Structural characterization and DPPH radical scavenging activity of an arabinoglucogalactan from Panax notoginseng root

The structure of an antiradical arabinoglucogalactan (1) from Panax notoginseng roots was determined. This polymeric carbohydrate was obtained through successive phosphate buffer (pH 7.0) extraction after cold-water pretreatment and purification by ion-exchange and gel-filtration chromatography. Monosaccharide analysis, permethylation analysis, NaIO4 and CrO3 oxidations, Smith degradation, graded acid hydrolysis, and IR and NMR experiments indicated that 1 possesses a backbone of (1 -> 3)-linked beta-D-galactofuranosyl residues, with branches Of alpha-L-Araf-(1 -> 4)-beta-D-Glcp-(1 -> residues at O-6. Additionally, 1 exhibited high scavenging activity against DPPH free radicals with a 50% scavenging concentration (SC50) Of 11.72 +/- 0.91 mu g/mL, suggesting that this arabinoglueogalactan is a potential antiradical.