Sulfated Derivatives of Arabinogalactan and Their Anticoagulant Activity

A comparison of IR spectra and molecular weight distribution of arabinogalactan sulfates as sodium and ammonium salts obtained using various sulfating reagents was performed. According to the data, sulfated derivatives of arabinogalactan differ from each other in the nature of hydrogen bonds and molecular weight distribution. Using coagulological tests during activation of coagulation of platelet-poor human plasma in vitro, the anticoagulant properties of sulfated arabinogalactan derivatives in various salt forms differing in the preparation method, sulfation degree, and molecular weight were studied. It was found that the sample in the form of the sodium salt of sulfated arabinogalactan (SAG 1) with a sulfur content of 13.2 wt % and a polydispersity degree of 1.52 exhibited twofold greater anticoagulant activity than the sample in the form of the ammonium salt of sulfated arabinogalactan (SAG 2) with a sulfur content of 6.6 wt % and a polydispersity degree of 1.30. The antithrombin (aIIa) activity of the samples obtained by sulfation with a complex of pyridine and sulfuric anhydride (SAG 1) and a complex of sulfamic acid (SAG 2) was 23.42 ± 1.86 and 10.20 ± 1.50 U/mg, respectively; the value of the antifactor Xa activity of SAG 1 and SAG 2 was 2.13 ± 0.42 and 0.37 ± 0.08 U/mg; the aIIa/aXa ratio for SAG 1 and SAG 2 was 11 and 28, respectively. The antifactor Xa (aXa) activity of SAG, which is lower than that of unfractionated heparin (UFH), and a high aIIa/aXa activity ratio may contribute to less provocation of bleeding by SAG samples compared to UFH.