Effect of degree of acetylation on thermoplastic and melt rheological properties of acetylated konjac glucomannan

Konjac glucomannan exerts regulatory effects on macrophages and its applications in biomedical engineering

Konjac glucomannan (KGM) molecular chains contain a small amount of acetyl groups and a large number of hydroxyl groups, thereby exhibiting exceptional water retention and gel-forming properties. To meet diverse requirements, KGM undergoes modification processes such as oxidation, acetylation, grafting, and cationization, which reduce its viscosity, enhance its mechanical strength, and improve its water solubility. Researchers have found that KGM and its derivatives can regulate the polarization of macrophages, inducing their transformation into classically activated M1-type macrophages or alternatively activated M2-type macrophages, and even facilitating the interconversion between M1 and M2 phenotypes. Concurrently, the modulation of macrophage polarization states holds significant importance for chronic wound healing, inflammatory bowel disease (IBD), antitumor therapy, tissue engineering scaffolds, oral vaccines, pulmonary delivery, and probiotics. Therefore, KGM has the advantages of both immunomodulatory effects (biological activity) and gel-forming properties (physicochemical properties), giving it significant advantages in a variety of biomedical engineering applications.

Production and Characterization of a Novel Exopolysaccharide from Ramlibacter tataouinensis

The current study examines the desiccation-resistant Ramlibacter tataouinensis TTB310^T as a model organism for the production of novel exopolysaccharides and their structural features. This bacterium is able to produce dividing forms of cysts which synthesize cell-bound exopolysaccharide. Initial experiments were conducted on the enrichment of cyst biomass for exopolysaccharide production under batch-fed conditions in a pilot-scale bioreactor, with lactate as the source of carbon and energy. The optimized medium produced significant quantities of exopolysaccharide in a single growth phase, since the production of exopolysaccharide took place during the division of the cysts. The exopolysaccharide layer was extracted from the cysts using a modified trichloroacetic acid method. The biochemical characterization of purified exopolysaccharide was performed by gas chromatography, ultrahigh-resolution mass spectrometry, nuclear magnetic resonance, and Fourier-transform infrared spectrometry. The repeating unit of exopolysaccharide was a decasaccharide consisting of ribose, glucose, rhamnose, galactose, mannose, and glucuronic acid with the ratio 3:2:2:1:1:1, and additional substituents such as acetyl, succinyl, and methyl moieties were also observed as a part of the exopolysaccharide structure. This study contributes to a fundamental understanding of the novel structural features of exopolysaccharide from a dividing form of cysts, and, further, results can be used to study its rheological properties for various industrial applications.

Review on Modification of Glucomannan as an Excipient in Solid Dosage Forms

Glucomannan (GM)-a polysaccharide generally extracted from the tuber of Amorphophallus konjac-has great potential as a filler-binder in direct compression, disintegrant in tablets, or gelling agent due to its strong hydrophilicity and extremely high viscosity. However, it has poor water resistance and low mechanical strength when used as an excipient in solid form. Several physical and chemical modifications have been carried out to improve these drawbacks. Chemical modification affects the characteristics of GM based on the DS. Carboxymethylation improves GM functionality by modifying its solubility and viscosity, which in turn allows it to bind water more efficiently and thus improve its elongation and gel homogeneity. Meanwhile, physical modification enhances functionality through combination with other excipients to improve mechanical properties and modify swelling ability and drug release from the matrix. This review discusses extraction of GM and its modification to enhance its applicability as an excipient in solid form. Modified GM is a novel excipient applicable in the pharmaceutical industry for direct compression, as a tablet disintegrant, a film-forming agent, and for encapsulation of macromolecular compounds or drug carriers for controlled release.

Box-Behnken design-based optimization for deproteinization of crude polysaccharides in Lycium barbarum berry residue using the Sevag method

Deproteinization of crude polysaccharides in the residue from Lycium barbarum berries (LBBs) was conducted using the Sevag method. A Box-Behnken design based on single-factor experiments was employed to optimize the deproteinization technology. The results showed that the deproteinization conditions had significant effects on the extraction yield of polysaccharides and the residual protein content in Lycium barbarum polysaccharides (LBP). The experimental data were fitted to a second-order polynomial equation, using multiple regression analysis with a high coefficient of determination (R²) value. The optimal conditions were as follows: a ratio of raw material to water extract concentrate from the residual LBBs of 0.15 g/mL; a ratio of chloroform to n-butyl alcohol of 2.17 mL/mL; and a ratio of water extract concentrate from residual LBBs to Sevag reagent of 0.50 mL/mL; with a maximum polysaccharide yield of 0.49% and minimum residual protein content of 0.087%. The results were confirmed through validation experiments. GPC analysis indicated that deproteinized LBP molecules became much more homogeneous. X-ray diffraction indicated that the hydrogen bonding of deproteinized LBP was weakened. This optimization of LBP should be a useful method for purification of crude LBP.

Optimising wheat straw alkali-organosolv pre-treatment to enhance hemicellulose modification and compatibility with reinforcing fillers

Hemicellulose acetylation, filler compatibility and film hydrophobicity were enhanced by optimising alkali-catalysed organosolv treatment conditions for wheat straw before hemicellulose extraction. Two optimum (OPT) conditions were established by varying organosolv components' concentrations [ethanol (EC) (50-80%) and NaOH (1-13%)], and time (2-6 h), in a Box-Behnken experimental design. The OPT1 (1% NaOH/50% EC/6h) that enhanced acetylation and filler compatibility, and OPT2 (13% NaOH/80% EC/5h) that enhanced hydrophobicity by minimising degree of acetylation (DS), uronic acid content and arabinose/xylose ratio. The films made from OPT2 hemicellulose had higher water contact angle (68.1°) than OPT1 hemicellulose (39.90°). However, OPT1 hemicellulose had a higher DS (1.7 vs 0.4), and their acetylated nanocellulose reinforced films had higher tensile strength (10.59 vs 4.87 MPa) and Young modulus (590.15 vs 323.64 MPa) than OPT2 hemicellulose. Therefore, hemicellulose acetylation, hydrophobicity and filler interaction can be engineered by manipulating the organosolv treatment conditions.

Effect of Various Temperatures on Bletillae Rhizoma Polysaccharide Extraction and Physicochemical Properties

Six fractional polysaccharides were prepared by water extraction and alcohol precipitation under controlled temperature from bletillae rhizoma, a traditional Chinese medicine. Based on this, yields of bletillae rhizome polysaccharides (RBPs) were obtained. The extracting temperature impacted the characteristics of the fractional polysaccharides. The fractional polysaccharides were characterized by glucomannan (GM) content, thermal stability, scanning electron microscopy (SEM), Fourier-transform infrared (FTIR) spectroscopy, gel permeation chromatography (GPC), and x-ray diffraction (XRD). For the analysis, 2.0% w/v dispersions of the six fractional polysaccharides were prepared and their flow behaviors were evaluated using a rotational rheometer. The results showed that increased extraction temperature led to increased GM extraction yields and extraction rate, but GM content was relative stable (over 90%). The average molecular weight (Mw) of fractional polysaccharides obtained at 30, 40, 50, 60, 70, and 80 °C was 3.598 × 104, 4.188 × 104, 8.632 × 104, 8.850 × 104, 2.372 × 105, and 3.081 × 105 g/mol, respectively. SEM revealed that fractional polysaccharides had a porous structure of different sizes and densities. Thermal analysis, FTIR, and XRD results indicated that extraction temperature affects the structure and moisture content of fractional polysaccharides. All results showed that the extraction temperature has an obvious impact on the morphology, molecular weight, and polydispersity of the RBPs. This simple process is a promising method for the preparation of fractional polysaccharides.

Characteristics of glucomannan isolated from fresh tuber of Porang (Amorphophallus muelleri Blume)

Porang is a potential source of glucomannan. This research objective was to find a direct glucomannan isolation method from fresh porang corm to produce high purity glucomannan. Two isolation methods were performed. In first method, sample was water dissolved using Al₂(SO₄)₃ as flocculant for 15 (AA15) or 30 (AA30) minutes with purification. In second method, sample was repeatedly milled using ethanol as solvent and filtered for 5 (EtOH5) or 7 (EtOH7) times without purification. The characteristics of obtained glucomannan were compared to those of commercial porang flour (CPF) and purified konjac glucomannan (PKG). High purity (90.98%), viscosity (27,940 cps) and transparency (57.74%) of amorphous glucomannan were isolated by EtOH7. Ash and protein level significantly reduced to 0.57% and 0.31%, respectively, with no starch content. Water holding capacity (WHC) of EtOH7 glucomannan significantly enhanced, whereas its solubility was lower than those of PKG due to its ungrounded native granular form.

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.

Study of Konjac Glucomannan Esterification with Dicarboxylic Anhydride and Effect of Degree of Esterification on Water Absorbency

Dicarboxylic anhydride esterified Konjac glucomannan (DCKGM) was prepared to reduce the unusual water absorbency of native Konjac Glucomannan (KGM). The dependence of degree of substitution (DS) on the reaction conditions and influence of the DS on water absorbency were studied. The esterification was conducted using refluxing KGM in hot acetic acid which contains phthalic anhydride and pyridine catalyst. The chemical structure and characteristic of DCKGM were analyzed by GPC-MALLS and FI-IR. The results showed that the water absorbency for DCKGM is inversely proportional to DS increase. DCKGM may be a promising biomaterial in application of drug carrier, heavy metal ion adsorption and functional packing materials.