A Chinese traditional medicine, juzentaihoto, inhibits the O2- generation by macrophages.

Guinea pig peritoneal macrophages generate superoxide anion (O2-), when stimulated with N-formyl-L-methionyl-L-leucyl-L-phenylalanine (fMLP), phorbol-myristate acetate (PMA) or ovalbumin complex of guinea pig IgG2 antibody (OA gamma 2). These responses were found to be inhibited by a Chinese traditional medicine, Juzentaihoto (JT). When the inhibition was assayed by the use of fMLP as a stimulant, at least one of the substances responsible for the inhibitory activity of JT was identified to be cinnamic acid. An authentic sample of cinnamic acid also inhibited the O2- generation by fMLP-stimulated macrophages. Cinnamic acid, however, did not inhibit the O2- generation, when macrophages were stimulated with PMA and OA gamma 2. These results indicate that a certain cinnamic acid-inhibitable factor may be involved in the intracellular triggering event(s) initiated by fMLP, leading to activation of the respiratory burst reduced nicotinamide adenine dinucleotide phosphate oxidase, but not in those by PMA and OA gamma 2.