Unhydrolyzed and hydrolyzed konjac glucomannans modulated cecal and fecal microflora in Balb/c mice

Exploring the Antibacterial Potential of Konjac Glucomannan in Periodontitis: Animal and In Vitro Studies

Background and Objectives: Periodontitis is an inflammatory disease in the supporting tissues of the teeth caused by specific microorganisms or groups of microorganisms. P. gingivalis bacterium is the keystone pathogen in periodontitis, so even at low concentrations, it has a considerable influence on the oral community. Antimicrobials and antiplaque agents can be used as adjunctive therapy for periodontitis treatment. Konjac glucomannan (KGM), as a natural polysaccharide, has flavonoid (3,5-diacetyltambulin) and triterpenoids (ambylon) compounds that show antibacterial activity. This research aims to analyze the antibacterial activity of KGM on animal and in vitro periodontitis models. Materials and Methods: The animal study divided 48 mice into four groups (control, KGM, periodontitis, KGM + periodontitis). Mice were given an intervention substance by oral gavage from day 1 to day 14, periodontitis was induced on day 7, and decapitation was performed on day 14. Samples from the right maxillary jaw of mice were used for histological preparations and morphometrics analysis. In vitro studies were carried out by adding several concentrations of KGM (25, 50, and 100 μg/mL) into a planktonic P. gingivalis and P. gingivalis biofilm. Results: In the animal model, KGM could prevent alveolar bone loss in the periodontitis mice model, both in histologic and morphometrics assessments. In vitro, KGM had antibacterial activity against P. gingivalis with better bacteriostatic (15-23%) than bactericidal (11-20%) ability, proven by its ability to inhibit P. gingivalis proliferation. Conclusions: KGM can be considered to have the potential as an antibacterial agent to prevent periodontitis. The prevention of periodontitis may improve patient well-being and human quality of life.

Can prebiotics help tackle the childhood obesity epidemic?

Globally, excess weight during childhood and adolescence has become a public health crisis with limited treatment options. Emerging evidence suggesting the involvement of gut microbial dysbiosis in obesity instills hope that targeting the gut microbiota could help prevent or treat obesity. In pre-clinical models and adults, prebiotic consumption has been shown to reduce adiposity partially via restoring symbiosis. However, there is a dearth of clinical research into its potential metabolic benefits in the pediatric population. Here, we provide a succinct overview of the common characteristics of the gut microbiota in childhood obesity and mechanisms of action of prebiotics conferring metabolic benefits. We then summarize available clinical trials in children with overweight or obesity investigating the effects of prebiotics on weight management. This review highlights several controversial aspects in the microbiota-dependent mechanisms by which prebiotics are thought to affect host metabolism that warrant future investigation in order to design efficacious interventions for pediatric obesity.

Glucomannan in Dendrobium catenatum: Bioactivities, Biosynthesis and Perspective

Dendrobium catenatum is a classical and precious dual-use plant for both medicine and food in China. It was first recorded in Shen Nong's Herbal Classic, and has the traditional functions of nourishing yin, antipyresis, tonifying the stomach, and promoting fluid production. The stem is its medicinal part and is rich in active polysaccharide glucomannan. As an excellent dietary fiber, glucomannan has been experimentally confirmed to be involved in anti-cancer, enhancing immunity, lowering blood sugar and blood lipids, etc. Here, the status quo of the D. catenatum industry, the structure, bioactivities, biosynthesis pathway and key genes of glucomannan are systematically described to provide a crucial foundation and theoretical basis for understanding the value of D. catenatum and the potential application of glucomannan in crop biofortification.

Konjac oligosaccharides attenuate DSS-induced ulcerative colitis in mice: mechanistic insights

This study aims to explore the protective effect of konjac oligosaccharides (KOS) on inflammatory bowel disease in colitis mice. During the experimental period, mice were administered 200 mg kg^-1 or 600 mg kg^-1 KOS, 200 mg kg^-1 sulfasalazine and a combination of KOS and sulfasalazine for 14 days. The mice were then treated with drinking water containing 2.5% DSS for 9 days, while the intervention of KOS and sulfasalazine continued. At the end of the experiment, the phenotype, pathological lesion of the colon, parameters of cytokines and gut microbiota were evaluated. The results showed that mice treated with KOS exhibited alleviated pathological lesion of the colon tissue and significantly increased expression of tight junction proteins (p < 0.05). The level of inflammatory cytokines in the colon tissue of the colitis mice tended to be normal. Moreover, the analysis of the gut microbiota revealed that the structures and composition of the intestinal microorganisms were also regulated by KOS treatment. The possible internal mechanism is that KOS down-regulates the abundance of pro-inflammatory bacteria (Proteobacteria, Campilobacterota and Clostridiaceae) and up-regulates the abundance of anti-inflammatory bacteria (Bifidobacteriaceae and Akkermansiaceae). These findings provide new insights into dietary management for patients with inflammatory bowel disease.

A novel neutral thermophilic β-mannanase from Malbranchea cinnamomea for controllable production of partially hydrolyzed konjac powder

Partially hydrolyzed konjac powder (PHKP) can be used to increase the daily intake of dietary fibers of consumers. To produce PHKP by enzymatic hydrolysis, a novel β-mannanase gene (McMan5B) from Malbranchea cinnamomea was expressed in Pichia pastoris. It showed a low identity of less than 52% with other GH family 5 β-mannanases. Through high cell density fermentation, the highest β-mannanase activity of 42200 U mL^-1 was obtained. McMan5B showed the maximal activity at pH 7.5 and 75 °C, respectively. It exhibited excellent pH stability and thermostability. Due to the different residues (Phe214, Pro253, and His328) in catalytic groove and the change of β2-α2 loop, McMan5B showed unique hydrolysis property as compared to other β-mannanases. The enzyme was employed to hydrolyze konjac powder for controllable production of PHKP with a weight-average molecular weight of 22000 Da (average degree of polymerization 136). Furthermore, the influence of PHKP (1.0%-4.0%) on the qualities of steamed bread was evaluated. The steamed bread adding 3.0% PHKP had the maximum specific volume and the minimum hardness, which showed 11.0% increment and 25.4% decrement as compared to the control, respectively. Thus, a suitable β-mannanase for PHKP controllable production and a fiber supplement for steamed bread preparation were provided in this study. KEY POINTS: • A novel β-mannanase gene (McMan5B) was cloned from Malbranchea cinnamomea and expressed in Pichia pastoris at high level. • McMan5B hydrolyzed konjac powder to yield partially hydrolyzed konjac powder (PHKP) instead of manno-oligosaccharides. • PHKP showed more positive effect on the quality of steamed bread than many other dietary fibers including konjac powder.

Recent advances in biotransformation, extraction and green production of D-mannose

D-mannose is a natural and biologically active monosaccharide. It is the C-2 epimer of glucose and a component of a variety of polysaccharides in plants. In addition, D-mannose also naturally exists in some cells of the human body and participates in the immune regulation of cells as a prebiotic. Its good physiological benefits to human health and wide application in the food and pharmaceutical industries have attracted widespread attention. Therefore, in-depth research on preparation methods of D-mannose has been widely developed. This article summarizes the main production methods of D-mannose in recent years, especially the in-depth excavation from biomass raw materials such as coffee grounds, konjac flour, acai berry, etc., to provide new ideas for the green manufacture of D-mannose.

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Various methods of recent mannose production were comprehensively summarized.

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The new technical progress of obtaining mannose from biomass as emphatically discussed.

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Discuss various preparation methods including different pretreatments, enzymatic hydrolysis, etc.

Konjac Glucomannan (KGM), Deacetylated KGM (Da-KGM), and Degraded KGM Derivatives: A Special Focus on Colloidal Nutrition

Konjac flour, mainly obtained and purified from the tubers ofAmorphophallus konjac C. Koch, yields a high molecular weight (M_w) and viscous hydrocolloidal polysaccharide: konjac glucomannan (KGM). KGM has been widely applied in the food industry as a thickening and gelation agent as a result of its unique colloidal properties of effective viscosity enhancement and thermal-irreversible gelling. This review first narrates the typical commercial KGM source species, the industrial production, and the purification process of KGM flour. The structural information on native KGM, gelation mechanisms of alkali-induced deacetylated KGM (Da-KGM) hydrogel, progress on degraded KGM derivatives, cryoprotection effect, and colloidal nutrition are highlighted. Finally, the regulatory requirements of konjac flour and KGM among different countries are briefly introduced. The fine structure and physicochemical properties of KGM can be regulated in a great range via the deacetylation or degradation reaction. Here, the relationship between the physicochemical properties, such as viscosity, solubility, gelation, and nutritional effects, of native KGM, Da-KGM, and degraded KGM derivatives was preliminary established, which would provide theoretical guidance for designing KGM-based products with certain nutritional needs.

Intragastric Administration of Casein Leads to Nigrostriatal Disease Progressed Accompanied with Persistent Nigrostriatal-Intestinal Inflammation Activited and Intestinal Microbiota-Metabolic Disorders Induced in MPTP Mouse Model of Parkinson's Disease

Gut microbial dysbiosis and alteration of gut microbiota composition in Parkinson's disease (PD) have been increasingly reported, no recognized therapies are available to halt or slow progression of PD and more evidence is still needed to illustrate its causative impact on gut microbiota and PD and mechanisms for targeted mitigation. Epidemiological evidence supported an association between milk intake and a higher incidence of Parkinson's disease (PD), questions have been raised about prospective associations between dietary factors and the incidence of PD. Here, we investigated the significance of casein in the development of PD. The mice were given casein (6.75 g/kg i.g.) for 21 days after MPTP (25 mg/kg i.p. × 5 days) treatment, the motor function, dopaminergic neurons, inflammation, gut microbiota and fecal metabolites were observed. The experimental results revealed that the mice with casein gavage after MPTP treatment showed a persisted dyskinesia, the content of dopamine in striatum and the expression of TH in midbrain and ileum were decreased, the expression of Iba-1, CD4, IL-22 in midbrain and ileum increased continuously with persisted intestinal histopathology and intestinal barrier injury. Decreased intestinal bile secretion in addition with abnormal digestion and metabolism of carbohydrate, lipids and proteins were found, whereas these pathological status for the MPTP mice without casein intake had recovered after 24 days, no significant differences were observed with regard to only treated with casein. Our study demonstrates that intestinal pathologic injury, intestinal dysbacteriosis and metabolism changes promoted by casein in MPTP mice ultimately exacerbated the lesions to dopaminergic neurons.

Effects of three different mannans on obesity and gut microbiota in high-fat diet-fed C57BL/6J mice

To compare the effects of three mannans, Konjac glucomannan (KGM), guar gum (GG) and locust bean gum (LBG), on obesity and obesity-related metabolic disorders in mice fed with high-fat diet (HFD), and to investigate the potential modulation of gut microbiota, we performed a 14 week study on C57BL/6J mice fed a HFD with/without mannan supplementation. The results showed that supplementing 8% KGM, GG, and LBG to a HFD dramatically reduced the body weight gain and adipose accumulation, attenuated liver injury, and antagonized glycolipid metabolism and inflammation-related parameters of HFD-fed mice in different degrees. However, only LBG had such roles when the supplement dose was reduced to 2%. In addition, it was found that LBG required more time to exert its impacts on weight control and lipid metabolism. Furthermore, 16S rRNA gene sequencing of gut microbiota indicated that mannans with different structures and supplement doses affected the overall structure of the gut microbiota to a varying extent and specifically changed the abundance of some OTUs. Moreover, several OTUs belonging to the genera Muribaculum, Staphylococcus, [Eubacterium] fissicatena group, and Christensenella had a high correlation with obesity and obesity-related metabolic disorders of the host. In summary, all the three mannans had the potential to be used as alternative dietary supplements or functional foods to prevent obesity and obesity-related metabolic disorders induced by a HFD, but the effects of the dose and time varied, and the functions of the mannans were associated with their ability to regulate the gut microbiota.

Similar hypoglycemic effects of glucomannan and its enzyme degraded products from Amorphophallus albus on type 2 diabetes mellitus in mice and potential mechanisms

In the present study, the hypoglycemic effects of glucomannan (AGM) and its enzyme-degraded products from Amorphophallus albus were investigated. Four degraded products were prepared through ultrafiltration of β-glucanase-degraded products of AGM. The hypoglycemic activities were evaluated in HFD-STZ-induced type 2 diabetes mellitus (T2DM) mice, and the diversity of gut bacteria was analyzed by 16S rRNA gene sequencing; the fecal short chain fatty acids (SCFAs) and endogenous metabolites were determined by UPLC-QTOF-MS/MS. It was found that AGM and its enzyme-degraded products, though with different molecular weights, had similar β-glycosidic bonds and monosaccharide compositions, exerted similar strength of hypoglycemic effects, and reinstated with a similar extent the disordered gut microbiota and the contents of SCFAs and endogenous metabolites. It was speculated that the hypoglycemic activity of AGM is decided by not the molecular weight but the glycosidic bonds/monosaccharide composition of AGM, which might be structurally specific to the gut bacteria, and thus certain SCFAs and endogenous metabolites that are related to the occurrence and therapy of T2DM. This study provides a scientific basis for using AGM as potential prebiotics beneficial for prevention or therapeutic treatment of T2DM.

Konjac Oligosaccharides Modulate the Gut Environment and Promote Bone Health in Calcium-Deficient Mice

This study aimed to investigate the beneficial effect of konjac oligosaccharides (KOS) on bone health in calcium-deficient mice. During the experimental period, low-calcium diet-fed mice were administered with calcium chloride to simulate daily calcium supplementation. Meanwhile, different levels of KOS intervened by adding them into the diet. After 8 weeks, the calcium balance status, bone mass parameters, and gut environment modulation were evaluated. The results showed that dietary KOS intervention alleviated the negative calcium balance, significantly promoted the trabecular number and cortical thickness, and remarkably enhanced the skeletal mechanical strength. Moreover, Pearson's correlation analysis among significantly changed gut microbiota, gut metabolites, and relevant physiological indexes showed that the microbial genera of Lactobacillus, Bifidobacterium, Mucispirillum, Alistipes, and unidentified Clostridia and gut metabolites of kynurenine and testosterone were significantly associated with increased bone mass. These findings provided a new insight into the effect of prebiotics on bone health.

Molar mass effect in food and health

It is demanded to supply foods with good quality for all the humans. With the advent of aging society, palatable and healthy foods are required to improve the quality of life and reduce the burden of finance for medical expenditure. Food hydrocolloids can contribute to this demand by versatile functions such as thickening, gelling, stabilising, and emulsifying, controlling texture and flavour release in food processing. Molar mass effects on viscosity and diffusion in liquid foods, and on mechanical and other physical properties of solid and semi-solid foods and films are overviewed. In these functions, the molar mass is one of the key factors, and therefore, the effects of molar mass on various health problems related to noncommunicable diseases or symptoms such as cancer, hyperlipidemia, hyperglycemia, constipation, high blood pressure, knee pain, osteoporosis, cystic fibrosis and dysphagia are described. Understanding these problems only from the viewpoint of molar mass is limited since other structural characteristics, conformation, branching, blockiness in copolymers such as pectin and alginate, degree of substitution as well as the position of the substituents are sometimes the determining factor rather than the molar mass. Nevertheless, comparison of different behaviours and functions in different polymers from the viewpoint of molar mass is expected to be useful to find a common characteristics, which may be helpful to understand the mechanism in other problems.

Dietary Fructooligosaccharides Reduce Mercury Levels in the Brain of Mice Exposed to Methylmercury

Methylmercury (MeHg) exposure during pregnancy is a concern because of its potential health risks to fetuses. Intestinal microbiota has important roles in the decomposition and fecal excretion of MeHg. We investigated the effect of nondigestible saccharides on the accumulation and excretion of Hg after MeHg exposure. Female BALB/cByJ mice were fed a basal diet or the same diet supplemented with 5% fructooligosaccharides (FOS) or 2.5% glucomannan. Six weeks after feeding, mice were administered MeHg chloride (4 mg Hg/kg, per os (p.o.)), and urine and feces were collected for 28 d. FOS-fed mice had lower total Hg levels in all tissues (including the brain) compared with that of controls. The glucomannan diet had no effect on tissue Hg levels. No differences in tissue concentrations of inorganic Hg among groups were found. Fecal Hg excretion was markedly higher in FOS-fed mice than that in controls, but urinary Hg excretion was similar. FOS-fed mice had a higher proportion of inorganic Hg in feces than that of controls, with a significant increase in fecal Hg excretion. Analysis of fecal bacterial population showed the relative abundance of Bacteroides in FOS-fed mice to be higher than that in controls. The results suggest that FOS enhanced fecal Hg excretion and decreased tissue Hg levels after MeHg administration, possibly by accelerating MeHg demethylation by intestinal bacteria (the candidate genus Bacteroides). This demethylation also reduces MeHg absorption in the large intestine. In conclusion, daily FOS intake may decrease tissue Hg levels in animals and humans exposed to MeHg.

Polysaccharides: bowel health and gut microbiota

Polysaccharides that contain many sugar monomers include starch and non-starch polysaccharides (NSPs) together with resistant starch (RS). Dietary polysaccharides are well known to have a wide range of biological benefits for bowel health. Gut microbiota and their fermentative products, short chain fatty acids (SCFA), which have recently been highlighted as metabolic regulators, are thought to mediate the function of dietary complex carbohydrates and bowel health. We discuss the influence of various polysaccharides on human bowel health and the mechanisms underlying these effects. We also describe their biological effects on intestinal health and the mechanisms underlying their activity; the polysaccharides were divided into three categories: dietary, microbial, and host-derived polysaccharides. Physiological impacts of non-starch polysaccharides (NSPs) and resistant starch (RS), both of which pass through the small intestine nearly intact and can be fermented by gut microbiota in the large intestine, are similar to each other. They exert a wide range of beneficial effects including anti-inflammation, gut epithelial barrier protection, and immune modulation through both microbiota-dependent and -independent mechanisms. Bacterial polysaccharides usually found in the cell wall generally act as immune modulators, and host-derived polysaccharides not only protect host cells from pathogenic microbial neighbors but also affect overall intestinal health via interactions with gut microbes. Considering these observations, further studies on polysaccharides will be important for bowel health.

Effects of Ultrasonication on the Conformational, Microstructural, and Antioxidant Properties of Konjac Glucomannan

This study aims to evaluate the effects of ultrasonication (US) on the conformational, microstructural, and antioxidant properties of konjac glucomannan (KGM). US treatment with a 20-kHz and 750-W ultrasonic processor at 60% amplitude was applied for partial degradation of KGM with an average molecular weight (MW) of 823.4 kDa. Results indicated that the US treatment caused dramatic reduction in the MW, apparent viscosity, hydrodynamic radius, and z-average mean radius of gyration. The flexibility of chain conformation of native KGM was slightly increased during the US treatment. According to electronic microscopic imaging, the compact, smooth, and orderly fibrous strings formed by KGM were changed to amorphous, porous flakes and globular particles after US treatment. KGM and its US-treated fractions showed moderate radical-scavenging and ferric-reducing antioxidant activity. US degradation of KGM affected these activities either positively or negatively, depending on the US treatment period. In summary, ultrasonic degradation of KGM caused changes in its conformation characteristics, microstructure, and antioxidant activities.

Health-promoting effects of konjac glucomannan and its practical applications: A critical review

Konjac glucomannan (KGM) is a dietary fiber hydrocolloidal polysaccharide isolated from the tubers of Amorphophallus konjac. Over the last few decades, the purified KGM has been offered as a food additive as well as a dietary supplement in many countries. Also, a diet containing konjac flour or KGM is considered as healthier, and these foods are popular in many Asian and European markets. Further, due to the adhesive property of KGM, it can form a defensive covering on the surface of the intestine. Additionally, KGM can reduce the levels of glucose, cholesterol, triglycerides, and blood pressure and can enable weight loss. Its wide-ranging effects prevent many chronic diseases through the regulation of metabolism. In this review, the recent studies on the health benefits such as anti-diabetic, anti-obesity, laxative, prebiotic, and anti-inflammatory activities of KGM were discussed. Also, this review deals with the applications of KGM and its derivatives in bio-technical, pharmaceutical, tissue engineering, fine chemical fields, etc.

Depolymerized konjac glucomannan: preparation and application in health care

Konjac glucomannan (KGM) is a water-soluble polysaccharide obtained from the roots and tubers of konjac plants. Recently, a degraded product of KGM, depolymerized KGM (DKGM), has attracted attention because of its low viscosity, improved hydrophily, and favorable physiological functions. In this review, we describe the preparation of DKGM and its prebiotic effects. Other health benefits of DKGM, covering antioxidant and immune activity, are also discussed, as well as its safety. DKGM could be a candidate for use as a tool for the treatment of various diseases, including intestinal flora imbalance, and oxidative- and immune-related disorders.

Metagenomic Mining and Functional Characterization of a Novel KG51 Bifunctional Cellulase/Hemicellulase from Black Goat Rumen

A novel KG51 gene was isolated from a metagenomic library of Korean black goat rumen and its recombinant protein was characterized as a bifunctional enzyme (cellulase/hemicellulase). In silico sequence and domain analyses revealed that the KG51 gene encodes a novel carbohydrate-active enzyme that possesses a salad-bowl-like shaped glycosyl hydrolase family 5 (GH5) catalytic domain but, at best, 41% sequence identity with other homologous GH5 proteins. Enzymatic profiles (optimum pH values and temperatures, as well as pH and thermal stabilities) of the recombinant KG51 bifunctional enzyme were also determined. On the basis of the substrate specificity data, the KG51 enzyme exhibited relatively strong cellulase (endo-β-1,4-glucanase [EC 3.2.1.4]) and hemicellulase (mannan endo-β-1,4-mannosidase [EC 3.2.1.78] and endo-β-1,4-xylanase [EC 3.2.1.8]) activities, but no exo-β-1,4-glucanase (EC 3.2.1.74), exo-β-1,4-glucan cellobiohydrolase (EC 3.2.1.91), and exo-1,4-β-xylosidase (EC 3.2.1.37) activities. Finally, the potential industrial applicability of the KG51 enzyme was tested in the preparation of prebiotic konjac glucomannan hydrolysates.

Effect of Dietary Acidolysis-Oxidized Konjac Glucomannan Supplementation on Serum Immune Parameters and Intestinal Immune-Related Gene Expression of Schizothorax prenanti

The present study was conducted to investigate the effects of dietary acidolysis-oxidized konjac glucomannan (A-OKGM) (0%, 0.4%, 0.8%, and 1.6%) supplementation on the immunity and expression of immune-related genes in Schizothorax prenanti. After feeding for eight weeks, the serum and guts were used for measurement of biochemical parameters, and immune-related gene expression in the gut were also analyzed by real-time quantitative polymerase chain reaction (RT-qPCR). C-reactive protein and IgM levels were significantly higher in the A-OKGM fed groups than in the control group, regardless of the dosage. The 0.4% and 1.6% A-OKGM groups showed significant up-regulation of tumor necrosis factor α (TNFα) in the anterior gut. The 0.8% and 1.6% A-OKGM groups also showed significantly enhanced TNFα expression in the mid- and distal guts. Interleukin-1β (IL-1β) expression in the anterior gut of fish fed with 0.4% and 1.6% A-OKGM diets was significantly enhanced. The 0.8% and 1.6% A-OKGM diets resulted in significantly increased the expression of IL-1β in the distal gut. Similarly, the interleukin-6 (IL-6) messenger RNA (mRNA) levels in the 0.4% and 1.6% diet groups were significantly higher in the anterior gut. The 0.8% and 1.6% A-OKGM diet groups showed significant induction of IL-6 gene expression in the distal gut. A-OKGM modified from KGM can act as an immunostimulant to enhance the immunity of S. prenanti.

Acemannan and Fructans from Aloe vera (Aloe barbadensis Miller) Plants as Novel Prebiotics

The nutraceutical properties of Aloe vera have been attributed to a glucomannan known as acemannan. Recently information has been published about the presence of fructans in Aloe vera but there are no publications about acemannan and fructans as prebiotic compounds. This study investigated in vitro the prebiotic properties of these polysaccharides. Our results demonstrated that fructans from Aloe vera induced bacterial growth better than inulin (commercial FOS). Acemannan stimulated bacterial growth less than fructans, and as much as commercial FOS. Using qPCR to study the bacterial population of human feces fermented in a bioreactor simulating colon conditions, we found that fructans induce an increase in the population of Bifidobacterium spp. Fructans produced greater amounts of short chain fatty acids (SCFA), while the branched-chain fatty acids (BCFA) did not increase with these polysaccharides. Acemannan increased significantly acetate concentrations. Therefore, both Aloe vera polysaccharides have prebiotic potentials.

Manufacture and Properties of Glucomannans and Glucomannooligosaccharides Derived from Konjac and Other Sources

Glucomannans (GM) are polymers that can be found in natural resources, such as tubers, bulbs, roots, and both hard- and softwoods. In fact, mannan-based polysaccharides represent the largest hemicellulose fraction in softwoods. In addition to their structural functions and their role as energy reserve, they have been assessed for their healthy applications, including their role as new source of prebiotics. This paper summarizes the scientific literature regarding the manufacture and functional properties of GM and their hydrolysis products with a special focus on their prebiotic activity.

Deacetylated Konjac Glucomannan Is Less Effective in Reducing Dietary-Induced Hyperlipidemia and Hepatic Steatosis in C57BL/6 Mice

Konjac gel foods that mainly consist of deacetylated konjac glucomannan (Da-KGM) are considered to have the same health benefits as native konjac glucomannan (KGM); however, no definitive data support this notion. The objective of this study was to compare the effects of Da-KGM and KGM on the hyperlipidemia and liver steatosis induced by high-fat diet feeding and to investigate the underlying molecular mechanisms. C57BL/6 mice were fed (1) normal chow diet, (2) high-fat diet, (3) HFD with KGM, or (4) HFD with Da-KGM for 10 weeks. KGM, but not Da-KGM, showed decreased fat accumulation, improved blood and liver lipid profiles, and prevention of liver lipid droplet deposition compared with HFD. Compared with Da-KGM, KGM increased the outputs of fecal bile acid (KGM 22.5 ± 2.34 mg/g vs Da-KGM 19.3 ± 1.87 mg/g), fat (KGM 5.56 ± 0.68 mg/g vs Da-KGM 4.42 ± 0.57 mg/g) and cholesterol (KGM2.67 ± 0.43 mg/g vs Da-KGM 1.78 ± 0.28 mg/g), fecal concentrations of total short-chain fatty acids (KGM 103 ± 14.8 μmol/g vs Da-KGM 74.5 ± 8.49 μmol/g), and improved hepatic antioxidant status and upregulated CYP7A1 and LDLR gene expression. These findings suggest that deacetylation of KGM negatively affects its fermentation characteristics and its inhibition of lipid absorption, which thereby reduces Da-KGM's health benefits.

Infant food applications of complex carbohydrates: Structure, synthesis, and function

Professional health bodies such as the World Health Organization (WHO), the American Academy of Pediatrics (AAP), and the U.S. Department of Health and Human Services (HHS) recommend breast milk as the sole source of food during the first year of life. This position recognizes human milk as being uniquely suited for infant nutrition. Nonetheless, most neonates in the West are fed alternatives by 6 months of age. Although inferior to human milk in most aspects, infant formulas are able to promote effective growth and development. However, while breast-fed infants feature a microbiota dominated by bifidobacteria, the bacterial flora of formula-fed infants is usually heterogeneous with comparatively lower levels of bifidobacteria. Thus, the objective of any infant food manufacturer is to prepare a product that results in a formula-fed infant developing a breast-fed infant-like microbiota. The goal of this focused review is to discuss the structure, synthesis, and function of carbohydrate additives that play a role in governing the composition of the infant microbiome and have other health benefits.

Effects of dietary oxidized konjac glucomannan sulfates (OKGMS) and acidolysis-oxidized konjac glucomannan (A-OKGM) on the immunity and expression of immune-related genes of Schizothorax prenanti

In the present study, konjac glucomannan (KGM) was degraded by H2O2, and then used trisulfonated sodium amine and HCl, individually, to obtain two kinds of derivatives: oxidized konjac glucomannan sulfates (OKGMS) and acidolysis-oxidized konjac glucomannan (A-OKGM). The effects of two OKGM modified products on the immune parameters and expressions of toll-like receptor 22 (TLR22), myeloid differentiation factor 88 (MyD88) and interferon regulatory factors 7 (IRF7) genes in Schizothorax prenanti were determined. The alternative haemolytic complement (ACH50) activity was found to be significantly increased by the OKGMS diets. The immunoglobulin M (IgM) level was significantly enhanced by the OKGMS diets. The lysozyme activity was significantly increased by both OKGMS and A-OKGM diets. The superoxide dismutase (T-SOD) activity in fish fed with all doses of OKGMS diets was significantly higher than that in fish fed with basal diet. The glutathione peroxidase (GSH-PX) activity in fish fed with 0.8% and 1.6% A-OKGM diets was significantly higher than control group. The malondialdehyde (MDA) level was significantly decreased by both OKGMS and A-OKGM diets. The 0.8% A-OKGM diet significantly up-regulated TLR22 gene expression in the head kidney and spleen. TLR22 gene expression was significantly promoted by all OKGMS diets in the mesonephros and liver. The MyD88 mRNA level in 1.6% A-OKGM group significantly increased in the head kidney. The low dose of OKGMS significantly induced the MyD88 gene expression in the mesonephros, gut and liver, while 0.8% A-OKGM group also showed a significantly enhanced MyD88 mRNA expression in the gut. High dose of OKGMS significantly increased the IRF7 mRNA expression in the mesonephros and spleen. Fish fed with low dose of A-OKGM showed significantly higher expression of IRF7 in the gut and liver. Present study suggested that OKGMS and A-OKGM can act as immunostimulant to improve the immune indexes and up-regulate the immune-related gene expressions.

Beneficial health characteristics of native and hydrolysed konjac (Amorphophallus konjac) glucomannan

The impact of ingesting glucomannans on health is not limited to colonic-focused fermentation into short-chain fatty acids (SCFAs), which might have some local health benefits; it also helps in treating disease states and enhancing the body's immune system, both within the gut and in/on other parts of the body. The local and systemic roles of hydrolysed glucomannans, especially konjac glucomannans, in the mouth, oesophagus, stomach, small intestine, large intestine, gut-associated lymphoid tissue (GALT), skin and vagina, are highlighted. Therapeutic applications are discussed. © 2015 Society of Chemical Industry.

Konjac glucomannan, a promising polysaccharide of Amorphophallus konjac K. Koch in health care

In recent year, konjac glucomannan (KGM) has attracted more attention due to its non-harmful and non-toxic properties, good biocompatibility, biodegradability and hydrophilic ability. Moreover, KGM and their derivatives have several importances in the multidirectional research areas such as nutritional, biotechnological and fine chemical fields. In the previous article, we have reviewed the nutritional aspects of KGM covering the various aspects of functional foods, food additives and their derivatives. This review aims at highlighting the diverse biomedical research conducted on KGM in the past ten years, covering therapies for anti-obesity, regulation in lipid metabolism, laxative effect, anti-diabetic, anti-inflammatory, prebiotic to wound dressing applications. Moreover, this review deals with global health aspects of KGM and the disparate health related factors associated with diseases and their control measures.

Cellulases: Classification, Methods of Determination and Industrial Applications

Microbial cellulases have been receiving worldwide attention, as they have enormous potential to process the most abundant cellulosic biomass on this planet and transform it into sustainable biofuels and other value added products. The synergistic action of endoglucanases, exoglucanases, and β-glucosidases is required for the depolymerization of cellulose to fermentable sugars for transformation in to useful products using suitable microorganisms. The lack of a better understanding of the mechanisms of individual cellulases and their synergistic actions is the major hurdles yet to be overcome for large-scale commercial applications of cellulases. We have reviewed various microbial cellulases with a focus on their classification with mechanistic aspects of cellulase hydrolytic action, insights into novel approaches for determining cellulase activity, and potential industrial applications of cellulases.

Immune responses to Aeromonas hydrophila infection in Schizothorax prenanti fed with oxidized konjac glucomannan and its acidolysis products

The objective of the present study was to determine the effect of dietary oxidized konjac glucomannan (OKGM) and its acidolysis products (L-OKGM) on the immune parameters and the gene expression profile of some inflammatory-related cytokines from Schizothorax prenanti during the early stages of injection with Aeromonas hydrophila. Fish were orally administered with seven different diets containing 0 g kg(-1) (control diet), 8.0, 16.0 and 32.0 g kg(-1) OKGM and L-OKGM diets for 60 days prior to injection. After 60 days, the control and the treated fish were intraperitoneally injected with 0.2 ml PBS or 2 × 10(7) cfu/ml bacteria per fish and sampled at time 6 h post-injection. The results showed that the serum lysozyme activity and complement C3 level of fish fed 8.0 g kg(-1) L-OKGM was significantly increased after bacterial infection. Moreover, the injection with A. hydrophila generally up-regulated the expression of all measured genes when compared to their corresponding controls. When compared with the control group, the expression of TLR22, TNF-α and IL-1β was significantly increased in fish fed OKGM and L-OKGM diet after bacterial injection. Furthermore, the L-OKGM diet showed higher activity to trigger the immune response against bacteria, especially the low dosage L-OKGM diet. The results suggested that both of OKGM and L-OKGM are promising feed additive for S. prenanti in aquaculture.

In vitro fermentation of prebiotic carbohydrates by intestinal microbiota in the presence of Lactobacillus amylovorus DSM 16998

The aim of this study was to evaluate the assimilation of the prebiotics fructooligosaccharides (FOS), galactooligosaccharides (GOS), and Konjac glucomannan oligosaccharides (KGMO) by three human (H1, H2 and H3) and pig (P1, P2 and P3) faecal microbiotas in the presence of the potentially probiotic strain Lactobacillus amylovorus DSM 16698, using an in vitro batch fermentation model. Total bacteria and L. amylovorus populations were quantified using qPCR and biochemical features (pH, production of short chain fatty acids (SCFA), lactate, ammonia, and carbohydrate assimilation) were determined. L. amylovorus did not have a competitive advantage under in vitro conditions, reflected by its reduced relative abundance during fermentation despite the carbohydrate sources added. Pig microbiota sustained more stable probiotic counts. Intermittently produced lactate was possibly assimilated by the microbiota and converted to other SCFA as the carbohydrates were assimilated, with H3 probably having a methanogenic metabolism with high lactate and acetate consumption except in the presence of FOS, which assimilation resulted in the highest total SCFA for this volunteer. Addition of FOS also resulted in lower pH and ammonia, which might have been used as nitrogen source by pig microbiota. KGMO needed longer fermentation periods to be completely assimilated by both human and porcine faecal microbiotas. Overall, our results reinforce the notion that care must be taken when generalising the effects claimed for a given probiotic or potentially probiotic strain, including the combination with different prebiotic substrates, since they may vary considerably among individuals, which is important when studying potentially pro- and prebiotic combinations for application as functional foods and feed ingredients.

The effects of dietary oxidized konjac glucomannan and its acidolysis products on the immune response, expression of immune related genes and disease resistance of Schizothorax prenanti

In the present study, KGM was degraded by H2O2 and HCl to obtain two products with different molecular weights: oxidized konjac glucomannan (OKGM, 4.7 × 10(5) Da) and low-molecular-weight oxidized konjac glucomannan (L-OKGM, 9.2 × 10(3) Da). The effects of the two OKGM products on IL-1β, TNF-α, and TLR22 gene expression, and immune parameters and the resistance to Aeromonas hydrophila of Schizothorax prenanti were determined. The results showed that the lysozyme activity was significantly enhanced by the L-OKGM diets. The SOD activity was significantly increased by both OKGM and L-OKGM diets. The MDA level of fish fed the OKGM and L-OKGM diets was significantly lower than the control group. IL-1β mRNA level in the spleen significantly increased in all L-OKGM fed groups. The 8.0 g kg(-1) L-OKGM diet also significantly up-regulated IL-1β gene expression in the head kidney. In the gut, IL-1β mRNA levels were significantly higher in fish fed with the 8.0 g kg(-1) OKGM and 16.0 g kg(-1) L-OKGM diets. The TNF-α mRNA level of L-OKGM group significantly increased in the spleen, head kidney and gut. High dosing of OKGM significantly up-regulated TNF-α transcription in the head kidney, while only the 8.0 g kg(-1) OKGM group showed significantly higher TNF-α mRNA expression in the mesonephros. Fish fed the L-OKGM diets showed significantly higher expression of TLR22 in the spleen, head kidney and mesonephros. After the injection of A. hydrophila, the 8.0 g kg(-1) L-OKGM group showed a significantly higher survival rate than did the control group. Present study suggests that OKGM and L-OKGM can up-regulate immune-related gene expression and enhance disease resistance in S. prenanti, and L-OKGM exhibits higher immunomodulatory activity.

Effect of short term administration of konjac glucomannan hydrolysates on adult blood lipid parameters and glucose concentrations

Purpose

– This paper aims to evaluate the effect of depolymerised glucomannan in regulating blood lipid and glucose concentrations.

Design/methodology/approach

– Twenty adult volunteers were recruited. Blood samples were taken at Day 0. The volunteers consumed drinks containing 3.0 g active glucomannan hydrolysates (AMH) for 14 days, after which time blood samples were retaken (Day 15). Blood samples were analysed to determine the blood lipid and glucose concentrations.

Findings

– The average fasting blood glucose at the start of the trial was 2.54 mmol/L but reduced slightly to 2.49 mmol/L after consumption of the glucomannan. The total average cholesterol at the start of the trial was higher (6.69 mmol/L) than desirable ( < 5.0 mmol/L). This was reduced after consuming the glucomannan to 6.44 mmol/L (3.74 per cent). The triglyceride content was also higher initially than recommended (2.88 mmol/L) but was reduced by 11.5 per cent. The high-density lipoprotein (HDL) was within the desirable range before and after consumption (1.57 and 1.52 mmol/L, respectively), while the average low-density lipoprotein (LDL) was higher than recommended ( < 3.0 mmol/L), representing 4.55 mmol/L and 4.40 mmol/L before and after consumption, respectively. Both parameters were reduced by over 3.0 per cent. The consumption of the glucomannan hydrolysates also reduced the total cholesterol/HDL and LDL/HDL ratios.

Originality/value

– The AMH was effective in lowering blood cholesterol and glucose concentrations. Consumption of such carbohydrates could prove useful for these physiological disorders. Further studies are desirable to characterise the exact mechanism.

Effect of dietary oxidized konjac glucomannan on Schizothorax prenanti growth performance, body composition, intestinal morphology and intestinal microflora

The aim of the present study was to examine the effect of oxidized konjac glucomannan (OKGM) on Schizothorax prenanti growth performance, body composition, intestinal morphology and intestinal microflora. Fish were fed a basal diet or basal diet plus 4.0, 8.0, 16.0 and 32.0 g kg(-1) OKGM for 60 days. The results indicated that WGR and SGR were significantly higher in fish fed 8.0 and 16.0 g kg(-1) OKGM diets (P < 0.05) than those in fish fed basal diet, and PER was significantly higher and FCR was significantly lower in fish fed 16.0 g kg(-1) OKGM diet (P < 0.05). The content of body protein, lipid and moisture was affected by the OKGM diets. The light and electron microscopy demonstrated that intestinal morphology of fish fed 8.0 and 16.0 g kg(-1) OKGM diet was better (P < 0.05) than the control group, including mucosa fold height, mucosal epithelial height, submucosa height, longitudinal muscularis thickness and circular muscularis thickness. Compared with the control group, fish fed 32.0 g kg(-1) OKGM diet showed significantly lower goblet cell number in anterior intestine (P < 0.05). Furthermore, intestinal microflora was analyzed by PCR-DGGE, and the results showed that OKGM diets also significantly modulated the intestinal microflora of fish (P < 0.05). The study clearly demonstrates that OKGM could enhance the growth performance, improve intestinal morphology and modulate intestinal microflora of S. prenanti, and the optimal dietary OKGM levels was suggested to be 16.0 g kg(-1).

Preparation and characterization of a novel pH-response dietary fiber: chitosan-coated konjac glucomannan

The purpose of this study was to prepare a kind of novel pH-response dietary fiber from chitosan-coated konjac glucomannan (KGM) powders (KGM/Chitosan or K/C powders) by a physical grind method. The K/C powders were selectively soluble in aqueous solutions of different pH. Meanwhile, the coated chitosan could largely decrease the viscosity of KGM in neutral condition, which is the main limitation for KGM application in food industry. Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), swelling ability and rheological measurements were utilized to characterize the performance of K/C powders. K/C powders exhibited much higher viscosity and swelling ability in acidic condition than in neutral condition. Therefore, this study will extend the application of KGM in food industry and in other pH-specific applications as well.