| Propylene Glycol Alginate Sodium Sulfate (PSS) is the first marine polysaccharide drug in China which has been mainly used in the treatment and prevention of cerebrovascular diseases such as brain prothrombotic, cerebral infarction and transient ischemic attack (TIA) and cardiovascular diseases such as hypertension, hyperlipidemia and coronary heart diseaze (CHD) during the clinical application. PSS is also approved for disseminated intravascular coagulation (DIC), chronic glomerulonephritis, hemorrhagic fever, etc. In addition, PSS is also used as antidiabetics, hypotensor and so on. PSS is prepared from alginic acid extracted from kelp seaweed by the processes of degradation, esterification and sulfonation reactions. The preparation process results in PSS as a mixture of polymannuronic acid and polyglunuronic acid with different molecular weight, degree of esterification and sulfonation. It also results in their different pharmaceutical activities of PSS in clinical.In this paper, PSS with different molecular weight were prepared to study their structure-activity-relationship. During the study, a new PSS of better curative effect and less side-effect in the clinical was expected to be obtained for further research.Firstly, in this paper, using Fenton degradation strategy, low-molecular-weight PSS (LMWPSS) with different weight-average molecular weight (Mw)(9000,6000,4000and3000Da) were prepared effectively. The physicochemical properties including contents of total sugar, uronic acid, sulfate and molecular weight were analyzed. The result showed that the molecular weight distribution of LMWPSS was narrower than the original PSS, and all the other items were consistent with the original PSS. The structures were analyzed by IR,13C NMR and MS. The results showed that the main function groups, backbone and ring structure of the polysaccharides were in substantial agreement. In conclusion, it is a potential method to afford LMWPSS by Fenton degradation because all the results showed that LMWPSS had a relative stability property and there was ho significant difference on their chemical structures.Both anticoagulant activity and antithrombotic activity of LMWPSS were evaluated in vitro and vivo, compared with high-molecular-weight PSS gained through precipitation by ethanol. In vitro, the inhibition of ATⅢmediated F X a, FⅡa experiments showed that different molecular weight LMWPSS inhibited F II a more effectively. However, the ability of inhibiting FⅩ a depended on higher concentration of PSS. The inhibition of both the two factors became more effective when the molecular weight went up. Rat plasma APTT could be prolonged obviously by LMWPSS and also increased with the molecular weight. In vivo, the influences of LMWPSS over mouse cogulation time, mouse bleeding time, mouse thrombus formation in vitro, rat thrombus formation in vitro, rat thrombus formation in vivo, rat serum Type Plasminogen Activator (t-PA) were studied. Results showed that mouse coagulation time and were prolonged obviously, the length and weight of rat thrombus formation in vitro was dropped distinctly by LMWPSS. The results also indicated that LMWPSS had anticoagulant activity which became more effective when the molecular weight went up. Consequently, compared with original PSS, the bleeding time and subcutaneous bleeding side effect of LMWPSS was decreased but its inhibition effect of thrombus formation caused by platelet aggregation was kept. So LMWPSS is expected to be a novel antithrombotic agent. The rat arteria carotis communis thrombus formation by electrophotoluminescence time was prolonged obviously by LMWPSS which suggested that LMWPSS had satisfactory therapeutic effect on rat thrombus formation in vivo but its activation on fibrinolytic system was not obvious.In short, Fenton degradation is a feasible method to prepare LMWPSS. Due to its weaker side effect and more obvious anticoagulation and antithrombotic activity, LMWPSS is a potential antithrombotic drug which is worth further investigation. |
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