STRUCTURAL STUDY OF POLYSACCHARIDES FROM CETRARIA-CUCULLATA AND CETRARIA-ISLANDICA LICHENS

Extraction of lichens Cetraria cucullata and Cetraria islandica with h ot water resulted in coldwater insoluble lichenans of identical struct ure (beta-D-glucans with beta-1,3- and beta-1,4-bound D-glucose residu es) and water soluble isolichenans built from alpha-1,3- and alpha-1,4 -bound D-glucose residues. The structures of polysaccharides were esta blished by methylation analysis, enzymic hydrolysis, the Smith degrada tion, and C-13 NMR spectroscopy. The subsequent extraction of lichens with an aqueous alkali gave the mixtures of heteropolysaccharides buil t from the residues of D-mannose, D-galactose, D-glucose, and an hexur onic acid.