Effects of phycocyanin extract on tumor necrosis factor-alpha and nitrite levels in serum of mice treated with endotoxin

Phycocyanin is a biliprotein which exerts antioxidative and anti-inflammato ry effects in various in vivo and in vitro experimental models. In this stu dy phycocyanin effects on tumor necrosis factor-alpha (TNF alpha) and nitri te levels in serum of mice treated with lipopolysaccharide (LPS) was examin ed. TNF alpha was measured by cytotoxicity on L-929 cells and nitrite by th e Griess reaction, after reduction of all nitrates to nitrites by nitrate r eductase. 1 h after LPS injection (0.5 mg/kg Lp) there was a significant in crease in TNF alpha levels in mouse serum. Phycocyanin (50-300 mg/kg p.o), administered 1 h before LPS, reduced dose-dependently the TNF alpha concent ration in serum. After 18 h, LPS (30 mg/kg Lp) also induced a substantial i ncrease in serum nitrite levels, which were reduced dose-dependently by phy cocyanin pretreatment (100-300 mg/kg p.o). The results indicate that phycoc yanin exerts inhibitory effects on TNF alpha and NO production which might be ascribed to the antioxidative properties of the biliprotein.