Effect of antitumour polysaccharides on the higher structure of serum protein

Immunostimulatory properties and antitumor activities of glucans (Review)

New foods and natural biological modulators have recently become of scientific interest in the investigation of the value of traditional medical therapeutics. Glucans have an important part in this renewed interest. These fungal wall components are claimed to be useful for various medical purposes and they are obtained from medicinal mushrooms commonly used in traditional Oriental medicine. The immunotherapeutic properties of fungi extracts have been reported, including the enhancement of anticancer immunity responses. These properties are principally related to the stimulation of cells of the innate immune system. The discovery of specific receptors for glucans on dendritic cells (dectin-1), as well as interactions with other receptors, mainly expressed by innate immune cells (e.g., Toll-like receptors, complement receptor-3), have raised new attention toward these products as suitable therapeutic agents. We briefly review the characteristics of the glucans from mycelial walls as modulators of the immunity and their possible use as antitumor treatments.

Pharmacological, structural, and drug delivery properties and applications of 1,3-β-glucans

1,3-β-Glucans are a class of natural polysaccharides with unique pharmacological properties and the ability to form single- and triple-helical structures that can be formed into resilient gels with the application of heat and humidity. The pharmacological capabilities of 1,3-β-glucans include the impartation of tumor inhibition, resistance to infectious disease, and improvements in wound healing. Curdlan is a linear 1,3-β-glucan that has been used extensively to study the nature of these helical structures and gels, and Curdlan sulfates have found ongoing application in the inhibition of HIV infection. 1,3-β-Glucan gels have been used in food science as stabilizers and encapsulating agents, in nanoscience as scaffolds to build nanofibers and nanowires, and in drug delivery to form nanoparticles and create helical micelles encapsulating polynucleotides. 1,3-β-Glucans are beginning to have enormous significance due to their dual nature as structure-forming agents and pharmacological substances, and research is especially focused on the application of these polymers in animal nutrition and drug delivery.

The skewing to Th1 induced by lentinan is directed through the distinctive cytokine production by macrophages with elevated intracellular glutathione content

In vivo lentinan (LNT)-elicited peritoneal macrophages (Mps) showed the reduced release of prostaglandins (PGs), IL-10 and IL-6, while it endowed Mps with the elevated capability to produce IL-12 and nitric oxide (NO) upon in vitro triggering, due to the elevated intracellular glutathione (GSH) content in Mps. Deprivation of intracellular GSH completely ablated the production of IL-12. Conversely, lipopolysaccharide (LPS) induced peritoneal Mps with the reduced intracellular GSH content and the reciprocal profile of mediator production. Mps with the elevated intracelluar GSH is arbitrarily termed as reductive Mp (RMp) and that with reduced amount as oxidative Mp (OMp). OMp was converted to RMp when GSH was replenished with glutathione monoethylester (GSH-OEt). The IL-2 administration in combination with LNT exerted the synergistic induction of RMp, resulting in synergistic augmentation of IL-12, NO and reduction of IL-6 production. It was also confirmed that CD4+T cells derived of LNT-administered mice showed augmented IFN-gamma and reduced IL-4 production upon in vitro anti-CD3 stimulation. Taken together it is concluded that skewing of Th1/Th2 balance to Th1 by a beta-(1-3)-glucan, LNT, is directed through the distinctive production of IL-12 versus IL-6, IL-10 and prostaglandin E2 (PGE2) by Mps, depending on intracellular GSH redox status. To the efficient tumor immunotherapy, it may be one of the critical elements to induce a reductive form of Mps in tumor stromal tissues to maintain Th1 response.

Chemical and computer probing of RNA structure

Ribonucleic acids (RNAs) are one of the most important types of biopolymers. RNAs play key roles in the storage and multiplication of genetic information. They are important in catalysis and RNA splicing and are the most important steps of translation. This chapter describes experimental methods for probing RNA structure and theoretical methods allowing the prediction of thermodynamically favorable RNA folding. These methods are complementary and together they provide a powerful approach to determine the structure of RNAs. The three-dimensional (tertiary) structure of RNA is formed by hydrogen-bonding among functional groups of nucleosides in different regions of the molecule, by coordination of polyvalent cations, and by stacking between the double-stranded regions present in the RNA. The tertiary structures of only some small RNAs have been determined by high-resolution X-ray crystallographic analysis and nuclear magnetic resonance analysis. The most widely used approach for the investigation of RNA structure is chemical and enzymatic probing, in combination with theoretical methods and phylogenetic studies allowing the prediction of variants of RNA folding. Investigations of RNA structures with different enzymatic and chemical probes can provide detailed data allowing the identification of double-stranded regions of the molecules and nucleotides involved in tertiary interactions.

Correlation between the antitumor activity of a polysaccharide schizophyllan and its triple-helical conformation in dilute aqueous solution

Eight samples of a polysaccharide schizophyllan ranging in weight-average molecular weight Mw (in water) from 5 x 10(3) to 1.3 x 10(5) were prepared and their antitumor activity (expressed in terms of the tumor inhibition ratio) against Sarcoma 180 ascites, intrinsic viscosities [eta], and gel-filtration chromatograms in aqueous solution were determined. The tumor inhibition ratio was essentially unity for samples with Mw higher than 9 x 10(4), but reduced to zero or even to a negative value when Mw was lower than 10(4). The [eta] data combined with the chromatographic data showed that above Mw approximately 9 x 10(4) the predominant species of schizophyllan in aqueous solution is the previously found rigid triple helix, whereas below Mw approximately 9 x 10(4) both triple helices and single chains coexist in the solution and the fraction of triple helices decreases monotonically to zero as Mw is decreased to 5 x 10(3). From these findings it was concluded that the antitumor potency of schizophyllan in water is related to the amount of triple helices relative to that of single chains.

Relationship between the chemical structure and anti-tumour activity of glucans prepared from Grifora umbellata

Glucans from Grifora umbellata and their enzyme-treated fractions have been tested for antitumour activity against subcutaneously implanted Sarcoma 180 (solid type). The results indicate that the basic common unit of the glucans is of primary importance for the antitumour activity, which is also influenced by the type of sugar linkage, length of branch, branching frequency, molecular size, and molecular conformation.