Synthesis of curdlan sulfates having inhibitory effects in vitro against AIDS viruses HIV-1 and HIV-2

Plant type II arabinogalactan: Structural features and modification to increase functionality

Type II arabinogalactans (AGs) are a highly diverse class of plant polysaccharides generally encountered as the carbohydrate moieties of certain extracellular proteoglycans, the so-called arabinogalactan-proteins (AGPs), which are found on plasma membranes and in cell walls. The basic structure of type II AG is a 1,3-β-D-galactan main chain with 1,6-β-D-galactan side chains. The side chains are further decorated with other sugars such as α-l-arabinose and β-d-glucuronic acid. In addition, AGs with 1,6-β-D-galactan as the main chain, which are designated as 'type II related AG' in this review, can also be found in several plants. Due to their diverse and heterogenous features, the determination of carbohydrate structures of type II and type II related AGs is not easy. On the other hand, these complex AGs are scientifically and commercially attractive materials whose structures can be modified by chemical and biochemical approaches for specific purposes. In the current review, what is known about the chemical structures of type II and type II related AGs from different plant sources is outlined. After that, structural analysis techniques are considered and compared. Finally, structural modifications that enhance or alter functionality are highlighted.

Exploiting diol reactivity for the access to unprecedented low molecular weight curdlan sulfate polysaccharides

Curdlan is a bacterial sourced polysaccharide, consisting of a linear backbone of β-1 → 3-linked glucose (Glc) units. The high interest in pharmaceutical applications of curdlan and derivatives thereof is fueling the study of multi-step sequences for regioselective modifications of its structure. Here we have developed semi-synthetic sequences based on a regioselective protection-sulfation-deprotection approach, allowing the access to some, new, low molecular weight curdlan polysaccharide derivatives with unprecedented sulfation patterns. Three different semi-synthetic schemes were investigated, all relying upon the installation of a cyclic benzylidene protecting group on Glc O-4,6-diols, followed by either direct sulfation and deprotection, or some additional steps - including a hydrolytic or oxidative cleavage of the benzylidene rings - prior to sulfation and deprotection. The six obtained polysaccharides were subjected to a detailed structural characterization by 2D-NMR analysis, revealing that some of them showed the majority of Glc units along the polymeric backbone decorated by unprecedented sulfation motifs.

Exploiting the Amazing Diversity of Natural Source-Derived Polysaccharides: Modern Procedures of Isolation, Engineering, and Optimization of Antiviral Activities

Naturally occurring polysaccharide sulfates are highly diverse, owning variations in the backbone structure, linkage pattern and stereochemistry, branching diversity, sulfate content and positions of sulfate group(s). These structural characteristics bring about diverse sulfated polymers with dissimilar negative charge densities and structure-activity relationships. Herein, we start with a short discussion of techniques needed for extraction, purification, chemical sulfation, and structural characterization of polysaccharides. Processes of isolation and sulfation of plant-derived polysaccharides are challenging and usually involve two steps. In this context, we describe an integrated extraction-sulfation procedure that produces polysaccharide sulfates from natural products in one step, thereby generating additional pharmacological activities. Finally, we provide examples of the spectrum of natural source-derived polysaccharides possessing specific features of bioactivity, in particular focusing on current aspects of antiviral drug development and drug-target interaction. Thus, the review presents a detailed view on chemically engineered polysaccharides, especially sulfated derivatives, and underlines their promising biomedical perspectives.

Hybrid Curdlan Poly(γ -Glutamic Acid) Nanoassembly for Immune Modulation in Macrophage

A nanoformulation composed of curdlan, a linear polysaccharide of 1,3-β-linked d-glucose units, hydrogen bonded to poly(γ -glutamic acid) (PGA), was developed to stimulate macrophage. Curdlan/PGA nanoparticles (C-NP) are formulated by physically blending curdlan (0.2 mg mL^-1 in 0.4 m NaOH) with PGA (0.8 mg mL^-1 ). Forster resonance energy transfer (FRET) analysis demonstrates a heterospecies interpolymer complex formed between curdlan and PGA. The ¹ H-NMR spectra display significant peak broadening as well as downfield chemical shifts of the hydroxyl proton resonances of curdlan, indicating potential intermolecular hydrogen bonding interactions. In addition, the cross peaks in ¹ H-¹ H 2D-NOESY suggest intermolecular associations between the OH-2/OH-4 hydroxyl groups of curdlan and the carboxylic-/amide-groups of PGA via hydrogen bonding. Intracellular uptake of C-NP occurs over time in human monocyte-derived macrophage (MDM). Furthermore, C-NP nanoparticles dose-dependently increase gene expression for TNF-α, IL-6, and IL-8 at 24 h in MDM. C-NP nanoparticles also stimulate the release of IL-lβ, MCP-1, TNF-α, IL-8, IL-12p70, IL-17, IL-18, and IL-23 from MDM. Overall, this is the first demonstration of a simplistic nanoformulation formed by hydrogen bonding between curdlan and PGA that modulates cytokine gene expression and release of cytokines from MDM.

Structural Features, Modification, and Functionalities of Beta-Glucan

Β-glucan is a strongly hydrophilic non-starchy polysaccharide, which, when incorporated in food, is renowned for its ability to alter functional characteristics such as viscosity, rheology, texture, and sensory properties of the food product. The functional properties of β-glucans are directly linked to their origin/source, molecular weight, and structural features. The molecular weight and structural/conformational features are in turn influenced by method of extraction and modification of the β-glucan. For example, whereas physical modification techniques influence only the spatial structures, modification by chemical agents, enzyme hydrolysis, mechanical treatment, and irradiation affect both spatial conformation and primary structures of β-glucan. Consequently, β-glucan can be modified (via one or more of the aforementioned techniques) into forms that have desired morphological, rheological, and (bio)functional properties. This review describes how various modification techniques affect the structure, properties, and applications of β-glucans in the food industry.

Sulfated polysaccharides from Rhodiola sachalinensis reduce d-gal-induced oxidative stress in NIH 3T3 cells

In this study, three sulfated polysaccharides (S-RSP_1-2, S-RSP_1-4 and S-RSP_1-8) from Rhodiola sachalinensis were produced by chlorosulfonic acid-pyridine method. d-gal was used to develop an oxidative stress model in the mouse embryonic fibroblast cell line NIH 3T3. Effects of the three sulfated polysaccharides on d-gal-induced oxidative stress were investigated. The results showed that S-RSP_1-4 improved the viability of the d-gal-induced oxidative stress in NIH 3T3 cells. The sulfated polysaccharides were found to have a better protective effect against d-gal-induced oxidative stress as compared to the native polysaccharide. Scanning electronmicroscopy also showed a significant change in the surface morphology of sulfated polysaccharides. In addition, the sulfated polysaccharides had noticeable DPPH radical-scavenging activity. In summary, our results demonstrated that d-gal was able to induce oxidative stress in NIH 3T3 cells, and sulfated group might play an important role in resistance to d-gal-induced oxidative damage.

Design, synthesis, and biomedical applications of synthetic sulphated polysaccharides

This review summarizes the synthetic methods to sulphated polysaccharides, describes their compositional and structural diversity in regards to activity, and showcases their biomedical applications.

In vitro investigations on the effects of semi-synthetic, sulphated carbohydrates on the immune status of cultured common carp (Cyprinus carpio) leucocytes

The rapid emergence of drug resistance, unfavourable immunosuppression and mounting evidence to suggest the deleterious accumulation of drug breakdown residues within animal tissues has driven a strong desire to move away from these current methods of disease control. Some natural products such as β-glucan, which are extracted from, for example, plants and fungi, are able to modulate the immune system and increase protection against diseases. However, these products are heterogeneous and their effects can be variable thus limiting their applicability and reliability. Carbohydrates were modified via chemical sulphation and these semi-synthetic, sulphated carbohydrates analysed for their immunological activity utilising carp pronephric cells and a carp leucocyte cell line (CLC). A sulphated β(1,4)-glucan, methyl hydroxyethyl cellulose sulphate (MHCS), demonstrated a stimulatory effect on fish immune cells. MHCS induced a range of bioactive effects in carp leucocyte cells whilst not affecting cell viability when cells were exposed for 24 h at concentrations of 1-150 μgml^-1. MHCS stimulated the innate immune system where a significant increase in respiratory burst activity was observed at concentrations 25-250 μgml^-1 in comparison to control (sterile water), cellulose ether, MacroGard^® and zymosan. Also, under in mock bacterial and viral infection conditions i.e. Lipopolysaccharide (LPS) and polyinosinic:polycytidylic acid (Poly(I:C)), MHCS enhanced the immune responses of pronephric cells by stimulating the respiratory burst activity at concentrations 50 and 150 μgml^-1. MHCS also enhanced the expression of cytokines including interleukin 1 beta (IL1β), tumor necrosis factor alpha 1 and 2 (TNFα 1,2), interferons alpha 2 (IFN α2) and inducible nitric oxide synthase (iNOS) in carp pronephric cells. It is proposed that this new semi-synthetic carbohydrate is a potential candidate for the development of a new generation of immunostimulants and adjuvants for use in vaccination strategies in aquaculture.

Identification of Heparin Modifications and Polysaccharide Inhibitors of Plasmodium falciparum Merozoite Invasion That Have Potential for Novel Drug Development

Despite recent successful control efforts, malaria remains a leading global health burden. Alarmingly, resistance to current antimalarials is increasing and the development of new drug families is needed to maintain malaria control. Current antimalarials target the intraerythrocytic developmental stage of the Plasmodium falciparum life cycle. However, the invasive extracellular parasite form, the merozoite, is also an attractive target for drug development. We have previously demonstrated that heparin-like molecules, including those with low molecular weights and low anticoagulant activities, are potent and specific inhibitors of merozoite invasion and blood-stage replication. Here we tested a large panel of heparin-like molecules and sulfated polysaccharides together with various modified chemical forms for their inhibitory activity against P. falciparum merozoite invasion. We identified chemical modifications that improve inhibitory activity and identified several additional sulfated polysaccharides with strong inhibitory activity. These studies have important implications for the further development of heparin-like molecules as antimalarial drugs and for understanding merozoite invasion.

Anti-angiogenic activity and mechanism of a chemically sulfated natural glucan from Phellinus ribis

A sulfated polysaccharide named PRP-S16 was obtained by sulfation of a glucan from Phellinus ribis using the chlorosulfonic acid method. PRP-S16 could significantly block the formation of new vessels in chicken chorioallantoic membrane (CAM). It could also inhibit the proliferation, migration, and tube formation and significantly reduced the mRNA expression of vascular endothelial growth factor (VEGF) in EA.hy926 endothelial cells. Western blotting indicated that PRP-S16 down regulated the protein expression of VEGF and VEGF receptor-1 (VEGFR-1), and inhibited the phosphorylation of VEGFR-2, protein kinase B (Akt) and extracellular signal-regulated kinase (ERK1/2) in EA.hy926 cells. These findings suggest that the mechanism of action of the anti-angiogenesis activity of PRP-S16 is related to the inhibition of VEGF-induced signaling pathway. PRP-S16 might be utilized as an effective antagonist in combating diseases associated with angiogenesis.

A semi-synthetic glycosaminoglycan analogue inhibits and reverses Plasmodium falciparum cytoadherence

A feature of mature Plasmodium falciparum parasitized red blood cells is their ability to bind surface molecules of the microvascular endothelium via the parasite-derived surface protein Plasmodium falciparum erythrocyte membrane protein 1 (PfEMP1). This ligand is associated with the cytoadherence pathology observed in severe malaria. As pRBC treated with effective anti-malarial drugs are still able to cytoadhere, there is therefore a need to find an adjunct treatment that can inhibit and reverse the adhesion process. One semi-synthetic, sulfated polysaccharide has been identified that is capable of inhibiting and reversing sequestration of pRBC on endothelial cells in vitro under physiological flow conditions. Furthermore, it exhibits low toxicity in the intrinsic (APTT assay) and extrinsic (PT assay) clotting pathways, as well as exhibiting minimal effects on cell (HUVEC) viability (MTT proliferation assay). These findings suggest that carbohydrate-based anti-adhesive candidates may provide potential leads for therapeutics for severe malaria.

Improved curdlan production with discarded bottom parts of Asparagus spear

BACKGROUND

This work evaluated the improvement of curdlan production of Agrobacterium sp. ATCC 31749 by using culture medium containing juice of discarded bottom part of green Asparagus spear (MJDA). Curdlan production was carried out using Agrobacterium sp. ATCC 31749 in flasks with different volumes of MJDA and its non-juice-adding control (CK) incubated in shaker at 30 °C, 200 rpm rotation for 168 h.

RESULTS

All MJDA media increased Agrobacterium sp. ATCC 31749 cell mass and enhanced the cells' ability to utilise sucrose, the carbon source for curdlan biosynthesis, and thereby produced higher concentration of curdlan than CK which is used for commercial production of curdlan. After 168 h of fermentation, 10% MJDA produced 40.2 g/l of curdlan whiles CK produced 21.1 g/l. Curdlan production was increased by 90.4% higher in 10% MJDA than CK. Curdlan produced by 10% MJDA contains 1.2 and 1.5 µg/ml of Asparagus flavonoids and saponins respectively as additives which have wide range of health benefits. The mass of sucrose needed to produce 1.0 g curdlan by Agrobacterium sp. ATCC 31749 in CK is 1.7-fold more than in 10% MJDA.

CONCLUSION

The results strongly revealed that 5-10% MJDA is a good curdlan fermentation media which increase curdlan production yield with cheaper cost of production and simultaneously reduce environmental waste resulting from the large scaled discarded bottom parts of green Asparagus spear during Asparagus production.

"Click" chemistry mediated construction of cationic curdlan nanocarriers for efficient gene delivery

A cationic group has been quantitatively and selectively introduced into C6 position of each glucose units of Curdlan by "Click Chemistry" successfully. The resulting cationic Curdlan-Imidazole-lysine polymers (Cur-6-100Lys) exhibit excellent water solubility. Structure of the Cur-6-100Lys complexes was verified by FTIR and NMR spectroscopic measurements, and analysis of Cur-6-100Lys by GPC, DLS and SEM revealed that they have stoichiometric, nanosized spheroidal structures. Cytotoxicity measurement, electrophoretic mobility shift assay and EGFP-pDNA transfection have been carried out respectively. The results clearly show that Cur-6-100Lys nanocarriers have bound to dsDNA promptly, are less cytotoxic to both 7901 cells and HeLa cells, and are readily able to transport EGFP-pDNA into HepG2 cells. Our studies indicated that Cur-6-100Lys can potentially be used as a versatile nano platform for efficient gene delivery in living cells.

Antitumor activities and immunomodulatory of rice bran polysaccharides and its sulfates in vitro

Polysaccharides purified from rice bran show antitumor activity against tumor cells, yet the mechanism of this action remains poorly understood. To address this issue, our study evaluated the effect of rice bran polysaccharides on mouse melanoma cell line B16, and Raw264.7 macrophages. Rice bran polysaccharides (RBP) failed to inhibit B16 cell growth in vitro. However, Raw264.7 macrophages treated by RBP enhancement of cytotoxic effects. The cytotoxicity was confirmed by the stimulation of nitric oxide (NO) production and tumor necrosis factor-α (TNF-α) secretion on Raw264.7 macrophages in a dose-dependent manner. RBP2, a fraction of RBP, notably enhanced the inhibition of B16 cells and boosted the immunepotentiation effect compared with RBP. To further enhance the inhibition of B16 cell growth, sulfated polysaccharides (SRBP) was derived using the chlorosulfonic acid-pyridine method. SRBP2 was found to suppress B16 cell growth, reduce B16 cell survival and stimulate NO and TNF-α production. However, SRBP2 displayed a cytotoxic effect on Raw264.7 macrophages. These results suggest that the antitumor activity of RBP and RBP2 is mediated mainly through the activation of macrophages. SRBP2 exerts its antitumor activity by inducing apoptosis in tumor cells and the secretion of NO and TNF-α.

Cell Type-Specific Delivery of RNAi by Ligand-Functionalized Curdlan Nanoparticles: Balancing the Receptor Mediation and the Charge Motivation

Tissue-specific delivery of therapeutic RNAi has great potential for clinical applications. Receptor-mediated endocytosis plays a crucial role in targeted delivery of biotherapeutics including short interfering RNA (siRNA). Previously we reported a novel Curdlan-based nanoparticle for intracellular delivery of siRNA. Here we designed a nanoparticle based on ligand-functionalized Curdlan. Disaccharides were site-specifically conjugated to 6-deoxy-6-amino Curdlan, and the cell line specificity, cellular uptake, cytotoxicity, and siRNA delivery efficiency of the corresponding disaccharide-modified 6-deoxy-6-amino-Curdlan were investigated. Observation by fluorescence microscopy as well as flow cytometry showed that galactose-containing Curdlan derivatives delivered fluorescently labeled short nucleic acid to HepG2 cells expressing ASGPR receptor but not in other cells lacking surface ASGPR protein. Moreover, highly galactose-substituted Curdlan derivatives delivered siRNA specifically to ASGPR-expressing cells and induced RNAi activities, silencing endogenous GAPDH gene expression. Our data demonstrated that galactose-functionalized 6-deoxy-6-amino-Curdlan is a promising carrier for short therapeutic nucleic acids for clinical applications.

Sulfated polysaccharides from Cyclocarya paliurus reduce H2O2-induced oxidative stress in RAW264.7 cells

In this study, two sulfated polysaccharides (S-CP1-4 and S-CP1-8) from Cyclocarya paliurus were produced by chlorosulfonic acid-pyridine method. Hydrogen peroxide (H2O2) was used to develop an oxidative stress model in the mouse macrophage cell line RAW264.7. Effects of the two sulfated polysaccharides on H2O2-induced oxidative stress were investigated. The results showed that S-CP(1-8) improved the viability of the H2O2-induced stressed RAW264.7 cells, as well as inhibited the lipid oxidation as determined by the level of malondialdehyde (MDA). Meanwhile, treatment with S-CP(1-4) increased superoxide dismutase (SOD) activity in these cells. The sulfated polysaccharides were found to have a better protective effect against H2O2-induced oxidative stress as compared to the native polysaccharide. Scanning electron microscopy also showed a significant change in the surface morphology of sulfated polysaccharides, but the degradation of main chain of polysaccharides was unconspicuous according to the results of monosaccharide composition. In addition, the sulfated polysaccharides had noticeable DPPH radical scavenging activity. In summary, our results demonstrated that H2O2 was able to induce oxidative stress in RAW264.7 cells, and sulfated group might play an important role in resistance to H2O2-induced oxidative damage.

Effective Immobilization of Agrobacterium sp. IFO 13140 Cells in Loofa Sponge for Curdlan Biosynthesis

Curdlan production by Agrobacterium sp. IFO13140 immobilized on loofa sponge, alginate and loofa sponge with alginate was investigated. There was no statistically-significant difference in curdlan production when the microorganism was immobilized in different matrices. The loofa sponge was chosen because of its practical application and economy and because it provides a high stability through its continued use. The best conditions for immobilization on loofa sponge were 50 mg of cell, 200 rpm and 72 h of incubation, which provided a curdlan production 1.50-times higher than that obtained by free cells. The higher volumetric productivity was achieved by immobilized cells (0.09 g/L/h) at 150 rpm. The operating stability was evaluated, and until the fourth cycle, immobilized cells retained 87.40% of the production of the first cycle. The immobilized cells remained active after 300 days of storage at 4 °C. The results of this study demonstrate success in immobilizing cells for curdlan biosynthesis, making the process potentially suitable for industrial scale-up. Additional studies may show a possible contribution to the reduction of operating costs.

Preparation, antiangiogenic and antitumoral activities of the chemically sulfated glucan from Phellinus ribis

Two sulfated derivatives (PRP-S1 and PRP-S2) of a β-glucan from Phellinus ribis with different degrees of substitution were obtained by chlorosulfonic acid method. The derivatives could block formation of new vessels in zebrafish and inhibit the proliferation of human umbilical vein endothelial cells (HUVECs). The two sulfated derivatives had remarkably high antitumor activities in vivo (in BALB/c mice inoculated with H22 hepatocellular carcinoma) as well as in vitro (against human ovary cancer SKOV-3 cells), without producing any overt signs of general toxicity. The results of immunohistochemistry assay indicated that the derivatives significantly reduced the average number of microvessel density (MVD) and inhibited the expression of vascular endothelial growth factor (VEGF) in tumor. Thus, these derivatives exhibit pronounced antiangiogenic and antitumoral properties. Except for cytotoxic effects on tumor cells, it is reasonable to expect that the antitumoral effects of PRP-S1 and PRP-S2 are mediated via their antiangiogenic properties.

Sulfated polysaccharide, curdlan sulfate, efficiently prevents entry/fusion and restricts antibody-dependent enhancement of dengue virus infection in vitro: a possible candidate for clinical application

Curdlan sulfate (CRDS), a sulfated 1→3-β-D glucan, previously shown to be a potent HIV entry inhibitor, is characterized in this study as a potent inhibitor of the Dengue virus (DENV). CRDS was identified by in silico blind docking studies to exhibit binding potential to the envelope (E) protein of the DENV. CRDS was shown to inhibit the DENV replication very efficiently in different cells in vitro. Minimal effective concentration of CRDS was as low as 0.1 µg/mL in LLC-MK2 cells, and toxicity was observed only at concentrations over 10 mg/mL. CRDS can also inhibit DENV-1, 3, and 4 efficiently. CRDS did not inhibit the replication of DENV subgenomic replicon. Time of addition experiments demonstrated that the compound not only inhibited viral infection at the host cell binding step, but also at an early post-attachment step of entry (membrane fusion). The direct binding of CRDS to DENV was suggested by an evident reduction in the viral titers after interaction of the virus with CRDS following an ultrafiltration device separation, as well as after virus adsorption to an alkyl CRDS-coated membrane filter. The electron microscopic features also showed that CRDS interacted directly with the viral envelope, and caused changes to the viral surface. CRDS also potently inhibited DENV infection in DC-SIGN expressing cells as well as the antibody-dependent enhancement of DENV-2 infection. Based on these data, a probable binding model of CRDS to DENV E protein was constructed by a flexible receptor and ligand docking study. The binding site of CRDS was predicted to be at the interface between domains II and III of E protein dimer, which is unique to this compound, and is apparently different from the β-OG binding site. Since CRDS has already been tested in humans without serious side effects, its clinical application can be considered.

There is no specific approved antiviral and vaccine for treatment or prevention of dengue, an acute mosquito-transmitted viral disease that affects more than 50 million people each year. Dengue virus (DENV) entry is a critical step that establishes the infection and enables virus replication. Curdlan sulfate (CRDS) is known to inhibit the entry and propagation of HIV-1 in the laboratory. Here we applied a computational binding site identification strategy, which suggested that CRDS could be a probable entry inhibitor of the viral surface E protein. CRDS potently blocked DENV infection at an early stage of the virus lifecycle in vitro. In addition, CRDS prevented antibody dependent enhancement, which is considered to be one of the most important clinical observations in DENV-infected patients. CRDS shows a favorable selectivity index against all serotypes of DENV. Further computational docking indicates that the compound binds to a pocket on the DENV E protein. Since CRDS has already been tested in humans without serious side effects, it can be a good candidate for clinical application.

Sulfation of Aegle marmelos gum: synthesis, physico-chemical and functional characterization

The present investigation was aimed at optimizing the conditions for preparing sulfated derivative of gum obtained from partially ripe fruits of Aegle marmelos. Elemental analysis, FTIR-ATR and NMR studies confirmed successful sulfation. The ratio of chlorosulfonic acid to pyridine exerted maximum influence on the degree of substitution followed by reaction temperature and reaction time. The sulfated derivative showed higher swelling in both acidic and alkaline pH as compared to unmodified gum. It also possessed higher negative zeta potential, higher viscosity, work of shear, firmness, consistency, cohesiveness and index of viscosity as compared to both unmodified gum as well as sodium alginate. Sulfated derivative was superior to unmodified gum and sodium alginate in terms of antimicrobial and anticoagulant activity. The sulfated sample appears to be a potential substitute over the unmodified gum sample and sodium alginate for modulating physicochemical properties of food and drug release dosage forms.

'Supramolecular wrapping chemistry' by helix-forming polysaccharides: a powerful strategy for generating diverse polymeric nano-architectures

We have exploited novel supramolecular wrapping techniques by helix-forming polysaccharides, β-1,3-glucans, which have strong tendency to form regular helical structures on versatile nanomaterials in an induced-fit manner. This approach is totally different from that using the conventional interpolymer interactions seen in both natural and synthetic polymeric architectures, and therefore has potential to create novel polymeric architectures with diverse and unexpected functionalities. The wrapping by β-1,3-glucans enforces the entrapped guest polymer to adopt helical or twisted conformations through the convergent interpolymer interactions. On the contrary, the wrapping by chemically modified semi-artificial β-1,3-glucans can bestow the divergent self-assembling abilities on the entrapped guest polymer to create hierarchical polymeric architectures, where the polymer/β-1,3-glucan composite acts as a huge one-dimensional building block. Based on the established wrapping strategy, we have further extended the wrapping techniques toward the creation of three-dimensional polymeric architectures, in which the polymer/β-1,3-glucan composite behaves as a sort of amphiphilic block copolymers. The present wrapping system would open several paths to accelerate the development of the polymeric supramolecular assembly systems, giving the strong stimuli to the frontier of polysaccharide-based functional chemistry.

Surface Engineering of Polycaprolactone by Biomacromolecules and their Blood Compatibility

Improving blood compatibility of biodegradable polymers is an area of intensive research in blood contacting devices. In this study, curdlan sulphate and heparin-modified poly (caprolactone) (PCL) hybrids were developed by physically entrapping these molecules on the PCL surface. This modification technique was performed by reversible gelation of the PCL surface region following exposure to a solvent and nonsolvent mixture. The presence of these biomacromolecules on the PCL surface was verified by atomic force microscopy (AFM) and scanning electron microscopy and energy dispersive X-ray analysis (SEM-EDAX) analysis, while wettability of the films was investigated by dynamic contact angle measurements. The blood compatibilities of the surface-modified films were examined using in vitro platelet and leukocyte adhesion and thrombus formation. Mouse RAW 264.7 macrophage cells were used to assess the cell adhesion and inflammatory response to the modified surface by quantifying mRNA expression levels of proinflammatory cytokines namely TNF-α and IL-1β using real-time polymerase chain reaction (RT-PCR). A lower platelet and leukocyte adhesion and activation was observed on the modified films incubated with whole human blood for 2 h. The thrombus formation on the PCL was significantly decreased upon immobilization of both curdlan sulphate (39%, *p<0.05) and heparin (28%, *p<0.01) when compared to bare PCL (80%). All of these results revealed that improved blood compatibility was obtained by surface entrapment of both curdlan sulphate (CURS) and heparin (HEP) onto PCL films. Both PCL-CURS and PCL-HEP films reduced RAW 264.7 macrophage cell adhesion (*p<0.05) with respect to the base unmodified PCL. The cellular inflammatory response was suppressed on the modified substrates. The mRNA expression levels of proinflammmatory cytokines (TNF-α and IL-1β) were upregulated on bare PCL, while it was significantly lower on PCL-CURS and PCL-HEP substrates (**p<0.001). Thus, this biomacromolecule entrapment process can be applied on PCL in order to achieve improved blood compatibility and reduced inflammatory host response for its future blood contacting applications.

Enhancement of antitumor activities in sulfated and carboxymethylated polysaccharides of Ganoderma lucidum

Two water-soluble derivatives, sulfated and carboxymethylated Ganoderma lucidem polysaccharides, coded as S-GL and CM-GL, were prepared using derivatization of water-insoluble polysaccharides (GL-IV-I) extracted from the fruit body of G. lucidem . The degree of substitution (DS) of S-GL and CM-GL was 0.94 and 1.09, respectively. The weight-average molecular mass (Mw) of GL-IV-I, S-GL, and CM-GL was determined with light scattering to be 13.3x10(4), 10.1x10(4), and 6.3x10(4), respectively. S-GL and CM-GL inhibited the in vitro proliferation of Sarcoma 180 (S-180) tumor cells in a dose-dependent manner, with an IC50 value of 26 and 38 microg/mL, respectively. They also inhibited the growth of S-180 solid tumors implanted in BALB/c mice, with low toxicity to the animals. Flow cytometric studies revealed that treatment of S-GL and CM-GL with S-180 tumor cells could mediate the cell-cycle arrest in the G2/M phase. The expression of Bax increased, and the expression of Bcl-2 decreased dramatically, as shown by immuno-histochemical staining of S-180 tumor tissue excised from the animals. The sulfated and carboxmethylated groups in the polysaccharides played an important part in enhancing their antitumor activities, leading to the potential to be developed into antitumor drugs.

Physicochemical properties and antitumor activities for sulfated derivatives of lentinan

Five fractions of lentinan, a beta-(1-->3)-D-glucan bearing beta-(1-->6)-d-glucopyranosyl branches, were treated with chlorosulfonic acid for 90 min at 60 degrees C in pyridine medium to synthesize water-soluble sulfated derivatives having the substitution degree of 1.44-1.76. The (13)C NMR spectra of the sulfated beta-glucans indicated that the C-6 position was preferentially substituted by the sulfate groups. The values of the weight-average molecular weight (M(w)), radius of gyration (s(2)(z)(1/2)), and intrinsic viscosity ([eta]) of the sulfated lentinan fractions were determined by size-exclusion chromatography with multi-angle laser light scattering (SEC-MALLS) and viscometry in 0.15 M aq NaCl at 25 degrees C, respectively. The dependence of [eta] on M(w) for the sulfated lentinan was found to be [eta]=8.93 x 10(-3)M(w)(0.73+/-0.02) (mL/g) in 0.15 M aq NaCl (for M(w) ranging from 14.6 x 10(4) to 50.4 x 10(4)). On the basis of the Yamakawa-Fujii-Yoshizaki (YFY) theory, the conformational parameters of the sulfated lentinan were calculated as 950 nm(-1) for the molar mass per unit contour length (M(L)), 4.8 nm for the persistence length (q), and 13.9 for the characteristic ratio (C(infinity)), indicating relatively extended single flexible chains in solution. The sulfated glucan fractions exhibited in vitro antiproliferative activities against sarcoma 180 (S-180) cells, and their inhibition ratios were lower than that of the triple-helix lentinan, but higher than that for the one with single random-coil lentinan chains.