Structural characterization and antitumor activity of a pectic polysaccharide from the roots of Angelica acutiloba

The polysaccharide fraction from the root of Angelica acutiloba Kitagawa showed a potent antitumor activity against ascitic form of Sarcoma-180, IMC carcinoma, and Meth A fibrosarcoma as well as the solid form of MM-46 tumor. An active polysaccharide, AR-4E-2, was purified by precipitation with cetyl-trimethylammonium bromide, anion-exchange chromatography on DEAE-Sepharose, and gel filtration on Sepharose CL-4B from the polysaccharide fraction. An active polysaccharide fraction showed a weak anti-complementary activity. AR-4E-2 was composed of arabinose, galactose, and rhamnose in the molar ratios of 3.3:1.0:0.7, and also contained 14.5% galacturonic acid and 3.2% protein. Methylation analysis and base-catalysed beta-elimination studies suggested that AR-4E-2 contained a rhamnogalacturonan moiety in which 2,4-di-substituted rhamnose residues were attached to 4-substituted galacturonic acid through position 2 of rhamnose. AR-4E-2 also contained highly branched 3,5-arabinan and (1----4)-galactan.