Immunomodulating polysaccharides from aqueous extracts of Cetraria islandica (Iceland moss)

Several polysaccharide fractions, isolated from a hot aqueous extract of Cetraria islandica (L.) Ach, by ethanol fractionation and ion-exchange chromatography, exerted significant in vitro anti-complementary activity and pronounced enhancement of in vitro granulocytic phagocytosis. Prior to aqueous extraction, low molecular weight compounds were removed from the plant material by organic extraction. An aqueous extract, prepared by the traditional method of briefly boiling the lichen directly with water, also exhibited significant anti-complementary and enhanced phagocytic activity. When tested for reticuloendothelial phagocytic activity in the in vivo carbon clearance test, the extract gave rise to a significant increase in the rate of colloidal carbon elimination. Results show, that in addition to an immunostimulating alkali-soluble galactomannan previously isolated from Iceland moss, the plant also contains water soluble polysaccharides, extractable by traditional methods, which exert immunomodulating effects.