Study On The Extraction, Purification And Biological Activities Of Polysaccharides From Ulva Lactuca

Ulva lactuca is an edible macroalgae of Chlorophy. It contains rich nutrient substance such as protein, polysaccharides, vitamin, mineral element etc., which is good for body's growth, development and health. The processing conditions of extraction of Ulva lactuca polysaccharides were optimized. One sample was gained by separation, purification and hydrolysis of Ulva lactuca and its biological activities were further studied in the paper.Hot water extraction method and ultrasonic extraction method were optimized by using phenol sulfuric method and orthogonal experiment, in the standard of observing and studying the content polysaccharide of Ulva lactuca. By analysis of range, the optimized condition of hot water extraction method: extracting 4 hours at 90℃, water totalling of 50 times, the extraction rate of content polysaccharide was 11.3%; the optimized condition of supersonic extraction method processing extracting time being 20min, water totalling of 50 times, ultrasonic power being 800w, the extraction rate was 14.57%. The Sevag method was used to remove the protein of polysaccharide from Ulva lactuca. The optimum result of the method is that the rate of protein-removed was 93.5% and the rate of polysaccharide-lost was 17.5% after three times treatment of sevag method.The polysaccharides ULS (extracted by water) and ULC (extracted by ultrasonic) were separated by DEAE-Sepharose Fast Flow column and Sephadex G-200 column chromatography. Authentication the feasibility of ultrasonic extraction method through the comparison of the property of ULS and ULC. As a result, we found the method of ultrasonic extraction is superior to water extraction. Because ultrasonic extraction method is more efficient, more sufficient extracting, and has the same property of polysaccharide. Through the separation and purification of ULC and ULS, we gain ULCF₁ and ULSF₁₁. The composition of ULCF₁ and ULSF₁₁ were determined by ionic chromatography, their Mr were measured by gel filtration, the structures were determined by IR. Besides, we analysed physicochemical property of the polysaccharides.The antiviral effects of polysaccharides samples on CVB3 and their cytotoxicity on Hela cell were studied by CPE and MTT method. The results showed all samples had peotent antiviral activities. The cytotoxicity of samples on Hela cell was smaller.The antioxidation activities of Ulva lactuca polysaccharides samples in vitro were studied: the deoxidization of these polysaccharides samples was measured to analyze their antioxidation activities; the ability of the polysaccharides to scavenge hydroxyl radicals was tested by phenanthroline-Fe²⁺-H₂O₂ reaction; the capability of the polysaccharides to eliminate was determined through pyrogallol auto oxidation; the ability of the polysaccharides to scavenge DPPH. The result showed that they all had antioxidation effects in vitro except ULCF₂.