Chemotypes significance of lichenized fungi by structural characterization of heteropolysaccharides from the genera Parmotrema and Rimelia

Galactoglucomannans were isolated from the lichenized fungi of the genus Parmotrema (Parmotrema austrosinense, Parmotrema delicatulum, Parmotrema mantiqueirense, Parmotrema schindlerii, and Parmotrema tinctorum and that of Rimelia (Rimelia cetrata and Rimelia reticulata) via successive hot alkaline extraction and precipitation with Fehling solution. The structure of each polysaccharide was investigated using 13C NMR and HSQC-DEPT spectroscopy, methylation analysis, and HPSEC-MALLS. The galactoglucomannans had a (1 → 6)-linked main chain of α-Manp units, substituted preferentially at O-2 and O-4 by α-Galp and β-Galp nonreducing end-units, respectively. The C-1 region of the 13C NMR spectra of these heteropolysaccharides is typical of the lichen species, and is an additional tool in lichenized fungi classification.