11-O-acetylcyathatriol inhibits MAPK/p38-mediated inflammation in LPS-activated RAW 264.7 macrophages and has a protective effect on ethanol-induced gastric injury

Abstract

The present study investigated the effects of 11-O-acetylcyathatriol, a natural cyathane diterpene, on the release of inflammatory mediators and on the activation of the nuclear factor (NF)-κB or the mitogen-activated protein kinase (MAPK) transduction pathways in lipopolysaccharide (LPS)-activated macrophages. MTT was used to evaluate the cytotoxicity. A Griess assay was used to determine the production of nitrous oxide (NO). The levels of tumor necrosis factor (TNF)-α and interleukin (IL)-6 were determined using ELISA kits. The protein expression levels of inducible nitric oxide synthase (iNOS), cyclooxygenase (COX)-2, phosphorylated (p)-extracellular signal-regulated kinase (ERK1/2), p-J-N-terminal kinase (JNK), p-p38 and inhibitor of NFκB (IκB)-α were detected using western blot analysis. 11-O-acetylcyathatriol significantly inhibited the overproduction of NO and the release of IL-6, but had no inhibitory effect on the release of TNF-α. It also significantly downregulated the high expression levels of iNOS and COX-2 induced by LPS. In addition, it markedly inhibited the phosphorylation of the MAPK/p38 protein, but only exhibited weak inhibition on the phosphorylation of the ERK1/2 and JNK proteins, and the degradation of the IκB-α protein. The possible protective effect of 11-O-acetylcyathatriol on ethanol-induced gastric injury was also examined using an in vivo animal experiment. Following gavage administration, it showed an important protective effect on ethanol-induced gastric mucosal injury in rats. These results suggested the possibility that the anti-inflammatory effect of 11-O-acetylcyathatriol was predominantly due to the inhibition of iNOS and COX-2 proteins, and may be associated with the MAPK/p38 transduction pathway, but not the NF-κB transduction pathway. These findings provide an explanation for the underlying mechanism of anti-inflammatory action of 11-O-acetylcyathatriol, which may assist with its clinical application and future development.