title: Acetylation and carboxymethylation of the polysaccharide from Ganoderma atrum and their antioxidant and immunomodulating activities.
abstract: A water-soluble polysaccharide extracted from Ganoderma atrum was chemically modified to obtain its acetyled and carboxymethylated derivatives. The results of chemical analysis, Fourier-transform infrared and (13)C nuclear magnetic resonance spectroscopy showed that these modifications were successful, although the molecular weight of these derivatives decreased due to slight degradation during the reaction. The antioxidant and immunomodulating activities of these derivatives were then investigated to determine the structure-bioactivity relationship. Results showed that the acetyled derivative with appropriate degree of substitution and lower molecular weight exhibited stronger antioxidant abilities on scavenging DPPH radical, and inhibitory effects in β-carotene-linoleic acid systems compared with the native polysaccharide. In addition, it also enhanced the macrophage phagocytosis capacity and tumor necrosis factor-α secretion, whereas the carboxymethylated derivative was shown to be slightly less effective. These results indicated that the type of substitution group and their degree of substitution play a decisive role in the bioactivities of the derivatives.
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, People's Republic of China.
authors.forename: Hui
authors.initials: H
authors.lastname: Zhang
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, People's Republic of China.
authors.forename: Yuanxing
authors.initials: Y
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, People's Republic of China.
authors.forename: Shaoping
authors.initials: S
authors.lastname: Nie
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, People's Republic of China.
authors.forename: Chang
authors.initials: C
authors.lastname: Li
authors.affiliation: State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047, People's Republic of China. Electronic address: myxie@ncu.edu.cn.
authors.forename: Mingyong
authors.initials: M
authors.lastname: Xie
mesh_terms: D000107:Acetylation; D000975:Antioxidants / Q000737:chemistry*; D032902:Ganoderma / Q000737:chemistry*; D011134:Polysaccharides / Q000737:chemistry*; D017382:Reactive Oxygen Species; D013329:Structure-Activity Relationship
chemical_list: D000975:Antioxidants; D011134:Polysaccharides; D017382:Reactive Oxygen Species
keywords: Acetylation; Antioxidant activity; Carboxymethylation; Ganoderma atrum polysaccharides; Immunomodulating activity