| Porphyra haitanensis is an important economic seaweed which is pruduced in the south China sea area, it is also polysaccharides of porphyra haitanensis extracted source. Polysaccharides of porphyra haitanensis is a kind of galactosan sulfate and a water soluble polysaccharide. The main composition of polysaccharides is galactose, 3, 6-anhydrogalactose, still contain a small amount of rhamnose, fucose, arabinose and xylose, and so on. Polysaccharides of porphyra haitanensis has been extensively studied due to its numerous interesting biological activities, including antitumor, antifatigue, antimutagenic antioxidant, antivirus, reducing blood pressure and blood fat, and so on. The desirable biological activities of fucoidan are closely related to its sulfate group and molecular weight. In this paper, the extraction process, purification method through the ultrafiltration technology, the physical and chemical characters of polysaccharide degradation were systematically studied, the antioxidant and antibacterial activity in vitro were also preliminarily explored.This article selects the purchased porphyra haitanensis in the jin jiang laver as research object. It is dried, shattered and a 80 mesh screen. Conditions of extract process were extracting temperature was 100 °C, extracting time was 5 h, 4000 r/min centrifugal and remove precipitation. The supernatant is joined in 0.1% of the alkali protease processing 55 °C water bath 3 h, 4000 r/min centrifugal to precipitate. Compared with freeze-drying and ethanol precipitation. The method of freeze-drying, the yield of crude polysaccharides and the composition of total sugar, sulphate and ash content were 49.03%, 33.33%, 19.25% and 18.68% respectively; but thecontents of polysaccharides which is extracted by ethanol precipitation were 35.77%, 43.65%, 15.29% and 16.04% respectively. The results of the study showed that the method of direct freeze drying is better than ethanol precipitation.Large-scale membrane seperation process of polysaccharides of porphyra haitanensis. Polysaccharides was ultrafiltrated by Lab-Scale TFF system with the ulrafiltration membrane of 50, 30, 10 and 5 k Da molecular weight cutoff. Results showed that the pigments could be effectively removed from extraction mixture by ultrafiltration and the rate of decolorization was 92.01%. Besides, the fraction whose molecular weight beyond 50 k Da was highest. The yield of polysaccharides was 61.15%, the composition of total sugar and sulphate was 38.47% and 21.60% respectively.The research on hydrolysis of polysaccharides, there are two ways to hydrolyze polysaccharides, which includes acid and oxidation hydrolysis, discovering the two ways have degraded the polysaccharides. Samples of SP2 and SP3 compares with other products of polysaccharide, the contents of sulfate of polysaccharides don’t apparently reduce. They are(17.65±0.94)% and(19.78±0.77)% respectively,but SP4, SP5, SP6, SP7, SP8, SP9 and SP10 of the sulfate content are(16.23±0.48)%,(15.74±0.44)%,(16.32±0.63)%,(15.16±0.35)%,(16.81±0.94)%,(14.45±0.21)% and(13.56±0.35)% respectively. The result proves the two ways have ability to degrade the content of sulfate in polysaccharide.It is researched that the size of the molecular weight of polysaccharides affected antioxidant and antibacterial in vitro. Hydrolyze polysaccharides are more effective in antioxidant effct. The most significant polysaccharide is degradation oxidation. The results showed polysaccharides had a strongly ability to scaveage both hydroxyl and DPPH free radicals. Hydrolyze polysaccharides could inhibit the growth of stap hylococcus aureus, but no inhibition effect on the other Bacteria and fungi was observed. |
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