WANG Ximei, LIU Jingyu, FENG Cuiping, WANG Yuanfeng, GUAN Xiao, LIU Peng, YANG Yan
Five concentrations of NaCl (0.3, 0.6, 0.9, 1.2, 1.5 mol·L-1) were used to extract glycoproteins from Hericium erinaceus (designated as Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ, respectively). The resultant glycoproteins Ⅰ, Ⅱ, Ⅲ, Ⅳ, and Ⅴ were compared for polysaccharide content, protein content, structural characteristics (proportions of different secondary protein structures, monosaccharide composition, amino acid composition), as well as in vitro antioxidant activity and immunological activity. The correlations between NaCl concentration and these parameters were also analyzed. The results showed that the polysaccharide and protein contents of the five kinds of H. erinaceus glycoproteins were 5.55%-8.15% and 40.46%-75.96%, respectively. Glycoprotein III had the highest polysaccharide content (8.15%), while glycoprotein II had the highest protein content (75.96%). The secondary structures of all five glycoproteins were predominantly composed of β-sheets and random coils. Regarding monosaccharide composition, glycoproteins I, II, and III were mainly composed of glucose and mannose, whereas glycoproteins IV and V primarily contained glucose and galactose. Compared with Ⅳ and Ⅴ, glycoproteins Ⅰ, Ⅱ and Ⅲ contained higher levels of basic amino acids, acidic amino acids and essential amino acids. Glycoproteins I, II, and III showed superior DPPH and ABTS radical scavenging abilities compared with IV and V. All five glycoproteins stimulated the release of NO, TNF-α, and IL-6 from RAW264.7 macrophages. Compared with III-V, glycoproteins I and II exhibited better immunostimulatory activity. NaCl extraction concentration was negatively correlated with protein content, amino acid content, α-helix proportion, β-turn proportion, and total uronic acid content, while it was positively correlated with polysaccharide content, β-sheet proportion, and random coil proportion.
