The Study Of The Preparation Of Different Molecular Weight Fucoidan From Sargassum And Its Hypolipidemic Mechanism

Sargassum belongs to Phaeophyta, Fucales, sargassaceae, sargassum. Fucoidan is anunique activity polysaccharide with sulfate group, with significant antiviral,antitumor, antibacterial, anti-coagulation and improves the immunity activety of humanbody. Because of its high molecular weight and poor solubility, it is hard to be absorbed byhuman body, so the reaearch and the application were restricted.This paper researched on the acid degradation, the purification and chemicalproperties of Sargassum fucoidan. Discussed the different components of fucoidanregulation effect on the lipid of hyperlipidemic mice, and preliminary studied thehypolipidemic mechanism of Sargassum fucoidan. Finally provide the theory basis forevaluating the nutritional value of Sargassum fucoidan, and provide the reference for thedevelopment of sargassum. The main research content is as follows.(1) Using DEAE-52cellulose chromatography purified the crude Sargasso fucoidan,and separated two components containing sulfuric acid group (F1and F2). Thenrespectively using sulfate acid degradation and Sephacry S-200HR chromatography, andget four components (named MMWF1, MMWF2, LMWF1and LMWF2). Detectingchemical composition of each component, the total sugar content of MMWF1, MMWF2,LMWF1and LMWF2were57.89%、55.45%、56.18%and52.64%, the sulfate contentwere18.89%,25.11%,14.42%and19.76%, fucose content were15.77%,17.91%,13.44%and16.49%, the content of uronic acid were6.34%,6.31%,6.28%and6.17%. MMWF1,MMWF2, LMWF1and LMWF2were single peak, the average molecular weight were16.32K、15.49K、7.65K�'�7.21K respectively. Use gas chromatography determination themonosaccharide composition of MMWF1, MMWF2, LMWF1and LMWF2. The fourcomponents were composed of rhamnose, fucose, xylose, mannose, glucose and galactose,but the content of monosaccharide is different. The structure determination of MMWF1,MMWF2, LMWF1and LMWF2were adopted infrared spectroscopy, the results showedthat the absorption peaks of four components contains polysaccharide and sulfate groupabsorption peak.(2) The high fat diet induced hyperlipidemia model in mice, to investigate the effectof different molecular weight of Sargassum fucoidan hypolipidemic activity. The results show that intragastric four kinds of fucoidan on experimental mice had no significanteffects (p﹥0.05). However, four kinds of fucoidan in high doses can significantlyreduce the liver index of mice (p﹤0.05), and prevent the fatty liver. The four componentsof fucoidan can significantly decrease the level of serum TC、TG、LDL-C content ofhyperlipidemia mice, and increase the content of HDL-C (p﹤0.05). The high dose groupwas the most significant, and in a dose dependent.(3) Comparative studied the antioxidase activity of four kinds of Sargassum fucoidanin hyperlipidemia mice. The results showed that, four kinds of Sargassum fucoidan caneffectively improve the mice anti-oxidant capacity, performance of MDA in serum andliver (MDA) content decreased, serum and liver superoxide dismutase(SOD), glutathioneperoxidase(GSH-PX), peroxidase(POD) activity increased, and the high dose group andpart of the low-dose group reached significant level (p﹤0.05or p﹤0.01). The resultsshowed that four kinds of Sargassum fucoidan can improve the antioxidant ability ofdisordered lipid metabolism. Sargassum fucoidan probably by scavenging free radicals orin collaboration with other antioxidants enhance the antioxidant capacity, and restore thebody’s oxidation-antioxidant balance system. Then reducing the lipid peroxidation,protected the lipid metabolism enzymes in the body, and recover the normal metabolism oflipids.(4) Comparative study of the effect of four kinds of Sargassum fucoidan on lipidmetabolism related enzymes and cholesterol synthesis key enzyme in hyperlipidemis mice.The results showed that four kinds of fucoidan can significantly increase serum lecithincholesterol acyltransferase (LCAT), hepatic lipase (HL), lipoprotein lipase (LPL) and liverLCAT, LPL activity, but the effects on liver HL activity was not significant. Four kinds offucoidan can significantly decrease the serum and liver3-3-hydroxyl, methyl glutarylcoenzyme A reductase (HMG-CoA reductase) activity. Sargassum fucoidan possibly byincreasing the key enzyme of lipoprotein metabolism to accelerated the catabolism of TCand LDL, or by inhibiting cholesterol synthesis enzyme HMG-CoA reductase to decreasethe cholesterol synthesis. Thus the Sargassum fucoidan hypolipidemic mechanism is bymultiple ways to achieve.