The anti-coagulant activity of some carrageenans

Duncan, Jessie G. C (1965) The anti-coagulant activity of some carrageenans. MSc(R) thesis, University of Glasgow.

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Introduction The biological properties of the carrageenans and of certain other sulphated polysaccharides have been reviewed, and since the object of this work was to study the anticoagulant activity of intravenously-administered carrageenan, current theory of blood coagulation has been outlined. For comparison, the properties and mode of anticoagulant action of heparin have been reviewed. Experimental The practical work is reported in three sections. A preliminary section deals with the anticoagulant activity, in the rabbit, of a number of carrageenans, fractionated where appropriate, into k- and lambda-components. Doses fatal to rabbits vathin 24 hours are also recorded since many of these carrageenans were acutely toxic when administered intravenously. Frequently, lethal doses were close to anticoagulant doses and there seemed, from the preliminary work, reason to believe that the anticoagulant effect of these substances was associated with their toxic manifestations. In the main section, a more detailed study of the anticoagulant activity of the k- and lambda-carrageenana of Chondrus crisms from four habitats, of the carrageenan from Polyides rotundus and of degraded carrageenan from Kucheuma spinosum, is reported, and comparisons are made with heparin. Tests of clotting function were used to localise the anticoagulant activity in the clotting mechanism. The results of some preliminary experiments to determine the effects of carrageenan on platelets and fibrinogen are reported because it is believed that the toxicity of certain high molecular weight sulphated polysaccharides is caused by fibrinogen precipitation complicated by platelet and blood cell involvement in the precipitated complex, so blocking important vascular beds. These preliminary results give adequate confirmation that the toxic carrageenans behave similarly, while the non-toxic carrageenan does not. Conclusions The results of this study confirm the belief that the anticoagulant activity of lambda-carrageenan is greater than that of k-carrageenan and indicate that this holds for Chondrus carrageenans in general, in spite of marked variations in the properties of different carrageenans. They also show that the relationship between activity and ester sulphate, previously believed to be critical, is not a simple one, although the lambda-carrageenan from any seaweed is always higher in sulphate content than the corresponding k-carrageenan. Of all the carrageenans examined, that of Polyides showed greatest activity. Degraded Eucheuma carrageenan was the least toxic of those examined and of lowest molecular weight; hut although of high sulphate content, a much higher dose was required to show anticoagulant activity than of other carrageenans. The anticoagulant activity of the carrageenans can he detected at all stages of the clotting reaction examined, and this supports the view that a non-specific complexing reaction with many plasma proteins is involved, in contrast to the more localised action of heparin.

Item Type: Thesis (MSc(R))
Qualification Level: Masters
Additional Information: Adviser: W Anderson
Keywords: Pharmacology
Date of Award: 1965
Depositing User: Enlighten Team
Unique ID: glathesis:1965-73653
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 14 Jun 2019 08:56
Last Modified: 14 Jun 2019 08:56

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