Polyglucan from Cetraria islandica (L.) Ach., Parmeliaceae (Iceland Moss). Isoln: Peat et al., J. Chem. Soc. 1957, 3916. Linear polysaccharide structure composed of regular sequences of two (1→4)- and one (1→3)-β-d-glucopyranosyl residues: Perlin, Suzuki, Can. J. Chem. 40, 50 (1962); Fleming, Manners, Biochem. J. 100, 4, 24 (1966). Exhibits antineoplastic activity: Shibata, JP 71 17147 (1971), C.A. 75, 67474z (1971); Tadahiro et al., Chem. Pharm. Bull. 20, 2445 (1972). NMR spectrum: D. Gagnaire, M. Vincedon, Bull. Soc. Chim. Fr. 1977, 479.