Structure analysis of a heteropolysaccharide from Taraxacum mongolicum Hand.-Mazz. and anticomplementary activity of its sulfated derivatives

• A homogenous polysaccharide, DPSW-A, was extracted from the herb Taraxacum mongolicum Hand.-Mazz.
• The chemical structure of DPSW-A was determined.
• The sulfated derivatives of DPSW-A exhibit anticomplementary activity.
• The relationship of the chemical structure with the anticomplementary activity of sulfated polysaccharides was discussed.

A homogenous water-soluble polysaccharide, DPSW-A, with a deduced chemical structure was extracted from the herb Taraxacum mongolicum Hand.-Mazz. Moreover, 80.813-kDa DPSW-A is composed of three types of monosaccharide, namely rhamnose, arabinose, and galactose, at a molar ratio of 1.0:10.7:11.9. The main chain of DPSW-A contains Terminal-Galp, 1,3-Galp, 1,6-Galp, 1,3,6-Galp, and 1,2,4-Rhap; the branched chain contains Terminal-Araf, 1,5-Araf, and 1,3,5-Araf. The sulfated derivatives prepared from DPSW-A showed inhibitory effects on complement activation through the classical pathway (CH50: Sul-DPSW-A, 3.94 ± 0.43 μg/mL; heparin, 104.40 ± 3.82 μg/mL) and alternative pathway (AP50: Sul-DPSW-A, 42.76 ± 0.46 μg/mL; heparin, 43.42 ± 0.22 μg/mL). Mechanism studies indicated that Sul-DPSW-A inhibited complement activation by blocking C1q, C1r, C1s, and C9, but not C2, C3, C4, and C5. In addition, Sul-DPSW-A displayed limited anticoagulant effects. These results suggest that Sul-DPSW-A prepared from DPSW-A is valuable for treating diseases caused by excessive complement system activation.