Structural characterization of an arabinogalactan from Platycodon grandiflorum roots and antiangiogenic activity of its sulfated derivative.

A water-soluble polysaccharide, PGAW1, with an average molecular mass of 9.2 kDa determined by high performance gel permeation chromatography (HPGPC), was isolated from radix of Platycodon grandiflorum . Monosaccharide composition analysis indicated that PGAW1 contains Ara and Gal in the molar ratio of 1.42:1.0. Using methylation analysis, partial hydrolysis, endo-1,4-β-d-galactanase digestion, NMR and ESI-MS, PGAW1 was determined to possess a backbone consisting of 1,4- and 1,6-linked galactopyranosyl residues, with branches attached to O-3 of 1,6-linked galactose residues. By the chlorosulfonic acid-pyridine method we produced a sulfated derivative of PGAW1, Sul-w1, with a substitution degree of 1.52. The substitution was at O-6 on 1,4-linked Gal residues according to the (13)C NMR spectra. Bioactivity test showed that Sul-w1 could inhibit tube formation by human microvascular endothelial cells (HMEC) in a dose-dependent manner.