Heparin derivatives anticoagulant activity

The physiological function of heparin is not completely understood. It is found only in trace amounts in normal circulating blood. It exerts an antihpemic effect by releasing lipoprotein lipase from endothehal cells heparinlike proteoglycans produced by endothelial cells have anticoagulant activity. Heparin decreases platelet and inflammatory cell adhesiveness to endothelial cells, reduces the release of platelet-derived growth factor, inhibits tumor cell metastasis, and exerts an antiproliferative effect on several types of smooth muscle. 

Chitin and chitosan derivatives have also been studied as blood compatible materials both in vivo and in vitro [520], Anticoagulant activity was greatest with O sulfated N acetyl chitosan, followed by N,0 sulfated chitosan, heparin, and finally sulfated N acetyl chitosan. The lipolytic activity was greatest for N,0 sulfated chitosan followed by heparin. The generally poor performance of chitosan was attributed to polyelectrolyte complexes with free amino groups present on the membrane surface. The O sulfate or acidic group at the 6 position in the hexosamine moiety was identified as the main active site for anticoagulant activity. 

Lauenstein, Friedrich and Haberland investigated the effects of the parenteral administration of heparin, sodium polyethylene sulphonate and a number of other sulphated polysaccharides on oedema of the rat-foot produced by Zymosan . Two heparin preparations were almost inactive but a heparinoid derived from fungal mycelium exhibited marked effects unaltered by adrenalectomy. These authors conclude that it is unlikely that the anti-inflammatory effects of heparinoids are dependent on anticoagulant activity. 

Heparins and heparinoids are grouped in Table 3.2. Some are naturally occurring compounds, whilst others are derivatives prepared from heparins or from mucopolysaccharides. Semi-synthetic compounds have been prepared by degradation of natural polysaccharides followed by sulphation with chlorsulphonic acid or methyl sulphate . The common activities shown by the heparins and heparinoids—complexing with organic bases and proteins, antilipaemic activity and anticoagulant activity—are also shown by various sulphonic acid dyes and by polyphosphates. The table is completed with a list of those preparations that have been issued to provide depot preparations of heparins and heparinoids. 

IV-Acyl derivatives, hepo rides. Similar to heparin in clearing alimentary lipemia but are practically devoid of its anticoagulant activity-... 

Table I. Carboxylic Derivatives (Heparin-C-N-R) and Their Anticoagulant Activities...

It is known that sulfated polysaccharides, including natural and synthesized ones, had great blood-compatibility or even anticoagulant activity [34]. After sulfation of sodium alginate, its derivative contains both sulfate and carboxyl groups, whose chemical structure is analogous to the natural blood anticoagulant heparin. Fan et al. 

Hog mucosal heparin and its partially Af-desulphated derivatives retained biological (anticoagulant) activity after reaction with 5-isothiocyanatofluorescein to yield the corresponding A -fluoresceinylcarbamoylheparins. ... 

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