Structure Of The Water-soluble Polysaccharide (RCP) From Roots Of Rubus Crataegiflolius Bge

Rubus crataegiflolius Bge is also called "niudiedu" and "malinguo" in China. Its fruits and roots are medicinal in folk prescription to treat rheumatic arthritis, hepatitis and lung cancer. Biological activities of small molcular had been researched ,but studies on the structure and activities of polysaccharides from roots have not been reported. Since most polysaccharides have the effects of immunomodulatory and anti-tumor, in this paper, the structure feature and biological activities of polysaccharide isolated from water extract of the roots of Rubus crataegiflolius Bge were reported. The results may help the development of Rubus crataegiflolius Bge in the future. Crude water-soluble polysaccharides were isolated from the roots of Rubus crataegiflolius Bge by hot water extraction followed by ethanol precipitation. After removed starch and protein and fractionated by ultra filtration and gel chromatography, the polysaccharide (RCP) was obtained. Homogeneity and molecular weight of RCP were determined by specific optical rotation measurement and High-performance liquid chromatography (HPLC). The sugar composition was determined by methanolysis and gas chromatography (GC). The results revealed that RCP was homogeneous. Its molecular weight was about 7000. It was consisted of glucose with trace of rhamnose. RCP was a neutral heteropolysaccharide The structure of RCP was determined by partial acid hydrolysis, periodate oxidation, Smith degradation, methylation analysis and nuclear magnetic resonance (NMR) analysis. These analyses indicated that RCP has the following structure: an (1→4)-D-glucose backbone with side chains of (1→6)-D-glucose residues bound to the O-6 position of the glucose residues. On an average, there is one branch every 9 hexose residues. Acolorimetric tetrazolium MTT method was used for the determination of anti-tumor activity evaluation, but no sufficiently directly cytotoxic effect was detected.