Effect Of Ultrasonic Degradation On The Biological Activity Of Extracellular Polysaccharide Of Porphyridium Cruentum

Porphyridium cruentum exopolysaccharide (EPS) is a high-molecular-weight sulfated polysaccharide with anti-virus, anti-radiation, antimicrobial activity and so on. Many properties of polysaccharide such as viscosity and biological activities, are closely related to its molecular weight.In this study the influence of ultrasonic degradation on extracellular polysaccharide of Porphyridium cruentum was determined by the viscosity of the solution. Uniform design method was used to optimize the parameter of ultrasonic, i.e. amplitude, irradiation time and pulse on the degradation of extracellular polysaccharide from Porphyridium cruentum, the optimal condition for the viscosity was as follows: amplitude 39%, irradiation time 245 s and pulse 9.5 s. Under the optimal condition, the calculated value was 2.98 mm²·s^-1 and the experimental value of the viscosity of the extracellular polysaccharide achieved to 3.09 mm²·s^-1 and the error is 3.7%. We used quadratic polynomial stepwise regression of DPS software to analysis the result of the experiment, and tested the significance of model and regression coefficients in order to establish a regression equation aimed at the viscosity of extracellular polysaccharide.DEAE-Sepharose Fast Flow ion-exchange column was used to purified and gradated EPS. Then two purified fractions were obtained: EPSⅠand EPSⅡ. Both Sepharose CL-6B gel chromatography and GPC analysis of EPSⅡperformed one peak. Infrared spectra showed that original and ultrasonic treatment extracellular polysaccharide of P. cruentum are mainly consists of pyranose.The in vitro anti-proliferation ability of two kinds of extracellular polysaccharides, P.cruentum and Rhodella reticulate , on lymphoma cell line CA46 was tested. The results showed that the inhibition rate increased with the increasing of polysaccharide concentration , and the inhibition rate of ultrasonic treated Porphyridium cruentum extracellular polysaccharide was higher than the untreated ones under the same concentration.In vitro test shows that both ultrasonic treated and untreated Porphyridium cruentum extracellular polysaccharide inhibited the growth of rat sarcoma S180 cells on a dose- and time- dependent manner; the ultrasonic treated polysaccharide had the maximum inhibition rate (49.39%). The in vivo test results also indicated that extracellular polysaccharide of Porphyridium cruentum inhibited the growth of tumor. The polysaccharide-treated group could effectively protect the organ of the mice compare to positive-control.