Immunomodulatory effects of esculetin (6,7-dihydroxycoumarin) on murine lymphocytes and peritoneal macrophages.

Coumarins belong to a diverse group of naturally occurring non-nutrient phytochemicals known as benzo-alpha-pyrones. In this study, esculetin, a 6,7-dihydroxy derivative of coumarin with pleiotropic biological activities, was found to have no significant cytotoxic effect on normal murine macrophages, but it could increase the in vivo migration of the thioglycollate-elicited macrophages in a dose-dependent manner. Moreover, esculetin significantly increased the endocytic activity, and augmented the nitric oxide production and iNOS gene expression in LPS-treated macrophages.