Characterization and Purification of Anti-Complement Polysaccharide from Spirodela polyrhiza

We purified and characterized a crude polysaccharide from Spirodela polyrhiza with anti-complement activities. The crude polysaccharide fraction (SP-0) which had potential anti-complement activity was extracted in hot water for 4 hrs at 10$0^{\circ}C$. The ethanol-precipitate, the crude polysaccharide traction (SP-1), showed a potent anti-complement activity. Further purification of the crude polysaccharide (SP-1) was carried out by cetavlon, ion exchange chromatography and gel column chromatography. Among cetavlon fractions, SP-4 showed the most potent anti-complement activity. When 100 $\mu\textrm{g}$/mL of SP-4 was incubated with an equal volume of normal human serum (NHS), the TCH$_{50}$ was reduced by about 78%. When the SP-4 fraction was further purified by DEAE-Sepharose (Cl$^{[-10]}$ ), the SP-4IIa, SP-4IIb and SP-4IIc, absorbed fractions, were almost the same as the anti-complement activities of SP-4. SP-4IIc, having the greatest potential activation and the highest yield by ion exchange chromatography, was further purified by gel column chromatography on a Sepharose CL-6B column. Four polysaccharide fractions of SP-4IIc-1, SP-4IIc-2, SP-4IIc-3 and SP-4IIc-4 were obtained, consisting mainly of arabinose, rhamnose, galactose and glucose, with approximate molecular weights of about 305,000, 132,000, 64,000 and 12,000, respectively. Among these subfractions, SP-4IIc-1 had the most potent anti-complement activity. When the SP-4IIc-1 aggregate was applied to a gel column chromatography in 10 mM and 50 mM NaCl solution, the position of the peak fractions shifted to a low molecular weight region, and the molecular weight of SP-4IIc-1 decreased with increased NaCl concentration in the gel column chromatography. It was found that the self-aggregation formed spontaneously in void volume by gel column chromatography using Sepharose CL-6B in water and the self-aggregation significantly affected the anti-complement function.