The anticoagulant activity of the microcrystalline cellulose sulfate (MCCS) extracted from the wood of Abies sibirica Ledeb (molecular weight 86,000, sulfur substitution level 1.63) were studied in vitro and ex vivo. The antithrombin activity was 87.4 ± 0.7 U/mg and activity against activated factor X was 18.3 ± 0.2 U/mg. S.c. administration of high doses (5, 20, and 40 mg/kg) of MCCS to rabbits increased plasma antithrombin activity. A cellulose sulfate dose of 10 mg/kg produced the same area under the pharmacodynamic curve for plasma antithrombin activity as unfractionated heparin (5 mg/kg).The sulfated polysaccharide unfractionated heparin (UFH), a glycosaminoglycan, is used in the treatment of thromboses [1]. The UFH molecule consists of a chain of repeating disaccharide units consisting of a-D-glucosamine and uronic acid connected by 1 -4 glycoside bonds (® 4-a-IdoA2S-1 ® 4-a-GlcNS6S-1 ® ) [2]. The rate of inhibition of clotting factors Ia, Xa, and IXa by antithrombin (AT) increases on interaction with UFH [3]. The anticoagulant (AC) activity of UFH includes roles for both the negatively charged sulfate groups and the glycan of the main chain of the molecule, operating as the "substrate" for the inhibitor, which is an enzyme [4]. Some investigators have demonstrated methods for increasing the anticoagulant activity of heparin [5], though side effects and the sources of UFH (mammalian tissues) [1] point to the need to develop alternative, plant-derived, AC, such as chemically modified cellulose. Cellulose is a linear homoglycan built of glucose residues joined by b(1 ® 4) bonds. Carboxymethylcellulose sulfate, like UFH, accelerated the inhibition of the AT activity of clotting factors, due to a specific sequence of 13 sugar residues simultaneously binding the protease and the inhibitor [6]. Microcrystalline cellulose (MCC) is known to have greater reactivity in alkylation and esterification reactions taking place in both alkaline and acidic conditions than the initial cellulose, so its use in sulfation reactions yields water-soluble derivatives in mild conditions [7].The aim of the present work was to analzye the effects of microcrystalline cellulose sulfate (MCCS) extracted from the wood of the Siberian fir (Abies sibirica Ledeb) on the clotting of rabbit plasma after s.c. administration.
EXPERIMENTAL CHEMICAL SECTIONMCC was prepared and sulfated using methods developed at the Institute of Chemistry and Chemical Technology, Siberian Branch, Russian Academy of Sciences [8,9]. At the first stage, 10 g of fir sawdust dried at 105°C to constant weight was placed in a 0.2-liter stainless steel reactor and supplemented with to 150 ml of aqueous solution containing 25.8% acetic acid, 4.2% hydrogen peroxide, and 2% sulfuric acid. The reactor was placed in a heater and held at 130°C for 2 h. The mixture was then cooled and filtered, and the resulting fibrous product was washed with water to neutral pH. At the second stage, the fibrous product was subjected to solvolysis in 150 ml of aqueous solution containing 23.6% ...
