Stimulation of nitric oxide synthesis in macrophage cell line RAW 264.7 cells by several traditional Chinese herbal medicines

The effect of 18 traditional Chinese herbal medicines [Kampo medicines (KMs)] on nitric oxide (NO) synthesis in vitro was assessed by using macrophage cell line RAW 264.7 cells. All of the prescriptions enhanced NO synthesis, and eight prescriptions showed strong activity relative to the other remaining prescriptions. After dialysis of the water-soluble part of the prescriptions, the retaintate showed significant activity, suggesting that macromolecular fractions enhanced NO synthesis. Egg white lysozyme, which can bind to lipopolysaccharide (LPS) and neutralize its biological activities, abrogated NO synthesis of a part oi the macromolecular fractions. These results suggest that KM-stimulated NO synthesis was independent of the contaminated LPS. The NO synthesis was inhibited by NC-monomethyl-L-arginine acetate, an inhibitor of nitric oxide synthase (NOS), showing that induced NO resulted from the activation of inducible NOS but not from nitrite in crude drugs. (C) 1995 Wiley-Liss, Inc.