Natural Polysaccharides (natural + polysaccharide)

Distribution by Scientific Domains

Selected Abstracts

Study on the Kinetics for Enzymatic Degradation of a Natural Polysaccharide, Konjac Glucomannan

Guangji Li
Abstract The enzymatic degradation of konjac glucomannan (KGM) was conducted using ,-mannanase from an alkalophilic Bacillus sp. in the aqueous medium (pH 9.0) at 30C. The intrinsic viscosity ([,]), molecular weight (Mw) and molecular weight distribution (MWD) of the degraded KGM were measured. The mathematical relation between [,] and Mw, [,] = 5.06 10,4Mw0.754, was established. The kinetic analysis reveals a dependence of the rate constant (k) on the period of reaction and the initial substrate concentration (c0) over the range of substrate concentration (1.0,2.0%) used in this work. The results indicate that the enzymatic degradation of KGM is a complex reaction combining two reaction processes with different orders. In the initial phase of degradation k is inversely proportional to c0, which is characteristic of a zeroth-order reaction; while in the following phase k is independent of c0, implying the degradation follows a first-order reaction. The reactivity difference in breakable linkages of KGM, the action mechanism of an enzyme on KGM macromolecules, and the theory concerning the formation of an enzyme-substrate complex and ,substrate saturation' can be used to explain such a kinetic behavior. In addition, the enzymatic degradation of KGM was also carried out using the other enzymes like ,-mannanase from a Norcardioform actinomycetes, ,-glucanase Finizym and a compound enzyme Hemicell as a biocatalyst. By comparing and analyzing the degradation processes of KGM catalyzed by four different enzymes, it can be observed that there is a two-stage reaction with two distinct kinetic regimes over a certain range of degradation time for each of the degradation processes. These results are useful to realize controllable degradation of polysaccharides via an environmental benign process. [source]

PEI,PEG,Chitosan-Copolymer-Coated Iron Oxide Nanoparticles for Safe Gene Delivery: Synthesis, Complexation, and Transfection

Forrest M. Kievit
Abstract Gene therapy offers the potential of mediating disease through modification of specific cellular functions of target cells. However, effective transport of nucleic acids to target cells with minimal side effects remains a challenge despite the use of unique viral and non-viral delivery approaches. Here, a non-viral nanoparticle gene carrier that demonstrates effective gene delivery and transfection both in vitro and in vivo is presented. The nanoparticle system (NP,CP,PEI) is made of a superparamagnetic iron oxide nanoparticle (NP), which enables magnetic resonance imaging, coated with a novel copolymer (CP,PEI) comprised of short chain polyethylenimine (PEI) and poly(ethylene glycol) (PEG) grafted to the natural polysaccharide, chitosan (CP), which allows efficient loading and protection of the nucleic acids. The function of each component material in this nanoparticle system is illustrated by comparative studies of three nanoparticle systems of different surface chemistries, through material property characterization, DNA loading and transfection analyses, and toxicity assessment. Significantly, NP,CP,PEI demonstrates an innocuous toxic profile and a high level of expression of the delivered plasmid DNA in a C6 xenograft mouse model, making it a potential candidate for safe in vivo delivery of DNA for gene therapy. [source]

Electrospun Alginate Nanofibers with Controlled Cell Adhesion for Tissue Engineering,

Sung In Jeong
Abstract Alginate, a natural polysaccharide that has shown great potential as a cell scaffold for the regeneration of many tissues, has only been nominally explored as an electrospun biomaterial due to cytotoxic chemicals that have typically been used during nanofiber formation and crosslinking. Alginate cannot be electrospun by itself and is often co-spun with poly(ethylene oxide) (PEO). In this work, a cell adhesive peptide (GRGDSP) modified alginate (RA) and unmodified alginate (UA) were blended with PEO at different concentrations and blending ratios, and then electrospun to prepare uniform nanofibers. The ability of electrospun RA scaffolds to support human dermal fibroblast cell attachment, spreading, and subsequent proliferation was greatly enhanced on the adhesion ligand-modified nanofibers, demonstrating the promise of this electrospun polysaccharide material with defined nanoscale architecture and cell adhesive properties for tissue regeneration applications. [source]

Hydration of polysaccharide hyaluronan observed by IR spectrometry.

BIOPOLYMERS, Issue 1 2003

Abstract This article is the first one in a series dedicated to the study of hyaluronan as observed by IR spectrometry. The goal is to determine its hydration mechanism and the structural changes this mechanism implies. Hyaluronan is a natural polysaccharide that is widely used in biomedical applications and cosmetics. Its macroscopic properties are significantly dependent on its degree of hydration. In this article we record the IR spectrum of a several micron thick dried film and deduce that four or five residual H2O molecules remain around each disaccharide repeat unit in the dried film. We then compare the spectra of sodium hyaluronan and its acid form to assign vibrational bands linked to the carboxylate group. We proceed with a qualitative analysis of the spectral changes induced by changes of temperature and hygroscopicity, two independent parameters that act by modifying the hydrogen bond network of the sample. This enables us to assign most of the vibrational bands of the hydrophilic groups and to distinguish the bands that are due to these hydrophilic groups when they are or are not hydrogen bonded. It constitutes a prerequisite for the quantitative analysis of hydration spectra that will be described in the following articles of this series. 2002 Wiley Periodicals, Inc. Biopolymers (Biospectroscopy) 72: 10,20, 2003 [source]

Activation of phospholipase C pathways by a synthetic chondroitin sulfate-E tetrasaccharide promotes neurite outgrowth of dopaminergic neurons

Naoki Sotogaku
Abstract In dopaminergic neurons, chondroitin sulfate (CS) proteoglycans play important roles in neuronal development and regeneration. However, due to the complexity and heterogeneity of CS, the precise structure of CS with biological activity and the molecular mechanisms underlying its influence on dopaminergic neurons are poorly understood. In this study, we investigated the ability of synthetic CS oligosaccharides and natural polysaccharides to promote the neurite outgrowth of mesencephalic dopaminergic neurons and the signaling pathways activated by CS. CS-E polysaccharide, but not CS-A, -C or -D polysaccharide, facilitated the neurite outgrowth of dopaminergic neurons at CS concentrations within the physiological range. The stimulatory effect of CS-E polysaccharide on neurite outgrowth was completely abolished by its digestion into disaccharide units with chondroitinase ABC. Similarly to CS-E polysaccharide, a synthetic tetrasaccharide displaying only the CS-E sulfation motif stimulated the neurite outgrowth of dopaminergic neurons, whereas a CS-E disaccharide or unsulfated tetrasaccharide had no effect. Analysis of the molecular mechanisms revealed that the action of the CS-E tetrasaccharide was mediated through midkine-pleiotrophin/protein tyrosine phosphatase , and brain-derived neurotrophic factor/tyrosine kinase B receptor pathways, followed by activation of the two intracellular phospholipase C (PLC) signaling cascades: PLC/protein kinase C and PLC/inositol 1,4,5-triphosphate/inositol 1,4,5-triphosphate receptor signaling leading to intracellular Ca2+ concentration-dependent activation of Ca2+/calmodulin-dependent kinase II and calcineurin. These results indicate that a specific sulfation motif, in particular the CS-E tetrasaccharide unit, represents a key structural determinant for activation of midkine, pleiotrophin and brain-derived neurotrophic factor-mediated signaling, and is required for the neuritogenic activity of CS in dopaminergic neurons. [source]

Sedum telephium L. Polysaccharide Content Affects MRC5 Cell Adhesion to Laminin and Fibronectin

In traditional medicine the fresh leaves and juice of Sedum telephium L. are used as wound-healing promoters. Cell adhesion represents a primary event in wound repair and in tissue homeostasis, and therefore we have investigated the effect of Sedum juice and its main fractions, polysaccharides and flavonols, on human fibroblast (MRC5) adhesion to fibronectin and laminin. Our findings revealed that total Sedum juice strongly inhibited cell adhesion to laminin and fibronectin (EC50 1.03 0.12 mg mL,1). This anti-adhesive feature was concentrated mainly in the two polysaccharide fractions (EC50 values comprised between 0.09 and 0.44 mg mL,1). The flavonol fractions did not seem to contribute to this effect. A first attempt to elucidate the polysaccharide-related anti-adhesive feature of Sedum juice was also performed. The results confirmed that natural polysaccharides, with chemical structures different from heparin, were able to interfere with integrin-mediated cell behaviour and they contributed to the outstanding effects of Sedum juice and to the role of polysaccharides in cell-matrix interaction. [source]


Peggy Vauchel
Alginates are natural polysaccharides that are extracted from brown seaweeds and widely used for their rheological properties. The central step in the extraction protocol used in the alginate industry is the alkaline extraction, which requires several hours. In this study, a significant decrease in alginate dynamic viscosity was observed after 2 h of alkaline treatment. Intrinsic viscosity and average molecular weight of alginates from alkaline extractions 1,4 h in duration were determined, indicating depolymerization of alginates: average molecular weight decreased significantly during the extraction, falling by a factor of 5 between 1 and 4 h of extraction. These results suggested that reducing extraction time could enable preserving the rheological properties of the extracted alginates. [source]

Challenge of synthetic cellulose

Shiro Kobayashi
Abstract This article focuses on why and how the chemical synthesis of cellulose was accomplished. The synthesis of cellulose was an important, challenging problem for half a century in polymer chemistry. For the synthesis, a new method of enzymatic polymerization was developed. A monomer of ,- D -cellobiosyl fluoride (,-CF) was designed and subjected to cellulase catalysis, which led to synthetic cellulose for the first time. Cellulase is a hydrolysis enzyme of cellulose; cellulase, inherently catalyzing the bond cleavage of cellulose in vivo, catalyzes the bond formation via the polycondensation of ,-CF in vitro. It is thought that the polymerization and hydrolysis involve a common intermediate (transition state). This view led us to a new concept, a transition-state analogue substrate, for the design of the monomer. The preparation of cellulase proteins with biotechnology revealed the enzymatic catalytic functions in the hydrolysis and polymerization to cellulose. High-order molecular structures were in situ formed and observed as fibrils (cellulose I) and spherulites (cellulose II). In situ small-angle neutron scattering measurements suggested a fractal surface formation of a synthetic cellulose assembly. The principle of cellulose synthesis was extended to the synthesis of other natural polysaccharides, such as xylan and amylose, and unnatural polysaccharides. 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 693,710, 2005 [source]