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 ibitipocae, Cladonia imperialis, Cladonia miniata, Cladonia penicillata, Cladonia salmonea, Cladonia signata, Cladonia substellata and Cladonia uncialis. They were extracted with 10% aqueous KOH at 100 degreesC, giving polysaccharides with varying yields and proportions of mannose, galactose and glucose. Their aqueous solutions were freeze-thawed giving precipitates of mixed alpha -glucan (nigeran) and beta -glucans, which were isolated and suspended in 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 methylation analysis, which gave rise to 2,4,6-tri-O-methylglucitol acetate only, corresponding to (1 --> 3)-linkages. Its specific rotation (+4 degrees) and one- and two-dimensional nuclear magnetic resonance (NMR) spectra were consistent with beta -linkages. C-13 and H-1-1 signals were observed, respectively, 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 from the glucans from the other 14 Cladonia spp. The beta -D-glucans of the laminaran type seems to be present in all Cladonia spp. being significant for chemotyping since it was observed in every species studied. (C) 2001 Federation of European Microbiological Societies. Published by Elsevier Science B.V. All rights reserved.