Extraction Of Polysaccharides From Enteromorpha Prolifera Purification And Structure Characterization

Enteromorpha which grows in China's coastal area widely is a large algae. Usually enteromorpha is used as food, feed and fertilizer etc. According to the domestic and foreign related reports, it has a high nutritional value and medicinal functions. Polysaccharide is the main active ingredient of enteromorpha. It has a lot of medicinal value such as reducing blood fat, having an anti-oxidation effect, inhibiting tumor cell growth, improving immunity etc. In this paper, extraction, isolation and purification, distribution of the relative molecular weight, structure and bioactivity of polysaccharides from enteromorpha were studied. The results were as follows :The basic chemical compositions of powder of frozen dried entermorpha were: total 53.64%, protein 10.21%, fat 1.02%, ash 25.87%, moisture 5.25%.The effects of extraction time, extraction temperature, ultrasonic time and ultrasonic power on the yield of polysaccharide were investigated by using ultrasonic assisted water extraction. The optimum level of each factor were initially determined by single factor experiments. Then, the optimum level of the temperature of the water extraction, ultrasonic time, ultrasonic power and their interactions were studied and discussed by adopting the response surface analysis under the single-factor tests. According to the results of regression analysis, the optimum extraction processes of polysaccharide were: extraction temperature 91.5℃, ultrasonic power 625 W, ultrasonic time 26 min; under this condition, the yield of polysaccharide from enteromorpha could reach 14.52%. In this chapter the processes of removing proteins were optimized by trichloro acetic acid method.The results showed that the final concentration of trichloroacetic acid was 3% and precipitation time was 2 h, the effect of removing proteins were best.Crude polysaccharides were initially purified by DEAE cellulose-52 column. Two major fraction of SP-Ⅰa nd SP-Ⅱwere eluted by deionized water; next, fraction of SP-Ⅲwas eluted by 0.3 mol/L NaCl.These three fractions accounted for 16.65%, 10.08% and 72.12% respectively. Then they were purified further by Sephadex G-100 and got SPP-Ⅰ, SPP-Ⅱand SPP-Ⅲrespectively.The chemical compositions and structures of SPP-Ⅰ, SPP-Ⅱand SPP-Ⅲwere respectively discussed by high performance gel filtration chromatography, PMP pre-column derivatization HPLC method. The results showed that the relative molecular weight of SPP-Ⅰ, SPP-Ⅱ, and SPP-Ⅲwere 5.21×10~5, 7.94×10~3, 4.53×10~4; monosaccharide composition of SPP-Ⅰis D-Fru : L-Sor =1.00:4.82; monosaccharide composition of SPP-Ⅱis D-Fru :Man : D-Gal= 1.00:20.63:2.5; monosaccharide composition of SPP-Ⅲis D-Xyl:D-Ara:D-Glc= 1.00: 1.43 :0.62.This experiment found that enteromorpha polysaccharides has good moisturizing activity, so it's necessary for researching it. The result indicated that:under the condition of RH 40% enteromorpha polysaccharide moisture absorption rate and moisturizing rate were higher than the glycerin and propylene glycol; Environmental humidity had no effect on moisture retention of enteromorpha polysaccharide.