Structural characterization of a low-molecular-weight polysaccharide from Angelica pubescens Maxim. f. biserrata Shan et Yuan root and evaluation of its antioxidant activity.

A novel heteropolysaccharide with about twenty sugar residues named DF80-2 was obtained from Angelica pubescens Maxim. f. biserrata Shan et Yuan root, one of the most widely used traditional Chinese medicines for thousands of years in China. The possible structure of DF80-2 was proposed considering the comprehensive results of physicochemical properties, methylation analysis, and 1D/2D NMR spectroscopy, which showed that its main chain was composed of (1→3)-, and (1→4)-linked-α-d-Glcp, (1→4)-linked-ß-d-Galp, (1→6)-linked-α-d-Manp, and (1→3)-linked-α-l-Araf, and the branch was present as the α-d-Glcp-(1→3)-ß-d-GalpA disaccharides stretched from O-6 position of (1→4)-linked-α-d-Glc moiety in the main chain. Congo red analysis, scanning electron microscopy and atomic force microscopy showed that DF80-2 possessed a triple helical conformation, and its branched monomers were interlaced with one another forming a regular network structure. DF80-2 exhibited antioxidant activity by effectively scavenging DPPH, and hydroxyl radicals, and chelating ferrous ions.

Physicochemical analysis, structural elucidation and bioactivities of a high-molecular-weight polysaccharide from Phellinus igniarius mycelia.

Phellinus igniarius is a well-known edible and medicinal fungus consumed in Asia for centuries. In the present study, a polysaccharide named PIP-1 was obtained from Phellinus igniarius mycelia, its physicochemical properties were determined, its detailed structures were elucidated by analysis of its depolymerized product, and its antioxidant and antitumor activities were evaluated. Results showed that PIP-1 had a high molecular weight, a high intrinsic viscosity and a linear repeating backbone composed of glucopyranose (Glcp), galactopyranose, and mannopyranose joined by α-(1 → 4), α-(1 → 3), and α-(1 → 6) linkages, and single α­terminal­D­Glcp as side chains 6-O-linked to the main chain according to the GC-MS and NMR results, and exhibited triple helical structure. Pharmacological results revealed that PIP-1 could effectively scavenge hydroxyl radicals, partly scavenge DPPH radials and chelate ferrous metal ions. Furthermore, PIP-1 showed potent inhibitory effects on growth of HT-29 and MCF-7 cells. These findings suggested that high-molecular-weight PIP-1 containing triple helical structure and only α-type glycosidic bond holds promise as novel functional foods and agents to promote human health.