Aciculatin inhibits lipopolysaccharide-mediated inducible nitric oxide synthase and cyclooxygenase-2 expression via suppressing NF-κB and JNK/p38 MAPK activation pathways

Abstract

ObjectivesNatural products have played a significant role in drug discovery and development. Inflammatory mediators such as inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) have been suggested to connect with various inflammatory diseases. In this study, we explored the anti-inflammatory potential of aciculatin (8-((2R,4S,5S,6R)-tetrahydro-4,5-dihydroxy-6-methyl-2H-pyran-2-yl)-5-hydroxy-2-(4-hydroxyphenyl)-7-methoxy-4H-chromen-4-one), one of main components of Chrysopogon aciculatis, by examining its effects on the expression and activity of iNOS and COX-2 in lipopolysaccharide (LPS)-activated macrophages.MethodsWe used nitrate and prostaglandin E2 (PGE2) assays to examine inhibitory effect of aciculatin on nitric oxide (NO) and PGE2 levels in LPS-activated mouse RAW264.7 macrophages and further investigated the mechanisms of aciculatin suppressed LPS-mediated iNOS/COX-2 expression by western blot, RT-PCR, reporter gene assay and confocal microscope analysis.ResultsAciculatin remarkably decreased the LPS (1 μg/mL)-induced mRNA and protein expression of iNOS and COX-2 as well as their downstream products, NO and PGE2 respectively, in a concentration-dependent manner (1-10 μM). Such inhibition was found, via immunoblot analyses, reporter gene assays, and confocal microscope observations that aciculatin not only acts through significant suppression of LPS-induced NF-κB activation, an effect highly correlated with its inhibitory effect on LPS-induced IκB kinase (IKK) activation, IκB degradation, NF-κB phosphorylation, nuclear translocation and binding of NF-κB to the κB motif of the iNOS and COX-2 promoters, but also suppressed phosphorylation of JNK/p38 mitogen-activated protein kinases (MAPKs).ConclusionOur results demonstrated that aciculatin exerts potent anti-inflammatory activity through its dual inhibitory effects on iNOS and COX-2 by regulating NF-κB and JNK/p38 MAPK pathways.

Mollugin Inhibits the Inflammatory Response in Lipopolysaccharide-Stimulated RAW264.7 Macrophages by Blocking the Janus Kinase-Signal Transducers and Activators of Transcription Signaling Pathway

“…The phosphorylation and nuclear translocation of p65 NF-κB were reported to peak within 1 h after lPS stimulation, 26,27) and a 30-minute exposure to LPS resulted in a significant increase in the phosphorylation of JNK, p38, and ERK. 28) The activation of JAK-STAT pathway caused by LPS occurs much later. Consistent with previous reports, 21) we found that the tyrosine phosphorylation of STAT1 and STAT3 was detected at 2 h, and at least 6 h was needed to reach the maximum levels of phosphorylation after exposure to LPS.…”

Toll-Like Receptor-2 Ligand Peptidoglycan Upregulates Expression and Ubiquitin Ligase Activity of CHIP through JNK Pathway

“…There are three main members of MAPK family in mammalian cells stress-activated protein kinase c-Jun NH2-terminal kinase (JNK), stress-activated protein kinase 2 (SAPK2 or p38) and the extracellular signal-regulated protein kinases (ERK1/2, p44/p42) [5]. MAPKs are activated by not only cellular stresses such as hypoxic and oxidative stress, but also proinflammatory cytokines, including TNFα, IL-6, IL-1 or LPS [6,7,8]. Recently, Bhatt et al found that PGN activates MAPK pathway in mouse peritoneal macrophages, which results in the expression of inducible Nitric Oxide [9].…”

Anti-neuroinflammatory effects of DPTP, a novel synthetic clovamide derivative in in vitro and in vivo model of neuroinflammation

“…It has been reported that microglia play a dual role of being either neurotoxic through the production of inflammatory molecules, or have a neuroprotective role by supporting neural growth, metabolism and by scavenging cytotoxic agents (Gomes-Leal, 2012 of microglia leads to the excessive release of various neurotoxic substances, such as nitric oxide (NO), prostaglandin E2, superoxide, and proinflammatory cytokines like interleukin-6 (IL-6), IL-1␤ and tumor necrosis factor-␣ (TNF-␣) (More et al, 2013a), which have been implicated in various neurodegenerative diseases. The induction of proinflammatory mediators and cytokines primarily involves activation of mitogen-activated protein kinase (MAPK) signaling cascades, such as c-Jun N-terminal kinase (JNK) and extracellular signal-regulated kinase (ERK) (Bhat et al, 1998;Hsieh et al, 2011), including members of the nuclear factor-B (NF-B) (Lawrence, 2009). Various studies have demonstrated that suppressing the exaggerated inflammatory response by activated microglial cells helps to attenuate the severity of neurodegenerative diseases (Hirsch et al, 2012;Maccioni et al, 2009).…”