Comparative studies of the polysaccharides isolated from lichenized fungi of the genus Cladonia: significance as chemotypes

beta -D-Glucans of the laminaran type were prepared from 15 Cladonia spp., Cladonia bellidiflora, Cladonia boryi, Cladonia clathrata, Cladonia connexa , Cladonia crispatula, Cladonia furcata, Cladonia gracilis, Cladonia ibitip ocae, Cladonia imperialis, Cladonia miniata, Cladonia penicillata, Cladonia salmonea, Cladonia signata, Cladonia substellata and Cladonia uncialis. Th ey were extracted with 10% aqueous KOH at 100 degreesC, giving polysacchari des with varying yields and proportions of mannose, galactose and glucose. Their aqueous solutions were freeze-thawed giving precipitates of mixed alp ha -glucan (nigeran) and beta -glucans, which were isolated and suspended i n aqueous 0.5% KOH at 50 degreesC, which preferentially dissolved the beta -glucan. In the case of the C. uncialis product, it was subjected to methyl ation analysis, which gave rise to 2,4,6-tri-O-methylglucitol acetate only, corresponding to (1 --> 3)-linkages. Its specific rotation (+4 degrees) an d one- and two-dimensional nuclear magnetic resonance (NMR) spectra were co nsistent with beta -linkages. C-13 and H-1-1 signals were observed, respect ively, at delta 102.8 (C-1), 86.0 (C-3), 76.2 (C-5), 72.6 (C-2), 68.3 (C-4) and 60.7 (C-6), and 4.55 (H-1), 3.31 (H-2), 3.49 (H-3), 3.27 (H-4), 3.27 ( H-5), 3.48 (H-6) and 3.72 (H-6'). Similar C-13-NMR spectra were obtained fr om the glucans from the other 14 Cladonia spp. The beta -D-glucans of the l aminaran type seems to be present in all Cladonia spp. being significant fo r chemotyping since it was observed in every species studied. (C) 2001 Fede ration of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.