Structural analysis and anti-complement activity of polysaccharides from Kjellmaniella crsaaifolia

Abstract

Two polysaccharides, named KCA and KCW, were extracted from Kjellmaniella crassifolia using dilute hydrochloric acid and water, respectively. Composition analysis showed that these polysaccharides predominantly consisted of fucose, with galactose, mannose and glucuronic acid as minor components. After degradation and partial desulfation, electrospray ionization mass spectrometry (ESI-MS) was performed, which showed that the polysaccharides consisted of sulfated fucooligosaccharides, sulfated galactofucooligosaccharides and methyl glycosides of mono-sulfated/multi-sulfated fucooligosaccharides. The structures of the oligomeric fragments were further characterized by electrospray ionization collision-induced dissociation tandem mass spectrometry (ESI-CID-MS2 and ESI-CID-MS3). Moreover, the activity of KCA and KCW against the hemolytic activity of both the classical and alternative complement pathways was determined. The activity of KCA was found to be similar to KCW, suggesting that the method of extraction did not influence the activity. In addition, the degraded polysaccharides (DKCA and DKCW) displayed lower activity levels than the crude polysaccharides (KCA and KCW), indicating that molecular weight had an effect on activity. Moreover, the desulfated fractions (ds-DKCA and ds-DKCW) showed less or no activity, which confirmed that sulfate was important for activity. In conclusion, polysaccharides from K. crassifolia may be good candidates for the treatment of diseases involving the complement pathway.

Figure 1

The IR spectra of polysaccharides.

Figure 2

Negative ion mode ESI-MS spectra of ds-DKCW (a) and ds-DKCA (b).

Figure 3

Negative ion mode ESI-CID-MS² spectrum of the ion [MeFuc₇SO₃Na-Na]⁻ at m/z 1133.415 (−1).

Figure 4

Negative ion mode ESI-CID-MS² spectrum of the ion at m/z 421.129 (−2) (a) and negative ion mode ESI-CID-MS³ spectra of the ions at m/z 681.208(−1) (b) and 383.103 (−2) (c).

Figure 5

Negative ion mode ESI-CID-MS² spectrum of the ion [MeFuc₅(SO₃Na)₂-2Na]²⁻ at m/z 460.120 (−2).

Figure 6

Negative ion mode ESI-MS² spectrum of ion [Fuc₆(SO₃Na)₂-2Na]²⁻ at m/z 526.141 (−2).

Figure 7

Inhibition of the classical pathway-mediated hemolysis of EA (a and b) and alternative pathway-mediated hemolysis of ER (c and d) in 1:10-diluted NHS in the presence of increasing amounts of the polysaccharides. Heparin was used as the reference. The results are expressed as percent inhibition of hemolysis. Data are the means from 3 determinations ± S.E.M.