Nitric oxide (NO) is an antitumour molecule produced in activated macrophages and Solanum 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-γ (rIFN-γ), there was a marked cooperative induction of NO production. The increase in NO synthesis was reflected as an increased amount of inducible NO synthase (iNOS) protein. The production of NO from rIFN-γ plus Solanum nigrum-stimulated peritoneal macrophages was decreased by treatment with N G-monomethyl-L-arginine or N α-tosyl-Phe chloromethyl ketone, an iNOS inhibitor. Additionally, the increased production of NO from rIFN-γ plus Solanum nigrum-stimulated cells was almost completely inhibited by pretreatment with 100 μmol/l of pyrrolidine dithiocarbamate, an inhibitor of nuclear factor κB (NF-κB). Furthermore, Solanum nigrum increased activation of NF-κB. These findings suggest that Solanum nigrum increases the production of NO by rIFN-γ-primed macrophages and NF-κB plays a critical role in mediating these effects.
1College of Oriental Medicine, Kyung Hee University, 1 Hoegi-Dong, Dongdaemun-Gu, Seoul, 130-701, South Korea
2College of Pharmacy, Wonkwang University, Iksan, Jeonbuk, 570-749, South Korea
3Department of Physiology, School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk, 570-749, South Korea
4Department of Food and Nutrition, School of Human Environmental Science, Wonkwang University, Iksan, Jeonbuk 570-749, South Korea
5Professional Graduate School of Oriental Medicine, Wonkwang University, Iksan, Jeonbuk 570-749, South Korea
6Department of Emergency, Wonkwang University School of Medicine, Iksan, Jeonbuk 570-749, South Korea
Correspondence to: H-M Kim. Fax: (+82) 2 968 1085.
Received 9 August 2004 Accepted 11 January 2005