Purification of anti-ulcer polysaccharides from the roots of Bupleurum falcatum.

A water-soluble crude polysaccharide fraction (BR-1) prepared from the root of Bupleurum falcatum L. (Japanese name = Saiko) prevented HCl/ethanol induced ulcerogenesis in mice significantly. BR-1 was fractionated into four polysaccharide fractions (BR-2, BR-3, BR-4, and BR-5) by the addition of cetyltrimethylammonium bromide, and the strongly acidic polysaccharide fraction BR-2 showed the most potent inhibition of gastric lesion formation. When BR-2 was further fractionated by anion-exchange chromatography, the most potent anti-ulcer activity was observed in the pectin-like polysaccharide, bupleuran 2IIc. Bupleuran 2IIc was homogeneous as determined by electrophoresis and gel filtration. Bupleuran 2IIc was composed mainly of galacturonic acid with small proportions of arabinose, rhamnose, and galactose, and its average relative molecular mass was estimated to be 63,000 d. BR-2 lost most of its activity after treatment with periodate or digestion with endo-polygalacturonase indicating that the polygalacturonan region and/or the molecular mass may contribute to activity.