Modulation of activated murine peritoneal macrophages functions by emodin, aloe-emodin and barbaloin isolated from Aloe barbadensis

Abstract

Activated murine macrophages produce high level of nitric oxide by inducible nitric oxide synthase (iNOS), which is an important mechanism in macrophage-induced inflammation. In the present study, we isolated emodin, aloe-emodin and barbaloin compounds from Aloe barbadensis and investigated their inhibitory effects on the production of nitric oxide (NO), tumor necrosis factor-α (TNF-α) and interleukin (IL-12) from murine macrophages activated by lipopolysaccharide (LPS) and interferon-gamma (IFN-γ). Our results showed that the 50% inhibition concentration (IC50) of emodin, aloe-emodin and barbaloin on NO, TNF-α and IL-12 from activated peritoneal macrophages were 120, 30 and 200 μM respectively. Our experimental results showed that reduction of NO level by emodin might inhibit both at the pretreated LPS/IFN-γ activation and post-LPS/IFN-γ activation pathway. Activities of aloe-emodin and barbaloin could be caused by inhibition at the pretreated LPS/IFN-γ activation event. Chemical structures of all the isolated components were identified by comparison of NMR, mass spectral data and melting points with those reported in literature.