Potent Anti-inflammatory and Analgesic Actions of the Chloroform Extract of Dendropanax morbifera Mediated by the Nrf2/HO-1 Pathway

Dendropanax morbifera LEVEILLE (DP) has been used in traditional Korean medicines to treat a variety of inflammatory diseases. Although the in vitro anti-inflammatory potential of this plant is understood, its in vivo efficacy and underlying molecular mechanism of anti-inflammatory effects are largely unknown. We elucidated the anti-inflammatory and analgesic activities and the underlying molecular mechanisms of DP using in vitro and in vivo models. Lipopolysaccharide (LPS)-stimulated murine macrophages were used to analyze the in vitro anti-inflammatory potential of DP extract and to elucidate the underlying mechanisms. In vivo animal models of phorbol 12-myristate 13-acetate (TPA)-induced ear edema and acetic acid-induced writhing response tests were used to analyze the in vivo anti-inflammatory effects and anti-nociceptive effects of DP extract, respectively. Methanolic extract of DP (DPME) significantly inhibited the release of nitric oxide (NO) and prostaglandin E-2 (PGE(2)) in LPS-activated macrophages. Among the five sub-fractions, the chloroform fraction (DP-C) showed the most potent suppressive effects against pro-inflammatory mediators and cytokines in LPS-stimulated macrophages. These effects were attributed to inhibition of nuclear factor-kappa B (NF-kappa B) nuclear translocation and c-Jun N terminal kinase (JNK) 1/2 phosphorylation and to activation of NF-E2-related factor 2/heme oxygenase-1 (Nrf2/HO-1) signaling. DP-C exhibited strong protective in vivo effects in TPA-induced ear edema mouse model and acetic acid-induced writhing response test. Our data suggest that DP-C has potent anti-inflammatory and analgesic activities and may be a promising treatment against a variety of inflammatory diseases.