Isolation, Structure And Activity Of Polysaccharides From Gracilaria Chorda Holmes And Ulva Lactuca L.in The South China Sea

Gracilaria chorda Holmes and Ulva lactuca L. are common seaweeds in Hainan province. The polysaccharides from seaweeds have good biological function, such as antioxidant, anticoagulation, anti-viral, anti-cancer, etc. These activities make seaweed polysaccharides have great potential in the application of medicine. In this paper, the extraction, structure and activity of Gracilaria chorda Holmes and Ulva lactuca L. polysaccharides were studied. This research aims to provide theoretical data for the development and application of seaweed polysaccharides.In paper, solvent extraction and ultrasound-assisted extraction were used to extract polysaccharides from G. chorda Holmes (GCP) and from Ulva lactuca L (ULP). The ultrasound-assisted extraction is better. The extraction conditions including NaOH solution concentration, solid/liquid ratio, extraction time, extraction temperaturewere optimized through Single factor experiments and Orthogonal experiments. The highest extraction rate of GCP was20.01%, and that of ULP was17.57%.Crude polysaccharides were purified through stepwise ethanol precipitation. Three components GCP20, GCP40, and GCP50were obtained after precipitation from GCP. And two components ULP1, ULP2were obtained from ULP. The molecular weight was measured through GPC. The molecular weight of GCP20, GCP40, GCP50, ULP70, ULP80was117kDa,116kDa,113kDa,189kDa,230kDa respectively. Physical and chemical properties analysis showed that the total sugar content of GCP was26.00%, and that of ULP47.50%. The uronic acid contents of GCP20, GCP40, GCP50were13.79%,16.71%,15.67%, and those of ULP70,ULP80were16.81%,16.82%. The sulfate content of GCP20, GCP40, GCP50were0.72%,0.24%,0.32%, and those of ULP70, ULP80were12.00%,26.80%. Elemental analysis showed that, the ratio of C, H, O complies with carbohydrate formula, and S content of GCP20, GCP40, GCP50were less than those of ULP70, ULP80.HPLC and GC were used to analyse the composition of polysaccharide. GCP20, GCP40, GCP50were composed of fucose, xylose, mannose, galactose, glucuronic acid, and ULP70, ULP80were composed of rhamnose, xylose, glucose, glucuronic acid. GCP20may contain l→xyl, l→,1→6,1→3,1→2,3,1→2,4,1→3,4, l→2,3,4linked to galactose,1→3,1→2,3,1→2,4,1→3,4,1→2,3,4connected to mannose, glucuronic acid, l→,1→3, l→2,3, l→2,4, l→3,4, l→2,3,4linked to fucose; GCP40may have1→,1→2linked to xylose,1→,1→6, l→2, l→2,6linked to galactose; l→,1→6,1→2, l→2,6, l→3,1→2,3, l→2,4,1→3,4,0l→2,3,4connected to mannose;1→, l→2,1→3linked to fucose and glucuronic acid. GCP50may contain1→,1→2linked to xylose,1→, l→6, l→2, l→2,6linked to galactose; l→, l→6, l→2, l→2,6, l→3, l→2,3,1→2,4,1→3,4,1→2,3,4connected to mannose;1→,1→2linked to fucose and glucuronic acid. ULP70, ULP80may contain a-(1→3)L-rhamnose、a-(l→2)-glucose、 β-(1→2)-D-xylose、a-D-glucuronic acid.The hydroxyl radical scavenging abilities of GCP20, GCP40, GCP50, ULP70, ULP80were measured through electron spinning resonance. All the samples expressed good antioxidant activity. The antioxidant activity of GCP20was best. The hydroxyl radical scavenging ability of20mg/mL GCP20was81.37%, The scavenging ability against ABTS free radical was all almost100%. However, the antioxidant activity of ULP70, ULP80were lower than that of GCPs. Anticoagulant activity was tested in vitro. TT of0.5mg/mL GCP40was extended7.3s, which indicated that GCP40had good anticoagulant activity, while the anticoagulant activity of ULP80was not so obvious. The surface tension of GCP, GCP20, GCP40, GCP50were51.60mN/m,53.05mN/m,53.49mN/m,51.39mN/m, and those of ULP, ULP70, ULP80were53.03mN/m,51.63mN/m,57.37mN/m, respectively, the critical micelle concentration of GCP and ULP were O.lmg/mL,0.5mg/mL...