Studies on Hydrogen Bonding Network Structures of Konjac Glucomannan

In this paper, the hydrogen bonding network models of konjac glucomannan （KGM） are predicted in the approach of molecular dynamics （MD）. These models have been proved by experiments whose results are consistent with those from simulation. The results show that the hydrogen bonding network structures of KGM are stable and the key linking points of hydrogen bonding network are at the O（6） and O（2） positions on KGM ring. Moreover, acety has significant influence on hydrogen bonding network and hydrogen bonding network structures are more stable after deacetylation.

Study on Molecular Chain Morphology of Konjac Glucomannan

The long-range structure of konjac glucomannan(KGM)is studied by using laser light scatter(LLS), gel permeation chromatography(GPC)and method of viscosidity. The weight-average molecular weight(Mw), root-mean-square ratio of gyration[(S2)1/2], second viral coefficient(A2)and multi-dispersion coefficient(Mw/Mn)are 1.04×106, 105. 0±0. 9 nm,(-1. 59±0.28)×10-3 mol ml g-2 and 1.015±0.003, respectively. Mark-Houwink equation is established as [η] = 5. 96×10-2Mw0.73 and the molecular chain parameters are as follows: ML=982. 82 nm-1, Lp = 27. 93 nm, d = 0. 74 nm, h = 0. 26 nm, L = l 054.11 nm. Further more molecular chain morphology of KGM is studied by using atom force microscope(AFM)and transmission electronic microscope(TEM), and the result shows that the KGM molecular is an extending semi-flexible linear chain without branch. Therefore, the image of molecular chain morphology confirms the deduction drawn by Mark-Houwink equation and molecular chain parameters.

Dynamics Study of the Influence of Temperature on Konjac Glucomannan Saline Solution’s Viscosity

Molecular dynamics （MD） method is adopted to simulate the conformation variations of konjac glucomannan （KGM） saline solution at different temperatures, and structurally analyze the trends and reasons of viscosity change in KGM saline solution with temperature. The experimental results have been analyzed to find out that the sum of formative hydrogen bonds decreases with the rise of temperature and the amount of intramolecular hydrogen bonds suddenly increases at 323 K. Besides, in terms of molecular orbital data obtained from simulation, we can know that hydrogen bonding energy also decreases with the rise of temperature. Therefore, we can predict the viscosity of KGM saline solution decreases gradually when rising the temperature.

Studies on Single Chain Structure of Konjac Glucomannan

The simulation is carried out by employing the method of molecular dynamics with the single chain of konjac glucomannan （KGM） in vacuum as the structural model to discuss the factors that affect the single chain structure, the dynamic structure of the chain and the acting forces that maintain the chain structure. The results show that the shape and stability of the chain are affected by the degree of polymerization. As for the KGM with high degree of polymerization, its chain presents random coiling state and its stability declines. Both before and after deacetylation in the process of dynamic motion, the chain of KGM presents random coiling state with periodic variation of extension and coil and demonstrates favorable flexibility, indicating acetyl is not the main factor that affects the shape of chain, whereas dihedral angle and static actions are respectively the key bonding and nonbonding acting forces that influence the single chain conformations in vacuum.

Analysis of Influential Factors of Konjac Glucomannan(KGM) Molecular Structure on Its Activity

Biological activity of konjac glucomannan is closely related to its structure,in particular to its high-level structure.Researches on the activity mechanism of konjac glucomannan are significant for revealing the mysteries of participation in life activity.In this paper,analysis of the effects of konjac glucomannan configuration and various factors on its structure and activity was conducted,mechanism of biological activity of konjac glucomannan was explored,and the hot research topic of konjac glucomannan was given.

Hydrogen Bond Networks' QSAR and Topologica Analysis of Konjac Glucomannan Chains

Based on the knot theory and researching of network structures of glucomannan molecules, the polysaccharides were analyzed. The link prediction analysis is to further reveal the interactions between polysaccharides, to elaborate QSAR of polysaccharides, and to analyze the network conformation relationships among polysaccharides. We made a classification for glucomannan molecules based on the related domestic and international theories, and investigated their network structures and application prospects. The knot theory and the link predictions not only simplify the glucomannan microscopic descriptions but also play a guiding role in predicting and regulating the structures.

Studies on the Molecular Chain Conformation Stability of Aminated Konjac Glucomannan

Konjac glucomannan （KGM） was aminated by 2-chloroethyl-amine （CEA） as reagent so as to study the influence of concentration of CEA （based on the amount of KGM）, concentration of NaOH, reaction time and temperature on the extent of amination. And the molecular simulation technology was adopted to analyze the conformation stability of aminate （AKGM）. The results indicate that when the amount of CEA is higher, the extent of amination is higher. The optimum concentration of NaOH, reaction time and temperature are 10% NaOH, 70 ℃ and 45 rain, respectively. IR shows KGM is successfully aminated. The conformation of AKGM is in a random clew-like shape.

Study on the Hydration Shell of Single-helical of Konjac Glucomannan

The local maxima of water density in the space near the single-helical of Konjac glucomannan as well as the dominant conformation of the system was studied by molecular dyna-mics under the water environment. The results indicate that the hydration shell,potential energy,and its hydrogen bond network with water bridges of the left-handed single-helix conformation was favored compared to those of right-handed single-helix conformation. This work suggests that the left-handed single-helix conformation was the dominant conformation of KGM in the water environment.

Quantum Mechanical Analysis of Sodium Alginate Effects on the Konjac Glucomannan Stability

Konjac glucomannan （KGM） and sodium alginate were chosen as the research objects, and the hydrogen bond conformation of compound system was studied with the molecular dynamics simulation, which simulated the energy variety in composite process. Combining with Hamiltonian in quantum mechanics calculation, the mechanism of hydrogen bond in KGM and sodium alginate compound system stability was analyzed from a micro angle. The results showed that, the hydrogen bonds occurring between the molecule of KGM and sodium alginate are in large number, and they mainly appeared between the -OH on C（6）, C（3） in the mannose residues of KGM and C（2）, C（3） of sodium alginate. The formation of hydrogen bonds results in the energy expectation value of the Hamiltonian thermal density matrix of the compound system to be negative, the energy of the system to decrease, and the compounds tending to form stable conformations.

Gelation and Swelling Behavior of Oxidized Konjac Glucomannan/Chitosan Hydrogel

The gelating and swelling mechanisms of the hydrogel formed from oxidized konjac glucomannan (OKGM) and chitosan (CS) were studied by Fourier transform infrared (FT-IR) spectrometry. FT-IR spectra illustrate that the interaction of polysaccharides forms the hydrogen bonds and interchain salt bonds and the dissocation of which dominates the swelling behavior in buffer solutions of different pH. The concentration of salt ion has effect on swelling behavior through the difference of salt ion concentration between in solution and in network of hydrogel, which causes penetrating pressure. Moreover, the Swelling degree and hydrogel strength could be modulated by varying conditions. It is indicated that the hydrogel has pH-sensitive and salt ion sensitive properties. The prepared optimum condition selected by varying conditions is thatr=0.2;t=30 min;T p

Studies on the Hydrogen Bonding Network Structures of Amino-konjacglucomannan-zinc Chelate

Amino-Konjacglucomannan （NH2-KGM） was prepared through the reaction of ammonium hydroxide with KGM by ultrasonic. The influence of amount of ammonium hydroxide, concentration of KGM and ultrasonic time on the extent of amination was studied. Then, NH2-KGM and zinc sulfate were used as materials for the preparation of NH2-KGM-Zn complex. The results indicated that the extent of amination increases with increasing the ammonium hydroxide. The optimum concentration of KGM and ultrasonic time are 0.3% and 75 rain respectively. IR showed KGM is successfully aminated and NH2-KGM forms stable complex with zinc（II ）. The hydrogen bonding network structures of NH2-KGM-Zn are more stable and the key linking points of hydrogen bonding network are at the OH（6） and 0（3） positions of mannose and OH（2） of glucose and 0（3） of mannose on the KGM ring. It is more favorable for NH2-KGM-Zn to form intermolecular hydrogen bonds between KGM.

Incorporation ofκ-carrageenan improves the practical features of agar/konjac glucomannan/κ-carrageenan ternary system

Three materials(agar,konjac glucomannan(KGM)andκ-carrageenan)were used to prepare ternary systems,i.e.,sol-gels and their dried composites conditioned at varied relative humidity(RH)(33%,54%and 75%).Combined methods,e.g.,scanning electron microscopy,small-angle X-ray scattering,infrared spectroscopy(IR)and X-ray diffraction(XRD),were used to disclose howκ-carrageenan addition tailors the features of agar/KGM/κ-carrageenan ternary system.As affirmed by IR and XRD,the ternary systems withκ-carrageenan below 25%(agar/KGM/carrageenan,50:25:25,m/m)displayed proper component interactions,which increased the sol-gel transition temperature and the hardness of obtained gels.For instance,the ternary composites could show hardness about 3 to 4 times higher than that for binary counterpart.These gels were dehydrated to acquire ternary composites.Compared to agar/KGM composite,the ternary composites showed fewer crystallites and nanoscale orders,and newly-formed nanoscale structures from chain assembly.Such multi-scale structures,for composites withκ-carrageenan below 25%,showed weaker changes with RH,as revealed by especially morphologic and crystalline features.Consequently,the ternary composites with lessκ-carrageenan(below 25%)exhibited stabilized elongation at break and hydrophilicity at different RHs.This hints to us that agar/KGM/κ-carrageenan composite systems can display series applications with improved features,e.g.,increased sol-gel transition point.

Effect of High Hydrostatic Pressure Processing on the Structure and Property of Konjac Glucomannan–Casein Mixture

High hydrostatic pressure（HHP） processing is applied to a Konjac glucomannan（KGM）-casein（CS） mixture to explore the changes in the mixture＇s properties and microstructures.The mixture＇s viscosity increases by -18.1% at low HHP（200 MPa） and decreases by about 5.3-31.7% at high HHP（600 MPa）.Scanning electron microscopy analysis shows that low HHP induces a denser and more compact structure,and high HHP leads to a porous and reticular structure.X-ray diffraction shows that the mixture is amorphous without dramatic changes; only some small crystalline peaks appear under excessive pressure.Fourier transform infrared analysis indicates that the non-covalent interactions（hydrogen bonds,etc.） are probably the most important factors for the modification of mixture properties.Bonding enhances under low pressure,and weakens with increasing pressure and time.

Formation of composite hydrogel of carboxymethyl konjac glucomannan/gelatin for sustained release of EGCG

Development of functional bioinspired hydrogels that have good releases control character is necessary for the application of these materials in biomedical engineering.Herein,we report a composite hydrogel prepared from several biocompatible carboxymethyl konjac glucomannan(CKGM)/gelatin(G)/tannic acid(TA)functional nano-hydroxyapatite(TA@n-HA),which has good biodegradability and pH sensitivity.The mechanism of interaction between hydrogels was confirmed by Fourier transform infrared spectroscopy,X-ray diffraction,Scanning electron microscopy and Thermogravimetric analysis.The physico-chemical properties of CKGM/G hydrogels have been significantly improved through the incorporation of TA@n-HA within the matrix.Studies in the sustained release of epigallocatechin gallate(EGCG)demonstrated that the TA@n-HA/CKGM/G hydrogels exhibit not only better pH sensitive properties,but also enhanced biocompatibility and encapsulation in comparison to the matrix devoid of TA@n-HA.Consequently,TA@n-HA/CKGM/G hydrogels using EGCG as a drug release model show the potential for drug delivery.

Konjac glucomannan enhances 5-FU-induced cytotoxicity of hepatocellular carcinoma cells via TLR4/PERK/CHOP signaling to induce endoplasmic reticulum stress

5-Fluorouracil(5-FU)is a commonly used chemotherapeutic agent for various cancers.However,the drug resistance developed by tumor cells hinders the therapeutic effect.Konjac glucomannan(KGM)is indicated to sensitize 5-FU-resistant hepatocellular carcinoma(HCC)cells to 5-FU.In our study,we found that KGM or 5-FU treatment alone did not affect the malignant cell behaviors and endoplasmic reticulum(ER)stress of 5-FU-resistant HCC cells or HepG2/5-FU and Bel-7402/5-FU cells,while cotreatment with KGM and 5-FU significantly facilitated HCC cell apoptosis and ER stress and suppressed cell proliferation potential and migration abilities.Moreover,we explored the underlying mechanism by which KGM induces 5-FU cytotoxicity in HCC cells.We found that Toll-like receptor 4(TLR4)was downregulated in KGM-and 5-FU-treated HCC cells.TLR4 overexpression reversed the KGM and 5-FU cotreatment-induced inhibition of the malignant behaviors of 5-FU-resistant HCC cells.Furthermore,KGM enhanced 5-FU-induced ER stress by inhibiting TLR4 to activate PERK/ATF4/CHOP signaling.Xenograft mouse models were established using HepG2/5-FU cells,and KGM was demonstrated to reverse 5-FU resistance in HCC tumors in vivo by suppressing TLR4 to enhance ER stress and activate PERK/ATF4/CHOP signaling.In conclusion,KGM combined with 5-FU treatment significantly promoted apoptosis and reduced cell proliferation,migration and ER stress in 5-FU-resistant HCC cells compared with KGM or 5-FU treatment alone by downregulating TLR4 to activate PERK/ATF4/CHOP signaling.

Zein/konjac glucomannan复合颗粒制备的Pickering乳液稳定性研究

Pickering乳液因其稳定性好、生物相容性高和无表面活性剂的优势而备受关注.食品级颗粒乳化剂稳定的Pickering乳液作为具有生物活性物质的输送载体的研究相对较少.将玉米醇溶蛋白(Zein,Z)与魔芋葡甘聚糖(konjac glucomannan,K)通过不同质量比制备了一系列的复合颗粒以稳定Pickering乳液,并探究了Pickering乳液的储藏稳定性及其消化特性.结果表明:玉米醇溶蛋白/魔芋葡甘聚糖(Zein/konjac glucomannan,Z/K)复合颗粒能够稳定Pickering乳液,当质量比Z/K=2:1,4:3,1:1(w/w)时,复合颗粒稳定的Pickering乳液可稳定放置110天;荷载姜黄素的乳液经过1小时体外模拟胃消化和2小时的体外模拟肠消化,游离脂肪酸(free fatty acid,FFA)释放率以91.56±4.62%(玉米油)> 55.05±7.09%(Z/K复合颗粒稳定的Pickering乳液)> 46.87±5.56%(Tween20稳定的乳液)的顺序递减,姜黄素的生物利用度以5.87±0.94%(玉米油)<8.84±0.32%(Tween20稳定的乳液)<9.81±0.24%(Z/K复合颗粒稳定的Pickering乳液)的顺序逐渐增加. Z/K复合颗粒界面层的空间阻碍作用保护了Pickering乳液中的姜黄素.该研究将有助于蛋白质颗粒稳定的Pickering乳液物理化学特性的进一步研究,为口服功能性食品原料的应用提供理论依据.

Preparation and Investigation on Novel Biodegradable Films Based on Konajac Glucomannan and Palmitoylated Konjac Glucomannan

Konjac glucomannan(KGM) has been generally used in food,film-former and biomedical applications,especially in the edible packing films due to its excellent film-forming ability,good biocompatibility and biodegrade-ability.It has the common flaws of natural polymers,such as low mechanical properties and poor antimicrobial activity,which severely limit their applications.In this paper,novel biodegradable films(NBF) of KGM with palmitoylated KGM(PKGM) were prepared by using the solventcasting technique.The structure,thermal and mechanical properties of the NBF were investigated.The results suggested that a strong hydrogen bonding was formed in NBF,which resulted in good miscibility between KGM and PKGM.The tensile strength and elongation at break of the NBF were enhanced significantly with the increase of PKGM in a certain range.With the addition of 0.75%PKGM by weight,tensile strength and elongation at break of NBF were improved largely to 117.12 MPa and 14.39%.From this work,we hope to provide one of the promising ways to design new edible food films and coatings materials with good mechanical properties.

Effect of carboxymethyl konjac glucomannan coating on curcumin-loaded multilayered emulsion:stability evaluation

The stability against various environmental stresses of the curcumin-loaded secondary and tertiary emulsions that was emulsified by whey protein isolate(WPI)and coated by chitosan(CHI),carboxymethyl konjac glucomannan(CMKGM),or their combination through layer-by-layer assembly was investigated.Generally,the multilayered emulsions were destabilized in high Na Cl concentrations or medium p H that could interrupt the electrostatic interaction between the three polyelectrolytes or deprotonate CHI,indicating that electrostatic interaction played an important role in the stability of emulsions.Compared with the primary emulsion that was solely stabilized by WPI,extra coating with CHI and CMKGM generally increased the stability of the emulsion against repeated freezing-thawing,improved the retention of curcumin against heating,UV irradiation,and long-term storage,and the effects were more remarkable in the tertiary emulsion with CMKGM locating in the outmost layer.Since CMKGM has shown the colon-targeted delivery potency,the multilayered emulsions assembled by layer-by-layer deposition,especially the tertiary emulsion,could be used as an effective carrier for the targeted delivery of curcumin.

Synthesis and Characterization of Phosphated Konjac Glucomannan Hydrogels

Konjac glucomannan （KGM） was crosslinked with sodium tripolyphosphate （STPP） to synthesize hydrogels. The crosslinking reaction was confirmed by FT-IR. The results of degradation test show that the hydrogels retain the enzymatic degradation character of KGM and can be degraded for 74.45% in 5 days by cellulase E0240.

Study on Gel Formation Mechanism of Konjac Glucomannan

The transformation of molecular conformation after gelatinization of konjac glucomannan is characterized by means of GC, GPC, FT-IR, DSC, XRD and TEM. The results showed that the molecule of KGM had no branch, the monose composition and connecting type of the molecular chain had no change, the transformation of molecule weight was little, and its drying powder sample formed an evidently new crystalline region. The hollow double helix structure of KGM in hydrosol changed from stretch chain into intercross and entwisted after gelatinization. The gelatin formation mechanism of konjac glucomannan is thereby expounded.