Molecular properties and gut health benefits of enzyme-hydrolyzed konjac glucomannans

Regulation of glycose and lipid metabolism and application based on the colloidal nutrition science properties of konjac glucomannan: A comprehensive review

The physicochemical properties of dietary fiber in the gastrointestinal tract, such as hydration properties, adsorption properties, rheological properties, have an important influence on the physiological process of host digestion and absorption, leading to the differences in satiety and glucose and lipid metabolisms. Based on the diversified physicochemical properties of konjac glucomannan (KGM), it is meaningful to review the relationship of structural characteristics, physicochemical properties and glycose and lipid metabolism. Firstly, this paper bypassed the category of intestinal microbes, and explained the potential of dietary fiber in regulating glucose and lipid metabolism during nutrient digestion and absorption from the perspective of colloidal nutrition. Secondly, the modification methods of KGM to regulate its physicochemical properties were discussed and the relationship between KGM's molecular structure types and glycose and lipid metabolism were summarized. Finally, based on the characteristics of KGM, the application of KGM in the main material and ingredients of fat reduction food was reviewed. We hope this work could provide theoretical basis for the study of dietary fiber colloid nutrition science.

Oxidized konjac glucomannan: A safe dietary fiber influencing mouse gut microbiota

In this 13-week study, the potential effects of oxidized konjac glucomannan (OKGM) on ICR mice's metabolic health and gut microbiota were investigated and contrasted with enzyme-hydrolyzed KGM (EKGM) at a same molecular weight. Mice were fed diets containing 0 %, 2.5 %, 5.0 %, and 7.5 % of OKGM for 13 weeks. Results indicated that OKGM induced no adverse effects, with overall health, body weight gain, food consumption, and clinical pathology parameters being comparable to the control group. The no-observed-adverse-effect-level for OKGM was determined at 7.5 % in the diet, corresponding to 10.21 and 12.01 g/kg/day for male and female mice, respectively. OKGM intake positively regulated gut microbiota, characterized by a reduction in the relative abundance of Firmicutes, an increase in Bacteroidetes, and an enhanced presence of Lactobacillus, particularly Lactobacillus reuteri. In comparison, EKGM differently modulated the microbiota, notably increasing Muribaculaceae. These findings suggest that OKGM has the potential to be a functional food additive.

Electrospray alginate microgels co-encapsulating degraded Konjac glucomannan and quercetin modulate human gut microbiota in vitro

Alginate microgels co-encapsulating degraded Konjac glucomannan (KGM60) underwent in vitro fecal fermentation and their effects on human microbiota and metabolites were investigated. KGM60 delayed quercetin release and enhanced phenolic metabolites production. Microgels co-encapsulating KGM60 and quercetin increased linear short chain fatty acid but decreased branched chain fatty acid production. Microgels encapsulated with quercetin with or without KGM60 decreased Firmicutes while increased Bacteroidetes over 24 h of fermentation, at genus level promoted Bacteroides growth at 24 h and decreased the abundance of Negativibacillus, Ruminococcus_NK4A214, and Christensenellaceae R_7. Faecalibacterium and Collinsella levels were exclusively promoted by microgels encapsulating KGM60 with or without quercetin, highlighting prebiotic effect of KGM60. Only microgels co-encapsulating both KGM60 and quercetin enhanced Dialister while inhibited Lachnoclostridium, indicating synergism between KGM60 and quercetin. Our study indicates that co-encapsulating KGM60 and quercetin in alginate microgel is effective in modulating human gut microbiota and metabolites production potentially beneficial to gut health.

Self-healing hydrogels based on biological macromolecules in wound healing: A review

The complete healing of skin wounds has been a challenge in clinical treatment. Self-healing hydrogels are special hydrogels formed by distinctive physicochemically reversible bonds, and they are considered promising biomaterials in the biomedical field owing to their inherently good drug-carrying capacity as well as self-healing and repair abilities. Moreover, natural polymeric materials have received considerable attention in skin tissue engineering owing to their low cytotoxicity, low immunogenicity, and excellent biodegradation rates. In this paper, we review recent advances in the design of self-healing hydrogels based on natural polymers for skin-wound healing applications. First, we outline a variety of natural polymers that can be used to construct self-healing hydrogel systems and highlight the advantages and disadvantages of different natural polymers. We then describe the principle of self-healing hydrogels in terms of two different crosslinking mechanisms-physical and chemical-and dissect their performance characteristics based on the practical needs of skin-trauma applications. Next, we outline the biological mechanisms involved in the healing of skin wounds and describe the current application strategies for self-healing hydrogels based on these mechanisms. Finally, we analyze and summarize the challenges and prospects of natural-material-based self-healing hydrogels for skin applications.

Application of chromatography in purification and structural analysis of natural polysaccharides: A review

Polysaccharides are widely distributed in natural sources from monocytic microorganisms to higher animals, and are found in a variety of biological activities in recent decades. Natural polysaccharides have the characteristics of large molecular weight, diverse composition, and complex structure, so their purification and structural analysis are difficult issues in research. Chromatography as a powerful separation technique, plays an irreplaceable role in the separation and structural analysis of natural polysaccharides, especially in the purification of polysaccharides, the separation of hydrolysates, and the analysis of monosaccharide composition. The separation mechanisms and application of different chromatographic methods in the studies of polysaccharides were summarized in this review. Moreover, the advantages and drawbacks of various chromatography methods were discussed as well.

Regulation strategy, bioactivity, and physical property of plant and microbial polysaccharides based on molecular weight

Structural features affect the bioactivity, physical property, and application of plant and microbial polysaccharides. However, an indistinct structure-function relationship limits the production, preparation, and utilization of plant and microbial polysaccharides. Molecular weight is an easily regulated structural feature that affects the bioactivity and physical property of plant and microbial polysaccharides, and plant and microbial polysaccharides with a specific molecular weight are important for exerting their bioactivity and physical property. Therefore, this review summarized the regulation strategies of molecular weight via metabolic regulation; physical, chemical, and enzymic degradations; and the influence of molecular weight on the bioactivity and physical property of plant and microbial polysaccharides. Moreover, further problems and suggestions must be paid attention to during regulation, and the molecular weight of plant and microbial polysaccharides must be analyzed. The present work will promote the production, preparation, utilization, and investigation of the structure-function relationship of plant and microbial polysaccharides based on their molecular weight.

Advanced structural characterization and in vitro fermentation prebiotic properties of cell wall polysaccharide from Kluyveromyces marxianus

Through previous study, the three yeast α-mannans (MPS) from various sources of Kluyveromyces marxianus (LZ-MPS, MC-MPS, and G-MPS) were preliminarily characterized. In this study, the advanced structural characterization and the in vitro human fecal fermentation behavior of the three MPS were investigated. According to the results of this study, the polysaccharide molecules of the three MPS were aggregated in solution, supporting their branched chain structure. After in vitro fermentation, the molecular weight and pH of fermentation broth decreased significantly, indicating that the three MPS could be utilized by human gut microbiota. Meanwhile, the production of total short-chain fatty acids (SCFAs) of the three MPS was promoted, especially the production of propionic acid was 45.55, 38.23, and 38.87 mM, respectively. In particular, the three MPS have the ability to alter the composition of human gut microbiota, especially to promote the proliferation of Bacteroidetes, suggesting that the bioactivities of the three MPS can be significantly influenced by intestine Bacteroidetes. In terms of metabolism, all MPS can promote cofactors, vitamins, amino acid metabolism, and glycan biosynthesis and metabolism of bacteria. In consequence, the three MPS were confirmed to regulate the human gut microbiota, increase the level of SCFAs, promote the metabolisms of bacteria on amino acid and glycan, and improve the intestinal health.

Hypoglycemic effects of different molecular weight konjac glucomannans via intestinal microbiota and SCFAs mediated mechanism

The hypoglycemic effects of konjac glucomannans (KGMs) are well recognized, and our previous study showed KGMs with different molecular weight have different hypoglycemic effects on diabetes rats, but the detailed mechanisms still remain unclear. In this study, KGMs with medium molecular weight (KGM-M, 757.1 kDa) and low molecular weight (KGM-L, 87.3 kDa) were utilized to investigate the possible mechanism on hypoglycemic effects of type 2 diabetic (T2DM) rats. The results revealed that KGM-M had better effects than KGM-L on decreasing fasting blood glucose, mitigating insulin resistance and improving inflammation. Further mechanism analysis showed that KGM-M better enriched gut flora diversity and the abundance of Ruminococcus and Lachnoclostridium, which was accompanied by increased short chain fatty acids (SCFAs) production and expression of G protein-coupled receptors (GPCRs), and improved regulation on bile acid synthesis. Antibiotics treatment eliminated the beneficial effects of KGMs on gut flora, SCFAs, GPCRs and bile acid synthesis. By contrast, fecal microbiota transplantation (FMT) treatment restored the structure of intestinal microbiota. And after FMT treatment, KGM-M displayed higher hypoglycemic activity than KGM-L, probably due to the better effects on intestinal microbiota, SCFAs production, GPCRs expression and bile acid synthesis inhibition.

Partial enzymolysis affects the digestion of tamarind seed polysaccharides in vitro: Degradation accelerates and gut microbiota regulates

Two hydrolyzed fractions of tamarind seed polysaccharide (TSP), denoted ETSP1 (176.68 kDa) and ETSP2 (34.34 kDa), were prepared by partial degradation via endo-xyloglucanase, and then characterized and evaluated by simulated gastrointestinal digestion in vitro. The results showed that the hydrolyzed TSPs remained indigestible in gastric and small intestinal media, and were fermented by gut microbiota, similar to the native TSP (M_w = 481.52 kDa). Although the degradation of hydrolyzed TSPs was accelerated during fermentation with a decreasing degree of polymerization, the content of produced total short-chain fatty acids (SCFAs) decreased. After fermentation, the gut microbiota composition was modified, esp. the Firmicutes/Bacteroidetes ratio decreased (1.06 vs. 0.96 vs. 0.80) with a decreasing degree of polymerization, which implied that the potential anti-obesity prebiotic effect was enhanced. At the genus level, hydrolyzed TSPs maintained similar roles as native TSP, including promoting beneficial bacteria (Bifidobacterium, Parabacteroides, and Faecalibacterium) and inhibiting enteropathogenic bacteria (Escherichia-Shigella and Dorea). Moreover, ETSP1 had additional potential due to abundant Bacteroides vulgatus (LDA = 4.68), and ETSP2 might perform better as related to Bacteroides xylanisolvens (LDA = 4.40). All these results indicated the prebiotic potential of hydrolyzed TSP with detailed information about changes in degradation and gut microbiota based on enzyme-hydrolysis.

The intervention effects of konjac glucomannan with different molecular weights on high-fat and high-fructose diet-fed obese mice based on the regulation of gut microbiota

Konjac is a high-quality dietary fiber rich in β-glucomannan, which has been reported to possess anti-obesity effects. To explore the effective components and the structure-activity relationships of konjac glucomannan (KGM), three different molecular weight components (KGM-1 (90 kDa), KGM-2 (5 kDa), KGM-3 (1 kDa)) were obtained, and systematical comparisons of their effects on high-fat and high-fructose diet (HFFD)-induced obese mice were investigated in the present study. Our results indicated that KGM-1, with its larger molecular weight, reduced mouse body weight and improved their insulin resistance status. KGM-1 markedly inhibited lipid accumulation in mouse livers induced by HFFD by downregulating Pparg expression and upregulating Hsl and Cpt1 expressions. Further investigation revealed that dietary supplementation with konjac glucomannan at different molecular weights caused β-diversity changes in gut microbes. The potential weight loss effect of KGM-1 maybe attributed to the abundance of changes in Coprobacter, Streptococcus, Clostridium IV, and Parasutterella. The results provide a scientific basis for the in-depth development and utilization of konjac resources.

Does supplementing β-mannanase modulate the feed-induced immune response and gastrointestinal ecology in poultry and pigs? An appraisal

The provision of adequate and balanced nutrients is critical for efficient and profitable animal protein production. However, non-nutritive components in feedstuffs can elicit responses that can negatively impact nutrient utilization efficiency. For example, dietary β-mannans are recognizable by cell surface mannose receptors are pivotal for diverse cellular functions. This review will evaluate the physiological implications of dietary native β-mannans, the utility of supplemental feed β-mannanase in hydrolyzing β-mannans, and subsequent metabolic responses. Dietary native β-mannans have been implicated in inadvertent stimulation of immune response through a phenomenon called the feed-induced immune response (FIIR), that has been associated with intestinal inflammation and depression in animal performance. Supplemental β-mannanase blunted the FIIR by hydrolyzing native β-mannans to smaller fragments with a reduced ability to stimulate the innate immune system as indicated by the modulation of oxidative stress, mucosal permeability, and blood concentration of acute phase proteins and immunoglobulins in broilers and piglet models. Moreover, β-mannanase hydrolysis of native β-mannans to mannooligosaccharides (MOS) impacted gastrointestinal microbial ecology. Indeed, β-mannanase-derived MOS reduced the concentration of pathogenic bacteria such as Escherichia coli and Salmonella and increased the production of short-chain fatty acids in gastrointestinal tracts of various animal models. Consequently, by hydrolyzing native β-mannans, supplemental β-mannanase may have nutritional, metabolic, and microbial ecology benefits. In summary, integrating multi-functional feed additives such as β-mannanase into feeding programs for monogastric animals will be critical for efficient and sustainable animal protein production in the context of evolving challenges such as the mandated elimination of use of antibiotics for growth promotion.

Air packaging is obviously beneficial to the heterogeneous hygrothermal degradation of konjac glucomannan

Heterogeneous hygrothermal degradation (HHTD) is a cost-effective and environmentally friendly method for the successful preparation of partially depolymerized konjac glucomannan (DKGM). This study investigated the degradation of konjac glucomannan (KGM) in two packaging methods and detected that compared with natural KGM, the M_w of vacuum-packaged DKGM with 20 % moisture content treated at 130 °C for 40 min was reduced by 23.34 %, while that of air-packaged DKGM was decreased by 63.14 %, the vacuum-packaged DKGM with only 0.5 % H₂O₂ added was dropped by 69.36 %. It was verified that oxygen in air-packaging plays a crucial role in HHTD. Furthermore, the effects of moisture content, treatment temperature and time on the M_w and apparent viscosity of air-packaged DKGM were explored. The properties and structure of DKGM were characterized by rheometer, TGA, XRD, FT-IR and SEM. Results established that treatment temperature had a stronger promoting effect on HHTD. The rheological properties of DKGM samples changed markedly, and the thermal decomposition temperature and crystallinity were increased, with its infrared absorption peaks very close. This research is expected to provide theoretical bases and reference ideas for efficient HHTD method of KGM in actual production.

Intestinal Mucosal Barrier Improvement with Prebiotics: Histological Evaluation of Longish Glucomannan Hydrolysates-Induced Innate T Lymphocyte Activities in Mice

Use of prebiotics is a growing topic in healthcare. A lightweight molecule and water-soluble fiber ingredient, longish glucomannan hydrolysates (LGH), has been developed to improve the intestinal mucosal barrier and confer gut health benefits. This study aims to investigate the implications of continuous LGH intervening in intestinal epithelium integrity and protective immunity against chemical dextran sodium sulfate (DSS)-induced colitis. Twelve male BALB/c mice were randomly arranged into four groups. The LGH/DSS group had results in bodyweight variance, epithelial cell density, and aberrancy score as good as the LGH group, and both were equivalent to the control group. LGH consumption effectively protects the distal intestinal epithelium by activating innate T lymphocytes. Meanwhile, T-cell subsets in subepithelial interspersion take a bystander role in these microenvironmental alterations. Under this stress, the cluster of differentiation 3 (CD3)⁺ T cells infiltrate the epithelium, while CD4⁺ T cells inversely appear in submucosal large lymphoid aggregates/isolated lymphoid follicles (ILFs) in which significant CD3⁺, CD4⁺, and CD8⁺ T-cell populations agglomerate. Moreover, forkhead box P3 (Foxp3) and interleukin 17 (IL-17) are observed in these ILFs. Agglomerated CD4⁺ T-cell lineages may have roles with proinflammatory T helper 17 cells and anti-inflammatory regulatory T cells in balancing responses to intraluminal antigens. Collectively, LGH administration may function in immune modulation to protect against DSS-induced inflammation.

Evaluation of the effect of prebiotic sesame candies on loperamide-induced constipation in mice

Constipation is one of the most common gastrointestinal tract symptoms. In this study, prebiotic sesame sugar (PSC) was prepared from isomalto-oligosaccharide, konjac glucomannan and sesame, and the relieving effect of PSC on constipation induced by loperamide was explored. The results showed that PSC treatment profoundly improved the defecation function and boosted intestinal motility. Moreover, PSC repaired gastrointestinal tissue injury and inflammation induced by constipation, which confirmed the effectiveness of PSC intervention in the treatment of constipation. The mechanism of PSC improving constipation might be that PSC improved the imbalance of gastrointestinal neurotransmitters and increased the content of short-chain fatty acids in feces. In conclusion, PSC dietotherapy could effectively alleviate the symptoms and lay a theoretical foundation for the development of an anti-constipation diet.

Comparative effects of different enzymatic hydrolysates of konjac glucomannan on gut flora and constipation rats

This study aimed to compare the effects of different hydrolysates (named GKOS and MKOS) on constipated rats, which were degraded to obtain from konjac glucomannan by β-glucanase and β-mannanase, respectively....

Plant Extracts in Obesity: A Role of Gut Microbiota

Obesity has become one of the most serious chronic diseases threatening human health. Its occurrence and development are closely associated with gut microbiota since the disorders of gut microbiota can promote endotoxin production and induce inflammatory response. Recently, numerous plant extracts have been proven to mitigate lipid dysmetabolism and obesity syndrome by regulating the abundance and composition of gut microbiota. In this review, we summarize the potential roles of different plant extracts including mulberry leaf extract, policosanol, cortex moutan, green tea, honokiol, and capsaicin in regulating obesity via gut microbiota. Based on the current findings, plant extracts may be promising agents for the prevention and treatment of obesity and its related metabolic diseases, and the mechanisms might be associated with gut microbiota.

The anti-obesity effects exerted by different fractions of Artemisia sphaerocephala Krasch polysaccharide in diet-induced obese mice

Artemisia sphaerocephala Krasch polysaccharide (ASKP) consists of two main fractions, 60P (molecular weight at 551 kDa) and 60S (molecular weight at 39 kDa). The anti-obesity effects of ASKP and its two fractions were investigated in high-fat-diet-fed mice and showed similar capability in efficiently preventing the development of obesity. The final body weight and body weight gain of obesity mice model were reduced by 12.44% and 35.33% by ASKP, 10.63% and 34.35% by 60P, and 7.82% and 20.04% by 60S. They also showed similar efficiency to ameliorate dyslipidemia, systematic inflammation, and gut dysbiosis. The colonic genes of barrier integrity were significantly upregulated and the genes of hepatic lipid metabolism and that of colonic inflammatory response were suppressed. They attenuated the gut dysbiosis in obese mice, such as the significant enrichment of beneficial genera (Bifidobacterium and Olsenella) and suppression of harmful ones (Mucispirillum and Helicobacter). Significant enrichment of carbohydrate metabolism associated with the promotion of short-chain fatty acid production and decrease of the metabolisms related to obesity and gut dysbiosis (valine, leucine, and isoleucine biosynthesis, and nitrogen metabolism) were also observed by the administration of ASKP, 60P, and 60S. Overall, these polysaccharides showed potential in acting as prebiotics in preventing high-fat-diet-induced obesity.

Prevention of loperamide induced constipation in mice by KGM and the mechanisms of different gastrointestinal tract microbiota regulation

Constipation is one of the most prevalent gastrointestinal tract diseases. Konjac glucomannan (KGM) dietotherapy can effectively relieve the clinical symptoms of patients with constipation. However, the causal relationship among KGM, constipation and different gastrointestinal microbiome (i.e., the stomach {St}, small intestine {S}, and large intestine {L}) remains poorly understood. In this study, constipated mice were treated with KGM (75, 150, 300 mg/kg bw). Results showed that KGM treatment improved the general physiological state, fecal character, small intestinal propulsive rate, gastric emptying rate, MTL and AchE activities, ET-1, 5-HT, and NO levels, and SCFA concentrations. KGM in the diets of constipated mice reduced the diversity of St and S microbiota, while increased those in the L. The KGM intervention regulated the microbiota profile, which afterwards was closer to the normal mouse group: confirmation was provided by different changes of bacteria like Lactobacillus, Bifidobacterium and Allobaculum spp et al.