Constitution of konjac glucomannan: chemical analysis and 13C NMR spectroscopy

Characterization of cellulases from softening fruit for enzymatic depolymerization of cellulose

Cellulose is a major renewable resource for a wide variety of sustainable industrial products. However, for its utilization, finding new efficient enzymes for plant cell wall depolymerization is crucial. In addition to microbial sources, cellulases also exist in plants, however, are less studied. Fleshy fruit ripening includes enzymatic cell wall hydrolysis, leading to tissue softening. Therefore, bilberry (Vaccinium myrtillus L.), which produces small fruits that undergo extensive and rapid softening, was selected to explore cellulases of plant origin. We identified 20 glycoside hydrolase family 9 (GH9) cellulases from a recently sequenced bilberry genome, including four of which showed fruit ripening-specific expression and could be associated with fruit softening based on phylogenetic, transcriptomic and gene expression analyses. These four cellulases were secreted enzymes: two B-types and two C-types with a carbohydrate binding module 49. For functional characterization, these four cellulases were expressed in Pichia pastoris. All recombinant enzymes demonstrated glucanase activity toward cellulose and hemicellulose substrates. Particularly, VmGH9C1 demonstrated high activity and ability to degrade cellulose, xyloglucan, and glucomannan. In addition, all the enzymes retained activity under wide pH (6-10) and temperature ranges (optimum 70 °C), revealing the potential applications of plant GH9 cellulases in the industrial bioprocessing of lignocellulose.

Chemical characterization and pharmacological properties of polysaccharides from Allium roseum leaves: In vitro and in vivo assays

Allium roseum is amongst the most important wild medicinal plants. It is known for its diverse biological properties, including antioxidant, antibacterial and antidiabetic activities. In this work, the polysaccharides (PARLs) were ultrasonically extracted from Allium roesum leaves then purified and analyzed by several techniques. Chemical composition and GC-MS analysis showed that the obtained polysaccharides were composed mainly of glucose (40.20 %), mannose (25.30 %), fructose (10.60 %) and galacturonic acid (15.11 %). Moreover, PARLs exhibited a potent antioxidant effect with higher capacities up to 69.61 % and 71.72 % for DPPH and ABTS free radicals, respectively. Furthermore, PARLs significantly modulated inflammatory response by reducing TNF-α, IL-6, and IL-8 pro-inflammatory mediators and promoting the anti-inflammatory IL-10 mediator in LPS stimulated THP-1 derived macrophages. The in-vivo tests proved that the extract was able to decrease carrageenan-induced rat paw swelling by around 68.15 % after 4 h of treatment. PARLs, significantly reduced the growth of U87 (glioblastoma) and IGROV-1 cancer cells with IC50 values of about 4.27 and 7.89 mg/mL respectively. This research clearly shows that Allium roseum polysaccharides can be used as natural antioxidants with anti-inflammatory and anticancer properties.

3D Printed Room Temperature Phosphorescence Materials Enabled by Edible Natural Konjac Glucomannan

Shaping room temperature phosphorescence (RTP) materials into 3D bodies is important for stereoscopic optoelectronic displays but remains challenging due to their poor processability and mechanical properties. Here, konjac glucomannan (KGM) is employed to anchor arylboronic acids with various π conjugations via a facile B─O covalent reaction to afford printable inks, using which full-color high-fidelity 3D RTP objects with high mechanical strength can be obtained via direct ink writing-based 3D printing and freeze-drying. The doubly rigid structure supplied by the synergy of hydrogen bonding and B─O covalent bonding can protect the triplet excitons; thus, the prepared 3D RTP object shows a striking lifetime of 2.14 s. The printed counterparts are successfully used for 3D anti-counterfeiting and can be recycled and reprinted nondestructively by dissolving in water. This success expands the scope of printable 3D luminescent materials, providing an eco-friendly platform for the additive manufacturing of sophisticated 3D RTP architectures.

Extraction, structural characterization and immunoactivity of glucomannan type polysaccahrides from Lilium brownii var. viridulum Baker

Homogeneous polysaccharide (LBP) was extracted and purified from the bulblets of Lilium brownii var. viridulum Baker with a molecular weight of 312 kDa. The monosaccharides are composed of mannose and glucose, and the corresponding molar ratios are 0.582 and 0.418, respectively. FT-IR, LC-MS, NMR, GC-MS and HPAEC were used to analyze the functional groups, glycosidic linkages and chemical structure of LBP, which was a 1-4-linked glucomannan and contained a dodecasaccharide repeating units of →4)-β-D-Manp-(1 → 4)-β-D-Manp-(1 → 4)-β-D-Manp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Manp-(1 → 4)-β-D-Manp-(1 → 4)-β-D-Glcp-(1 → 4)-α-D-Glcp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Glcp-(1 → 4)-β-D-Manp-(1 → 4)-β-D-Manp-(1 → . In vitro experimental results showed that LBP had noble biocompatibility, and a low dose of 5 μg/mL LBP significantly up-regulated the mRNA expression of TNF-α, iNOS, IL-6, IL-1β and Toll-like receptors family (TLRs) in RAW 264.7 cells. In conclusion, LBP played an important role in immunomodulation, and further studies on the specific immunomodulatory mechanisms of LBP on RAW 264.7 cells are still needed.

Chitosan/konjac glucomannan bilayer films: Physical, structural, and thermal properties

To overcome the limitations of chitosan (CS) and konjac glucomannan (KGM), the bilayer films of CS and KGM were prepared by layer-by-layer (LBL) casting method, and the effects of different mass ratios (i.e., C5: K0, C4:K1, C3:K2, C1:K1, C2:K3, C1:K4, and C0:K5) on the microstructures and physicochemical properties of bilayer films were examined to evaluate their applicability in food packaging. The results revealed that the bilayer films had uniform microstructures. When compared with pure films, the bilayer films displayed lower swelling degrees and water vapor permeability. However, the tensile tests revealed a reduction in the mechanical properties of the bilayer films, which was nonetheless superior to that of the pure KGM film. In addition, the intermolecular interactions between the CS and KGM layers were observed through FTIR and XRD analyses. Finally, TGA and DSC analyses demonstrated a decrease in the thermal stability of the bilayer films. Our cumulative results verified that CS-KGM bilayer films may be a promising material for use in food packaging and further properties of the bilayer films can be supplemented in the future through layer-by-layer modification and the addition of active ingredients.

Structurally Orientated Rheological and Gut Microbiota Fermentation Property of Mannans Polysaccharides and Oligosaccharides

Three mannan polysaccharides and their oligosaccharides were investigated in terms of physicochemical characteristics and effects on gut microbiota. Oligosaccharides from guar gum had the fastest fermentation kinetics for SCFAs generation at the initial stage, while the locust bean of both polymers and oligosaccharides demonstrated the lowest SCFAs through the whole fermentation process. In contrast, konjac gum steadily increased SCFAs and reached its maximum level at 24 h fermentation, indicating its fermentation character may be associated with its rheological properties. Compared to their corresponding polysaccharides, all the oligosaccharides demonstrated a faster fermentation kinetics, followed by an enriched abundance of propionate-producing bacterial Prevotella and a decreased abundance of Megamonas and Collinsella. Meanwhile, oligosaccharides reduced the Firmicutes/Bacteroidota ratio as well as the abundance of Bacteroidetes and Escherichia-Shigella. The fermentation of konjac substrate significantly promoted the abundance of butyrate-producing bacterial Faecalibacterium. In contrast, although the fermentation of locust bean and guar gum substrates benefited Bifidobacterium abundance due to their similar structure and monosaccharides composition, the fermentation of locust bean gum led to greater Bifidobacterium than the others, which may be associated with its higher mannose composition in the molecules. Interestingly, the partial hydrolysis of the three polysaccharides slightly reduced their prebiotic function.

Method for Simulating the Anti-Damage Performance of Consolidation Soil Balls at the Roots of Seedlings during Transportation Using Consolidated Soil Columns

In the process of landscaping or afforestation in challenging terrain, in order to improve the survival rate of transplanted seedlings, it is necessary to transplant seedlings with a mother soil ball attached. During transportation, the soil ball at the root of the seedlings is very susceptible to breakage due to compression, bumps, and collisions. In order to ensure the integrity of the soil ball of the transplanted seedlings and improve the survival rate of seedlings, a method of chemically enhancing the soil surface strength was employed. Specifically, a polymer-based soil consolidating agent was used to solidify the root balls of the seedlings. To examine the abrasion resistance performance of the soil balls formed by consolidating the surface with polymer adhesive during the transportation process, we utilized a polymer-based consolidating agent to prepare test soil columns and developed a method to simulate the damage resistance performance of seedling root balls during transportation using these soil columns. The method primarily encompasses two aspects of testing: compressive strength testing of the consolidated soil columns and resistance to transportation vibration testing. The first method for testing the resistance to transportation vibration of the consolidated soil columns is a combination test that includes three sets of tests: highway truck transportation vibration testing, combined wheel vehicle transportation vibration testing, and impact testing. Although the method is cumbersome, testing is more accurate. The second method for testing the resistance to transportation vibration of the consolidated soil columns involves simultaneously testing multiple consolidated soil columns using a simulated transportation vibration test platform. The testing method is concise and efficient, and the test results are more intuitive. The combined assessment of the resistance to transportation vibration and compressive strength testing of the consolidated soil columns allows for a comprehensive evaluation of the soil columns' resistance to damage during transportation. This study mainly provides a quick and effective method for detecting the damage resistance of consolidated soil columns/balls during transportation, providing technical support for the application of polymer-based consolidation agents in the field of seedling transplantation.

Synergistic effects of oxidized konjac glucomannan on rheological, thermal and structural properties of gluten protein

Oxidation is an effective way to prepare depolymerized konjac glucomannan (KGM). The oxidized KGM (OKGM) differed from native KGM in physicochemical properties due to different molecular structure. In this study, the effects of OKGM on the properties of gluten protein were investigated and compared with native KGM (NKGM) and enzymatic hydrolysis KGM (EKGM). Results showed that the OKGM with a low molecular weight and viscosity could improve rheological properties and enhance thermal stability. Compared to native gluten protein (NGP), OKGM stabilized the protein secondary structure by increasing the contents of β-sheet and α-helix, and improved the tertiary structure through increasing the disulfide bonds. The compact holes with shrunk pore size confirmed a stronger interaction between OKGM and gluten protein through scanning electron microscopy, forming a highly networked gluten structure. Furthermore, OKGM depolymerized by the moderate ozone-microwave treatment of 40 min had a higher effect on gluten proteins than that by the 100 min treatment, demonstrating that the excessive degradation of KGM weakened the interaction between the gluten protein and OKGM. These findings demonstrated that incorporating moderately oxidized KGM into gluten protein was an effective strategy to improve the properties of gluten protein.

Dynamic structural evolution of lignin macromolecules and hemicelluloses during Chinese pine growth

To comprehend the biosynthesis processes of conifers, it is essential to investigate the disparity between the cell wall shape and the interior chemical structures of polymers throughout the development of Chinese pine. In this study, branches of mature Chinese pine were separated according to their growth time (2, 4, 6, 8 and 10 years). The variation of cell wall morphology and lignin distribution was comprehensively monitored by scanning electron microscopy (SEM) and confocal Raman microscopy (CRM), respectively. Moreover, the chemical structures of lignin and alkali-extracted hemicelluloses were extensively characterized by nuclear magnetic resonance (NMR) and gel permeation chromatography (GPC). The thickness of latewood cell walls increased steadily from 1.29 μm to 3.38 μm, and the structure of the cell wall components became more complicated as the growth time increased. Based on the structural analysis, it was found that the content of β-O-4 (39.88-45.44/100 Ar), β-β (3.20-10.02/100 Ar) and β-5 (8.09-15.35/100 Ar) linkages as well as the degree of polymerization of lignin increased with the growth time. The complication propensity increased significantly over 6 years before slowing to a trickle over 8 and 10 years. Furthermore, alkali-extracted hemicelluloses of Chinese pine mainly consist of galactoglucomannans and arabinoglucuronxylan, in which the relative content of galactoglucomannans increased with the growth of the pine, especially from 6 to 10 years.

Evaluation of the composition of konjac glucomannan on the color changes during the deacetylation reaction

As a newly superior konjac variety, the Amorphophallus bulbifer (A. bulbifer) has several unique advantages of high reproductive coefficient, short growth cycle, high disease resistance, high konjac glucomannan (KGM) content and climate adaption to hot or humid conditions. However, the gel formed by KGM from the A. bulbifer flour is easily browning during the alkali-induced process and the mechanism underlying them is still unclear. In order to explore the browning mechanisms, the changes of composition and color parameters of KGM were investigated during deacetylation in this research. The L*, h*, total phenols, total flavonoids, reducing sugars, and amino acids decreased along with the increase of deacetylation degree of KGM while a*, ΔЕ, and browning index increased. The results indicated that the oxidation or polymerization of polyphenols and flavones in alkaline circumstances, and the carbonyl ammonia reaction between reducing sugars and amino acids may be the main reasons for color changes of KGM flour during deacetylation. Hence, this study was expected to provide the theoretical basis for the inhibition of KGM gel browning and further broaden the application range of KGM in food and other industries.

Effects of Combining High Pressure Processing Treatments and Konjac Glucomannan and Sodium Caseinate on Gel Properties of Myosin Protein

Effects of two high pressure processing treatments and various levels of konjac glucomannan (KGM) and sodium caseinate (SC) on texture properties, water-holding capacity, and ultra-structure of gels of rabbit myosin protein were investigated. The two high pressure processing treatments were as follows: (1) mean pressure (200 MPa), low temperature (37 °C), and holding for a short time (5 min) followed heating (80 °C for 40 min) (gel LP + H), and (2) high pressure (500 MPa), high temperature (60 °C), and holding for a long time (30 min) (gel HP). Gel LP + H have better gel properties (increased hardness, springiness, gumminess, adhesiveness, cohesiveness, and water binding capacity) than gels HP. Above all, gels myosin + SC:KGM (2:1) have best gel properties. KGM and SC both significantly improved the gel texture properties and water binding capacity.

Marine bacteroidetes use a conserved enzymatic cascade to digest diatom β-mannan

The polysaccharide β-mannan, which is common in terrestrial plants but unknown in microalgae, was recently detected during diatom blooms. We identified a β-mannan polysaccharide utilization locus (PUL) in the genome of the marine flavobacterium Muricauda sp. MAR_2010_75. Proteomics showed β-mannan induced translation of 22 proteins encoded within the PUL. Biochemical and structural analyses deduced the enzymatic cascade for β-mannan utilization. A conserved GH26 β-mannanase with endo-activity depolymerized the β-mannan. Consistent with the biochemistry, X-ray crystallography showed the typical TIM-barrel fold of related enzymes found in terrestrial β-mannan degraders. Structural and biochemical analyses of a second GH26 allowed the prediction of an exo-activity on shorter manno-gluco oligosaccharides. Further analysis demonstrated exo-α-1,6-galactosidase- and endo-β-1,4-glucanase activity of the PUL-encoded GH27 and GH5_26, respectively, indicating the target substrate is a galactoglucomannan. Epitope deletion assays with mannanases as analytic tools indicate the presence of β-mannan in the diatoms Coscinodiscus wailesii and Chaetoceros affinis. Mannanases from the PUL were active on diatom β-mannan and polysaccharide extracts sampled during a microalgal bloom at the North Sea. Together these results demonstrate that marine microorganisms use a conserved enzymatic cascade to degrade β-mannans of marine and terrestrial origin and that this metabolic pathway plays a role in marine carbon cycling.

Konjac Glucomannan: An Emerging Specialty Medical Food to Aid in the Treatment of Type 2 Diabetes Mellitus

There are many factors causing T2DM; thus, it is difficult to prevent and cure it with conventional treatment. In order to realize the continuous intervention of T2DM, the treatment strategy of combining diet therapy and traditional medication came into being. As a natural product with the concept of being healthy, konjac flour and its derivatives are popular with the public. Its main component, Konjac glucomannan (KGM), can not only be applied as a food additive, which greatly improves the taste and flavor of food and extends the shelf life of food but also occupies an important role in T2DM. KGM can extend gastric emptying time, increase satiety, and promote liver glycogen synthesis, and also has the potential to improve intestinal flora and the metabolic system through a variety of molecular pathways in order to positively regulate oxidative stress and immune inflammation, and protect the liver and kidneys. In order to establish the theoretical justification for the adjunctive treatment of T2DM, we have outlined the physicochemical features of KGM in this article, emphasizing the advantages of KGM as a meal for special medical purposes of T2DM.

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.

Structural and Mechanical Properties of Konjac Glucomannan Gels and Influence of Freezing-Thawing Treatments on Them

Freezing has been widely used for long-term food preservation. However, freezing-thawing (FT) treatment usually influences the texture and structure of food gels such as konjac. For their texture control after FT treatment, it is important to clarify the structural change of food gels during the FT process. In this study, we investigated the aggregated structures of konjac glucomannan (GM) gels during the FT process using simultaneous synchrotron small-angle X-ray/wide-angle X-ray scattering (SAXS/WAXS) techniques. The FT treatment resulted in more crystallization of GM, and consequently, a large increase in compressive stress. In-situ SAXS/WAXS measurements revealed the following findings: on freezing, water molecules came out of the aggregated phase of GM and after the thawing, they came back into the aggregated phase, but the aggregated structure did not return to the one before the freezing; the gel network enhanced the inhomogeneity due to the growth of ice crystals during freezing. Furthermore, we examined the influence of additives such as polyvinyl (alcohol) (PVA) and antifreeze glycoprotein (AFGP) on the mechanical and structural properties of freeze-thawed GM gels. Although the addition of PVA and AFGP suppressed the crystallization of GM, it could not prevent the growth of ice crystals and the increase in the inhomogeneity of the gel network. As a result, the compressive stresses for freeze-thawed GM gels containing PVA or AFGP were significantly higher compared with those of GM gels without FT treatments, although they were lower than those of freeze-thawed GM gels. The findings of this study may be useful for not only the texture control of freeze-thawed foods but also the improvement of the mechanical performance of the biomaterials.

Investigation on the influence of AC electric filed and KCl on the structure and gel properties of Konjac glucomannan

The influence of alternating current (AC) electric field and KCl on the structure and gel properties of Konjac Glucomannan (KGM) were studied in this work by high-performance gel permeation chromatography (HPGPC), acid-base titration, solid-state nuclear magnetic resonance (NMR), X-ray diffraction (XRD), simultaneous differential scanning calorimetry/thermo gravimetric analyzer (DSC/TGA) and a rheometer. HPGPC showed KGM was degraded by AC electric field and Acid-base titration showed that under the action of AC electric field and KCl KGM removed part of acetyl groups, which were consistent with the analysis of NMR. XRD and temperature sweep measurements respectively showed that the electrotreatment time and KCl concentration had important effects on the gel formation and its three-dimensional network. Simultaneous DSC/TGA and temperature sweep measurements both demonstrated the gel had good thermal stability.

Interaction between nanometer calcium oxalate and renal epithelial cells repaired with carboxymethylated polysaccharides

OBJECTIVE

Injury of renal tubular epithelial cells (HK-2) is an important cause of kidney stone formation. In this article, the repairing effect of polysaccharide (PCP0) extracted from the traditional Chinese medicine Poria cocos and its carboxymethylated derivatives on damaged HK-2 cells was studied, and the differences in adhesion and endocytosis of the cells to nanometer calcium oxalate monohydrate (COM) before and after repair were explored.

METHODS

Sodium oxalate (2.8 mmol/L) was used to damage HK-2 cells to establish a damage model, and then Poria cocos polysaccharides (PCPs) with different carboxyl (COOH) contents were used to repair the damaged cells. The changes in the biochemical indicators of the cells before and after the repair and the changes in the ability to adhere to and internalize nano-COM were detected.

RESULTS

The natural PCPs (PCP0, COOH content = 2.56%) were carboxymethylated, and three carboxylated modified Poria cocos with 7.48% (PCP1), 12.07% (PCP2), and 17.18% (PCP3) COOH contents were obtained. PCPs could repair the damaged HK-2 cells, and the cell viability was enhanced after repair. The cell morphology was gradually repaired, the proliferation and healing rate were increased. The ROS production was reduced, and the polarity of the mitochondrial membrane potential was restored. The level of intracellular Ca²⁺ ions decreased, and the autophagy response was weakened.

CONCLUSION

The cells repaired by PCPs inhibited the adhesion to nano-COM and simultaneously promoted the endocytosis of nano-COM. The endocytic crystals mainly accumulated in the lysosome. Inhibiting adhesion and increasing endocytosis could reduce the nucleation, growth, and aggregation of cell surface crystals, thereby inhibiting the formation of kidney stones. With the increase of COOH content in PCPs, its ability to repair damaged cells, inhibit crystal adhesion, and promote crystal endocytosis all increased, that is, PCP3 with the highest COOH content showed the best ability to inhibit stone formation.

Effect of Preparation Conditions on Application Properties of Environment Friendly Polymer Soil Consolidation Agent

In order to improve the survival rate of transplanted seedlings and improve the efficiency of seedling transplantation, we developed an environmental friendly polymer konjac glucomannan (KGM)/chitosan (CA)/polyvinyl alcohol (PVA) ternary blend soil consolidation agent to consolidate the soil ball at the root of transplanted seedlings. In the previous research, we found that although the prepared KGM/CA/PVA ternary blend soil consolidation agent can consolidate the soil ball at the root of the seedling, the medium solid content of the adhesive was high, which affects its spraying at the root of the seedling. At the same time, the preparation temperature of the KGM/CA/PVA ternary blend was also high. Therefore, to reduce the energy consumption and the cost of the KGM/CA/PVA ternary blend soil consolidation agent in the preparation process, this paper studied the influence of preparation conditions on the application performance of the environmental friendly polymer soil consolidation agent. We aimed to reduce the highest value CA content and preparation temperature of the KGM/CA/PVA ternary blend adhesive on the premise of ensuring the consolidation performance of the KGM/CA/PVA ternary blend adhesive on soil balls. It was prepared for the popularization and application of the environmental friendly polymer KGM/CA/PVA ternary blend soil consolidation agent in seedling transplanting. Through this study, it was found that the film-forming performance of the adhesive was better when the KGM content was 4.5%, the CA content was in the range of 2-3%, the PVA content was in the range of 3-4%, and the preparation temperature was higher than 50 °C. The polymer soil consolidation agent prepared under this condition has a good application prospect in seedling transplanting.

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.

•

Various methods of recent mannose production were comprehensively summarized.

•

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

•

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

Structural studies of a mannoglucan from Cremastra appendiculata (Orchidaceae) by chemical and enzymatic methods

Pseudobulb of Cremastra appendiculata (Orchidaceae) is a traditionally used medicine in China for treatment of certain cancers. The polysaccharides from this medicinal plant are poorly understood. Therefore, we focused on the isolation and fine structure characterization of C. appendiculata polysaccharides. After isolation by DE-52 and Superdex 200 gel chromatography, the purified polysaccharide (named as CAP) with Mw 557.5 kDa was obtained with a narrow and symmetric peak presented in the HPGPC. The monosaccharide composition results showed in HPAEC that CAP was a heteropolysaccharide composed of glucose and mannose at a molar ratio roughly 0.34:0.66. The methylation results indicated that CAP was a 1,4-β-mannose and 1,4-β-glucose linear linkage. The further NMR studies suggested a 0.208 acetylation substitution of CAP and a hexasaccharide repeating unit composed of 1,4-β-mannose and1, 4-β-glucose in the CAP structure. The chemical structure of CAP was confirmed further by the specific glucanase and mannanase hydrolysis results.

Antidiabetic effect of konjac glucomannan via insulin signaling pathway regulation in high-fat diet and streptozotocin-induced diabetic rats

Type 2 diabetes mellitus is a chronic metabolic disorder that tends to disarray various metabolic pathways. Dietary-mediated T2DM prevention garners much attention in recent decades. Hence, this study was intended to elucidate the antidiabetic properties of Konjac glucomannan (KGM) in diabetic rats. Our experimental design includes five groups, with six rats in each group. Group 1 feeding standard diet pallet alone served as control rats; group 2 was KGM control rats administered intragastrically with KGM (120 mg/kg b.w.). Group 3 was developed as diabetic rats with a high-fat diet and an intraperitoneal injection of Streptozotocin-40 mg/kg b.w. Group 4 were diabetic rats treated with KGM (80 mg/kg b.w.), and group 5 were diabetic rats received rosiglitazone treatment (4 mg/kg b.w.). The results showed that STZ-induced diabetic rats significantly elevate liver marker enzymes and gluconeogenesis enzymes. Diminished glycolytic enzymes, liver glycogen, insulin signaling genes, and proteins were also seen in diabetic rats. Treatment with KGM augmented glycolytic enzymes and liver glycogen. On the other hand, KGM diminished gluconeogenesis, liver marker enzymes, upregulated gene, and protein expression of the insulin pathway. The current results suggest dietary KGM can offer a better health benefit in the treatment of T2DM.

3D bioprinting of an electroactive and self-healing polysaccharide hydrogels

Polysaccharide hydrogels including alginate, agarose, hyaluronic acid and chitosan have been widely used as scaffolds in 3D bio-printing field. Konjac glucomannan (KGM) exhibits excellent properties of water solubility, biocompatibility and biodegradability. Herein composite hydrogels were prepared via schiff-base reaction between the aldehyde group of oxidized konjac glucomannan (OKGM) and the amino group of branched polyethyleneimine (PEI). The OKGM/PEI composite hydrogel displayed self-healing ability and pH sensitivity and showed shear thinning capability, which is suitable for 3D bio-printing technology. Furthermore, the OKGM/PEI electroactive composite hydrogel was obtained by adding carbon nanotubes (CNTs). Then the rheological behavior and morphology of OKGM/PEI electroactive hydrogels were thoroughly characterized. The conductivities of OKGM/PEI electroactive composite hydrogels increased with increasing the content of carbon nanotubes. The rheological behavior and 3D bio-printability of OKGM/PEI electroactive hydrogels were also tested. It was found that carbon nanotubes can also improve the bio-printability of OKGM/PEI electroactive hydrogels. Thus, the OKGM/PEI electroactive hydrogels could be employed as scaffolds for muscle and cardiac nerve tissue regeneration. This article is protected by copyright. All rights reserved.

Preparation and characterization of konjac glucomannan and gum arabic composite gel

Compounding is a safe method to avoid limitations of a singular gel. Here, composite gels were prepared with konjac glucomannan (KGM) and gum arabic (GA) and evaluated by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), water solubility index (WSI), water absorption index (WAI), texture profile analysis (TPA) and rheological analysis. The gel stratified when GA concentration ≥ 2.5%. FTIR indicated that the interactions of KGM and GA were mainly related to hydrogen bonds and acetyl groups, and the solution separated from gels only included GA and water molecules. The microstructures became denser and contained smaller holes at high GA concentrations as seen by SEM. WSI and WAI both increased with GA increasing. Hardness and springiness dropped when GA concentration increased from 0 to 2.0%, but they increased when GA increased from 2.0% to 4.0%. Rheological analysis showed the gels were non-Newtonian pseudoplastic fluids, with anti-thixotropy (GA ≤ 3.5%) and thixotropy (GA ≥ 4.0%). Furthermore, the gels could be classified as non-covalent gels, with higher gel strength at high GA concentrations. The non-covalent linkages included hydrogen bonding and hydrophobic interaction, and hydrogen bonding held the dominated status. Therefore, KGM and GA have antagonistic and synergistic effects.

Preparation of konjac oligoglucomannans with different molecular weights and their in vitro and in vivo antioxidant activities

In this paper, konjac oligoglucomannan (KOGM) was obtained with a hydrolysis rate of 56.24% by controlling the hydrolysis conditions. KOGM was passed through a 0.2 kDa dialysis bag, a 3 kDa ultrafiltration tube, and a 5 kDa ultrafiltration tube, creating samples with molecular weights of 0.2–3 kDa (IV), 3–5 kDa (III), and >5 kDa (II), respectively. The in vitro antioxidant activities of the KOGM samples were tested by measuring their removal effects on ˙OH, O2−\documentclass[10pt]{article}\usepackage{wasysym} \usepackage[substack]{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage[mathscr]{eucal} \usepackage{mathrsfs} \usepackage{pmc} \usepackage[Euler]{upgreek} \pagestyle{empty} \oddsidemargin -1.0in \begin{document} {\text{O}}_{2}^{-} \end{document}, and DPPH˙. The in vivo antioxidant activities of the samples were analyzed by measuring their impacts on the malondialdehyde (MDA) content, superoxide dismutase (SOD) activity, and glutathione peroxidase (GSH-PX) activity in mice. The results show that the KOGM samples in groups III and IV could effectively remove ˙OH, O2−\documentclass[10pt]{article}\usepackage{wasysym} \usepackage[substack]{amsmath} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage[mathscr]{eucal} \usepackage{mathrsfs} \usepackage{pmc} \usepackage[Euler]{upgreek} \pagestyle{empty} \oddsidemargin -1.0in \begin{document} {\text{O}}_{2}^{-} \end{document}, and DPPH˙; the KOGM samples in all three groups could enhance the SOD and GSH-PX activities and reduce the MDA content in the liver tissues of mice; finally, the antioxidant activity of KOGM is negatively correlated with the molecular weight.

Gel growth of aqueous konjac glucomannan solution containing sodium trimetaphosphate dialyzed with dilute sodium hydroxide

The growth rate of the hydrogel of the aqueous konjac glucomannan (KGM) solution containing sodium trimetaphosphate (STMP) dialyzed with aqueous NaOH was investigated in a rectangular cell. The growth rate of the KGM-STMP gel depended on both the KGM and STMP concentrations in addition to the NaOH concentration. The initial growth rate of the KGM-STMP gel was closely related to the diffusion of NaOH into the KGM-STMP solution, leading to the ring-opening reaction of STMP and the deacetylation of KGM at the interface. The time course of the gelation of the KGM-STMP solution was analyzed on the basis of the moving boundary picture theory by introducing the characteristic length to express the consumption of NaOH in the gel layer accompanying the decomposition of STMP. Dynamic mechanical measurements were performed to compare the gelation of the KGM-STMP solution mixed homogeneously with dilute NaOH and the gel dynamics by the dialysis method.

A Purified Glucomannan Oligosaccharide from Amorphophallus konjac Improves Colonic Mucosal Barrier Function via Enhancing Butyrate Production and Histone Protein H3 and H4 Acetylation

A structurally defined konjac glucomannan oligosaccharide (KGMOS) with a relatively high molecular weight and narrow molecular weight distribution (molecular weight ranging from 3000 to 4000 Da, degree of polymerization (dp) 8-11) was prepared from native konjac glucomannan (KGM), and the beneficial effects and molecular mechanisms of KGMOS on colonic functions were investigated in C57BL/6 mice. The results are the first to reveal that KGMOS regulated intestinal microflora composition to facilitate the production of colonic butyrate. Elevated butyrate production further increased the acetylation of histone proteins H3 and H4 and thus enhanced the transcription of the major colonic mucin gene Muc2 and the secretion of mucin elements, which represents a new molecular mechanism of KGM oligosaccharide consumption. The findings indicate that KGM oligosaccharides with specific molecular sizes have highly desirable functional properties and potentially could improve gut health by promoting the barrier function of the colonic mucosa.

Global transcriptomic analysis of functional oligosaccharide metabolism in Pediococcus pentosaceus

Lactic acid bacteria (LAB) are important in food fermentation and may enhance overall host health. Previous studies to explore LAB metabolism mainly focused on the genera Lacticaseibacillus and Lactococcus. Pediococcus pentosaceus, historically recognized as an important food fermentation bacterial strain, can produce bacteriocins and occasionally demonstrated probiotic functionalities. This study thoroughly surveyed the growth kinetic of three P. pentosaceus isolates in various culture formulations, especially in fructooligosaccharide (FOS), xylooligosaccharide (XOS), or konjac mannooligosaccharide (KMOS) conditions. Results showed that P. pentosaceus effectively metabolized KMOS, the culture of which led to 23.6-fold population increase. However, FOS and XOS were less metabolized by P. pentosaceus. On functional oligosaccharide cultures, P. pentosaceus could result in higher population proliferation, more acidified fermentation environment, and higher glycoside hydrolysis activities in the culture. RNA-Seq analysis classified 1572 out of 1708 putative genes as mRNA-coding genes. The dataset also revealed that the three functional oligosaccharides led to extensive global functional gene regulations. Phosphate conservation and utilization efficiency enhancement may serve as a leading transcriptional regulation direction in functional oligosaccharide metabolisms. In summary, these discovered metabolic characteristics could be employed to support future studies. KEY POINTS: • Konjac mannooligosaccharides effectively promoted P. pentosaceus proliferation. • Functional genes were highly regulated in functional oligosaccharide utilization. • Phosphate conservation was an important transcriptional regulation direction.

High-Performance Colorimetric Humidity Sensors Based on Konjac Glucomannan

High-humidity conditions (85-100% relative humidity (RH)) have very diverse effects on many aspects of people's daily lives. Despite remarkable progress in the development of structural coloration-based humidity sensors, how to significantly improve the sensitivity and visual humidity resolution of these humidity sensors under a high-humidity environment remains a great challenge. In this study, high-performance colorimetric humidity sensors based on environment-friendly konjac glucomannan (KGM) via thin-film interference are developed using a simple, affordable, and scalable preparation method. An effective strategy is demonstrated for substantially improving the sensor sensitivity and visual humidity resolution under a high-humidity environment via synergistic integration of multiorder interference peaks, sensor array technology, and superior water-absorbing polymer. The KGM full-range humidity sensors exhibit fast and dynamic response toward the humidity change without power consumption, and they also show high sensitivity and selectivity, little hysteresis, and excellent stability against high-humidity conditions. The KGM humidity sensors display extraordinary red shift of the reflection peak (e.g., 385 nm) and the visual humidity resolution as high as 1.5% RH in the visible range from 85 to 100% RH, which represent the largest spectra shift and highest visual humidity resolution, respectively, for structural coloration-based humidity sensors in high-humidity conditions.

Hypoglycemic effects and mechanism of different molecular weights of konjac glucomannans in type 2 diabetic rats

Konjac glucomannan (KGM) is a hypoglycemic polysaccharide with a wide range of molecular weights. But study on hypoglycemic effects of KGMs relate to molecular weight is limited. In this study, KGMs with high and medium molecular weights, and the degraded KGMs were analyzed with physicochemical properties, hypoglycemic effects and mechanisms. Results showed that as the molecular weight KGMs decreased, the viscosity decreased, molecular flexibility increased, while chemical groups, crystal structures and main chains showed little change. KGMs with medium molecular weights (KGM-M1, KGM-M2) showed better effects on increasing body weight, decreasing levels of fasting blood glucose, insulin resistance, total cholesterol and low density lipoprotein cholesterol, and enhancing integrity of pancreas and colon, than KGMs with high or low molecular weights (KGM-H, KGM-L) in type 2 diabetic rats. Mechanism analysis suggested that KGM-M1 and KGM-M2 had higher antioxidant and anti-inflammatory activities on elevating superoxide dismutase, decreasing malondialdehyde and tumor necrosis factor-α levels. Moreover, KGM-M1 and KGM-M2 increased gut microbiota diversity, Bacteroidetes/Firmicutes ratio and Muribaculaceae, decreased Romboutsia and Klebsiella, and improved 6 diabetic related metabolites. Combined, KGM-M1 and KGM-M2 showed higher hypoglycemic effects, due to regulatory activities of antioxidant, anti-inflammatory, intestinal microbiota, and relieved metabolic disorders.

Taro koji of Amorphophallus konjac enabling hydrolysis of konjac polysaccharides to various biotechnological interest

Due to the indigestibility, utilization of konjac taro, Amorphophallus konjac has been limited only to the Japanese traditional konjac food. Koji preparation with konjac taro was examined to utilize konjac taro as a source of utilizable carbohydrates. Aspergillus luchuensis AKU 3302 was selected as a favorable strain for koji preparation, while Aspergillus oryzae used extensively in sake brewing industry was not so effective. Asp. luchuensis grew well over steamed konjac taro by extending hyphae with least conidia formation. Koji preparation was completed after 3-day incubation at 30°C. D-Mannose and D-glucose were the major monosaccharides found in a hydrolyzate giving the total sugar yield of 50 g from 100 g of dried konjac taro. An apparent extent of konjac taro hydrolysis at 55°C for 24 h seemed to be completed. Since konjac taro is hydrolyzed into monosaccharides, utilization of konjac taro carbohydrates may become possible to various products of biotechnological interest.

Effect of Konjac Glucomannan (KGM) on the Reconstitution of the Dermal Environment against UVB-Induced Condition

Skin layers serve as a barrier against unexpected critical changes in the body due to environmental factors. Excessive ultraviolet (UV) B exposure increases the levels of age-related factors, leading to senescent cells and damaged skin tissues. Widely used as a dietary supplement, konjac (Amorphophallus konjac) glucomannan (KGM) has shown skin regeneration potential in patch or sheet form with anti-inflammatory or immunosuppressive effects. However, the ability of KGM to reconstitute senescent/damaged skin following UV radiation has not been explored. Here, we demonstrate that KGM alleviates skin damage by increasing the proportion of young cell populations in UVB-exposed senescent human epidermal primary melanocytes. Young cell numbers increased depending on KGM dosage, but the senescent cells were not removed. Real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis showed that mRNA and protein levels of age- and pigmentation-related factors decreased in a manner dependent on the rate at which new cells were generated. Moreover, an analysis of mRNA and protein levels indicated that KGM facilitated youth by increasing cell proliferation in UVB-damaged human fibroblasts. Thus, KGM is a highly effective natural agent for maintaining skin homeostasis by promoting the reconstitution of the dermal environment against UVB-induced acute senescence or skin damage.