The aqueous extract of Radix Glycyrrhizae stimulates mitogen-activated protein kinases and nuclear factor-kappaB in Jurkat T-cells and THP-1 monocytic cells

Radix Glycyrrhizae (RG) is a medicinal herb extensively utilized in numerous Chinese medical formulae for coordinating the actions of various components in the recipes and strengthening the body functions. In this report, we demonstrate that the aqueous extract of Radix Glycyrrhizae is capable of stimulating the c-Jun N-terminal kinase and p38 subgroups of mitogen-activated protein kinases (MAPKs), and the nuclear factor-kappaB (NFkappaB) in Jurkat T-lymphocytes. The activation magnitudes of MAPKs and NFkappaB were dose-dependent (EC(50) approximately 1 mg/ml) and time-dependent (maximal around 15-30 minutes). Stimulations of MAPKs and NFkappaB were not associated with changes in intracellular Ca(2+) mobilization. Similar activation profiles of MAPK and NFkappaB were obtained from THP-1 monocytes treated with the extract. In terms of chemotactic activity, the SDF-induced chemotaxis of Jurkat cells and THP-1 cells were inhibited by RG extract at 1-10 mg/ml, while a lower RG concentration (0.1-0.3 mg/ml) potentiated the SDF-induced chemotaxis for the former, but not the latter cell type. Given the fact that MAPKs and NFkappaB are important signaling intermediates for lymphocyte activities, our results suggest that Radix Glycyrrhizae may contain active constituents capable of modulating immuno-responses through various intracellular signaling pathways.