Quality Anslysis And Prebiotic Activity Assay Of The Polysaccharide From Ophiopogon Japonicus

The root of Ophiopogon japonicus(Mai-Dong in Chinese)is a traditional Chinese medicinal herb as well as functional food.It has the effect of nourishing Yin,nourishing Jin,promoting body fluid production,moistening the lung,easing thae mind and clearing away heart fire.Mai-Dong possess therapeutic effects against dry lung cough,asthenia cough,thirsty,insomnia,internal heat to quench thirst,intestinal dryness,constipation,diphtheria,and other disorders.Phytochemical studies have revealed various biologically active compounds,including polysaccharides,steroidal saponins,and homoisoflavonoids.Among them,a water-soluble β-D-fructan polysaccharide(MDP)has been reported as one of the main component,whose functional mechanisms remain to be further clarified.MDP may be served as prebiotic to adjust imbalance of intestinal microbes,from its chemical structure nature.In this paper,therefore,MDP of Ophiopogon japonicus from traditional Sichuan region was studied,from its preparation,quality determination to prebiotic activity assay in vitro,which could provide scientific data for its further development and application.Preparation of MD-P was conducted at first.The root of Ophiopogon japonicus was extracted by water at first,followed by AB-8 macroporous resin adsorption to remove other organic impurities and condensed to give MDP-E syrup.MDP-E was then purified by step-added ethanol participate,followed by Sephadex LH20 column purification to give MDP-S1 as the major fraction of MDP-E.MDP-S1 showed an average molecular weight of 19.2 kD as determined by high performance size exclusion column(HPSEC).MDP-S1 hydrolate was composed of fructose and glucose(about 19.9:1)as measured by HPLC.By comparisions of its 1H and 13C-NMR data with references,MD-S1 was a β-D-fructan polysaccharide,composed of a Fruf(2→1)backbone and a Fruf(2→6)branch,with a trace of α-D-Glc as its reducing terminal probably.The total content of MDP of Ophiopogon japonicus was then developed,which helped to evaluate quality of the herb.A UV-Vis spectroscopy method was adopted,using anthrone sulfuric acid as chromogenic agent.Fructose was selected as standard reagent,which gave a regression equation to be y=7.3449x+0.0165(r2=0.9926),with line range between 0.01014-0.1014 mg/mL.The method ran well as determined by accuracy,repetition,stability,and recovery rate tests.The total content of sugar of Ophiopogon japonicus was determined to be 38.47%,or 42.51%in dry form as equivalent to fructose.Moreover,the characteristic fraction composition of Ophiopogon japonicus could be analyzed by HPSEC,as that mentioned above.Intestinal flora plays important role in body health.Dynatic balance of intestinal flora varies according to gene,food nutrients,body health conditions etc.,and prebiotic such as food fibers(plant polysaccharides in major)could play important role in this way.Prebiotic activities of MDP-E were evaluated in this study,using normal SD rat fecal sample model.The population numbers of four species,Lactobacillus,Bifidobacterium,Enterococcus and Escherichia coli were accounted.As a result,MDP-E could promote the growth of Enterococcus and Lactobacillus obvious,but no obvious effect on Escherichia coli and Bifidobacterium.Compared with the blank control group,the B/E and L/E values of MDP-E group increased significantly either.It can be inferred that the fructan of Ophiopogon japonicus serve as prebiotic,which represent one of functional ingredient of Ophiopogon japonicus.