Lycium barbarum polysaccharides (LBP) are one of the major functional components in the fruit of Lycium barbarum, which have been demonstrated to exert immunomodulatory activity. Most of the existing studies are focused on the immunoenhancing effect of LBP, but in-depth research on its immunosuppressive effect is limited. This article reviews recent research on the immunoenhancing and immunosuppressive effects of different polysaccharide fractions extracted from Lycium barbarum fruit from different perspectives, like intestinal mucosa protection, intestinal flora changes, immune cells and the neuroendocrine immune system. The outcome of this review will be for the application of Lycium barbarum polysaccharides in antiviral therapy, antitumor therapy, vaccine development, immune-enhancing feed formulation and antiallergic agents or food products.

The purpose of this study was to explore the effects of konjac glucomannan (KGM) with different molecular masses (1, 5 and 90 kDa) on cognitive dysfunction and brain oxidative stress in mice induced by a high-calorie diet. In this study, 90 mice were randomly divided into nine groups: normal diet (ND), negative control (ND + 1 kDa KGM, ND +5 kDa KGM, and ND + 90 kDa KGM), high-fat and high-fructose diet (HFFD) model, intervention (HFFD + 1 kDa KGM, HFFD + 5 kDa KGM, and HFFD + 90 kDa KGM), and positive control (HFFD + KGM). Behavioral tests including open field, Y maze and Morris water maze tests were conducted to evaluate the learning and memory ability of mice.Meanwhile, the morphological changes of brain nerve cells were evaluated by pathological section, and the relative content of glutathione (GSH) and the relative activity of catalase (CAT) in brain tissue were determined by commercial kits.The results demonstrated that KGM, regardless of its molecular mass, could significantly improve the spatial working memory capacity of mice fed HFFD (P < 0.05). The total movement distance of mice in the 90 kDa KGM intervention group was significantly increased in the open field and water maze positioning navigation tests (P < 0.05), while supplementation of 1 kDa KGM significantly decreased the escape latency (P < 0.05) and significantly increased the number of times that mice crossed the platform location and the movement distance in the quadrant (P < 0.05). Immunohistochemical results showed that konjac glucomannan markedly inhibited the morphological abnormalities of hippocampal neurons in the mouse brain induced by HFFD. Similarly, 90 kDa KGM significantly increased the relative level of GSH (P < 0.05), and 1 kDa KGM significantly up-regulated the relative activity of CAT in mouse brain tissue (P < 0.05). These results indicated that konjac glucomannan with high molecular mass (90 kDa) can effectively enhance the spontaneous activity of mice, while konjac glucomannan with low molecular mass (1 kDa) can significantly improve the learning and memory ability of mice fed a high-calorie diet. The underlying mechanism may be related to the oxidative stress state in the brain.

β-Conglycinin is one of the major allergens existed in soybean. N-Glycans attached to the β-conglycinin influenced the immunoreactivity and antigen presenting efficiency of β-conglycinin. In this study, we described a new method used to release and collect the N-glycans from β-conglycinin, and the N-glycans existed in linear epitopes of β-conglycinin were identified. Glycopeptides hydrolyzed from β-conglycinin were purified by cotton hydrophilic chromatography. Trifluoromethylsulfonic acid was then used to release glycans from glycopeptides, and new glycopeptides containing one single N-acetyl-D-glucosamine (GlcNAc) moiety were then utilized for mass spectrometry. Five glycosylation sites (Asn-199, Asn-455, Asn-215, Asn-489 and Asn-326) and 22 kinds of glycopeptides were identified. It is noteworthy that the peptide VVN^#ATSNL (where ^# represents for the glycosylation site) was analyzed to be both glycopeptide and linear epitope. Our results provided a new method for the N-glycoform analysis of food allergens, and laid a foundation for understanding the relationship between glycosylation and food allergy.