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, NaIO 4 and CrO 3 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-Ara f-(1-->4)-beta- d-Glc p-(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 microg/mL, suggesting that this arabinoglucogalactan is a potential antiradical.