Enzymatic Synthesis and Characterization of Different Families of Chitooligosaccharides and Their Bioactive Properties

Abstract

Chitooligosaccharides (COS) are homo- or hetero-oligomers of D-glucosamine (GlcN) and N-acetyl-D-glucosamine (GlcNAc) that can be obtained by chitosan or chitin hydrolysis. Their enzymatic production is preferred over other methodologies (physical, chemical, etc.) due to the mild conditions required, the fewer amounts of waste and its efficiency to control product composition. By properly selecting the enzyme (chitinase, chitosanase or nonspecific enzymes) and the substrate properties (degree of deacetylation, molecular weight, etc.), it is possible to direct the synthesis towards any of the three COS types: fully acetylated (faCOS), partially acetylated (paCOS) and fully deacetylated (fdCOS). In this article, we review the main strategies to steer the COS production towards a specific group. The chemical characterization of COS by advanced techniques, e.g., high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD) and MALDI-TOF mass spectrometry, is critical for structure–function studies. The scaling of processes to synthesize specific COS mixtures is difficult due to the low solubility of chitin/chitosan, the heterogeneity of the reaction mixtures, and high amounts of salts. Enzyme immobilization can help to minimize such hurdles. The main bioactive properties of COS are herein reviewed. Finally, the anti-inflammatory activity of three COS mixtures was assayed in murine macrophages after stimulation with lipopolysaccharides.

Deep Chemical and Physico-Chemical Characterization of Antifungal Industrial Chitosans—Biocontrol Applications

“…Polymers of chitosan have not been observed yet using mass spectrometry because no multiply charged ions are formed using electrospray or MALDI techniques, indicating that these soft methods were inefficient for the complete analysis of these biopolymers. Moreover, the experimental conditions seemed to be very important in determining the type of COS present in chitosans by mass spectrometry [ 40 , 41 , 42 ].…”

Preparation of Polyurea Microcapsules by Interfacial Polymerization of Isocyanate and Chitosan Oligosaccharide

“…Some of the properties of COS differ from those of chitosan, e.g., it has good aqueous solubility. It has anti-inflammatory, anticancer, antioxidant, and antifungal properties and has been widely used in medical applications, animal feed, fertilizers, and pesticides [20][21][22][23][24][25][26][27][28][29][30][31]. In the field of crop protection, COS has been shown to change the soil flora, promote the growth of beneficial microorganisms, and induce disease resistance of plants; it can be used in biological pesticides, growth regulators, and fertilizers [20,[32][33][34][35].…”

Evaluation of Antibacterial and Antifungal Properties of Low Molecular Weight Chitosan Extracted from Hermetia illucens Relative to Crab Chitosan

“…In this regard, enzymatic hydrolysis represents a potential alternative, providing milder process conditions and reducing waste generation [23]. In nature, chitin and chitosan can be depolymerised by specific enzymes such as chitinases, chitosanases, and glucoaminidases [24]. According to the enzyme nomenclature committee, chitinases (EC 3.2.1.14) are defined as enzymes capable of performing endohydrolysis of b-1,4-linkages in chitin [11].…”