The involvement of the HO-1 pathway in the anti-inflammatory action of a sulfated polysaccharide isolated from the red seaweed Gracilaria birdiae.

Objectives: The aim of this study was to investigate the involvement of the hemoxigenase-1 (HO-1) pathway in the anti-inflammatory action of a sulfated polysaccharide from the red seaweed Gracilaria birdiae (SP-Gb).

Methods: SP-Gb (5, 10 and 20 mg/kg) was administered to Wistar rats in a peritonitis model using carrageenan or a paw edema model using carrageenan or dextran. To analyze the involvement of HO-1 in the anti-inflammatory activity of SP-Gb, the animals were pretreated subcutaneously with a specific HO-1 inhibitor (ZnPP IX). To evaluate the systemic effects, SP-Gb (10 mg/kg) was administered to mice intraperitoneally before waiting for 48 h or for 14 days.

Results: SP-Gb (10 mg/kg) caused an anti-inflammatory effect that was evidenced by a decrease in leukocytes in the peritoneal cavity. SP-Gb also reduced the paw edema induced by carrageenan and inhibited the paw edema induced by dextran in the first half-hour. After being inhibited by ZnPP IX, the anti-inflammatory effect of SP-Gb on carrageenan-induced rat paw edema was not observed. SP-Gb did not cause mortality or significant changes in the biochemical, hematological and histopathological parameters.

Conclusion: SP-Gb may be used as a tool for further investigations into the inflammatory processes associated with the hemoxigenase-1 pathway.