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Phagocytic activity is related to total polysaccharide concentration and percent (1,3), (1,4)-glucan in commercial mushroom extracts
Dectin-1 and Mannose Receptor (MR) are carbohydrate polymer receptors on human monocytes and polymorphonucleocytes (PMN); both are involved in host defence against microbial pathogens through recognition of carbohydrate polymers found in abundance in the cell walls of fungal and bacterial pathogens. The carbohydrate polymers beta-glucan and alpha-mannan are ligands for Dectin-1 and MR, respectively, and have been shown to be immunoactive in numerous studies. The nature and diversity of immune cell responses to immunoactive carbohydrate polymers, as well as the structural variety of the polymers themselves, confound efforts to define structure-activity relationships. This report delineates unique compositional and structural characteristics of carbohydrate polymers found in five fungal-derived commercial natural products sold by prescription or as dietary supplements, and relates these to in vitro biological effects on human monocyte and granulocyte phagocytosis activity. Each product analyzed contains carbohydrate polymers in concentrations ranging from 24.7% –94.1% composed primarily of beta-glucan in configurations unique in terms of pyranose diversity and ratio as well as linkage traits. In ex vivo testing of blood from five healthy human donors, these products were shown to promote phagocytic activity in human monocytes and polymorphonucleocytes to differing degrees. Degree of bioactivity for each product is related to carbohydrate concentration and to percent of (1,4)- and (1,3)-glucan. These results contribute to elucidation of beta-glucan structure function relationships, elaborate on surrogate markers of biological activity for use in quality control efforts of manufacturers, and may help to inform product selection for clinical trials assessing immunomodulating activities of beta-glucan containing natural products.
Acknowledgements: Beckman Coulter 1 , Dave Osborn
References: 1. Chen, J., Seviour, R. (2007) Mycol Res 111:635–652