Background: Euonymus alatus (EA) has been used for tumor therapy. However, it is still unclear how this herb prevents the diseases in experimental models. Nitric oxide (NO) as a potent macrophage-derived effector molecule against a variety of tumors has received increasing attention.
Methods: Using mouse peritoneal macrophages, we have examined the mechanism by which EA regulates NO production.
Results: When EA was used in combination with recombinant interferon-gamma (rIFN-gamma), there was a marked cooperative induction of NO production. However, EA had no effect on NO production by itself. The increased production of NO from rIFN-gamma plus EA-stimulated cells was almost completely inhibited by pre-treatment with pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear factor kappa B (NF-kappaB). Furthermore, treatment of peritoneal macrophages with rIFN-gamma plus EA caused a significant increase in tumor necrosis factor-alpha (TNF-alpha) production. PDTC also decreased the effects of EA on TNF-alpha production significantly.
Conclusions: EA increases the production of NO and TNF-alpha by rIFN-gamma-primed macrophages and suggest that NF-kappaB plays a critical role in mediating these effects of EA.