Immune-enhancing effects of Hibiscus syriacus roots in RAW264.7 macrcophages

In this study, we evaluated whether extracts of the roots of Hibiscus syriacus (HSR) exert immune activation activities and elucidated its potential mechanism in macrophages. The HSR dose-dependently increased the production of immunomodulators such as nitric oxide (NO), inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), interleukin-1β (IL-1β), and tumor necrosis factor (TNF-α) activated phagocytosis in macrophages. Inhibition of toll-like receptors 4 (TLR4) reduced the production of immunomodulators induced by HSR. Inhibition of mitogen-activated protein kinase (MAPKs), nuclear factor-κB (NF-κB) and phosphoinositide-3 kinase (PI3K) signaling attenuated the production of immunomodulators induced by HSR. Based on the results of this study, HSR was thought to activate macrophages through the production of immunomodulators and phagocytosis activation through TLR4-dependent MAPKs, NF-κB and PI3K signaling pathways. Therefore, it is thought that the HSR has the potential to be used as agents for enhancing immunity.