Anti-inflammatory effects of Scutellaria baicalensis extract via suppression of immune modulators and MAP kinase signaling molecules

A herbal preparation using Scutellaria baicalensis ( S. baicalensis) Georgi (Huang Qin, SB) was formulated to effectively protect cancer patients from inflammatory reactions. Although SB, is one of the most widely used herbs in oriental medicine for anti-inflammation, anti-cancer, anti-viral, anti-bacterial and tonifying the immune response, the underlying mechanism(s) by which these effects are induced remains unclear. Here, we report that SB displays anti-inflammatory effects in a zymosan-induced mouse air-pouch model by reducing the expression of nitric oxide (NO), inducible NOS (iNOS), Cyclooxygenase2 (COX-2), Prostaglandin E2 (PGE2), Nuclear Factor-kappaB (NF-κB) and IκBα as well as inflammatory cytokines, such as IL-1β, IL-2, IL-6, IL-12 and TNF-α. In a similar manner, SB also reduced the production of nitric oxide, PGE2, IL-1β, IL-2, IL-6, IL-12 and TNF-α, by decreasing the expression of iNOS, COX-2, IκB kinase αβ (IKKαβ) phosphorylation, IκBα and IκBα phosphorylation in LPS-treated Raw 264.7 cells. Additionally, SB interfered with the nuclear translocation of NF-κB p65 and p50, resulting in NF-κB-dependent transcriptional repression. We further demonstrate that SB attenuated the activity of c-Raf-1/MEK1/2, Erk1/2, p38 and JNK phosphorylation in LPS-treated Raw 264.7 cells. Taken together, these results confirm the strong anti-inflammatory properties of SB by inhibition of iNOS, COX-2, PGE2, IL-1β, IL-2, IL-6, IL-12 and TNF-α expression. This was achieved through the down-regulation of IKKαβ, IκBα, NF-κB activation via suppression of c-Raf-1/MEK1/2 (Mitogen-activated protein kinase/ERK kinase) and MAP kinase phosphorylation in the zymosan-induced mice air-pouch and Raw 264.7 cells. These results support the use of SB herbs for its potent anti-inflammatory activity.