Abstract
In order to improve the bioactivity of chitosan, we synthesized a novel series of chitosan derivatives: firstly, chitosan was reacted with methylclhlorofonmate obtaining N-methoxyformylated chitosan (1), which was then converted into N-pyridylurea chitosan derivatives (2a-2c) by amine-ester exchange reaction. In addition, N-pyridylurea chitosan derivatives were conducted by reacting with iodomethane to obtain quaternized N-pyridylurea chitosan derivatives (3a-3c). The structural characteristics of as-prepared chitosan derivatives were confirmed by fourier transform infrared (FT-IR), 1H nuclear magnetic resonance (1H NMR), elemental analysis, and scanning electron microscope (SEM). Meanwhile, the antioxidant activity of the chitosan derivatives was assessed in vitro. As shown in this paper, the antioxidant activity decreased in the order: c > b > a. Moreover, after the quaternization with iodomethane, quaternized N-pyridylurea chitosan derivatives immediately exhibited enhanced antioxidant capacity compared with N-pyridylurea chitosan derivatives. For example, in 1,1-Diphenyl-2-picrylhydrazyl (DPPH) radical scavenging assay, the scavenging activities of 3a-3c were 91.75%, 93.63%, and 97.63% while 2a-2c were 42.32%, 42.97%, and 43.07% at 0.4 mg/mL. L929 cells were also adopted for cytotoxicity test of chitosan and synthesized derivatives by CCK-8 assay and all samples showed decreased cytotoxicity. These results suggested that the novel pyridylurea-functionalized chitosan derivatives could be an ideal biomaterial.
Highlights
Free radicals generated from oxidation reactions may occur in various metabolic processes which can damage cell membranes, lipids, cellular proteins, and DNA, leading to heart, kidney, liver-related diseases such as liver damage, myocardial infarction, cancer, stroke, Parkinson’s disease, and Alzheimer’s disease [1,2,3]
In order to avoid the hydrolysis of methyl chloroformate and N-methoxyformylated chitosan, the reaction must be performed under conditions of lower temperature and weak acidity
The results suggest that quaternized N-pyridylurea chitosan derivativesand can CS
Summary
Free radicals generated from oxidation reactions may occur in various metabolic processes which can damage cell membranes, lipids, cellular proteins, and DNA, leading to heart, kidney, liver-related diseases such as liver damage, myocardial infarction, cancer, stroke, Parkinson’s disease, and Alzheimer’s disease [1,2,3]. Discovering new synthetic antioxidants is of great significance in the fields of antioxidant synthesis and organic transformations. (β-(1→4)-2-amino-2-deoxy-d-glucan, is generally produced via deacetylation of chitin [6,7,8]. Due to its unique cationic properties, it has attracted wide attention in various fields [9]. Chitosan has been employed in applications ranging from food and nutrition to cosmetics, wound healing, wastewater treatment, artificial skin, ophthalmology, and antimicrobial agents [10,11,12,13]
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