Isolation and characterization of an anti-complementary protein-bound polysaccharide from the stem barks of Eucommia ulmoides

EWDS-1, a homogeneous protein-bound polysaccharide, was isolated as an anti-complementary agent from the stem barks of Eucommia ulmoides. EWDS-1 was identified as a branched proteoglycan with average molecular weight about 2,000,000 Da, composed of Gal, Glc and Ara in the ratio of 2.1:1.0:0.9, along with trace of Rha, Xyl, Man, as well as 3.95% of protein. The linkages of the residues of EWDS-1 were deduced by methylation analysis and NMR technique. Bioassay showed that EWDS-1 inhibited complement activation on both the classic and alternative pathways with CH 50 and AP 50 values of 203 ± 20 μg/ml and 45 ± 8 μg/ml, respectively. Preliminary mechanism studies by using complement component depleted-sera indicated that EWDS-1 inhibits activation of complement system by interacting with C1q, C1r, C1s, C2, C3, C4, C5 and C9. The results suggested that EWDS-1 could be of promising benefits in treatment of the complement associated diseases.