Enhancement of Nitric Oxide Production from Activated Macrophages by Glycyrrhizin

We studied the actions of glycyrrhizin on nitric oxide production from macrophages and a macrophage cell line RA W264-7. Although glycyrrhizin did not induce nitric oxide from resting macrophages, it enhanced the production of nitric oxide from IFN-γ activated-macrophages or RA W cells. Glycyrrhizin also enhanced the production of nitric oxide from macrophages stimulated with the supernatant of con A-activated spleen cells. Further, glycyrrhizin enhanced tumor cell killing by macrophages activated with IFN-γ. This tumor cell killing was mainly by nitric oxide.