PROSPECTS FOR MODIFYING THE STRUCTURE OF CHITIN AND CHITOSAN OF HIGHER FUNGI TO EXPAND THE POTENTIAL OF THEIR APPLIED USE

Abstract

The review is devoted to summarizing scientific data in the field of the chemical structure and properties of chitin and chitosan obtained from fungal biomass, and to analyzing directions for their modification for use in medicine and the food industry as substances with antibacterial, antiviral, wound-healing and anticoagulant activity. The features of chitin biosynthesis by fungi of the Basidiomycota, Ascomycota, Deuteromycota departments and chitosan biosynthesis by fungi of the Zygomycota department are covered. It has been shown that higher fungi contain chitin in their cell walls in the form of a chitin-glucan complex, while lower fungi (zygomycetes) contain chitin in the form of chitosan-glucan. Effective components of substrates that influence the production of polysaccharides by fungi have been identified - carbohydrates in the form of glucose, sucrose and maltose, organic forms of nitrogen in the form of yeast extract and corn flour, mineral components in the form of dihydrogen phosphate and dipotassium monohydrogen phosphate. Particular attention is paid to methods for isolating chitin and modifying it to chitosan with a detailed description of the physicochemical and biological properties of polymers. The review also presents the main reactions and methods for obtaining carboxymethyl and sulfo derivatives of chitin and chitosan. The biological properties and application of these groups of substances are described. In the carboxymethylation of chitin and chitosan, the choice of appropriate reaction conditions and reagents makes it possible to obtain carboxymethyl chitin, N-, O-, N,O-carboxymethylchitosan, or N,N-dicarboxymethylchitosan. The properties and applications of carboxymethyl derivatives of chitin and chitosan strongly depend on their structure, degree of substitution, and arrangement of amino or hydroxyl groups. The main reagents in the preparation of carboxymethyl derivatives are sodium monochloroacetate, monochloroacetic and glyoxalic acids. Carboxymethyl derivatives of chitin and chitosan are used as drug delivery systems, antimicrobial agents, in tissue engineering, as components of cosmetics and food products. Modification of chitosan with sulfate groups makes it possible to obtain chitosan 2-N-, 6-O-, 2-N-6-O- and 3-O-sulphates. The main sulfonating agents are oleum, pyridine and chlorosulfonic acid. Sulfonic derivatives of chitin and chitosan can be used as a basis for obtaining hemocompatible materials (with antithrombotic and antibacterial activities).