Study On Extraction, Purification, Structure And In Vitro Bioactivity Of Polysacchrides From Bamboo Shoots

In this paper, extraction, separation, purification, structure and in vitro bioactivity ofpolysaccharides from bamboo shoots were studied. The main contents and results were asfollows:1. Study on the extraction, separation and purification of polysaccharides from bambooshoots. Firstly, the polysacchrides were extracted by water extraction. The influence ofliquid-solid ratio, extraction temperature, extraction time, extraction times and multiples of95%ethanol addition on polysaccharides extraction yield were investigated, respectively.On this basis, liquid-solid ratio, extraction temperature, extraction time and multiples of95%ethanol addition were chosen as factors and orthogonal experiments (L9(34)) wereconducted to determine the optimum extraction conditions. The optimal extractionconditions were liquid-solid ratio15:1, extraction temperature100℃, extraction time4hand multiples of95%ethanol addition4. And the highest extraction rate of polysaccharideswas7.58%. Thereafter the solution was centrifuged to obtain the supernate, which wasdeproteinizated by adding sevage reagent and discolored by D101macroporous rosinadsorption method. The resultant supernate was in turn dialyzed, precipited with95%ethanol and freeze-dried. The crude polysaccharides was obtained and named as WBP.WBP was further separated by the DEAE-cellulose-52column chromatography and elutedwith distilled water and different concentrations of NaCl solutions. The two larger peakswere obtained and the appropriate eluent were collected, concentrated and lyophilized,respectively. Finally, two polysacchrides fractions were got. Sephadex G-100was used tofurther purify the fractions and two more pure fractions were obtained (WBP1and WBP2).The deproteinization experiments showed that the optimal test times was4. In thedecolouration experiment of macroporous resin AB-8and D101, D101showed the besteffect when the ratio of macroporous resin and polysaccharides concentration was3:5.2. Study on the preliminary composition and structure of the polysaccharides. The totalsugar, protein, sulfates and uronic acid content were detected. With high-performance liquidchromatography (HPLC) analysis, WBP1and WBP2were homogeneous polysaccharidesand the molecular weights were83.44and80.01kDa, respectively. Amino acid analysisrevealed that the protein portion of the two polysaccharides fractions consisted of15aminoacids, including aspartic acid, threonine, serine, arginine and so on. The content of alaninewas the highest. From FT-IR, WBP1and WBP2were carbohydrate compounds and contained functional groups, such as-CH, C-O-C and-OH. According to GC analysis,WBP1and WBP2were heteropolysaccharides and were composed of rhamnose, arabinose,xylose, mannose, glucose, and galactose with molar ratio of5.05：6.06：10.13：97.19：28.11：33.41for WBP1and4.39：13.65：12.43：55.34：4.16：27.33for WBP2,respectively.3. Study on in vitro antioxidant activity of the two fractions, including reducing powerand scavenging effect toward hydroxyl radicals, superoxide anion radicals and hydrogenperoxide. The results showed that WBP1and WBP2exhibited not only certain scavengingeffect toward hydroxyl radicals, superoxide anion radicals and hydrogen peroxide, but alsogood reducing power. Scavenging effects of hydroxyl radicals and superoxide anionradicals presented positive correlations with the protein contents. Reducing powerpresented positive correlations with the sulfate contents. However, hydrogenperoxide-scavenging effect presented negative correlations with molecular weights of thefractions.4. The immunostimulating activity of the polysacchrides fractions was evaluated byusing MTT assay to test the effects of WBP1and WBP2with different concentrations onthe proliferation of mouse spleen cells. The results suggested that WBP1and WBP2havebeneficial effects on proliferation of mouse spleen cells, and exhibit the hightest cellproliferation activity at concentration of200μg/mL.5. Study on the effects of polysaccharides fractions on the growth of bifidobacteria invitro. Bifidobacterium bifidium and Bifidobacterium adolescentis were chosen as object ofthis study. OD and pH values of the medium were used as evaluation index. The resultsshowed that WBP1and WBP2had a certain role in promoting the growth of B. bifidiumand Bifidobacterium adolescentis, and were potential prebiotics. The fractions were used asthe nutrition of bifidobacteria. For B. bifidium, the growth-promoting effects ofpolysaccharides fractions were best when the concentration of WBP1and WBP2were2.0%and3.0%, respectively. For Bifidobacterium adolescentis, the growth-promotingeffects of the fractions were best at concentration of2.0%. In addition, the pH values of themedium were decreased, which indicated that the polysaccharides fractions might befermented by bifidobacteria. Through investigating on the growth curves of thebifidobacteria, some results were got as follows. The growth-promoting effects of WBP1and WBP2on B. bifidium were better than on Bifidobacterium adolescentis. Thegrowth-promoting effects of two samples on bifidobacterium were in order: WBP1>WBP2. The growth rate of bifidobacterium in medium containing glucose was faster than in the medium containing the fractions. The growth-promoting effects of WBP1and WBP2on B. bifidium were slightly stronger than on B ifidobacterium adolescentis.