Further studies on the structure of polysaccharides from the lichen Flavoparmelia caperata (L.) HALE

A water-soluble polysaccharide called PC-2 was previously isolated from Flavoparmelia caperata (L.) HALE and assigned to alpha(1-3)(1-4)glucan. However, PC-2 separated into three components, PC-2A, PC-2B, and PC-2C (a single peak in HPLC, respectively) on further purification. Methylation analysis and H-1- and C-13-NMR spectroscopic studies suggested that PC-2A is composed of repeating units of [alpha-D-Glc1-3](3): [alpha-D-Glc1-4](2), while PC-2B and PC-2C are partly branched galactoglucomannans consisting of (1-3)- and (1-4)-linked alpha-D-glucopyranosyl units as the main chain. In addition we confirmed that the polysaccharide fraction PB-2 from the lichen of the same genus, Flavoparmelia baltimorensis (GYELNIK & FORISS) HALE, is identical to PC-2 based on the chemical and spectroscopic data.