Study On Isolation, Biological Activity And Stability Of The Red Pigment From Chinese Jujube Peel

The current study of the red pigments from Chinese jujube peel mainly focuses attention on its extraction process, antioxidant activity, physical and chemical properties, and stability. Its extraction methods have been very well known. However, the chemical properties and structures of the pigments remain unknown, which is a serious impediment to its exploitation. Their structures need to be determined through separation and purification.In this experiment Xinjiang jujube peel was used as raw material. The pigment separation process and stability as well as the purification and biological activity of the fractions from ether fractionation of the pigments were investigated. The main results includes:(1) The results obtained by comparising the adsorption and desorption efficiency of macroporous resins for the pigments indicate that AB-8type macroporous resin showed higher adsorption efficiency and desorption efficiency. The optimum conditions for the resin adsorption were as follows:adsorption mass concentration,0.8mg/mL; static adsorption time,3.5h; material liquid ratio,90:40; adsorption rate,65.6%. The conditions for the resin elution are as follows:gradient elution, from10%,20%,..to90%ethanol water; elution rate,98.2%.(2)The red pigments from Chinese jujube peel are water-soluble. Sunlight had some destructive effects on the pigments. The pigments were stable under weak acid, alkaline solution, high temperature, and in citric acid, but very unstable in ascorbic acid solution. The specific reason is unknown, so the pigments should avoid ascorbic acid when preserving.(3) The fractions from ether fractionation of the pigments had good scavenging activities on superoxide anion radical and nitrite ion, which showed the pigments good natural free radical scavengers, but for their hydroxyl radical scavenging activity was very low. The fractions had significant inhibitory effects on K562leukemia cell growth. Further studies are needed to elucidate the exact mechanisms of this action. In summary, the red pigments from Chinese jujube peel are excellent natural pigments.(4)Two components were obtained from ether fractionation fractions of the pigments through AB-8type macroporous resin and Due to the trace and deficiency of purity, their molecular weights,411.2and382.1, were only detected, the chemical formula and chemical structures can not be determined. The two components were inferred to be saturated or unsaturated fatty acids based on the data of MS, IR and other assays. To the best of our knowledge this is the first report regarding the chemical composition of the red pigments from Chinese jujube peel. Moreover, the results also indirectly showed that AB-8type macroporous resin and Sephadex LH-20column chromatographic techniques were suitable for the separation of the pigments. These provide reference and basis for the further study of the pigment chemical composition.