Effects of extraction methods on immunology activity and chemical profiles of Lycium barbarum polysaccharides

It has been proven that polysaccharides have bioactivities and are beneficial to cure many diseases. Lycium barbarum fruit is widely used as a functional food all over the world, which main active component is L. barbarum polysaccharides (LBPs). In this study, classical hot water extraction (HWE), microwave assisted extraction (MAE), ultrasonic assisted extraction (UAE) and pressurized liquid extraction (PLE) were used to extracted LBP. The chemical properties of LBPs were evaluated in terms of total polysaccharide contents, uronic acid contents and protein contents. High performance size exclusion chromatography coupled with multi angle laser light scattering and refractive index detector was applied to measure the characters such as molecular weight, radius of gyration and polydispersity index. Then the immunomodulatory activity of LBPs was evaluated through RAW 264.7 cells. The results showed that HWE was the best method to get the highest total sugar and acidic polysaccharides, MAE was preferable to extract polysaccharide-protein complex, but PLE, UAE and HWE could get better immunomodulatory activity polysaccharides than MAE. Besides, the peak 3 in chromatogram of MAE extracted LBPs was obviously higher than those of LBPs produced by other 3 extraction methods, which suggested that peak 1 and peak 2 might be biologically active polysaccharides fractions in LBPs. Therefore, effect of different extraction methods on structure and composition of LBPs attributed to their variance of immunological activities. (C) 2020 Elsevier B.V. All rights reserved.