Preparation and anticoagulant activity of a low-molecular-weight sulfated chitosan

Synthesis of chitosan sulfates with low molecular weight (Mv 9000–35,000 Da) was carried out by sulfation of low molecular weight chitosan (Mv 10,000–50,000 Da). The oleum was used as sulfating agent and dimethylfornamide as medium. The chitosans were prepared by enzymatic and acidic hydrolysis of initial high molecular weight chitosan as well as by extrusion solid-state deacetylation of chitin. As was shown by FT-IR and NMR-methods and elemental analysis, the sulfation occurred at C-6 and C-3 positions and substitution degree is 1.10–1.63. The molecular weight sulfated chitosan was determined by viscometric method and the Mark–Houwink equation [η]=10−5 4.97 M0.77. Study of anticoagulant activity showed that chitosan sulfates with lowered molecular weight demonstrated a regular increase of anti-Xa activity like heparins.