Modulatory effect of plumbagin (5-hydroxy-2-methyl-1,4-naphthoquinone) on macrophage functions in BALB/c mice. I. Potentiation of macrophage bactericidal activity.

The modulatory ability of plumbagin, a natural product from Plumbago zeylanica, was studied on peritoneal macrophages of BALB/c mice. The macrophage functions evaluated were bactericidal activity, hydrogen peroxide and superoxide anion release. The bactericidal capacity of in vivo plumbagin-treated mouse macrophages was estimated against Staphylococcus aureus. In low doses plumbagin exerted a constant increase in bactericidal activity throughout the study period whereas with a high dose a higher response was observed up to six weeks. But in the next two weeks a considerable decline in the bactericidal activity was noticed compared to low dose. Plumbagin was also seen to exert a similar response on oxygen radical release by macrophages in vivo showing a clear correlation between oxygen radical release and the bactericidal activity. The data indicate that plumbagin augments the macrophage bactericidal activity by potentiating the oxyradical release at low concentration whereas at the higher concentration it has inhibitory activity.