Comparison of anti-inflammatory effects of berberine, and its natural oxidative and reduced derivatives from Rhizoma Coptidis in vitro and in vivo

Background Berberine (BBR) is the most abundant and major active constituent of Rhizoma Coptidis (RC), which has been widely used to treat inflammatory diseases in traditional oriental medicine. Despite BBR has been found to exhibit pronounced anti-inflammatory effect, the anti-inflammatory activities of its natural derivatives were sparsely dissected out. Purpose To comparatively investigate the anti-inflammatory potential of BBR, and its natural oxoderivative (oxyberberine, OBB) and reduced derivative (dihydroberberine, DHBB) in vitro and in vivo, and delineate the possible underlying mechanism. Methods LC-MS/MS was used to identify the natural derivatives of BBR in RC. The potential anti-inflammatory properties of BBR and its natural derivatives were comparatively evaluated in vitro by lipopolysaccharide (LPS)-induced RAW264.7 macrophages cells, and in vivo via three typical acute inflammation murine models. Some important inflammation-related molecules were analyzed by ELISA, qRT-PCR and Western blotting. Results LC-MS/MS led to the identification of BBR, OBB and DHBB in RC ethyl acetate extract. The in vitro assay indicated that BBR, OBB and DHBB (1.25, 2.5 and 5 μM) pretreatment significantly decreased the levels of pro-inflammatory cytokines tumor necrosis factor-α (TNF-α), interleukin-1β (IL-1β), interleukin-6 (IL-6), prostaglandinE2 (PGE2) and nitricoxide (NO), and inhibited the mRNA expressions of cyclooxygenase-2 (COX-2) and inducible nitricoxide synthase (iNOS) in a dose-dependent manner, with relative efficiency of OBB > BBR > DHBB. Furthermore, OBB, BBR and DHBB remarkably inhibited the phosphorylation of nuclear factor-κB (NF-κB) p65 and inhibitory kappa Bα (IκBα). In vivo, BBR (20 mg/kg) and OBB (5, 10, and 20 mg/kg) pretreatment significantly ameliorated the xylene-induced ear edema, carrageenan-stimulated paw edema, and acetic acid-elicited vascular permeability in mice in a dose-dependent manner, with OBB exhibiting superior anti-inflammatory effect at the same dose (20 mg/kg). Histopathological analysis indicated that OBB and BBR could markedly attenuate the inflammatory deterioration and decrease the cellular infiltration in paw tissues. Additionally, the carrageenan-induced increases in TNF-α, IL-6, IL-1β, PGE2 and NO productions, and COX-2 and iNOS mRNA expressions were effectually and concentration-dependently suppressed by OBB and BBR pretreatment. Conclusion The anti-inflammatory activity of BBR and its natural derivatives was in the order of OBB > BBR > DHBB. OBB was for the first time found to be endowed with pronounced anti-inflammatory property, which was probably associated with suppressing the activation of NF-κB signaling pathway, and the subsequent gene expressions and productions of pro-inflammatory mediators. The results might contribute to illuminating the pharmacodynamic underpinnings of RC and provide evidence for developing OBB as a safe and promising natural lead compound in inflammation treatment.