title: Protocatechuic acid grafted onto chitosan: Characterization and antioxidant activity.
abstract: In this study, protocatechuic acid (PA) was grafted onto chitosan (CS) by a carbodiimide mediated cross-linking reaction. The structural characterization, physical property and antioxidant activity of PA grafted CS (PA-g-CS) was investigated. As results, three copolymers with different grafting ratios (61.64, 190.11 and 279.69mg PAE/g) were obtained by varying the molar ratios of reaction substrates. PA-g-CS showed the same UV absorption peaks as PA at 258 and 292nm. As compared to CS, PA-g-CS exhibited a decreased band at 1596cm(-1) and a new band at 1716cm(-1), suggesting the formation of amide and ester linkages between PA and CS. New proton signals at δ6.77-7⋅33ppm were observed on (1)H NMR spectrum of PA-g-CS, assigning to the methine protons of PA. Signals at δ 150.8-116.6 ppm on (13)C NMR spectrum of PA-g-CS was assigned to the aromatic ring carbon of PA moieties. All the structural information confirmed the successful grafting of PA onto CS. SEM observation showed CS had a smooth surface, while PA-g-CS had a rough surface. TGA revealed the thermal stability of PA-g-CS was lower than CS. Antioxidant activity assays further verified the reducing power and DDPH radical scavenging activity of PA-g-CS was much higher than CS.
authors.affiliation: College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China. Electronic address: junliu@yzu.edu.cn.
authors.forename: Jun
authors.initials: J
authors.lastname: Liu
authors.affiliation: College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China.
authors.forename: Chen-Guang
authors.initials: CG
authors.lastname: Meng
authors.affiliation: College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China.
authors.forename: Ye-Hua
authors.initials: YH
authors.lastname: Yan
authors.affiliation: College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China.
authors.forename: Ya-Na
authors.initials: YN
authors.lastname: Shan
authors.affiliation: College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China.
authors.forename: Juan
authors.initials: J
authors.lastname: Kan
authors.affiliation: College of Food Science and Engineering, Yangzhou University, Yangzhou 225127, Jiangsu, China.
authors.forename: Chang-Hai
authors.initials: CH
authors.lastname: Jin
mesh_terms: D000975:Antioxidants / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D002234:Carbodiimides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D048271:Chitosan / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D003432:Cross-Linking Reagents / Q000737:chemistry; D016166:Free Radical Scavengers / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D062385:Hydroxybenzoates / Q000138:chemical synthesis / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D010084:Oxidation-Reduction; D010627:Phenethylamines / Q000737:chemistry; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology
chemical_list: D000975:Antioxidants; D002234:Carbodiimides; D003432:Cross-Linking Reagents; D016166:Free Radical Scavengers; D062385:Hydroxybenzoates; D010627:Phenethylamines; D011108:Polymers; C057485:1-(2,6-dimethylphenoxy)-2-(3,4-dimethoxyphenylethylamino)propane; C009091:protocatechuic acid; D048271:Chitosan
keywords: Carbodiimide; Characterization; Chitosan; Protocatechuic acid