Structure Elucidation of a Polysaccharide from Umbilicaria esculenta and Its Immunostimulatory Activity.

ABSTRACT: Umbilicaria esculenta has been used as a tonic food in China for several centuries owing to its pleasant flavor and health benefits. In this study, a water soluble polysaccharide, which we designated as UP2, with an average molecular weight of 3.33 × 105 Da, was isolated from U. esculenta cultivated in the Huangshan Mountain, by consecutive hot water extraction and anion-exchange chromatography. Gas chromatography analysis indicated that UP2 contained three kinds of monosaccharides, including mannose, glucose, and galactose at a molar ratio of 1.7:1.0:1.2. Linkage analysis of UP2 revealed the presence of (1 ? 6)-linked glucosyl, (1 ? 3,6)-linked glucosyl, t-linked galactosyl, (1 ? 6)-linked galactosyl and (1 ? 6)-linked mannosyl at a molar ratio of 0.7:4.6:4.1:2.2:9.1. Structural analysis determined that UP2 possessed a backbone consisting of (1 ? 6)-linked ?-D-glucopyranosyl and (1 ? 6)-linked ?-D-mannopyranosyl residues, which substituted at the O-3 position of (1 ? 6)-linked ?-D-glucopyranosyl residues by branches of (1 ? 6)-linked ?-D-galactopyranosyl and 1-linked ?-D-galactopyranosyl residues. Immunostimulatory activity analysis showed that UP2 could stimulate the proliferation of RAW264.7 cells in a dose-dependent manner, and all the samples (20-500 ?g/mL) were found to enhance nitric oxide production. The highest phagocytic activity of UP2 was observed at 200 ?g/mL. Thus, UP2 may be a potential source of biological and pharmacological agents.

SUBMITTER: Zhang BW 

PROVIDER: S-EPMC5172621 | biostudies-literature | 2016

REPOSITORIES: biostudies-literature