloids, lectins, and others. However, research about in vitro digestion impacts on the changes of bioactive compounds' release and related antioxidant potential in different Vigna beans is limited. This research aimed to assess the modifications that occur in the content and bioaccessibility of phenolic compounds in four Vigna samples (adzuki bean, black urid whole, black eye bean, and mung bean), their antioxidant properties, and short chain fatty acids (SCFAs) production through static in vitro gastrointestinal digestion and colonic fermentation. Adzuki bean exhibited relatively higher total phenolic content (TPC; 4.76 mg GAE/g) and antioxidant activities after in vitro digestion. The black eye beans' total flavonoid content (0.74 mg QE/g) and total condensed tannins (10.43 mg CE/g) displayed higher tendencies. For colonic fermentation, the greatest TPC value of entire samples was detected through a 2-h reaction. In most selected beans, phenolic compounds were comparably more bioaccessible during the oral phase. Acetic acid showed the highest level through SCFAs production, and the total SCFAs in adzuki beans was the greatest (0.021 mmol/L) after 16-h fermentation. Adzuki beans may be more beneficial to gut health and possess a stronger antioxidant potential after consumption.

Ultrasound-alkaline combined extraction improves the release of bound polyphenols from pitahaya (Hylocereus undatus 'Foo-Lon') peel: Composition, antioxidant activities and enzyme inhibitory activity

In this study, ultrasound-assisted alkaline hydrolysis was used to extract polyphenols from pitahaya peel. The effects of sonication time, ultrasonic density, NaOH concentration and the liquid-material ratio on the total phenolic content (TPC), total flavonoid content (TFC) and antioxidant activity of the extracts were studied. The composition and content difference of the extracts were analyzed and the inhibitory effect of α-amylase and α-glucosidase was measured. The results of single-factor analysis showed that when the sonication time was 45 min, the ultrasonic density was 32 W/L, the NaOH solution concentration was 6 M and the liquid-material ratio was 30 mL/g, the release of phenolic compounds was the largest and the antioxidant activity was the strongest. An UPLC-QTOF-MS/MS method was used to analyze the components and contents of the extracts. We found that there was a great difference in the component content of the free polyphenol extract and the bound polyphenol extract. From the results, we concluded that there was a strong correlation between the type and content of phenolic compounds and antioxidant activities, indicating that phenolic compounds were the main compounds of these biological activities. Moreover, the bound polyphenol extracts showed a significant inhibitory effect on α-amylase and α-glucosidase was stronger than that of the free polyphenol extracts. In addition, scanning electron microscopy showed that ultrasound-assisted extraction is crucial to the destruction of the cell wall and the release of bound polyphenols. Therefore, the pitahaya peel has the potential for therapeutic, nutritional, and functional food applications, and ultrasound-assisted alkaline hydrolysis is an effective means to release phenolic compounds.

Simulated Gastric and Intestinal Fluid Electrolyte Solutions as an Environment for the Adsorption of Apple Polyphenols onto β-Glucan

Interactions with dietary fibers in the gastrointestinal tract might affect the potential bioactivities of phenolic compounds. In this study, the interactions between apple phenolic compounds and β-glucan (a dietary fiber) were studied by studying the adsorption process in simulated gastric and intestinal fluid electrolyte solutions. Phenolic compounds were extracted from apples, adsorbed onto β-glucan (2 h, 37 °C, in gastric or intestinal fluid electrolyte solutions), and determined using high performance liquid chromatography. Phenolic compounds (flavan-3-ols, flavonols, phenolic acids, and dihydrochalcone) were stable in the gastric fluid (pH 3). In the intestinal fluid (pH 7), flavan-3-ols were not found and chlorogenic acid isomerized. Polyphenols from the apple peel (up to 182 and 897 mg g⁻¹) and flesh (up to 28 and 7 mg g⁻¹) were adsorbed onto β-glucan in the gastric and intestinal fluids, respectively. The adsorption was affected by the initial concentration of the polyphenols and β-glucan and by the environment (either gastric or intestinal fluid electrolyte solution). By increasing the initial polyphenol amount, the quantity of adsorbed polyphenols increased. Increasing the amount of β-glucan decreased the amount adsorbed. The results can be helpful in explaining the fate of phenolic compounds in the gastrointestinal tract.

Catabolism of polyphenols released from mung bean coat and its effects on gut microbiota during in vitro simulated digestion and colonic fermentation

Mung bean coat is a good source of dietary polyphenols. In this study,in vitro simulated digestion and colonic fermentation were performed to investigate the release of polyphenols from mung bean coat and their bioactivities. Polyphenols released by colonic fermentation were much higher than those released by digestion and reached a peak at 12 h, resulting in higher antioxidant capacities (DPPH, ORAC, FRAP assays). About 49 polyphenols and metabolites including quercetin, vanillin, catechin and p-hydroxybenzoic acid were identified, and possible biotransformation pathways were postulated. Moreover, the relative abundance of beneficial bacteria (such as Lactococcus and Bacteroides) was improved during colonic fermentation. Altogether, gut microbiota could release polyphenols, the released polyphenols and their catabolic metabolites, alongside dietary fiber in mung bean coat selectively regulated the composition of gut microbiota and promoted the synthesis of SCFAs. These findings indicated that polyphenols in mung bean coat potentially contributed to gastrointestinal and colonic health.

Fermented Carrot Pulp Regulates the Dysfunction of Murine Intestinal Microbiota

It was the focus of attention that probiotic control drink was packed with prebiotic nutrients and lactic acid bacteria. So, this study is aimed at revealing that the fermented carrot pulp regulation and protection function to the intestinal microecological disorders usually induced by antibiotic treatment. First, we study on lactobacillus fermentation conditions and effects on the secondary metabolism of fermented carrot juice, get its phenolic acids up, and get its flavonoids down. Then, establishment of the dysbacteriosis mouse model was used to validate the fermented carrot pulp prevention and treatment of intestinal microbiota imbalance. After the antibiotic treatment, the mice showed impotence, laziness, slow movement, weight loss, thin feces, dull hair, and anal redness, while the mice in the control group were all normal in terms of the mental state, diet, weight, and bowl movement. Along with the treatment, the abnormal conditions of the mice in the model group and natural recovery group improved in different degrees, indicating that the fermentation treatment is of help to the intestinal microbiota recovery. The fermentation-treated group of mice recovered close to normal that the diarrhea disappeared, and the weight gain, mental state, and the feces became normal. The serum antioxidant (SOD, GSH, and MDA) levels of the mice were checked. The superoxide dismutase (SOD) levels and glutathione (GSH) levels in the ordinary fermentation-treated group and probiotic fermentation-treated group were significantly increased compare to the natural recovery group. The malondialdehyde (MDA) levels showed great differences between the fermentation-treated groups and the blank group. At last, the 16sRNA analysis revealed that the microbiota richness and diversity in probiotic fermentation (J) are much higher than those in the model group (H), ordinary fermentation group (I), and blank group (G). Groups J and I are of significantly higher antioxidant level than group H; however, only the glutathione (GSH) level in group J increased dramatically but not those in the other three groups. Antibiotic treatment-induced mouse intestinal microecological disorder reduce the microbiota richness and diversity. Prebiotics fermented carrot pulp treatment can help in the recovery from the microbiota richness and diversity level prior to the antibiotic treatment, which suggests it can regulate and protect the murine intestinal microbiome.

Characterization of Saponins from Differently Colored Quinoa Cultivars and Their In Vitro Gastrointestinal Digestion and Fermentation Properties

Quinoa contains rich saponins, which are removed during processing and cause ecological waste. We extracted saponins from quinoa (SEQ) in black, white, and red cultivars and compared their composition by spectrophotometric assay and high-performance liquid chromatography analysis combined with acid hydrolysis. The digestion and fermentation properties of SEQ were investigated using an in vitro model. Our results showed that acid hydrolysis released sapogenins, mainly phytolaccagenin (PA), hederagenin (HD), and oleanolic acid from SEQ. Varying from SEQ in red, SEQ in black and white had a similar composition and content of sapogenins. Gastrointestinal digestion did not release sapogenins from SEQ but reduced the antioxidant activity of SEQ. Gut microbiota from human feces released PA and HD from SEQ. Reciprocally, SEQ in black significantly increased the growth of Lactobacillus spp. and Bifidobacterium spp., while reducing the growth of Shigella spp. The present study provides guidance for further investigation about the bioactivities of saponins from quinoa.

Therapeutic Properties of Edible Mushrooms and Herbal Teas in Gut Microbiota Modulation

Edible mushrooms are functional foods and valuable but less exploited sources of biologically active compounds. Herbal teas are a range of products widely used due to the therapeutic properties that have been demonstrated by traditional medicine and a supplement in conventional therapies. Their interaction with the human microbiota is an aspect that must be researched, the therapeutic properties depending on the interaction with the microbiota and the consequent fermentative activity. Modulation processes result from the activity of, for example, phenolic acids, which are a major component and which have already demonstrated activity in combating oxidative stress. The aim of this mini-review is to highlight the essential aspects of modulating the microbiota using edible mushrooms and herbal teas. Although the phenolic pattern is different for edible mushrooms and herbal teas, certain non-phenolic compounds (polysaccharides and/or caffeine) are important in alleviating chronic diseases. These specific functional compounds have modulatory properties against oxidative stress, demonstrating health-beneficial effects in vitro and/or In vivo. Moreover, recent advances in improving human health via gut microbiota are presented. Plant-derived miRNAs from mushrooms and herbal teas were highlighted as a potential strategy for new therapeutic effects.