Sulfation of citrus pectin by pyridine-sulfurtrioxide complex and its anticoagulant activity

•We first use the pyridine sulfurtrioxide complex-DMSO system to prepare the sulfated CP.•The sulfation was mainly occurred in the C-2 and C-3 position of the GalA.•Sulfated CP showed high potency in prolonging APTT, TT.•Sulfated CP inhibited the activation of the thrombin mainly by HC II.•The sulfated CP with high content of GalA could be easily quality-controlled.

Citrus pectin (CP) was sulfated by the pyridine–sulfur-trioxide complex in dimethyl sulfoxide (DMSO). Monosaccharide composition analysis revealed a decrease in the GalA content after sulfation. A decrease in the average molecular weight (MW) and a fall in particle size of the pectin gave additional proof of pectin degradation during the sulfation reaction. Structural characterization by IR and NMR spectra indicated sulfation occurred mainly at positions C-2, C-3 of the GalA (located in backbone region of the CP). Anticoagulant assays demonstrated that sulfated CP (TBA-3) could prolong activated partial thromboplastin time and thrombin time, with an activity of 51.96 IU/mg and 15.2 IU/mg, respectively. Further investigation on coagulation factors indicated TBA-3 could achieve inactivation of thrombin with both heparin cofactor II and antithrombin. Our results indicated sulfated pectin might be a promising anticoagulant ingredient with excellent activity and simple monosaccharides, and could be a possible substitute for the limited heparin.