Further studies on anti-inflammatory activity of phycocyanin in some animal models of inflammation

Objective: To examine the effects of C-phycocyanin, a pigment found in blue-green algae which acts as an antioxidant in vitro and in vivo, in different animal models of inflammation. Material: Male Sprague Dawley rats and OF1 mice were used. Treatments: Oedema was induced by: a) AA (0.5 mg/ear) or TPA (4 mu g/ear) in the mouse ear b) carrageenan injection (0.1 mL of 1% suspension) in the rat paw (+/- adrenalectomy) and c) cotton pellet implantation in the rat axilla. Phycocyanin (50-300 mg/kg, p.o.) or indomethacin (1 mg/ear or 3-10 mg/kg, p.o.) as control were tested in the four animal models. Methods: Measurement of the increase in the weight (mg) of 6 mm ear punch biopsies from treated ears were made in comparison to control ears, together with myeloperoxidase (MPO) activity as an index of neutrophil infiltration. The increase in the paw thickness (mm) was measured with a dial caliper. Cotton pellet was implanted and seven days afterwards the granuloma was removed and the dry weight was determined. Acute toxicity was studied in mice and rats. Statistics were performed using one-way analysis of variance with the Duncan Multirange test. Results: Phycocyanin reduced significantly (p < 0.05) and in a dose-dependent manner ear oedema induced by AA and TPA in mice as well as carrageenan-induced rat paw oedema (both in intact and adrenalectomized animals). In the TPA test, phycocyanin also reduced MPO content. Phycocyanin also exerted an inhibitory effect in the cotton pellet granuloma test. In the acute toxicity test in rats and mice, even at the highest dose tested (3 000 mg/kg, p.o.), no toxicity was found. Conclusions: Phycocyanin shows anti-inflammatory activity in four experimental models of inflammation. Its antioxidative and oxygen free radical scavenging properties may contribute, at least in part, to its anti-inflammatory activity.