Lichenin

Lichenin (from the Greek lichen = lichen) is a colorless and tasteless, water-soluble, unbranched polysaccharide composed of 60-299 glucose residues, which occurs as a storage carbohydrate mainly in various lichens and mosses (in high concentrations, e.g. in Iceland moss). The sugar monomers of lichenin are 30% beta-1,3-glycosidic and 70% beta-1,4-glycosidic.

In oats and barley, lichenin can make up 6-8% of the dry matter, in wheat and rye at most about 2%. Lichenin is highly swelling. When boiled in water, it produces a colloidal solution which forms a jelly when cooled. Lichenin is indigestible for humans (humans lack the enzyme lichenase) and is used as a mucilage drug and expectorant.

1. Freysdottir J et al (2008) In vitro and in vivo immunomodulating effects of traditionally prepared extract and purified compounds from Cetraria islandica. Int Immunopharmacol 8:423-430.
2. Niu Q et al (2916) Purification and characterization of a thermophilic 1,3-1,4-β-glucanase from Bacillus methylotrophicus S2 isolated from booklice. J Biosci Bioeng 121:503-508.
3. Kim SY ET AL. (2014) Characterization of a lichenase isolated from soil metagenome. J Microbiol Biotechnol 24):1699-1706.