Effect of Xylan Sulfates on Coagulation of Human Blood Plasma.

Sulfated derivatives of xylan (isolated from Bétula pubéscens wood) with average molecular weight ~34 kDa, sulfur content of 11.3-17.5%, a degree of substitution of 0.74-1.64 are anticoagulants of direct type of action. Antithrombin and antifactor Xa activities in three tested xylan samples did not differ and reached 30.8-31.8 and 13.5-14.3 U/mg, respectively.

Aptamer RA36 inhibits of human, rabbit, and rat plasma coagulation activated with thrombin or snake venom coagulases.

RA36 DNA aptamer is a direct anticoagulant prolonging clotting time of human, rabbit, and rat plasma in the thrombin time test. Anticoagulant activity of RA36 is lower than that of recombinant hirudin. During inhibition of human plasma clotting activated with echitox (coagulase from Echis multisquamatus venom), the aptamer presumably binds to meisothrombin exosite I. The sensitivity of human plasma to the aptamer 5-fold surpasses that of rat plasma. Analysis of RA36 binding to coagulase of Agkistrodon halys venom (ancistron) is required for proving the effect of aptamer on polymerization of human fibrinogen.

[Relationship between the anticoagulant activity of sulfated plant polysaccharides and the area of their precipitation with polycations during biospecific electrophoresis].

Polyanions (in an amount within 1.5 - 6.0 mg), including cellulose sulfates (excreted from Gossipium hirsutum L., molecular weight 22.0 kDa, degree of sulfation within 0.8 - 1.8), inulin sulfates (excreted from Helianthus tuberosus, molecular weight 8.0 kDa, degree of sulfation within 0.6 - 1.6), pectin sulfates (excreted from Abies sibirica L., molecular weight 24.0 kDa, degree of sulfation within 0.8 - 1.1), give rise to peaks of precipitation with polycations of protamine sulfate. Only cellulose sulfates (in amount within 0.38 - 6.00 mg) give the peaks of precipitation with chitosan polycations (molecular weight 10 kDa, degree of deacetylation 85%) during horizontal biospecific electrophoresis. The height of the peak of precipitation with protamin sulfate was found to grow with increasing antithrombin activity of cellulose sulfates and pectin sulfate (for polyanions in an amount within 1.5 - 6 mg). The size of the area of precipitation with chitosan was found to decrease with increasing antithrombin activity of cellulose sulfates.

[Dependence of the anticoagulant activity of starch and inulin on their degree of sulfonation].

We have studied a relationship between the degree of sulfonation and anticoagulant activity of starch from Solanum tuberosum (molecular weight, 25000-30000 Da; sulfonation degree, 0.4-2.5) and inulin from Helianthus tuberosus (molecular weight, 7000-8000 Da; sulfonation degree, 0.6-1.6). Starch and inulin sulfates (i) increased the time of appearance of fibrin clots in plasma in coagulometric tests and (ii) reduced (via antithrombin) the rate of thrombin-induced hydrolysis of a chromogen substrate. The antithrombin (aIIa) activity of starch sulfates reached 16.8-70.0 IU/mg and the activity against factor Xa (aXa activity) was 2.3-16.6 IU/mg. The antithrombin activity of inulin sulfates was within 5.5-11.4 IU/mg and the activity against factor Xa (aXa activity) was within 0-1.4 IU/mg. An increase in the degree of sulfonation led to a growth in the anticoagulant activity of starch sulfates. The anticoagulant activity of starch sulfates and inulin sulfate with sulfonation degree 1.0 is mediated by antithrombin, which is the plasma inhibitor of serine proteases.

[Anticoagulant activity of extracts from cedar bark, anthocyanidins of spruce and birch bark, and cellulose of aspen, fir, and wheat straw].

We have investigated in vitro the anticoagulant (AC) activity of proanthocyanidins from the bark of birch, cedar, spruce, pine, and larch; sulfated arabinogalantan and dihydroquercetin from larch wood; extracts from birch, cedar, and spruce; microcrystalline cellulose (MCC) from aspen and fir wood and wheat straw; and methylcellulose (MC) from aspen wood. The AC properties of the investigated substances are related mostly to their antithrombin activity. The AC activity increases with the content of sulfur in MCC of wheat straw, MC of aspen wood, and arabinogalañtan of larch wood. The maximum AC activity was observed in samples of sulfated MCC from fir wood and wheat straw. Their antithrombin activity (134 +/- 8 and 96 +/- 6, respectively) is worth of carrying out model tests in vivo.

Synthesis of sulfated pectins and their anticoagulant activity.

The following pectins were sulfated: bergenan BC (the pectin of Bergenia crassifolia L), lemnan LM (the pectin of Lemna minor L), and galacturonan as a backbone of pectins. Pyridine monomethyl sulfate, pyridine sulfotrioxide, and chlorosulfonic acid were used as reagents for sulfation. Chlorosulfonic acid proved to be the optimal reagent for sulfation of galacturonan and other pectins. Galacturonan and pectin derivatives with different degrees of sulfation were synthesized and their anticoagulant activities were shown to depend on the quantity of sulfate groups in the pectin macromolecules.

[Anticoagulant activity of arabinogalactane sulfate and cedar bark extract studied in vitro].

We have studied in vitro the ability of the Siberian cedar crust (SCC) extract (Pinus sibirica Du Tour) and arabinogalactan sulphate (AGS) extracted from wood of Siberiam pine-tree (Larix sibirica Ledeb.) to increase the human blood plasma coagulation time and also to inhibit the amydolytic activity of thrombin (aIIa) and the coagulation factor Xa (aXa). A method has been developed by means of which SCC increases the aXa activity by a factor of 3.7 and the aIIà activity by a factor of 2.5. The AGS preparation increased the blood plasma coagulation time in the test for activated partial thromboplastin time. An effective concentration, at which the time of plasma coagulation was increased by a factor of 2 (in comparison to the control) was 2.94 +/- 0.33 mg/ml. AGS did not exhibit the ability to inhibit the Xa activity.

[The antithrombotic activity of para-aminobenzoic acid in experimental thrombosis]. / Antitromboticheskaia aktivnost' paraaminobenzoinoi kisloty pri éksperimental'nom tromboze.

It was shown for the first time that p-aminobenzoic acid (PABA), in addition to the previously described fibrinolytic activity, exerts the properties of a direct anticoagulant both in vitro and in vivo. PABA not only displays antithrombin activity, but also inhibits activated factor X and, upon intravenous injection to rats and rabbits, shows the antithrombotic effect. The most pronounced antithrombotic affect was observed at a dose of 1.5 mg/kg. PABA at 0.5 mg/kg has insignificant efficacy and at 3 mg/kg, a high efficacy, but induces hemolysis of erythrocytes in about a half of cases. Equally efficient antithrombotic activity of blood plasma of rats was noted after intravenous injection of low molecular weight heparin "Fraxiparin" at 40 anti-Xa U/kg and PABA at 25 anti-Xa U/kg (1.5 mg/kg). Unlike "Fraxiparin", which exerts an immediate effect, the effect of PABA was expressed within 1.5 to 5 h after injection with a peak of antithrombotic activity at 3 h (which correlates with anti-IIa and anti-Xa activities of plasma) and terminated by 5 h after injection. For PABA, the ratio of anti-Xa to anti-IIa activities (an important parameter, which determines the antithrombotic potential of drugs) equals 2.4. PABA at 0.5 or 1.5 mg/kg did not affect the number of thrombocytes, while at 3 mg/kg, it decreased the number of thrombocytes by 20%. Thus PABA at 1.5 mg/kg, which has a high anticoagulant activity and does not cause side effects, is most interesting for further studies.

[The effect of the joint administration of heparin and chitosan sulfate ether on hemostatic function]. / Vliianie sovmestnogo vvedeniia geparina i sernokislogo éfira khitozana na funktsiiu gemostaza.

We studied anticoagulant effects of combined administration of heparin (H) and chitosan sulfate ether (CS) (specific activity 20 UE/mg) in the ratio 1 : 1. CS enhanced anticoagulant activity of heparin in rabbits by a factor of 1.95 +/- 0.15. The intravenous injection of the mixture in a dose of 0.5 mg(H)/kg + 0.5 mg(CS)/kg and heparin injection in a dose of 1mg/kg induced the same effect. Haemorrhagic effect of this mixture was less pronounced compared to heparin, anticoagulant and antithrombotic activities remained the same. The mixture was found to decrease a number of platelets, however, this was also less pronounced compared to heparin. Thus, the use of the mixture CS + H (1 : 1) instead of double heparin dose resulted in the same effect.