Application of 2-aminopyridine fluorescence labeling in the analysis of in vivo and in vitro metabolism of dextran sulfate sodium by size-exclusion high-performance liquid chromatography

The present study describes a size-exclusion high-performance liquid chromatographic method for the separation and quantification of sulfated polysaccharides, such as dextran sulfate sodium (DSS). Pyridylamination of DSS was achieved without difficulty using 2-aminopyridine as a fluorometric label. In addition, 0.1–0.2 M phosphate buffer (pH 3.0) was found to be the mobile phase which produced the best separation. In vitro enzymatic degradation of the pyridylamino-DSS (PA-DSS5000, Mr 5000) using α-amylase and the in vivo metabolism in the rat feces after oral administration of PA-DSS5000 were then evaluated. Two small peaks of approximately Mr 380 and 600 appeared after co-incubation with α-amylase, indicating PA-DSS5000 may be considerably depolymerized. In vivo, however, PA-DSS5000 excreted in the feces was mainly of PA-DSS5000 polymer. No peaks of less than Mr 5000 were not clearly detectable in the feces because of background fluorescence attributable to gut lumen contents. This method of fluorometric analysis allows fairly selective detection of sulfated polysaccharides in biological materials.