Assessment of zymosan-induced leukocyte influx in a rat model using sulfated polysaccharides

Fucoidan, a sulfated polysaccharide from the brown algae Fucus vesiculosus, has diverse biological properties, including anti-inflammatory, anticoagulant and antithrombotic activity. This study analyzed the therapeutic activity of total fucoidan (TF) from F. vesiculosus and that of purified fractions (F1 and F2) on zymosan-induced arthritis. Arthritis was induced by injecting zymosan into the knee joint. Thus, three fucoidan fractions were obtained by acetone fractionation. Due to the yield obtained from F3, we used only fucoidans F1 and F2 in the induced inflammation tests. Chemical analyses and electrophoretic characterization of these fractions demonstrated that they contain polysaccharides, sulfate ester and very low protein levels. The fucoidans obtained from TF showed only an electrophoretic band in agarose gel with much lower polydispersion. The F2 fraction showed a migration between fucoidans F1 and F3. We administered TF (15, 30, 50 mg/kg I. P.), F1 or F2 (10, 25 and 50 mg/kg I. P.), diclofenac sodium (10 mg/kg I. P.), lumiracoxib (5 mg/kg O. A.) or L-NAME (30 mg/kg I. P.), 1 hour after induction of articular inflammation. We analyzed cell influx and nitrite levels in addition to performing histopathological analysis. TF (total fucoidan) at 15, 30, 50 mg/kg I. P. and its fractions (F1 and F2 at concentrations of 25 and 50 mg/kg I. P.) significantly reduced cellular influx and nitric oxide concentration. Moreover, the articular inflammation in zymosan-induced arthritis caused a progressive loss in glycosaminoglycan content. This loss decreased when TF (30 mg/kg) was administered. These data suggest that fucoidan exerts anti-inflammatory action in a zymosan-induced model of acute inflammation in rats. Taken together with the fact that these natural compounds have minimal toxicity, this may have important therapeutic implications.