Isolation,Purification And Structure Analysis Of Polysaccharides From Veratrum Nigrum L

Veratrum nigrum L (black hellebore) is a kind of perennial herb. The root of Veratrum contains a variety of active ingredients, such as steroidal alkaloids, stilbenes, resveratrol, polysaccharide, and so on. The veratrum root has been used as traditional medicine for thousands of years in China. Pharmacological research has confirmed that the veratrum root has anti-thrombosis and anti-tumor activities, as well as enhancing myocardial contractility, lowering blood pressure and inhibiting platelet aggregation. The polysaccharides are an important component, in veratrum root. However, no report has been focused on their isolation or function so far. In order to better understanding of the chemical structure and properties of veratrum polysaccharides, in this work, the extraction, separation, purification and structural analysis of VP have been studied.The water-soluble polysaccharides of the root of Veratrum nigrum L was extracted with hot water, then precipitated by80%ethanol. The yield of veratrum polysaccharides (VP) was14.6%. VP contained82.5%total carbohydrates,8.1%uronic acid. The monosaccharide composition of VP was Glc (84.1%), GalA (7.4%), Gal (5.0%), Man (1.6%), Ara (1.2%) and Rha (0.6%).VP was separated into two fractions by DEAE-Cellulose chromatography:an unbound fraction VPN eluted by water and a bound fraction VPA eluted by0.5M NaCl. VPN consisted of Glc (90.1%), Man (4.0%) and Gal (4.8%). VPA consisted of GalA (41.4%), Glc (27.4%), Gal (15.2%), Man (3.7%), Rha (5.5%) and Ara (5.3%). The distribution of VPN molecular weight on Sepharose CL-6B was wide and heterogeneous.VPA was further separated into five fractions on DEAE-Cellulose column: VPA-N, VPA-1, VPA-2, VPA-3and VPA-4corresponding to0,0.08,0.14,0.20and0.27M NaCl elution, respectively. Depending to the molecular weight distribution of the polysaccharide, the acidic fractions VPA-1, VPA-2, VPA-3and VPA-4were further separated on Sephadex G-75gel chromatography column. Seven fractions VPA-1-a, VPA-1-b, VPA-2-a, VPA-2-b, VPA-3-b, VPA-4-a and VPA-4-b were obtained, respectively. The monosaccharide composition analysis indicated that VPA-1-a consisted of mannoglucan and arabinogalactan; VPA-1-b and VPA-2-a consisted of mannoglucan and RG-I type pectin; VPA-2-b, VPA-3-b, VPA-4-a and VPA-4-b consisted of HG type pectin and a small amount of RG-I type pectin. Based on the molecular weight distribution of the seven fractions on HPGPC, VPA-1-a, VPA-1-b, VPA-2-a, VPA-2-b, VPA-3-b, VPA-4-a and VPA-4-b were homogenous with molecular weight of1.2×104Da,2.3×103Da,1.59×104Da,3.8×103Da,5.5×1O3Da,1.24x104Da and4.1×103Da respectively.So, VP was composed of VPN and VPA. The VPN contained of glucan, the molecular weight distribution was wide and heterogeneous. The VPA was composed of HG pectin and RG-I pectin. The molecular weight distribution was homogenous, ranging2.3×103to1.59×104Da.Veratrum nigrum L was incompatibility with ginseng in traditional Chinese medicine. It limited the application of Veratrum nigrum L. In this paper, the impact of polysaccharide about Veratrum nigrum L mixed with ginseng was studied. The mixture of Veratrum nigrum L with ginseng do not affect the yield, total sugar content, uronic acid content, monosaccharide composition and molecular weight distribution of polysaccharides.