Preparation of Novel Chitosan Oligosaccharide Quaternary Ammonium Derivatives Bearing Quinoline with Antioxidative and Antibacterial Activities

Abstract

In this study, five new chitosan oligosaccharide quaternary ammonium derivatives bearing quinoline are synthesized by reaction between 6‐O‐chloroacetyl‐2‐N, N, N‐trimethyl quaternary ammonium salt chitosan oligosaccharide (CTCOS, compound 1) and quinoline derivatives. The derivatives are characterized by analytical techniques including Fourier Transform Infrared (FTIR), 1H Nuclear Magnetic Resonance (1H NMR) spectroscopy, and elemental analysis. The obtained results confirm that quinoline groups are successfully introduced into the CTCOS molecule. Meanwhile, the antioxidant activities of the prepared chitosan oligosaccharide derivatives are evaluated in vitro. The experimental results show that the derivatives have excellent free radical scavenging ability. The free radical scavenging abilities are all over 75% at the concentration of 1.6 mg mL−1. Moreover, antibacterial tests show that derivative 2e has the best antibacterial activities. Its minimum inhibitory concentration (MIC) value and minimum bactericidal concentration (MBC) value against Staphylococcus aureus and Escherichia coli are 0.0625 and 0.03125 mg mL−1, respectively. In addition, the cytotoxicity of chitosan oligosaccharide and its derivatives is examined by MTT colorimetric assay in RAW 264.7 macrophages, observing that all derivatives are non‐cytotoxic. Consequently, the findings indicate that the enhanced antioxidant activity, antibacterial activity, and biocompatibility of these chitosan oligosaccharide derivatives can enlarge the scope of the application of chitosan oligosaccharides, particularly as antioxidant and antibacterial agents in food packaging, pharmaceutical, cosmetics industries, and other fields.

Strategies for the Preparation of Chitosan Derivatives for Antimicrobial, Drug Delivery, and Agricultural Applications: A Review

“…The hydrophilic quaternary ammonium group enhances the water solubility of CS by introducing a quaternary ammonium salt group. The salt increases the electrostatic charge and weakens intramolecular hydrogen bonds, resulting in a high level of water solubility [87]. This quaternary ammonium salt improves not only the hydrophilicity of the final CS derivatives but also enhances its antimicrobial properties, making it valuable in diverse applications, including wound dressings, drug carriers, and other biomedical fields [88].…”

“…To expand the scope of chemical modifications, O-quaternary ammonium N-acyl thiourea CS (3n; DS: 81-93%) was synthesized through the incorporation of ammonium thiocyanate and chloroacetyl chloride into the reaction sequence [108]. Another category of quaternary ammonium salt is the pyridinium salt group, which acts as a cationic surfactant, is soluble in water [87,109], and exhibits noteworthy antimicrobial and antifungal activities [110,111]. Pyridine functions as a nucleophile, capable of replacing the alkyl halide to synthesize the quaternary pyridinium compound [112].…”

“…Another category of quaternary ammonium salt is the pyridinium salt group, which acts as a cationic surfactant, is soluble in water [87,109], and exhibits noteworthy antimicrobial and antifungal activities [110,111]. Pyridine functions as a nucleophile, capable of replacing the alkyl halide to synthesize the quaternary pyridinium compound [112].…”