Effect of Physicochemical Modifications on Antioxidant Activity of Water-soluble Chitosan

Abstract

Water-soluble chitosan was processed using ultrasonication, microfluidisation and homogenisation to modify its physicochemical properties. The effect of using sonicated chitosan on formation of chitosan-glucose conjugates was investigated. Untreated and sonicated chitosan conjugates were prepared under varying reaction conditions (such as ratios of reactants, pH and temperature). The conjugates formed were evaluated for colour development and antioxidant activity. For both untreated and sonicated chitosans, the reactivity was found to be higher at pH 6.0/121°C than at pH 4.9/121°C. The reactivity was found to be lower at 105°C at both pH conditions than at 121°C. This clearly demonstrated the greater reactivity at higher temperature irrespective of the reaction pH. Antioxidant activity studies indicated that the conjugates formed at 121°C had higher activity. Although sonication of water-soluble chitosan led to slightly enhanced viscosity indicating higher reactivity, it did not improve the antioxidant activity.

Anti-Oxidant and Anti-Diabetes Potential of Water-Soluble Chitosan–Glucose Derivatives Produced by Maillard Reaction

“…The native water-soluble chitosan showed low anti-oxidant activity when only 25.44% of activity was observed at 10 mg/mL; consequently, its IC 50 could not be detected. This result was similar to other reports, which reveal that the low anti-oxidant activity of chitosan and glucose-conjugate was one of the potential ways to enhance the anti-oxidant activity of chitosan [17,19,20]. The mechanics of anti-oxidant activity of glucose-conjugated chitosan may relate to its hydrogen donating capacity [19].…”

“…Free radicals cause some serious damage in cells as well as tissues. The injurious effect of free radicals can be prevented or reduced by anti-oxidants [41], which include chitosan (in low molecular weight) and its derivatives [5,14,17,19,20,22,23]. Table 2 shows the anti-oxidant activity of WSCDs using DPPH radical scavenging assay.…”

“…In fact, the chitosan–sugar derivatives produced by Maillard reaction reveal enhanced anti-oxidant or anti-microbial activities. However, there are few reports on the bio-activities of water-soluble chitosan–glucose derivatives (WSCGDs) [20,21,22,23]. Additionally, the conditions for performing Maillard reactions, as well as water-soluble chitosan sources in those reports also differ.…”

Synthesis, anti-oxidant activity, and biodegradability of a novel recombinant polysaccharide derived from chitosan and lactose

“…It has been demonstrated that the anti-oxidation properties of chitosan after the modification of Maillard reaction were remarkably improved as compared with chitosan or N-alkylation chitosan derivative. To date, the majority of studies focused on Maillard reaction of chitosan with such mono-saccharides as glucose (Rao et al, 2011;Weerakkody, Labbett, Cheng, & Kosaraju, 2011) and fructose (Dong et al, 2014;Ying, Xiong, Wang, Sun, & Liu, 2011). Because of different chemical structure between mono-saccharides and disaccharides, it was expected that the MRPs from disaccharide and chitosan would display varying antioxidant activity from those from mono-saccharide and chitosan.…”