Further Studies on the Structure of Polysaccharides from the Lichen Flavoparmelia caperata (L.) HALE

Abstract

A water-soluble polysaccharide called PC-2 was previously isolated from Flavoparmelia caperata (L.) HALE and assigned to α(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 ¹H- and ¹³C-NMR spectroscopic studies suggested that PC-2A is composed of repeating units of [α-D-Glc1-3]₃, : [α-D-Glc1-4]₂, while PC-2B and PC-2C are partly branched galactoglucomannans consisting of (1-3)- and (1-4)-linked α-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.