Purification and chemical characterization of polysaccharides from alkaline extract of the Rhizoctonia solani biomass

• Grant number: 13/19244-7
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2014
• End date: December 31, 2014
• Field of knowledge: Biological Sciences - Biochemistry - Chemistry of Macromolecules
• Principal Investigator: Maria de Lourdes Corradi Custodio da Silva
• Grantee: Patricia Aline Hiraíwa
• Host Institution: Faculdade de Ciências e Tecnologia (FCT). Universidade Estadual Paulista (UNESP). Campus de Presidente Prudente. Presidente Prudente , SP, Brazil

Abstract

In recent years bioactive polysaccharides extracted from natural sources as plants, bacteria, algae and fungi, have attracted much attention in the field of Biochemistry and Pharmacology. These molecules have shown antitumor, immunostimulating, antiinflammatory, anticoagulant and antioxidant actions, and other.Whereas fungal mycelium may constitute an important source of chemical compounds and there are no records in the literature of polysaccharides from Rhizoctonia solani biomass, this work has as objective to purify and characterize this group of biomolecules, found in alkaline extract, rich in carbohydrates and proteinsThe purification procedures will begin with steps as simple as freezing and thawing. The soluble fraction will be deproteinazed by Sevag method. Polysaccharide containing mannose and/or galactose, if present, will be separated from glucans, by treatment with Fehling's solution. Gel filtration chromatography will be used for separation of the polysaccharides according to their molecular weight differences. All stages of purification will have their profiles monitored by steric exclusion chromatography coupled to the detection by refractive index.Since the future goal is to verify the biological activity of polymers, this work will also determine the chemical structure that is important to help in understanding the mechanism of action. The chemical structure will be effected by using the techniques of carbohydrate chemistry as hydrolysis and methylation analyses, followed by high-performance liquid chromatography and gas chromatography coupled to mass spectrometry, respectively. 13C and 1H NMR spectroscopic mono- and two-dimensional (homo-and heteronucleares) will also be carried out. The determination of the molecular weight of the polysaccharides will be held by HPSEC/RID, by comparison to the elution volume of patterns of polysaccharides with MM. To determine the average molecular weight of the homogeneous polysaccharides the standard curve of dextran with different molecular weights will be made. Keywords: polysaccharides, high performance chromatography, nuclear magnetic resonance spectroscopy.