One-Pot Chitin Conversion to High-Activity Antifungal N,N-Dimethyl Chitosan Oligosaccharides

Area of Science:

• Biochemistry
• Organic Chemistry
• Materials Science

Background:

• Chitosan oligosaccharides and their derivatives possess various biological activities.
• Developing efficient synthesis routes for functionalized chitosan derivatives is crucial for exploring their applications.
• Understanding the reaction mechanisms involved in modifying chitosan is key to optimizing synthesis and properties.

Purpose of the Study:

• To develop a convenient one-pot synthesis for N,N-dimethyl chitosan oligosaccharide (DMCOS) directly from chitin.
• To characterize the synthesized DMCOS, focusing on its degree of deacetylation, degree of methylation, and molecular weight.
• To evaluate the antifungal activity of DMCOS against Candida species and elucidate the underlying mechanism.

Main Methods:

• Acid-catalyzed tandem depolymerization-deacetylation-N-methylation of chitin using formaldehyde.
• Characterization of DMCOS using techniques to determine deacetylation degree, methylation degree, and average molecular weight.
• Antifungal activity assays against Candida species and mechanistic studies involving hydroxyl group effects.

Main Results:

• A convenient one-pot synthesis yielding 77% DMCOS from chitin was established.
• The synthesized DMCOS exhibited a high degree of deacetylation, high degree of methylation, and low average molecular weight.
• DMCOS demonstrated superior antifungal activity against Candida species compared to chitosan.
• A novel hydroxyl group-assisted effect facilitating reductive amination under acidic conditions was identified.

Conclusions:

• Direct synthesis of N,N-dimethyl chitosan oligosaccharide (DMCOS) from chitin is feasible using the described one-pot method.
• DMCOS possesses enhanced antifungal properties, particularly against Candida species.
• The findings highlight the potential of DMCOS as an antifungal agent and provide insights into its synthesis mechanism.