Preparation and in vitro antioxidant activities of 6‐amino‐6‐deoxychitosan and its sulfonated derivatives

Abstract

The 6-amino-6-deoxychitosan (NC) and their 2, 6-di-N-sulfonated derivatives were prepared via N-phthaloylation, tosylation, azidation, hydrazinolysis, reduction of azide groups and N-sulfonation, and their structures were systematically characterized by FT-IR, 2D HSQC NMR, XRD, gel permeation chromatography (GPC), and elemental analysis. The 6-amino-6-deoxychitosan showed effect in three selected antioxidant essays, including reducing power, superoxide anion radical scavenging ability, and hydroxyl radical scavenging effect. But the factors affecting each activity were different. The reducing power and the superoxide anion radical scavenging ability of NC were strong and closely related to the amino groups in the molecular chains. Both introducing N-sulfonated groups into NC and the concentration reduction of NC and its sulfonated derivatives decreased these activities. For the superoxide anion radical, the molecular charge property was also a significant influence factor. For the hydroxyl radical, NC only showed weak scavenging activity in a special inverse concentration-dependent manner. However, the incorporation of N-sulfonated groups significantly improved the scavenging activity, and the more N-sulfonated groups, the higher the concentrations, the stronger the activity was. The results could be due to the different conformations of NC and its sulfonated derivatives in aqueous solution.

Synthesis and antioxidant action of chitosan derivatives with amino-containing groups via azide-alkyne click reaction and N-methylation

“…Meanwhile, the results showed that aminofunctionalized chitosan derivative 7b exhibited the stronger antioxidant properties than hydroxyl-modified chitosan derivative 7a, which should be attributed to the appearance of eNH 2 group as a stronger hydrogen donor than eOH group. This result was in agreement with the reports of Luan et al (2018) and Yang et al (2015), in which they found that the antioxidant activities of chitosan derivatives had improved significantly after the introduction of amino group by substitution of hydroxyl group at C-6 on chitosan backbones. Moreover, because of the incorporation of 1,2,3-triazole in the present study, a higher scavenging rate against DPPH radical and a stronger reducing power at 0.4 mg/mL of amino-functionalized chitosan 7b were observed compared with that of 6-amino-6-deoxy chitosan at the same concentration reported early by our group (Luan et al, 2018).…”

Synthesis, Characterization, and Antifungal Activity of Pyridine-Based Triple Quaternized Chitosan Derivatives

“…Chitosan is one of the most abundant natural polysaccharides and its antifungal activity against various groups of pathogenic fungi has drawn a lot of attention [ 9 ]. As the only alkaline polysaccharide in nature, chitosan is mainly obtained via the deacetylation of chitin under alkaline conditions [ 10 , 11 , 12 ]. The main chain of chitosan is mainly composed of glucosamine and N -acetylglucosamine [ 13 ].…”

Synthesis of Novel Chitin Derivatives Bearing Amino Groups and Evaluation of Their Antifungal Activity

“…It is well-known that the width of X-ray diffraction peak is related to the size of crystallite and the broadened peak usually results from small crystallite [ 32 ]. In addition, weaker peak implies that there is more amorphous phase in the matrix.…”