Study On Extraction Technology Of Fucoidan With UF And Its Antibacterial Activities

Fucoidan is one of specific water-solubility heteropolysaccharide.It can be extracted from brown seaweed and some mollusks'body.It consists with L-fucose,as well as uronic acid,galactose,xylose and glucose et al,whose contents are different with the difference of the source and environment.These compositions are very complex.The results showed that fucoidan has many biological activities,such as antitumor,antioxidant,antivirus and anticoagulant et al.And its bio-activities are related with its molecular weight,the connection mode of monosaccharide,spatial structure and the content of sulphate radical and the site it binds to fucoidan.So,system to study the bio-activity of fucoidan is a very big project.Antibiotic is now one of the drugs used in clinical medical frequently.With the continuous extension of the scope of application and development of the types of drugs,it takes many problems more and more seriously.The resistance of a variety of antibiotics has reached 100%.Therefore,developing natural non-resistance low toxicity and low side effects of anti-bacterial drugs has become a hot topic in scientific fields.This article selects kelp as raw material.Isolating and purifing fucoidan is finished by pilot-scale UF system.The influence of molecular weight and the content of sulphate radical to antibacterial activities has been explored preliminary.Some research tasks have been done as follows:Farmed kelp from Fujian,dried,smashed and screened.The results showed that the best extracting condition were:temperature 4?,rate of material to liquid 1:30,extract 5 hours.Alginate removed under the condition of pH=2.0.50kDa of ultrafiltration membrane was used to purify fucoidan under the pressure of 0.2MPa.The permeated liquid was precipitated by ethanol and dried by vacuum-freeze drying.The yield of fucoidan was 2.32%.The compositions of total sugar and sulphate were 38.24%and 21.49%.The study of preparation of low-molecular fucoidan.Low-molecular fucoidan has been prepared with two methods,which are acid hydrolysis and oxidative degradation with H₂O₂under the ultrasonic wave.The result shows:the content of sulphate radical has improved after removing heavy metals;the content of sulphate radical has reduce 50%after acid hydrolysis;but it has reduced less than 10%after oxidative degradation with H₂O₂ under the ultra-sonic wave.Besides,the viscosity of fucoidan has reduced after hydrolysis.Study of the influence of removing heavy metals,hydrolysis and the method of hydrolysis to antibacterial.Hydrolyze fucoidan are more effective in antioxidant activity.3 tested bacteria have been picked up in the experiment of antibacterial activity.The result shows that the fucoidan after degradation with H₂O₂ under the ultra-sonic wave have apparent antibacterial activity,and have potential for alternative antibiotics.Complex heavy metals could inhibit the activities.The activities of fucoidan would be improved after hydrolysis.The activities of the fucoidan after degradation with H₂O₂ under the ultra-sonic wave would be stronger than ones after acid hydrolysis.