Effects of carboxylation of the side chains on the order-disorder transition in aqueous solution of schizophyllan, a triple helical polysaccharide

Solvent stabilizing effects on the order-disorder transition of schizophyllan in aqueous mixtures of carboxylic acids

Schizophyllan is a triple helical β-1,3-D-glucan, and shows the cooperative order-disorder transition in the aqueous solution at the triple helix state. In this paper, the solvent stabilizing effects of two carboxylic acids, acetic acid and citric acid, on the cooperative order-disorder transition of aqueous schizophyllan solution were investigated from DSC and SEC-MALS measurements. The transition temperature (Tr) was shifted to higher temperature with increasing the molar fraction of carboxylic acid in the mixture (x). The transition enthalpy (ΔHr) was increased with increasing x. These solvent stabilizing effects indicate that these carboxylic acid molecules were selectively associated with the branched side chains of schizophyllan to stabilize the ordered state. The composition dependencies of Tr and ΔHr were analyzed by the linear cooperative transition theory to estimate the association parameters between the side chains and carboxylic acid. The theoretical parameters obtained were compared with those for the other active substances for the transition to discuss the molecular interactions between the triple helix and carboxylic acid.

Association with Imidazole in the Cooperative Order-Disorder Transition in Aqueous Solution of Schizophyllan

Schizophyllan, a triple helical polysaccharide, exhibits cooperative order-disorder transition (CODT) in aqueous solutions. The transition transforms the ordered structure (triple helix I) formed between the branched side chains and solvent molecules into the disordered structure (triple helix II) without dissociation of the triple helix. The CODT behaviors in H₂O-imidazole mixtures containing HCl with different molar ratios of imidazole/HCl were investigated by adiabatic calorimetry and differential scanning calorimetry on two schizophyllan solutions with different molar masses. The transition temperature (T_r) and the transition enthalpy (ΔH_r) significantly depended on both of the mole fractions of imidazole and imidazole/HCl. The composition dependences of T_r and ΔH_r in H₂O-imidazole mixtures were analyzed with linear cooperative transition theory for the solvent-stabilizing effect in the mixture with active compounds. Theoretical analyses confirmed that both imidazole and imidazolium ions in the solutions competitively interact with the side chain of the triple helix.

Structural characterization and immunoregulatory activity of polysaccharides from Dendrobium officinale leaves

In this study, two kinds of polysaccharides from leaves of Dendrobium officinale, namely DLP-1 and DLP-2, were obtained by hot water extraction, ethanol sedimentation, and chromatographic separation using DEAE-52 cellulose and Sephadex G-100 columns. They were composed of different monosaccharides and the content of monosaccharides varied significantly while DLP-1 (M_w 1.38 × 10⁶  Da) was mainly composed of mannose (71.69%) and glucose (22.89%), and DLP-2 (M_w 1.93 × 10⁶  Da) was constituted by rhamnose (35.05%), arabinose (24.12%), and galactose (25.65%). A triple-helical conformation was exhibited by both of them. The scanning electron microscope image of DLP-1 showed an irregular and large lamellar shape, as well as a smooth surface and a porous interior, illustrating they had an amorphous structure. In contrast, DLP-2 revealed a rough, loose, and uneven surface consisting of large sponge-like particles. Nuclear magnetic resonance analysis showed that (1→4)-β-D-Manp, (1→4)-β-D-Glcp, and (1→4)-2-O-acetyl-β-D-Manp were the main linkage types of DLP-1, whereas DLP-2 was constituted by a large amount of (1→4)-β-D-Manp, (1→4)-β-D-Glcp, and other residues. Besides, DLP-1 and DLP-2 stimulated the proliferation and phagocytic capacities of RAW 264.7 cells and improved the production of nitric oxide, interleukin-6, TNF-α, and IL-1β. These results proved that both DLP-1 and DLP-2 possessed excellent immunoregulatory bioactivities and could be functional food or adjuvant drug. PRACTICAL APPLICATIONS: The leaf of Dendrobium officinale is a by-product with huge biomass. The lack of systematic research on its chemical composition and pharmacologic effect, leading to a great waste of resources. In order to maximize the value of D. officinale, this study aimed to investigate the structural characteristics and immunologic effects of two polysaccharide fractions (DLP-1 and DLP-2) from D. officinale leaves, showing that DLP-1 and DLP-2 in D. officinale leaves could be used as anti-inflammatory agents to avoid wasting.

Triple-helix polysaccharides: Formation mechanisms and analytical methods

Triple helix conformation of polysaccharides is generally believed to be associated with their biological activities. However, the formation mechanisms and analytical methods for the triple helix polysaccharides, to our best knowledge, have not been systematically investigated. This article reviews specifically the literature on the formation and characterization of triple-helix polysaccharides. The formation mechanisms and related structural-conformation-bioactivity relationships are discussed; various analytical methods for characterizing triple-helix polysaccharides are summarized. This review devotes to a better understanding of the formation of polysaccharides based triple-helix structure and related analytical methods. These could provide some insights and inspirations for their applications in both food and pharmaceutical industries.

Applications of Photoinduced Phenomena in Supramolecularly Arranged Phthalocyanine Derivatives: A Perspective

This review focuses on the description of several examples of supramolecular assemblies of phthalocyanine derivatives differently functionalized and interfaced with diverse kinds of chemical species for photo-induced phenomena applications. In fact, the role of different substituents was investigated in order to tune peculiar aggregates formation as well as, with the same aim, the possibility to interface these derivatives with other molecular species, as electron donor and acceptor, carbon allotropes, cyclodextrins, protein cages, drugs. Phthalocyanine photo-physical features are indeed really interesting and appealing but need to be preserved and optimized. Here, we highlight that the supramolecular approach is a versatile method to build up very complex and functional architectures. Further, the possibility to minimize the organization energy and to facilitate the spontaneous assembly of the molecules, in numerous examples, has been demonstrated to be more useful and performing than the covalent approach.

Conformation and cooperative order-disorder transition in aqueous solutions of β-1,3-d-glucan with different degree of branching varied by the Smith degradation

β-1,3-d-glucan with different degrees of branching were obtained by selectively and gradually removing side chains from schizophyllan, a water-soluble triple helical polysaccharide, using the Smith degradation. Size exclusion chromatography combined with a multi-angle light scattering detection was performed in aqueous 0.1 M NaCl. The degree of branching decreased after the Smith degradation, while the molar mass distributions were almost unchanged. The molecular conformation of the Smith-degraded β-1,3-d-glucan was analyzed on the basis of the molar mass dependency of the radius gyration, and found to be comparable to the original triple helix of schizophyllan. Differential scanning calorimetry in deuterium oxide-hexadeuterodimethylsulfoxide mixtures was performed to investigate the effects of the degree of branching on the cooperative order-disorder transition. Removal of side chains affects both the transition temperature and transition enthalpy. The ordered structure is formed by the residual side chains in the triplex unit, so that the linear cooperative system of the triplex is maintained after the Smith degradation.

Structure characterization, physicochemical property and immunomodulatory activity on RAW264.7 cells of a novel triple-helix polysaccharide from Craterellus cornucopioides

In the study, a new triple-helix polysaccharide with favorable stability was purified from C. cornucopioides. Its structural characterization, stability and solution behavior were investigated by the GC-MS, periodate oxidation-smith degradation, FT-IR, 1D and 2D NMR spectroscopy, methylation analysis, Scanning electron microscope, Congo-red, CD, TGA and DSC analysis. The results showed that Craterellus cornucopioide polysaccharide (CCP) possessed the molecular weight of 1.97 × 10³ kDa, is mainly composed of mannose (48.73%), galactose (17.37%), glucose (15.97%) and xylose (17.93%), respectively. It was a heteroglycan with (1 → 3)‑linked‑β‑d‑Manp‑(1 → 6)‑linked α‑d‑Galp backbone distributed by (1 → 4)‑linked‑α‑d‑Xylp‑t‑α‑d‑Manp and t‑β‑d‑Glup units at O-6. The result of TGA and DSC assay indicated that CCP has a favorable thermal stability. MTT and Scanning electro microscopy (SEM) assay showed that CCP could significantly improve the proliferation activity and induce cells activation of RAW264.7 in a certain range of concentrations and period.

Construction and Characterization of Phthalocyanine-Loaded Particles of Curdlan and Their Photosensitivity

To optimize the physicochemical properties of phthalocyanine (PC), we examined its behavior in particles of triple helix glucan curdlan (CUR). CUR was denatured and renatured in DMSO, in the presence of PC. Infrared spectroscopy and transmission electron microscopy (TEM) showed that PC and CUR formed an inclusion complex, in which PC was trapped inside CUR molecules. This redshifted the absorption peak of PC, which would improve its usefulness as a photosensitizer, because infrared light can penetrate more deeply into human tissues. The conductivity of the solution of CUR-PC was higher than the conductivities of either a CUR solution or a PC dispersion, indicating that CUR-PC is more water soluble than PC. In addition, CUR-PC was highly stable in water. Thus, the use of CUR as a carrier of PC improves several of its physical properties. PC is used as a photosensitizer for killing cancer cells, but its use is hampered by its low solubility. Further, its absorption range limits its use to a depth of 1–3 mm in tissues. CUR-PC, with its high solubility and infrared absorption peak, was highly effective as a photosensitizer. It killed 84% of HeLa cells under 15 min of long wavelength radiation and had little cytotoxicity in the absence of light. These results demonstrate that CUR-PC has promise as a photosensitizer, as well as provide theoretical support for a wide range of applications for PC and CUR.