Dynamic changes of structural characteristics of snow chrysanthemum polysaccharides during in vitro digestion and fecal fermentation and related impacts on gut microbiota

Effects of in vitro digestion and fecal fermentation on physico-chemical properties and metabolic behavior of polysaccharides from Clitocybe squamulosa

The aim of this study was to establish a human digestion model in vitro to explore the degradation characteristics of a novel high-purity polysaccharide from Clitocybe squamulosa (CSFP2). The results showed that the content of reducing sugars (C_R ) of CSFP2 increased from 0.13 to 0.23 mg/mL, the molecular weight (Mw) of CSFP2 decreased significantly during the saliva-gastrointestinal digestion. The constituent monosaccharides of CSFP2, including galactose, glucose, and mannose, were stable during in vitro digestion, but their molar ratios were changed from 0.023: 0.737: 0.234 to 0.496: 0.478: 0.027. The surface of CSFP2 changes from a rough flaky structure to a scattered flocculent or rod-shaped structure after the gastrointestinal digestion. However, the apparent viscosity of CSFP2 was overall stable during in vitro digestion. Moreover, CSFP2 still maintains its strong antioxidant capacity after saliva-gastrointestinal digestion. The results showed that CSFP2 can be partially decomposed during digestion. Meanwhile, some physico-chemical properties of the fermentation broth containing CSFP2 changed significantly after gut microbiota fermentation. For example, the pH value (from 8.46 to 4.72) decreased significantly (p < 0.05) after 48 h of fermentation. the OD ₆₀₀ value increased first and then decreased (from 2.00 to 2.68 to 1.32) during 48-h fermentation. In addition, CSFP2 could also increase the amounts of short-chain fatty acids (SCFAs) (from 5.5 to 37.15 mmol/L) during fermentation (in particular, acetic acid, propionic acid, and butyric acid). Furthermore, the relative abundances of Bacteriodes, Bifidobacterium, Catenibacterium, Lachnospiraceae_NK4A136_group, Megasphaera, Prevotella, Megamonas, and Lactobacillus at genus level were markedly increased with the intervention of CSFP2. These results provided a theoretical basis for the further development of functional foods related to CSFP2.

In vitro simulated digestion of and microbial characteristics in colonic fermentation of polysaccharides from four varieties of Tibetan tea

Polysaccharides as a functional prebiotic have numerous activities such as regulating intestinal microorganisms and polysaccharide is one of the functional active components in tea has been known. In this study, we aimed to investigate the physicochemical characteristics of polysaccharides from four kinds of Tibetan teas at simulated digestion stages and the effect on the microbiota of fecal fermentation stages in vitro. The results revealed that Tibetan tea polysaccharides were partially digested during digestion. Additionally, during in vitro fecal microbial fermentation, Tibetan tea polysaccharides can promote the growth of some beneficial bacteria such as Bifidobacterium, Prevotella and Phascolarctobacterium to change the composition of intestinal microorganisms and promote the production of short-chain fatty acids (SCFAs). Finally, a strong correlation was found between the production of SCFAs and microorganisms including Bacteroides, Bifidobacterium and Lachnoclostridium. These results suggest that Tibetan tea polysaccharides could be developed as a prebiotic to regulate human gut microbiota.

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.

A comparison study on polysaccharides extracted from Rosa sterilis S.D.Shi using different methods: Structural and in vitro fermentation characterizations

In this study, the structural and in vitro fermentation characterizations of Rosa sterilis S.D.Shi polysaccharides (RSP), extracted by hot water (HW), acid (AA), alkali (AK) and enzyme (EM) were investigated for the first time. The results indicated that extraction methods exhibited significant effects on the structure of RSPs, thus resulting in different probiotic effects. HW-RSP and AA-RSP had high contents of Gal, Glc and GalA, while AK-RSP and EM-RSP mainly contained Ara, Gal and GalA. EM-RSP was rich in RG-I and its size of average side chain were the largest. Moreover, HW-RSP and AK-RSP exhibited the smallest (57.55 kDa) and largest (922.20 kDa) molecular weights, respectively. All RSPs promoted the production of total SCFAs and the growth of beneficial bacteria like Bifidobacterium, Bacteroides, Faecalibacterium and Paraclostrium to varying degrees, but inhibited the growth of pathogenic bacteria such as Escherichia-shigella, thereby regulating the composition of gut microbiota. Furthermore, the function prediction results showed that EM-RSP had the most special metabolic pathways. Collectively, our findings provide new insights into the relationship between the structure and probiotic function of RSPs, and offer theoretical basis for the development of functional products of Rosa sterilis S.D.Shi.

Encapsulation of polyphenols in pH-responsive micelles self-assembled from octenyl-succinylated curdlan oligosaccharide and its effect on the gut microbiota

An amphiphilic polymer based on octenyl succinic anhydride-modified curdlan oligosaccharide (MCOS) was synthesized. The critical micelle concentration of MCOS was 3.91 μg·mL-1. MCOS could self-assemble into spherical micelles with a particle size of 230.1 nm and a zeta potential of - 37.9 mV. When used for polyphenol encapsulation, the loading capacity of curcumin and quercetin-co-encapsulated micelles was higher than that of single-polyphenol encapsulated micelles. In vitro gastrointestinal release test showed that the MCOS micelle presented a pH-dependent release, released a little polyphenol in simulated gastric fluid, but presented sustained release in the simulated intestinal fluid. The gastrointestinal-digested polyphenol-loaded micelles exhibited excellent antioxidant ability. In vitro human fecal fermentation indicated that the MCOS carrier could promote the production of short-chain fatty acids by gut microbiota and exhibited the highest relative abundance of Megamonas. In addition, the supplementation of curcumin and quercetin-co-loaded MCOS micelles increased the relative abundance of Bifidobacterium and inhibited the growth of Escherichia_Shigella. These findings indicated that the MCOS carrier can be potentially used for the colon-targeted delivery of hydrophobic polyphenols due to its pH-responsive property.

Simulated digestion, dynamic changes during fecal fermentation and effects on gut microbiota of Avicennia marina (Forssk.) Vierh. fruit non-starch polysaccharides

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Avicennia marina fruit non-starch polysaccharides (AMFPs) were obtained and analyzed.

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Dynamic changes of AMFPs during simulated digestion and fermentation were revealed.

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AMFPs were not digested by the digestive juice but were utilized by gut microbiota.

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Beneficial microbiota, such as Mistuokella, and Prevotella were obviously increased.

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Harmful bacteria were obviously inhibited and SCFA levels were obviously promoted.

Grey mangrove (Avicennia marina (Forssk.) Vierh.) fruit is a traditional folk medicine and health food consumed in many countries. In this study, its polysaccharides (AMFPs) were obtained and analyzed by chemical and instrumental methods, with the results indicating that AMFPs consisted of galactose, galacturonic acid, arabinose, and rhamnose in a molar ratio of 4.99:3.15:5.38:1.15. The dynamic changes in AMFPs during the digestion and fecal fermentation processes were then investigated. The results confirmed that AMFPs were not depolymerized by gastric acid and various digestive enzymes. During fermentation, 56.05 % of the AMFPs were utilized by gut microbiota. Galacturonic acid, galactose, and arabinose from AMFPs, were mostly consumed by gut microbiota. AMFPs obviously decreased harmful bacteria and increased some beneficial microbiota, including Megasphaera, Mistuokella, Prevotella, and Megamonas. Furthermore, AMFPs obviously increased the levels of various short-chain fatty acids. These findings suggest that AMFPs have potential prebiotic applications for improving gut health.

Physicochemical characteristics of Ganoderma lucidum oligosaccharide and its regulatory effect on intestinal flora in vitro fermentation

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G. lucidum oligosaccharide was obtained by ultrasonic enzymatic hydrolysis and Sephadex G25.

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GLO was a chain-like homogeneous oligosaccharide with a molecular weight of 1280 Da.

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GLO could not be easily degraded by digestion in the mouth, gastric and small intestine.

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GLO could be utilized and had good regulatory effects on intestinal flora.

This study explored the structure characteristics of an oligosaccharide from Ganoderma lucidum (GLO) and its regulatory functions on intestinal flora fermentation in vitro. GLO was extracted by ultrasonic-assisted enzymatic hydrolysis, and purified with a dextran gel column. Digestion properties and intestinal flora regulation effects of GLO were investigated by both simulation models. Results showed that GLO was a chain-like homogeneous oligosaccharide, composed of → 6)-β-d-Glcp-(1→, →4)-α-d-Glcp-(1→, β-d-Glcp-(1→, α-d-Manp-(1 →. Its structure could not be easily degraded by digestion in the mouth, gastric and small intestine. Accordingly, they can be utilized by the intestinal flora in large intestine. By evaluating the gas, short chain fatty acids, pH and flora abundance in vitro fermentation, it indicated that GLO had good regulatory effects on intestinal flora. Accordingly, GLO might be a potential prebiotic applied in functional foods.

Study on the Effect of Molecular Weight on the Gut Microbiota Fermentation Properties of Blackberry Polysaccharides In Vitro

This study aimed to investigate the effect of different molecular weights on the metabolic characteristics of blackberry polysaccharides (BBP). After degradation, three fractions, namely, BBP-8, BBP-16, and BBP-24, were obtained. During fermentation, all polysaccharide fractions were significantly degraded and utilized by the intestinal microbiota, and the lower-molecular-weight polysaccharides were easier to be fermented with higher gas production and carbohydrate consumption rates. Furthermore, the monosaccharide utilization sequence of all polysaccharides was glucose > galactose > arabinose > galacturonic acid. In addition, the lower-molecular-weight polysaccharides had a faster short-chain fatty acid (SCFA) production rate but did not affect the final SCFA yields. The fermentation of BBP promoted the increase of Bacteroidetes and the decrease of Firmicutes. The proportions of Bacteroidetes in BBP, BBP-8, BBP-16, and BBP-24 were 45.41, 47.50, 48.08, and 50.09%, respectively.

Positive effects of dietary fiber from sweet potato [Ipomoea batatas (L.) Lam.] peels by different extraction methods on human fecal microbiota in vitro fermentation

The purpose of this study was to compare the effects of sweet potato peels dietary fiber obtained by different extraction methods on intestinal health. Specifically, four different dietary fibers were extracted by hot water, microwave, ultrasonic and subcritical water methods. And the prebiotics effects of sweet potato peels dietary fibers were explored in an in vitro fermentation model, by determining intestinal gas content, short-chain fatty acid content, pH, ammonia content and the gut microbiota composition. The results showed that dietary fiber obtained by four different extraction methods could be utilized by GM and improve human health by increasing the abundance of beneficial bacteria (e.g., Bifidobacterium, Faecalibacterium, and Prevotella) and reducing the abundance of harmful bacteria (e.g., Proteobacteria, Romboutsia and Dorea), enhancing the relative abundance of SCFA-producing bacteria, promoting the production of short-chain fatty acids, reducing intestinal pH from 6.89 to 4.63 and ammonia. Among them, dietary fiber extracted by ultrasound is better than the other three extraction methods. This study suggests that all the four different extraction methods are available for sweet potato peels dietary fiber, and the extracted dietary fiber could be served as potential functional foods with great development value. In addition, it is beneficial to reduce the environmental pollution of sweet potato peels and improve the high-value processing and utilization of sweet potato by-products.

Prebiotic Properties of Exopolysaccharides from Lactobacillus helveticus LZ-R-5 and L. pentosus LZ-R-17 Evaluated by In Vitro Simulated Digestion and Fermentation

The in vitro digestion and fermentation behaviors of Lactobacillus helveticus LZ-R-5- and L. pentosus LZ-R-17-sourced exopolysaccharides (LHEPS and LPEPS) were investigated by stimulated batch-culture fermentation system. The results illustrated that LHEPS was resistant to simulated saliva and gastrointestinal (GSI) digestion, whereas LPEPS generated a few monosaccharides after digestion without significant influence on its main structure. Additionally, LHEPS and LPEPS could be consumed by the human gut microbiota and presented stronger bifidogenic effect comparing to α-glucan and β-glucan, as they promote the proliferation of Lactobacillus and Bifidobacterium in cultures and exhibited high values of selectivity index (13.88 and 11.78, respectively). Furthermore, LPEPS achieved higher contents of lactic acid and acetic acid (35.74 mM and 45.91 mM, respectively) than LHEPS (35.20 mM and 44.65 mM, respectively) during fermentation for 48 h, thus also resulting in a larger amount of total SCFAs (110.86 mM). These results have clearly indicated the potential prebiotic property of EPS fractions from L. helveticus LZ-R-5 and L. pentosus LZ-R-17, which could be further developed as new functional food prebiotics to beneficially improve human gut health.

In vitro digestion and fecal fermentation of Siraitia grosvenorii polysaccharide and its impact on human gut microbiota

In this study, the structure of Siraitia grosvenorii polysaccharides (SGPs) changed significantly after digestion. After 48 h of in vitro fecal fermentation, M_w decreased and the content of C_R showed a trend of increasing and then decreasing. The monosaccharide composition (glucose) of SGPs showed a trend of decreasing and then stabilizing during fecal fermentation, indicating that SGPs were partially degraded during in vitro fermentation and significantly degraded and utilized by the human intestinal microbiota. In addition, SGPs fermentation for 48 h increased the production of SCFAs especially acetic acid, propionic acid, and butyric acid. Moreover, after in vitro digestion and enzymatic digestion, the in vitro hypoglycemic activity of SGPs remained relatively high afterward, albeit reduced. This study contributes to a better understanding of the potential digestion and enzymatic mechanisms of SGP, which is important for the future development of SGP as a functional food and drug.

In vitro simulated digestion affecting physicochemical characteristics and bioactivities of polysaccharides from barley (Hordeum vulgare L.) grasses at different growth stages

In this study, three polysaccharides (BGPs: BGPs-Z21, BGPs-Z23, and BGPs-Z31) were successively extracted from barley (Hordeum vulgare L.) grasses (BG) at different growth stages, including seedling (Z21), tillering (Z23), and stem elongation (Z31). The effects of in vitro simulated saliva-gastrointestinal digestion on the physicochemical characteristics and biological activities of BGPs were investigated and compared. Results showed that the simulated saliva-gastrointestinal digestion had considerable influences on reducing sugar content, chemical components, monosaccharide constituents, and molecular weights of BGPs but hardly affected their preliminarily structural characteristics. Moreover, the antioxidant activities of BGPs were weakened after the simulated saliva-gastrointestinal digestion, but their bile acid-binding capacities were remarkably enhanced. The digested BGPs-Z31 by gastric juice possessed better antioxidant benefit, and bile acid-binding capacity (80.33 %) than other digested products. Overall, these results indicated that BGPs obtained from BG are valuable for functional foods as promising bioactive ingredients.

Role, Relevance, and Possibilities of In vitro fermentation models in human dietary, and gut-microbial studies

Dietary studies play a crucial role in determining the health-benefiting effects of most food substances, including prebiotics, probiotics, functional foods, and bioactive compounds. Such studies involve gastrointestinal digestion and colonic fermentation of dietary substances. In colonic fermentation, any digested food is further metabolized in the gut by the residing colonic microbiota, causing a shift in the gut microenvironment and production of various metabolites, such as short-chain fatty acids (SCFA). These diet-induced shifts in the microbial community and metabolite production, which can be assessed through in vitro fermentation models using a donor's fecal microbiota, are well known to impact the health of the host. Although in vivo or animal experiments are the gold standard in dietary studies, recent advancements using different in vitro systems, like artificial colon (ARCOL), mini bioreactor array (MBRA), TNO in vitro model of the colon (TIM), Simulator of the Human Intestinal Microbial Ecosystem (SHIME), M-SHIME, CoMiniGut, and Dynamic Gastrointestinal Simulator (SIMGI) make it easy to study the dietary impact in terms of the gut microbiota and metabolites. Such a continuous in vitro system can have multiple compartments corresponding to different parts of the colon, i.e., proximal, transverse, and distal colon, making the findings physiologically more significant. Further, post-fermentation samples can be analyzed using metagenomic, metabolomic, qPCR and flow cytometry approaches. Moreover, studies have shown that in vitro results are in accordance with the in vivo findings, supporting their relevance in dietary studies and giving confidence that shifts in metabolites are only due to microbes. This review meticulously describes the recent advancements in various fermentation models and their relevance in dietary studies. This article is protected by copyright. All rights reserved.

Oyster (Crassostrea gigas) polysaccharide ameliorates obesity in association with modulation of lipid metabolism and gut microbiota in high-fat diet fed mice

Oyster is nutritious shellfish, wildly consumed throughout the world. Its polysaccharide (OPS) has various bioactivity. In the present study, the anti-obesity effect of OPS was evaluated in obese mice induced by a high-fat diet (HFD). The results showed that OPS significantly alleviated weight gain, dyslipidemia, and metabolic endotoxemia of obese mice, and accelerated the production of short-chain fatty acids. OPS also regulated lipid metabolism of adipose and liver by activating the expression of p-AMPKα to further down-regulate the expression of SREBP-1c, PPARγ, and p-ACC-1. 16S rRNA results indicated that OPS corrected HFD-induced gut microbiota dysbiosis by enriching beneficial bacteria (Bifidobacterium, Lactobacillus, Dobosiella, and Faecalibaculum) and decreasing harmful bacteria (Erysipelatoclostridium, Helicobacter, and Mucispirillum). In summary, these results revealed that OPS could serve as a potential prebiotic to improve obesity.

Effect of Bergamot and Laoxianghuang Polysaccharides on Gut Microbiota Derived from Patients with Hyperlipidemia: An Integrative Analysis of Microbiome and Metabolome during In Vitro Fermentation

The aim of this study was to investigate the effects of bergamot polysaccharide (BP) and Laoxianghuang polysaccharides (LPs, fermented bergamot) on the microbiome and metabolome during the in vitro fermentation of gut microbiota from patients with hyperlipidemia. Results indicated that both BP and LPs were able to increase the production of acetic acid, propionic acid, and butyric acid. However, only LPs could decrease the content of isobutyric acid and isovaleric acid, which are detrimental to gut health. A 16S rRNA analysis showed that both BP and LPs could reduce the proportion of Fusobacterium, whereas they increased the Bacteroides content in hyperlipidemia. Untargeted UPLC-MS/MS metabolomic profiling found six bio-markers that were significantly changed after BP and LPs intervention, and four of the down-regulated metabolites were long-chain fatty acids associated with vascular diseases. These findings provide new evidence that BP and LPs have the potential to regulate imbalances in the gut microbiota in patients with hyperlipidemia and ameliorate its metabolic abnormalities.

Dynamic variations in physicochemical characteristics of oolong tea polysaccharides during simulated digestion and fecal fermentation in vitro

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Wuyi rock tea polysaccharides (WYP) were slightly degraded after in vitro digestion.

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The indigestible WYP could be degraded and utilized during the fecal fermentation.

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Dynamic variations in physicochemical profiles of WYP were revealed.

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Beneficial bacteria, such as Lactococcus and Bifidobacterium, increased.

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Acetic, propionic, and n-butyric acids increased during fecal fermentation.

In this study, dynamic variations in physicochemical characteristics of polysaccharides from ‘Wuyi rock’ tea (WYP) at different simulated digestion and fecal fermentation stages in vitro were studied. Results revealed that physicochemical characteristics of WYP were slightly altered after the simulated digestion in vitro, and its digestibility was about 8.38%. Conversely, physicochemical characteristics of the indigestible WYP, including reducing sugar, chemical composition, constituent monosaccharide, molecular weight, and FT-IR spectrum, were obviously altered after the fecal fermentation in vitro, and its fermentability was about 42.18%. Notably, the indigestible WYP could remarkably modulate the microbial composition via promoting the proliferation of profitable intestinal microbes, such as Bacteroides, Lactococcus, and Bifidobacterium. Moreover, it could also enhance the generation of short-chain fatty acids. The results showed that WYP was slightly digested in the gastrointestinal tract in vitro, but could be obviously utilized by intestinal microbiota, and might possess the potential to improve intestinal health.

Fecal fermentation characteristics of Rheum tanguticum polysaccharide and its effect on the modulation of gut microbial composition

Background

Rheum tanguticum is utilized as one of the well known traditional Chinese medicine for the treatment of gastrointestinal diseases. Recently, R. tanguticum polysaccharides (RP) have received increasing attention due to their diversely pharmacological activities. Usually, the pharmacological activities of polysaccharides are closely correlated to their metabolic properties from the stomach to the intestine. However, the digestive behavior and fecal fermentation characteristics of RP are unknown, which need to be fully investigated.

Methods

In this study, an in vitro simulated gastrointestinal model was carried out for the investigation of the digestive behavior and fecal fermentation characteristics of RP. The possible changes in physicochemical properties of RP, such as molecular weight, monosaccharide composition, reducing sugar released, chemical composition, pH value, and short chain fatty acids, were determined during in vitro simulated digestion and human fecal fermentation, and its effect on the modulation of gut microbial composition was also evaluated.

Results

The results revealed that RP was indigestible under the in vitro simulated digestion conditions according to its stabilities in physicochemical properties. Conversely, the indigestible RP (RPI) could be notably utilized by colonic microbiota in human feces after the in vitro fermentation, especially, at the initial fermentation stage (0–6 h). The fecal fermentation characteristics of RPI were revealed. Results showed that the content of reducing sugars obviously increased from 0.177 to 0.778 mg/mL at the initial stage of fermentation, and its molecular weight notably declined from 2.588 × 10⁵ to 0.828 × 10⁵ Da at the end stage of fermentation. Notably, the utilization of arabinose and galactose in RPI by colonic bacteria was faster than that of galacturonic acid. Besides, RPI could obviously modulate gut microbial composition via promoting the relative abundances of several beneficial bacteria, such as genera Bacteroides, Bifidobacterium, and Megamonas, resulting in the promoted production of several short-chain fatty acids, such as acetic, propionic, and butyric acids.

Conclusions

Results from this study showed that RP was indigestible in the human upper gastrointestinal tract in vitro, but could be easily utilized by colonic microbiota in human feces at the initial stage of fermentation. RP could be used as potential prebiotics for the improvement of intestinal health.

Inhibitory Effect of Fermented Flammulina velutipes Polysaccharides on Mice Intestinal Inflammation

To investigate the effect of Flammulina velutipes polysaccharides (FVPs) on mice intestinal inflammation, FVPs were extracted from Flammulina velutipes (FV) using a solid anaerobic fermentation technique. The antioxidant and anti-inflammatory capacities of FVP and fermented FVP (FFVP) induced by lipopolysaccharide (LPS) were investigated in vitro and in vivo. The results showed that the yield of FFVP (9.44%) was higher than that of FVP (8.65%), but the molecular weight (MW) of FFVP (15,702 Da) was lower than that of FVP (15,961 Da). The antioxidant and anti-inflammatory capacities of FFVP were higher than that of FVP in preventing mice diarrhea, enhancing antioxidant capacities, and reducing the secretion and mRNA expression of interleukin-1β (IL-1β), IL-6, IL-18, and tumor necrosis factor-α (TNF-α). The anti-inflammatory mechanisms of FVP and FFVP were analyzed by inhibiting the activation of the NLRP3 signaling pathway using an LPS-induced mice model. This study indicated that FFVP could be used as a functional antioxidant, indicating a potential application in functional food and health products.

Physicochemical characteristics and immunoregulatory activities of polysaccharides from five cultivars of Chrysanthemi Flos

This study compared the physicochemical characteristics and immunomodulatory activities of chrysanthemums' polysaccharides (JPs) from five cultivars. Significant differences were found in the molecular weights, the ratios of monosaccharide compositions, and morphological properties. Polysaccharides of Gongju (GJP) had the lowest molecular weight populations and polysaccharides of Boju (BJP) had the highest. SEM showed that GJP and polysaccharides of Qiju had looser and uniform surface structures, which are beneficial for being developed into instant products. Immunoregulatory assay revealed that JPs enhanced the phagocytosis and proliferation of RAW264.7 cells without obvious cytotoxicity, and upregulated the release level of TNF-α, IFN-γ, and NO. Immune-enhancing activity correlated with their molecular weights, the contents of glucuronic acid and arabinose, and microstructure, which performed differently according to different cultivars. The results suggested that BJP and polysaccharides of Hangbaiju are more suitable to be developed as new functional foods for enhancing immunity, and provided a reference for selection based on the immunization requirements.

Digestive Characteristics of Hericium erinaceus Polysaccharides and Their Positive Effects on Fecal Microbiota of Male and Female Volunteers During in vitro Fermentation

Hericium erinaceus polysaccharides (HEPs) have attracted widespread attention in regulating gut microbiota (GM). To investigate digestibility and fermentation of HEPs and their effects on GM composition, three polysaccharide fractions, namely, HEP-30, HEP-50, and HEP-70, were fractionally precipitated with 30%, 50%, and 70% ethanol concentrations (v/v) from hot water-soluble extracts of Hericium erinaceus, respectively. Three kinds of prepared HEPs were structurally characterized and simulated gastrointestinal digestion, and their effects on human fecal microbiota fermentations of male and female and short-chain fatty acid (SCFA) production in vitro were clarified. Under digestive conditions simulating saliva, stomach, and small intestine, HEPs were not significantly influenced and safely reached the distal intestine. After 24 h of in vitro fermentation, the content of SCFAs was significantly enhanced (p < 0.05), and the retention rates of total and reducing sugars and pH value were significantly decreased (p < 0.05). Thus, HEPs could be utilized by GM, especially HEP-50, and enhanced the relative abundance of SCFA-producing bacteria, e.g., Bifidobacterium, Faecalibacterium, Blautia, Butyricicoccus, and Lactobacillus. Furthermore, HEPs reduced the relative abundances of opportunistic pathogenic bacteria, e.g., Escherichia-Shigella, Klebsiella, and Enterobacter. This study suggests that gradual ethanol precipitation is available for the preparation of polysaccharides from Hericium erinaceus, and the extracted polysaccharide could be developed as functional foods with great development value.

Structural Characterization and In Vitro Fermentation Characteristics of Enzymatically Extracted Black Mulberry Polysaccharides

In this study, we systematically investigated the structural characterization and in vitro fermentation patterns of crude black mulberry fruit polysaccharides (BMPs), either extracted by water (BMP) or by enzymatic treatment. Different enzymatic treatments were pectinase-extracted (PE)-BMP, pectin lyase-extracted (PL)-BMP, cellulase-extracted (CE)-BMP, and compound enzymes-extracted (M)-BMP (pectinase:pectin lyase:cellulase = 1:1:1). Our results show that enzymatic treatment improved the polysaccharide yield and led to a different chemical composition and structure for the polysaccharides. Change dynamics during the in vitro fermentation indicated that BMPs could indeed be degraded and consumed by human fecal microbiota and that different BMPs showed different degrees of fermentability. In addition, BMPs stimulated the growth of Bacteroidetes and Firmicutes, inhibited the growth of Fusobacteria and Proteobacteria (except for CE-BMP), and induced the production of short-chain fatty acids (SCFAs). Furthermore, we found that BMP and PL-BMP exhibited better fermentability and prebiotic potential than the other polysaccharides.

Chlorella pyrenoidosa Polysaccharides as a Prebiotic to Modulate Gut Microbiota: Physicochemical Properties and Fermentation Characteristics In Vitro

This study was conducted to investigate the prebiotic potential of Chlorella pyrenoidosa polysaccharides to provide useful information for developing C. pyrenoidosa as a green healthy food. C. pyrenoidosa polysaccharides were prepared and their physicochemical characteristics were determined. The digestibility and fermentation characteristics of C. pyrenoidosa polysaccharides were evaluated using in vitro models. The results revealed that C. pyrenoidosa polysaccharides were composed of five non-starch polysaccharide fractions with monosaccharide compositions of Man, Rib, Rha, GlcA, Glc, Gal, Xyl and Ara. C. pyrenoidosa polysaccharides could not be degraded under saliva and the gastrointestinal conditions. However, the molecular weight and contents of residual carbohydrates and reducing sugars of C. pyrenoidosa polysaccharides were significantly reduced after fecal fermentation at a moderate speed. Notably, C. pyrenoidosa polysaccharides could remarkably modulate gut microbiota, including the promotion of beneficial bacteria, inhibition of growth of harmful bacteria, and reduction of the ratio of Firmicutes to Bacteroidetes. Intriguingly, C. pyrenoidosa polysaccharides can promote growth of Parabacteroides distasonis and increase short-chain fatty acid contents, thereby probably contributing to the promotion of intestinal health and prevention of diseases. Thus, these results suggested that C. pyrenoidosa polysaccharides had prebiotic functions with different fermentation characteristics compared with conventional prebiotics such as fructooligosaccharide, and they may be a new prebiotic for improving human health.

Characterization of polysaccharide from Pleurotus eryngii during simulated gastrointestinal digestion and fermentation

Pleurotus eryngii is a valuable new edible mushroom variety cultivated on a large scale in China. The polysaccharides found in this mushroom are strong bioactive. This study used simulated digestion and fermentation model to study the digestion and fermentation characteristics of Pleurotus eryngii polysaccharide (PEP) and its effect on gut microbiota. The results showed that the molecular weight of PEP remained unchanged after simulated digestion, and the overall structure of PEP was not destroyed, indicating that PEP was not decomposed during digestion. However, during fermentation, PEP was degraded and utilized by intestinal flora to produce a variety of short-chain fatty acids (SCFAs), which reduced the pH value in fecal cultures. Meanwhile, PEP regulated the composition of intestinal flora, and the relative abundance of Firmicutes increased significantly. These suggests that PEP can be used as a functional food to promote intestinal health and prevent disease.

Modulatory effects of polysaccharides from plants, marine algae and edible mushrooms on gut microbiota and related health benefits: A review

Naturally occurring carbohydrate polymers containing non-starch polysaccharides (NPs) are a class of biomacromolecules isolated from plants, marine algae, and edible mushrooms, and their biological activities has shown potential uses in the prevention and treatment of human diseases. Importantly, NPs serve as prebiotics to provide health benefits to the host through stimulating the proliferation of beneficial gut microbiota (GM) and enhancing the production of short-chain fatty acids (SCFAs). The composition and diversity of GM play a critical role in regulating host health and have been extensively studied in recent years. In this review, the extraction, isolation, purification, and structural characterization of NPs derived from plants, marine algae, and edible mushrooms are outlined. Importantly, the degradation and metabolism of these NPs in the intestinal tract, the effects of NPs on the microbial community and SCFAs generation, and the beneficial effects of NPs on host health by modulating GM are systematically highlighted. Overall, we hope that this review can provide some theoretical references and a new perspective for applications of NPs as prebiotics in functional food and drug development.

Microorganisms in Whole Botanical Fermented Foods Survive Processing and Simulated Digestion to Affect Gut Microbiota Composition

Botanical fermented foods have been shown to improve human health, based on the activity of potentially beneficial lactic acid bacteria (LAB) and yeasts and their metabolic outputs. However, few studies have explored the effects of prolonged storage and functional spices on microbial viability of whole fermented foods from fermentation to digestion. Even fewer have assessed their impact on the gut microbiota. Our study investigated the effects of production processes on LAB and yeast microbial viability and gut microbiota composition. We achieved this by using physicochemical assessments and an in vitro gastrointestinal and a porcine gut microbiota model. In low-salt sauerkraut, we assessed the effects of salt concentration, starter cultures, and prolonged storage, and in tibicos, prolonged storage and the addition of spices cayenne, ginger, and turmeric. In both food matrices, LAB counts significantly increased (p<0.05), reaching a peak of 7–8 log cfu/g, declining to 6–6.5 log cfu/g by day 96. Yeast viability remained at 5–6 log cfu/g in tibicos. Ginger tibicos had significantly increased LAB and yeast viability during fermentation and storage (p<0.05). For maximum microbial consumption, tibicos should be consumed within 28days, and sauerkraut, 7weeks. Simulated upper GI digestion of both products resulted in high microbial survival rates of 70–80%. The 82% microbial survival rate of cayenne tibicos was significantly higher than other treatments (p<0.05). 16S rRNA sequencing of simulated porcine colonic microbiota showed that both spontaneously fermented sauerkraut and tibicos increase the relative abundance of Megasphaera 85-fold. These findings will inform researchers, producers, and consumers about the factors that affect the microbial content of fermented foods, and their potential effects on the gut.

In vitro digestive characteristics and microbial degradation of polysaccharides from lotus leaves and related effects on the modulation of intestinal microbiota

Polysaccharides exist as one of the most abundant components in lotus leaves, which attract increasing attention owing to their promising health-promoting benefits. In this study, the digestive and microbial degradation characteristics of lotus leaf polysaccharides (LLP) were studied by using an in vitro gastrointestinal model. The results suggested that LLP was stable in the human upper gastrointestinal tract in vitro according to its digestive stabilities at different simulated digestion stages. Conversely, the indigestible LLP (LLPI) could be remarkably utilized by intestinal microbiota in human feces during in vitro fermentation, and its fermentability was 58.11% after the in vitro fermentation of 48 h. Indeed, the microbial degradation characteristics of LLPI during in vitro fermentation by human fecal inoculum were revealed. The results showed that the content of reducing sugars released from LLPI obviously increased from 0.498 to 2.176 mg/mL at the initial fermentation stage (0–6 h), and its molecular weight sharply decreased from 4.08 × 10⁴ to 2.02 × 10⁴ Da. Notably, the molar ratios of arabinose (Ara), galactose (Gal), and galacturonic acid (GalA) in LLPI decreased from 2.89 to 1.40, from 5.46 to 3.72, and from 21.24 to 18.71, respectively, suggesting that the utilization of arabinose and galactose in LLPI by intestinal microbiota was much faster than that of galacturonic acid at the initial fermentation stage. Additionally, LLPI could remarkably regulate gut microbial composition by increasing the abundances of several beneficial microbes, including Bacteroides, Bifidobacterium, Megamonas, and Collinsella, resulting in the promoted generation of several short-chain fatty acids, especially acetic, propionic, and butyric acids. The findings from the present study are beneficial to better understanding the digestive and microbial degradation characteristics of LLP, which indicate that LLP can be used as a potential prebiotic for the improvement of intestinal health.

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LLP was stable in the human upper gastrointestinal tract in vitro.

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The indigestible LLP could be remarkably utilized by intestinal microbiota.

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Arabinose and galactose were quickly utilized at the initial fermentation stage.

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Bacteroides, Bifidobacterium, Megamonas, and Collinsella obviously increased.

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SCFAs, especially acetic, propionic, and butyric acids, remarkably promoted.

In vitro fecal fermentation characteristics of bamboo shoot (Phyllostachys edulis) polysaccharide

The effects of Moso bamboo (Phyllostachys edulis) shoot polysaccharide (BSP) on the human gut microbiota composition and volatile metabolite components were investigated by in vitro fermentation. After fermentation for 48 h, BSP utilization reached 40.29% and the pH of the fermentation solution decreased from 6.89 to 4.57. Moreover, the total short-chain fatty acid concentration significantly (P < 0.05) increased from 13.46 mM (0 h) to 43.20 mM (48 h). 16S rRNA analysis revealed several differences in the gut microbiota community structure of the BSP-treated and water-treated (control) cultures. In the BSP group, the abundance of Firmicutes, Actinobacteria, and Proteobacteria was significantly increased, while that of Bacteroidetes and Fusobacteria significantly decreased. Moreover, the concentrations of benzene, its substituted derivatives, and carbonyl compounds in the volatile metabolites of the BSP-treated group decreased, while that of organic acids significantly increased after 48 h of fermentation. These results demonstrate that BSP improves gastrointestinal health.

In vitro simulated digestion and fermentation characteristics of polysaccharide from oyster (Crassostrea gigas), and its effects on the gut microbiota

Oyster is a kind of nutritious shellfish widely consumed globally, and its polysaccharide (OPS) has been verified to have strong functional activity. However, it is still unclear about the specific digestion and prebiotic properties of OPS. In the present study, the digestion and fermentation properties of OPS and its effect on gut microbiota were evaluated using simulated digestion (saliva, stomach, and small intestine) and fermentation models in vitro. The results showed that the molecular weight (Mw) of OPS decreased from 5.73 × 10⁶ to 4.35 × 10⁶ Da, and the reducing sugar content increased from 0.043 to 0.096 mg/mL, indicating that OPS was partially degraded during the saliva-gastrointestinal digestion. During fermentation, the Mw and carbohydrate residue of indigestible OPS (OPSI) decreased, and free monosaccharides were released, suggesting that OPSI could be further degraded and utilized by gut microbiota. Notably, OPSI could regulate the composition and diversity of the microbial community, especially increase the abundance of beneficial bacteria such as Bacteroides, Prevotella, and Faecalibacterium. Additionally, after fermentation for 24 h, OPSI promoted the production of short-chain fatty acids (SCFAs), and acetic acid, propionic acid, and n-butyric acid were the main metabolites. These results provided a reference for the digestive characteristics of OPS and revealed that OPS might be a potential prebiotic to prevent diseases by improving intestinal health.

Changes in Physicochemical and Biological Properties of Polyphenolic-Protein-Polysaccharide Ternary Complexes from Hovenia dulcis after In Vitro Simulated Saliva-Gastrointestinal Digestion

The present study aimed to explore the impacts of in vitro simulated saliva-gastrointestinal digestion on physicochemical and biological properties of the polyphenolic-protein-polysaccharide ternary complex (PPP) extracted from Hovenia dulcis. The results revealed that the in vitro digestion did remarkably affect physicochemical properties of PPP, such as content of reducing sugar release, content of bound polyphenolics, and molecular weight distribution, as well as ratios of compositional monosaccharides and amino acids. In particular, the content of bound polyphenolics notably decreased from 281.93 ± 2.36 to 54.89 ± 0.42 mg GAE/g, which might be the major reason for the reduction of bioactivities of PPP after in vitro digestion. Molecular weight of PPP also remarkably reduced, which might be attributed to the destruction of glycosidic linkages and the disruption of aggregates. Moreover, although biological activities of PPP obviously decreased after in vitro digestion, the digested PPP (PPP-I) also exhibited remarkable in vitro antioxidant and antiglycation activities, as well as in vitro inhibitory effects against α-glucosidase. These findings can help to well understand the digestive behavior of PPP extracted from H. dulcis, and provide valuable and scientific supports for the development of PPP in the industrial fields of functional food and medicine.