| Monostroma nitidum is a kind of marine green seaweed. The polysaccharide is its important bioactive substance.In this paper, Monostroma nitidum was extracted by cool water, boiling water and alkali liquid successively. Five kinds of polysaccharides were obtained and named as CW, HW1, HW2, AM1 and AM2, respectively. The physicochemical properties and monosaccharide compositions of these three polysaccharides CW, HW1 and HW2 were analysed by Phenol-sulphuric acid method, Folin-phenol reagent method, barium sulfate turbidimetry method, GC and HPLC. The results showed that the total yield of the crude polysaccharides was 54.2%. The yield of HW1 was 30.6%, and it was the highest in the three polysaccharides. The contents of the sulfate group were different, they were 21.8%, 29.1% and 26.9% respectively. These three polysaccharides mainly contained rhamnose with a little glucose and xylose. However, the CW also had trace of mannose and HW1 had trace of galactose and mannose. They all contained glucuronic acid.Based on the physicochemical analysis, HW1 was pured by ion-exchange chromatography and low-pressure gel permeation chromatography. WF1 and WF3 were obtained. The physicochemical properties and monosaccharide compositions of WF1 and WF3 were analysed by Phenol-sulphuric acid method, Folin-phenol reagent method, barium sulfate turbidimetry method, IR, GC and HPLC. The results showed that they were high purity, the molecular weights of them were 870 kD and 70 kD, respectively. The molecular weights of WF1 was higher than that of WF3. They both contained rhamnose, a little glucose and xylose. WF1 also had trace of galactose, WF3 had trace of mannose. In their IR spectrum, 1250 cm-1 showed strong absorption peaks of S=O stretching vibration.The structures of WF1 and WF3 were studied by desulfate reaction, periodate oxidation, Smith degradation, methylation reaction, HPLC, GC-MS, IR and NMR. The results showed that the main linkage pattern of WF1 was 1, 2-Rha, also had small amount of 1, 4 and 1, 3-Rha. The sulfate group position were mainly at C-3 and C-4, minor at C-2. However, WF3 was mainly consisted by 1, 3-Rha, minor 1, 2-Rha and 1, 2, 3-Rha. The sulfate group was at C-4, minor at C-2, C-3. From the NMR spectrum, the branching point of WF3 was at C-3. The sulfate groups were mainly at C-2 and C-4. The IR spectrum of WF1 and WF3 showed that they were bothαconfiguration.The anticoagulant activities of WF1 and WF3 were studied by APTT, TT and PT. APTT and TT were effectively prolonged by WF1 and WF3. WF1 and WF3 were lack of prolongation effect on PT. The prolongation of APTT indicates inhibition of the intrinsic and/or common pathway. TT assay is helpful to investigate the sample effect in thrombin accelerated clot formation in platelet poor plasma, whereas prolongation of TT suggests inhibition of thrombin activity or fibrin polymerization. Thus, WF1 and WF3 inhibited both the intrinsic and/or common pathways of coagulation and thrombin activity or conversion of fibrinogen to fibrin. WF1 and WF3 did not inhibit extrinsic pathway of coagulation. The differences between the anticoagulant activities of WF1 and WF3 were pronounced. WF3 had higher anticoagulant activity than WF1 at the same concentration in the APTT assay. The similar result was observed in the TT assay. The differences of anticoagulant activities between WF1 and WF3 may be directly due to their structural features variation. The anticoagulant activities of WF1 and WF3 were weaker than that of heparin.In this paper two polysaccharides WF1 and WF3 were obtained from Monostrom -a nitidum. So far there is no report about their structures.This research can supply basic data on polysaccharides from Monostroma nitidum. It is helpful to study structure-activity relationship and enrich'marine saccharide bank'. It is important to develop marine drug with Chinese features.
|
PDF Full Text Request