Anti-inflammatory activity of coptisine free base in mice through inhibition of NF-κB and MAPK signaling pathways

Coptisine is one of the main constituents of Coptis chinensis which has been widely used for the remedy of inflammatory disorders. Although the biological activities of coptisine have been well known, the pharmacological properties of its free base have seldomly been elucidated thus far. The aim of this study was to investigate the potential anti-inflammatory properties of coptisine free base (CFB, 8-hydroxy-7,8-dihydrocoptisine) on three animal models, namely xylene-induced ear edema, acetic acid-induced vascular permeability and carrageenan-induced paw edema. The results exhibited that CFB exerted a dose-dependent suppression on ear edema induced by xylene, significantly mitigated the aggravation of vascular permeability caused by acetic acid and paw edema induced by carrageenan. Additionally, CFB significantly suppressed the productions of interleukin-1β (IL-1β), interleukin-6 (IL-6), prostaglandinE2 (PGE2) and tumor necrosis factor (TNF-α) in the drug-treated groups as compared with the vehicle group after treatment with carrageenan. Signaling events of nuclear factor-κB (NF-κB) translocation, such as p-IKKα, p-IKKβ, p-IκBα and p65 (nucleus) were significantly inactivated, while inhibitor of nuclear factor κBα (IκBα) and p65 (cytosolic) were markedly up-regulated by CFB. Furthermore, CFB also significantly suppressed the mitogen-activated protein kinase (MAPK) pathway by blocking the phosphorylation of p-p38 (phospho-p38 mitogen-activated protein kinases) and p-JNK (phospho-c-jun N-terminal kinase) but not p-ERK (phospho-extracellular signal-regulated kinase). Hence, CFB efficiently prevented inflammation, at least partially, via inhibition of NF-κB and MAPK pathways. These findings provided a pioneering pharmacological basis for the anti-inflammatory effect of CFB and suggested CFB might be a potential candidate for the therapy of inflammatory disorders.