We investigated the effect of PS ( 1) on nitrite and reactive oxygen species (ROS) production in J774 macrophages stimulated with bacterial lipopolysaccharide (LPS) for 24 h. PS ( 1) inhibited in a concentration-dependent manner nitrite and ROS production as well as inducible nitric oxide synthase (iNOS) protein expression induced by LPS. Incubation of cells with PS ( 1) determined a significant decrease of nuclear factor-kappaB (NF-kappaB)/DNA binding activity which was correlated with a marked reduction of iNOS mRNA levels. These results show that PS ( 1) inhibits NF-kappaB activation and iNOS gene expression by preventing the reactive species production and suggest a role for this compound in controlling oxidative stress and/or inflammation.