ABSTRACT
Objective To investigate the physicochemica l properties and immunobiological activity of a polysaccharide (RAP-B-1) from stems of Rubus amabilis. Methods The crude polysaccharide (RAP) was obtained successively by boiling, ethanol precipitating and dialyzing. RAP was isolated with DEAE-cellulose and Sephadex G-100 to obtain a polysaccharide RAP-B-1. The physicochemical properties of RAP-B-1 were studied by hydrolysis, periodate oxidation, Smith degradation and methylation, CE, IR, NMR and GC-MS. The immunobiological activities were estimated by the proliferative activity of spleen lymphocytes and phagocytic activity of peritoneal macrophages in mice. Results The molecular weight of RAP-B-1 was 4.80×104 with specific optical rotation value [α] 20D+68.3 (c=1,H2O), and was composed of eight monosaccharides. The molar ratios were as Xyl: Ara: Glc: Rha:Gal: Man: GlcA: GalA = 1.0:6.9:0.8:1.1:6.9:0.3:0.5:3.3. RAP-B-1 was an arabinogalactan. The linkages of arabinose were →1) Ara (2,3→,→1) Ara(5→and→1) Ara, and the linkages of galactose were→1) Gal(4→,→1) Gal(6→and→1) Gal. RAP-B-1 could improve the proliferative activity of spleen T cells(P<0.05) and booste phagocytic activity of peritoneal macrophages at 50μg/ml concentration(P<0.01). Conclusion RAP-B-1 is an arabinogalactan and has immunobiological activity.