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

Abstract

Aim of the study: 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.

Results: 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-kappaB) and IkappaBalpha as well as inflammatory cytokines, such as IL-1beta, IL-2, IL-6, IL-12 and TNF-alpha. In a similar manner, SB also reduced the production of nitric oxide, PGE2, IL-1beta, IL-2, IL-6, IL-12 and TNF-alpha, by decreasing the expression of iNOS, COX-2, IkappaB kinase alphabeta (IKKalphabeta) phosphorylation, IkappaBalpha and IkappaBalpha phosphorylation in LPS-treated Raw 264.7 cells. Additionally, SB interfered with the nuclear translocation of NF-kappaB p65 and p50, resulting in NF-kappaB-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.

Conclusions: Taken together, these results confirm the strong anti-inflammatory properties of SB by inhibition of iNOS, COX-2, PGE2, IL-1beta, IL-2, IL-6, IL-12 and TNF-alpha expression. This was achieved through the down-regulation of IKKalphabeta, IkappaBalpha, NF-kappaB 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.