Structural Features and Anti-coagulant Activity of the Sulphated Polysaccharide SPS-CF from a Green Alga Capsosiphon fulvescens

Previously, we reported that the sulphated polysaccharides (SPS)-CF, a water-soluble polysaccharide isolated and purified from Korean green alga Maesaengi (Capsosiphon fulvescens, Chlorophyta), is a glucuronogalactomannan based mainly on the monosaccharide composition determined by high-performance liquid chromatography (HPLC) analysis after 1-phenyl-3-methyl-5-pyrazolone (PMP) labelling of sugars in the acid (trifluoroacetic acid (TFA)) hydrolyzates of SPS-CF, which showed mannose (55.4 mol %), galactose (25.3 mol %) and glucuronic acid (16.3 mol %) as major sugars (Na et al., Int Immunopharmacol 10:364–370, 2010). However, the results of the present study re-performed for monosaccharide composition of this polysaccharide using, in addition to HPLC of PMP-labelled sugars, other separation methods, i.e. high-performance anion-exchange chromatography with pulsed amperometric detection (HPAEC-PAD), gas chromatography with flame ionising detection (GC-FID) and thin-layer chromatography (TLC), clearly demonstrated that the most prominent neutral monosaccharides of SPS-CF are xylose (38.6–49.4 mol %) and rhamnose (39.6–45 mol %), while mannose and galactose are present at a much lesser extent or in negligible amount. These extensive monosaccharide analyses, correlation nuclear magnetic resonance (NMR), electrospray ionization mass spectrometry (ESI-MS) and matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) measurements confirmed the sulphated glucuronorhamnoxylan (ulvan) type of SPS-CF polysaccharide, whose backbone is composed of alternating sequence of 4-linked l-rhamnose-3-sulphate and d-xylose residues (ulvobiose U_3s) carrying monomeric d-glucuronic acid or d-glucuronic acid-3-sulphate on O-2 of some l-rhamnose-3-sulphate units as the side chains. The SPS-CF exhibited significant in vitro anti-coagulant activity by which the activated partial thromboplastin time (aPTT) and thrombin time (TT) were significantly prolonged. The results of this study demonstrated that the ulvan SPS-CF isolated from Korean Maesaengi C. fulvescens can be considered a potential anti-coagulant agent.