The effect of bound polyphenols on the fermentation and antioxidant properties of carrot dietary fiber in vivo and in vitro

Grain bound polyphenols: Molecular interactions, release characteristics, and regulation mechanisms of postprandial hyperglycemia

Frequent postprandial hyperglycemia causes many chronic diseases. Grain polyphenols are widely recognized as natural active ingredients with high potential to treat chronic diseases due to their excellent postprandial hyperglycemic regulating effects. However, previous studies on polyphenols in grains mainly focused on the functional properties of free polyphenols and the extraction and physicochemical properties of bound polyphenols, ignoring the functional properties of bound polyphenols. Comprehensively understanding the binding properties of grain bound polyphenols (GBPs) and their mechanisms in regulating blood glucose levels is essential for developing and applying grain resources. This review summarizes the molecular interactions between GBPs and grain components and their effects on release characteristics and bioavailability at various stages. Meanwhile, the review focuses on elucidating the regulatory mechanism of post-release GBPs on postprandial hyperglycemia levels, incorporating insights from molecular docking, the gastrointestinal-brain axis, and gut flora. GBPs slow food digestion by occupying the active site of digestive enzymes and altering the secondary structure of enzymes and the hydrophobic environment of amino acid residues to inhibit enzyme activity. They modulate intestinal epithelial transport proteins (SGLT1, GLUT2, and GLUT4) to limit glucose absorption and increase glucose consumption. They also stimulate the release of short-term satiety hormones (CKK, GLP-1, and PYY) through the gastrointestinal-brain axis to decrease post-meal food intake. Furthermore, they optimize gut microbiota composition, promoting short-chain fatty acid production and bile acid metabolism. Therefore, developing functional foods with glucose-modulating properties based on GBPs is crucial for obesity prevention, diabetes management, and low-GI food development.

Influence of autochthonous Lactiplantibacillus plantarum strains on microbial safety and bioactive compounds in a fermented quinoa-based beverage as a non-dairy alternative

Plant-based alternatives are considered microbiologically safe; however, recent studies have raised concerns about hygienic quality. Additionally, the relationship between microbiological safety and polyphenolic content in fermented products remains unexplored. This study assessed the potential of four autochthonous Lactiplantibacillus plantarum strains (3, 5, 9, and 10) to impact microbial composition and modulate polyphenol and saponin levels in a quinoa-based beverage. The results identified Lactiplantibacillus plantarum strains 3, 9, and 10 as effective in inhibiting Enterobacteriaceae (p = 0.001), and increasing concentrations of glycosylated flavonoids, 3-phenyllactic acid, and saponins. However, Lactiplantibacillus plantarum 10 demonstrated a decrease in saponin levels, whereas Lactiplantibacillus plantarum 5 increased the abundance of aglycones, highlighting strain-specific differences. Notably, principal component analysis revealed less differences between inoculated samples and control, indicating potential contribution of the native microbiota to the fermentation. This study enhances the understanding of interactions between starter cultures, native microbiota, and bioactive compounds in plant-based fermented beverages.

Exploring a maize-derived dietary fiber-phenolic acid complex with prebiotic effects

The structural, functional, and prebiotic properties of three maize-derived cell wall dietary fiber-phenolic acid complexes (CWDFPC1, CWDFPC2, and CWDFPC3) were investigated. The results showed that all three CWDFPCs had similar proximate composition and XRD pattern (type I). However, there were significant differences in the phytochemical profiles of their phenolic compounds (PC). Although the testa was the primary source of bound PC (BPC) in all three CWDFPCs, CWDFPC2 had the highest BPC content (15.41 mg GAE/g) and exhibited the greatest antioxidant activity in vitro (DPPH and ABTS assays). The water holding capacity of CWDFPC1 (6.53 g/g) and CWDFPC3 (6.86 g/g) was higher than CWDFPC2 (4.84 g/g), and three CWDFPCs had similar nitrite ion adsorption capacity, bile adsorption capacity, and cation-exchange capacity. After 48 h of in vitro fecal fermentation, CWDFPC2 produced more short-chain fatty acids (46.33 mM) compared to CWDFPC1 and CWDFPC3 (40.26 mM and 44.20 mM, respectively).

Study on the prebiotic effects of insoluble crude and fine fibers of wheat bran after simulated digestion in vitro

This study aims to evaluate the probiotic effects of insoluble crude and fine fibers of wheat bran on the intestine after simulated in vitro digestion. It was found that the particle size distribution of modified fine wheat bran (MWB) was significantly smaller than that of natural crude wheat bran (NWB). MWB had a looser texture and more porous structure. The dry matter digestibility and organic matter digestibility of MWB were 58.60 % and 59.05 %, which were significantly higher than that of NWB (53.64 % and 54.13 %). More SDF and free polyphenol were released from the MWB. At 12 h of fermentation, the SDF content of the MWB was 3.76 g/100 g, significantly higher than NWB (3.40 g/100 g), and the free polyphenol was 9.43 mg/g, significantly higher than NWB (9.01 mg/g). The content of short-chain fatty acids including formic acid, acetic acid, propionic acid, butyrate acid and valerate acid in the samples were significantly higher in MWB than in NWB. Analysis of the microbial flora structure and diversity of the fermentation samples revealed that the relative abundance of Lactobacillus was higher in the MWB group, and was closer to the oligofructose group (FOS) in terms of functional predictions.

A review of healthy role of dietary fiber in modulating chronic diseases

Dietary fiber (DF) is considered an interventional diet beneficial for human health. High DF intake effectively reduces the incidence of three major chronic diseases, type 2 diabetes (T2DM), cardiovascular disease (CVD), and colorectal cancer (CRC). The health benefits of DF are closely related to their physicochemical properties with major positive roles in human digestion and intestinal health. However, mechanisms linking DF with diseases remain unclear. The development of genomics, metabolomics, and immunology, and the powerful combination of animal models and clinical trials, have facilitated a better understanding of the relationships between DF and diseases. Accumulating evidence suggests that the physical existence of DF and DF-microbiota interaction are the key parameters controlling the action mechanisms of DF in chronic diseases. Therefore, this review discusses the potential mechanism of DF modulating T2DM, CVD, and CRC, therefore providing a theoretical basis for more effective use of DF to intervene in chronic diseases.

Polysaccharide-polyphenol interactions: a comprehensive review from food processing to digestion and metabolism

Most studies on the beneficial effects of polyphenols on human health have focused on polyphenols extracted using aqueous organic solvents, ignoring the fact that a portion of polyphenols form complexes with polysaccharides. Polysaccharides and polyphenols are interrelated, and their interactions affect the physicochemical property, quality, and nutritional value of foods. In this review, the distribution of bound polyphenols in major food sources is summarized. The effect of food processing on the interaction between polyphenols and cell wall polysaccharides (CWP) is discussed in detail. We also focus on the digestion, absorption, and metabolic behavior of polysaccharide-polyphenol complexes. Different food processing techniques affect the interaction between CWP and polyphenols by altering their structure, solubility, and strength of interactions. The interaction influences the free concentration and extractability of polyphenols in food and modulates their bioaccessibility in the gastrointestinal tract, leading to their major release in the colon. Metabolism of polyphenols by gut microbes significantly enhances the bioavailability of polyphenols. The metabolic pathway and product formation rate of polyphenols and the fermentation characteristics of polysaccharides are affected by the interaction. Furthermore, the interaction exhibits synergistic or antagonistic effects on the stability, solubility, antioxidant and functional activities of polyphenols. In summary, understanding the interactions between polysaccharides and polyphenols and their changes in food processing is of great significance for a comprehensive understanding of the health benefits of polyphenols and the optimization of food processing technology.

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.

Characterization and stability assessment of polyphenols bound to Lycium barbarum polysaccharide: Insights from gastrointestinal digestion and colon fermentation

Polysaccharides and polyphenols are biologically active components that coexist in Lycium barbarum fruit, and there may be interactions between them that affect the release of each other. In this study, polyphenols bound to L. barbarum polysaccharide (LBP) were characterized, and the stability of bound phenolics (BP) was assessed by gastrointestinal digestion and colon fermentation. The results showed that a total of 65 phytochemicals such as flavonoids, phenolic acids, and coumarins were identified by UPLC-MS/MS. Quantitative analysis revealed that the major phenolic constituents were rutin, p-coumaric acid, catechin, ferulic acid, protocatechuic acid, and gallic acid, and their contents were 58.72, 24.03, 14.24, 13.28, 10.39, and 6.7 mg GAE/100 g DW, respectively. The release of BP by gastric digestion and gastrointestinal digestion was 9.67 % and 19.39 %, respectively. Most polyphenols were greatly affected by gastric digestion, while rutin was released in small intestine. The BP were fully released (49.77 %) and metabolized by gut microorganisms, and a considerable number of intermediates and end-products were detected, such as phloroglucinol, phenylacetic acid, and phenyllactic acid. Microbiomics data emphasized the positive impact of LBP on gut bacteria of Bacteroides, Parabacteroides, and Clostridioides. These findings could deepen our understanding of the bioavailability and biological fate of BP and also provide reference data for nutrient release and utilization of L. barbarum as a whole.

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.

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.

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.

The synergistic effects of polyphenols and intestinal microbiota on osteoporosis

Osteoporosis is a common metabolic disease in middle-aged and elderly people. It is characterized by a reduction in bone mass, compromised bone microstructure, heightened bone fragility, and an increased susceptibility to fractures. The dynamic imbalance between osteoblast and osteoclast populations is a decisive factor in the occurrence of osteoporosis. With the increase in the elderly population in society, the incidence of osteoporosis, disability, and mortality have gradually increased. Polyphenols are a fascinating class of compounds that are found in both food and medicine and exhibit a variety of biological activities with significant health benefits. As a component of food, polyphenols not only provide color, flavor, and aroma but also act as potent antioxidants, protecting our cells from oxidative stress and reducing the risk of chronic disease. Moreover, these natural compounds exhibit anti-inflammatory properties, which aid in immune response regulation and potentially alleviate symptoms of diverse ailments. The gut microbiota can degrade polyphenols into more absorbable metabolites, thereby increasing their bioavailability. Polyphenols can also shape the gut microbiota and increase its abundance. Therefore, studying the synergistic effect between gut microbiota and polyphenols may help in the treatment and prevention of osteoporosis. By delving into how gut microbiota can enhance the bioavailability of polyphenols and how polyphenols can shape the gut microbiota and increase its abundance, this review offers valuable information and references for the treatment and prevention of osteoporosis.

Relationship between Physicochemical, Techno-Functional and Health-Promoting Properties of Fiber-Rich Fruit and Vegetable By-Products and Their Enhancement by Emerging Technologies

The preparation and processing of fruits and vegetables produce high amounts of underutilized fractions, such as pomace and peel, which present a risk to the environment but constitute a valuable source of dietary fiber (DF) and bioactive compounds. The utilization of these fiber-rich products as functional food ingredients demands the application of treatments to improve their techno-functional properties, such as oil and water binding, and health-related properties, such as fermentability, adsorption, and retardation capacities of glucose, cholesterol, and bile acids. The enhancement of health-promoting properties is strongly connected with certain structural and techno-functional characteristics, such as the soluble DF content, presence of hydrophobic groups, and viscosity. Novel physical, environmentally friendly technologies, such as ultrasound (US), high-pressure processing (HPP), extrusion, and microwave, have been found to have higher potential than chemical and comminution techniques in causing desirable structural alterations of the DF network that lead to the improvement of techno-functionality and health promotion. The application of enzymes was related to higher soluble DF content, which might be associated with improved DF properties. Combined physical and enzymatic treatments can aid solubilization and modifications, but their benefit needs to be evaluated for each DF source and the desired outcome.

A comprehensive review of matcha: production, food application, potential health benefits, and gastrointestinal fate of main phenolics

Matcha, a powder processed from tea leaves, has a unique green tea flavor and appealing color, in addition to many other sought after functional properties for a wide range of formulated food applications (e.g., dairy products, bakery products, and beverage). The properties of matcha are influenced by cultivation method and processing post-harvest. The transition from drinking tea infusion to eating whole leaves provides a healthy option for the delivery of functional component and tea phenolics in various food matrix. The aim of this review is to describe the physico-chemical properties of matcha, the specific requirements for tea cultivation and industrial processing. The quality of matcha mainly depends on the quality of fresh tea leaves, which is affected by preharvest factors including tea cultivar, shading treatment, and fertilization. Shading is the key measure to increase greenness, reduce bitterness and astringency, and enhance umami taste of matcha. The potential health benefits of matcha and the gastrointestinal fate of main phenolics in matcha are covered. The chemical compositions and bioactivities of fiber-bound phenolics in matcha and other plant materials are discussed. The fiber-bound phenolics are considered promising components which endow matcha with boosted bioavailability of phenolics and health benefits through modulating gut microbiota.

Synbiotics and Their Antioxidant Properties, Mechanisms, and Benefits on Human and Animal Health: A Narrative Review

Antioxidants are often associated with a variety of anti-aging compounds that can ensure human and animal health longevity. Foods and diet supplements from animals and plants are the common exogenous sources of antioxidants. However, microbial-based products, including probiotics and their derivatives, have been recognized for their antioxidant properties through numerous studies and clinical trials. While the number of publications on probiotic antioxidant capacities and action mechanisms is expanding, that of synbiotics combining probiotics with prebiotics is still emerging. Here, the antioxidant metabolites and properties of synbiotics, their modes of action, and their different effects on human and animal health are reviewed and discussed. Synbiotics can generate almost unlimited possibilities of antioxidant compounds, which may have superior performance compared to those of their components through additive or complementary effects, and especially by synergistic actions. Either combined with antioxidant prebiotics or not, probiotics can convert these substrates to generate antioxidant compounds with superior activities. Such synbiotic-based new routes for supplying natural antioxidants appear relevant and promising in human and animal health prevention and treatment. A better understanding of various component interactions within synbiotics is key to generating a higher quality, quantity, and bioavailability of antioxidants from these biotic sources.

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.

Neurotoxicity and Structure-Activity Relationships of Resveratrol and its two Natural Analogs, 4,4′-Dihydroxystilbene and Pinosylvin

Resveratrol (RES) and its two natural analogues, 4,4′-dihydroxystilbene (DHS) and pinosylvin (PIN), are very important polyphenols and have attracted considerable pharmaceutical interest because of their diverse biological activities. However, their adverse effects on motor nerves and glioma cells have not been properly assessed. Herein, we surveyed the toxicity and analyzed the structure-activity relationship of these three polyphenols using transgenic zebrafish ( Danio rerio) and U87. Results indicated that, in zebrafish embryos, both DHS (1 and 10 μg/mL) with hydroxyl groups at the 4 and 4′ positions, and PIN (1 and 10 μg/mL) with hydroxyl groups at the 3 and 5 positions inhibited motor neuron growth more effectively than RES (1 and 10 μg/mL) with hydroxyl groups at the 3, 4′, and 5 positions, although their appearance is normal. Both the DHS- (10 μg/mL) and PIN (10 μg/mL) -treated groups significantly reduced the swimming distance of zebrafish compared with the RES (10 μg/mL) -treated group. In addition, DHS with the hydroxyl groups at the 4 and 4′ positions (0.002, 0.02, 0.2, 2, and 20 μM) inhibited U87 cell aggregation in a concentration-dependent manner; PIN with the hydroxyl groups at the 3 and 5 positions (0.002, 0.02, 0.2, 2, and 20 μM) promoted U87 cell aggregation in a concentration-dependent manner, while RES with three hydroxyl groups promoted U87 cell aggregation at concentrations from 0.2 to 2 μM. Taken together, DHS and PIN are more neurotoxic than RES. The position and number of hydroxyl groups significantly affected the ability of the polyphenols to aggregate into tumors in the U87 cell.

Effect of different cadmium levels in Boletus griseus on bioaccessibility, bioavailability, and intestinal flora by establishing a complete bionic digestion system in vitro

The bioaccessibility and bioavailability of different cadmium (Cd) levels (low: 7.31 mg/kg, medium: 24.20 mg/kg, high: 41.64 mg/kg) in Boletus griseus were evaluated by establishing a bionic digestive system in vitro. The results showed that the bioaccessibility of high Cd level by gastrointestinal digestion was significantly higher than other two levels. Further, colonic digestion significantly increased the bioaccessibilities of low Cd level (p < 0.05). After intestinal flora fermentation, the bioaccessibilities of different Cd levels significantly decreased (p < 0.05), and high and medium Cd levels had no significant difference (p > 0.05). A Caco-2 monolayer cell model was established to evaluate the bioavailability of Cd. The bioavailabilities of low and high Cd levels by gastrointestinal digestion were 8.75 and 10.58%, and the bioavailabilities increased by 38.17% and 5.20% after colonic digestion, respectively. Furthermore, Cd could affect diversity, composition, and balance of intestinal flora, and the relative abundances of several genera were correlation with Cd levels in B. griseus.

Phytochemical profile, bioactivity and prebiotic potential of bound polyphenols released from Rosa Roxburghii fruit pomace dietary fiber during in vitro digestion and fermentation

The aim of this study was to elucidate liberation and phytochemical profile of bound polyphenols existed in dietary fiber (RPDF) isolated from Rosa roxburghii fruit pomace during in vitro simulated...

Polyphenols-Gut Microbiota Interrelationship: A Transition to a New Generation of Prebiotics

The present review summarizes the studies carried out on this topic in the last five years. According to the new definitions, among all the compounds included in the group of prebiotics, polyphenols are probably the most important secondary metabolites produced by the plant kingdom. Many of these types of polyphenols have low bioavailability, therefore reaching the colon in unaltered form. Once in the colon, these compounds interact with the intestinal microbes bidirectionally by modulating them and, consequently, releasing metabolites. Despite much research on various metabolites, little is known about the chemistry of the metabolic routes used by different bacteria species. In this context, this review aims to investigate the prebiotic effect of polyphenols in preclinical and clinical studies, highlighting that the consumption of polyphenols leads to an increase in beneficial bacteria, as well as an increase in the production of valuable metabolites. In conclusion, there is much evidence in preclinical studies supporting the prebiotic effect of polyphenols, but further clinical studies are needed to investigate this effect in humans.

UPLC-QTOF-MS/MS and GC-MS Characterization of Phytochemicals in Vegetable Juice Fermented Using Lactic Acid Bacteria from Kimchi and Their Antioxidant Potential

This study aims to investigate fermentative metabolites in probiotic vegetable juice from four crop varieties (Brassica oleracea var. capitata, B. oleracea var. italica, Daucus carota L., and Beta vulgaris) and their antioxidant properties. Vegetable juice was inoculated with two lactic acid bacteria (LAB) (Companilactobacillus allii WiKim39 and Lactococcus lactis WiKim0124) isolated from kimchi and their properties were evaluated using untargeted UPLC-QTOF-MS/MS and GC-MS. The samples were also evaluated for radical (DPPH^• and OH^•) scavenging activities, lipid peroxidation, and ferric-reducing antioxidant power. The fermented vegetable juices exhibited high antioxidant activities and increased amounts of total phenolic compounds. Fifteen compounds and thirty-two volatiles were identified using UPLC-QTOF-MS/MS and GC-MS, respectively. LAB fermentation significantly increased the contents of d-leucic acid, indole-3-lactic acid, 3-phenyllactic acid, pyroglutamic acid, γ-aminobutyric acid, and gluconic acid. These six metabolites showed a positive correlation with antioxidant properties. Thus, vegetable juices fermented with WiKim39 and WiKim0124 can be considered as novel bioactive health-promoting sources.

Sandalwood seed oil improves insulin sensitivity in high-fat/high-sucrose diet-fed rats associated with altered intestinal microbiota and its metabolites

Sandalwood seed oil (SSO), rich in ximenynic acid, is extracted from the seed kernels of Santalum spicatum. The current work aimed to clarify the potential mechanisms of SSO in preventing insulin resistance (IR) by investigating the intestinal microbiota and its metabolites. Fifty male Sprague-Dawley rats were randomly divided into a standard chow group (N), and four high-fat/high-sucrose (HFHS) diet-fed groups plus 7% of SSO, fish oil (FO), linseed oil (LO) or sunflower oil (SO), respectively. After 12 weeks, the feces were collected and subsequently the rats were sacrificed for collecting blood and tissues. The results indicated that the SSO, FO and LO groups had a lower ratio of Firmicutes to Bacteroidetes (F/B) and lower levels of Actinobacteria phylum in their feces compared to the SO group. HOMA-IR was positively correlated with F/B (r = 0.63) and Actinobacteria (r = 0.64). At the genus level, beneficial bacteria, including Oscillospira, Clostridium, Turicibacter, Ruminococcus and Coprococcus, were more abundant, while destructive bacteria, such as Collinsella, were less abundant in the SSO group than in the SO group. The concentrations of fecal short-chain fatty acids (SCFAs) were higher, and the serum LPS and trimethylamine N-oxide (TMAO) were lower in the SSO, FO and LO groups than the SO group. In addition, SCFAs were negatively (r: -0.45 to -0.82), and LPS (r: 0.12 to 0.42) and TMAO (r: 0.32 to 0.49) were positively correlated with HOMA-IR and serum IL-1β, IL-6 and TNF-α. In summary, the prevention effect of SSO on HFHS induced IR was associated with altered intestinal microbiota composition and the production of microbial metabolites.

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

Carrot powder digestion was researched utilizing an in vitro standardized static model associated with an in vitro colonic fermentation method to analyze the recovery, catabolism, and potential bioactivity of polyphenols from carrot. Twenty-seven polyphenols and their metabolites (hydroxybenzoic acids, hydroxycinnamic acids and its derivatives, etc.) were identified in samples before and after digestion/colonic fermentation, and the possible colonic pathways for major polyphenols were proposed. Polyphenols had low recovery during different phases of in vitro digestion (oral: -51.4%; gastric: -38%; intestinal: -35.3%, respectively). However, the concentration of polyphenols (p-hydroxybenzoic acid, gallic acid and protocatechuic acid) increased significantly after colonic fermentation for 12 h with 1391.7% recovery, then significantly declined after 48 h. Meanwhile, the released and catabolized polyphenols showed antioxidant activity and α-glucosidase inhibitory capacity (IC₅₀ = 9.91 μg GAE/mL). The microbe community structure was regulated by fecal fermented carrot powder through improving relative abundance (RA) of beneficial microbiota and suppressed RA of various harmful bacteria. This work indicated that polyphenols from carrot potentially play a role in gastrointestinal and colonic health.

Role of dietary polyphenols on gut microbiota, their metabolites and health benefits

The beneficial health roles of dietary polyphenols in preventing oxidative stress related chronic diseases have been subjected to intense investigation over the last two decades. As our understanding of the role of gut microbiota advances our knowledge of the antioxidant and anti-inflammatory functions of polyphenols accumulates, there emerges a need to examine the prebiotic role of dietary polyphenols. This review focused onthe role of different types and sources of dietary polyphenols on the modulation of the gut microbiota, their metabolites and how they impact on host health benefits. Inter-dependence between the gut microbiota and polyphenol metabolites and the vital balance between the two in maintaining the host gut homeostasis were discussed with reference to different types and sources of dietary polyphenols. Similarly, the mechanisms behind the health benefits by various polyphenolic metabolites bio-transformed by gut microbiota were also explained. However, further research should focus on the importance of human trials and profound links of polyphenols-gut microbiota-nerve-brain as they provide the key to unlock the mechanisms behind the observed benefits of dietary polyphenols found in vitro and in vivo studies.

Impact of the popping process on the structural and thermal properties of sorghum grains (Sorghum bicolor L. Moench)

The popping process has been widely used as a technique for obtaining snacks. This study evaluated the effect of the popping process on the structural and thermal properties of sorghum. Seven varieties of sorghum were used. Raw sorghum grains were adjusted to 11% moisture and popped at 210 °C for 90 s with hot air. Microstructure, thermal and viscosity properties, and X-Ray and infrared spectrum were measured in raw and popped sorghum. The popping process produced an ordered honeycomb-like structure in the sorghum. The viscosity profile showed an increase in the thermal stability of popped sorghum. DSC measurements showed a starch gelatinization and a second transition about to 145 °C. XRD diffractograms display a reduction in the amplitude of the crystalline orthorhombic structure peaks. Finally, infrared indicated a change in the short-range structure and protein denaturation due to the popping process.

Composition of bound polyphenols from carrot dietary fiber and its in vivo and in vitro antioxidant activity

Qualitative analysis of bound polyphenols from carrot dietary fiber (CDF-PP) was performed by ultra-performance liquid chromatography equipped with an electrospray ionization and quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS/MS). Eleven organic acids, nine hydroxybenzoic acids and derivatives, six hydroxycinnamic acids and derivatives, four phenolic alcohols and derivatives, three flavonoids and derivatives, seven esters and derivatives, two other compounds, were detected by matching their retention times, secondary mass spectrometry fragment information with authentic standards or literature data. Furthermore, in vitro antioxidant activity was determined by different kinds of assays, including DPPH, ORAC, PSC, demonstrated that CDF-PP could scavenge radicals in a dose dependent manner. Moreover, CDF-PP exhibited significantly reactive oxygen species (ROS) scavenging activity in living Caenorhabditis elegans. To our knowledge, this is the first comprehensive research to investigate composition and in vitro/in vivo antioxidant activity of bound polyphenols in CDF, which implied that CDF-PP could be a promising source of antioxidants.

Changes in Intestinal Microbiota and Predicted Metabolic Pathways During Colonic Fermentation of Mango (Mangifera indica L.)-Based Bar Indigestible Fraction

Mango (Mangifera indica L.) peel and pulp are a source of dietary fiber (DF) and phenolic compounds (PCs) that constituent part of the indigestible fraction (IF). This fraction reaches the colon and acts as a carbon and energy source for intestinal microbiota. The effect of mango IF on intestinal microbiota during colonic fermentation is unknown. In this study, the isolated IF of a novel 'Ataulfo' mango-based bar (snack) UV-C irradiated and non-irradiated (UVMangoB and MangoB) were fermented. Colonic fermentation occurred in vitro under chemical-enzymatic, semi-anaerobic, batch culture and controlled pH colonic conditions. Changes in the structure of fecal microbiota were analyzed by 16s rRNA gene Illumina MiSeq sequencing. The community´s functional capabilities were determined in silico. The MangoB and UVMangoB increased the presence of Faecalibacterium, Roseburia, Eubacterium, Fusicatenibacter, Holdemanella, Catenibacterium, Phascolarctobacterium, Buttiauxella, Bifidobacterium, Collinsella, Prevotella and Bacteroides genera. The alpha indexes showed a decrease in microbial diversity after 6 h of colonic fermentation. The coordinates analysis indicated any differences between irradiated and non-irradiated bar. The metabolic prediction demonstrated that MangoB and UVMangoB increase the microbiota carbohydrate metabolism pathway. This study suggests that IF of mango-based bar induced beneficial changes on microbial ecology and metabolic pathway that could be promissory to prevention or treatment of metabolic dysbiosis. However, in vivo interventions are necessary to confirm the interactions between microbiota modulating and intestinal beneficial effects.

Release and metabolism of bound polyphenols from carrot dietary fiber and their potential activity in in vitro digestion and colonic fermentation

Dietary fiber is a carrier of abundant polyphenols and the potential benefits have attracted increasing attention.