Solanum nigrum produces nitric oxide via nuclear factor-κB activation in mouse peritoneal macrophages

Nitric oxide (NO) is an antiturnour molecule produced in activated macrophages and Solanurn nigrum is a plant used in oriental medicine to treat tumours. In this study using mouse peritoneal macrophages, we have examined the mechanism by which Solanum nigrum regulates NO production. When Solanum nigrum was used in combination with 20 U/ml of recombinant interferon-gamma (rlFN-gamma), there was a marked cooperative induction of NO production. The increase in NO synthesis was reflected as an increased amount of inducible NO synthase (NOS) protein. The production of NO from rIFN-gamma plus Solanurn nigrum-stimulated peritoneal macrophages was decreased by treatment with N-G-monomethyl-(L)-arginine or N-alpha-tosyl-Phe chloromethyl ketone, an NOS inhibitor. Additionally, the increased production of NO from rIFN-gamma plus Solanum nigrum-stimulated cells was almost completely inhibited by pretreatment with 100 mu mol/l of pyrrolidine dithiocarbamate, an inhibitor of nuclear factor kappa B (NF-kappa B). Furthermore, Solanum nigrum increased activation of NF-kappa B. These findings suggest that Solanum nigrum, increases the production of NO by rIFISI-gamma-primed macrophages and NF-kappa B plays a critical role in mediating these effects. European Journal of Cancer Prevention 14:345-350 (c) 2005 Lippincott Williams & Wilkins.