Inhibitory Effects and Molecular Mechanism of Dieckol Isolated from Marine Brown Alga on COX-2 and iNOS in Microglial Cells

Abstract

To identify the neuroprotective effect of dieckol, a hexameric compound of phloroglucinol isolated from marine brown alga, Ecklonia cava , this study investigated the anti-inflammatory effect of dieckol on lipopolysaccharide (LPS)-stimulated murine BV2 microglia and elucidated the molecular mechanism. The results showed that dieckol suppresses LPS-induced production of nitric oxide (NO) and prostaglandin E(2) (PGE(2)) and expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in a dose-dependent manner, without causing cytotoxicity. It also significantly reduced the generation of proinflammatory cytokines, such as interleukin (IL)-1β and tumor necrosis factor (TNF)-α. Moreover, dieckol significantly reduced LPS-induced nuclear factor κB (NF-κB) and p38 mitogen-activated protein kinases (MAPKs) activation, as well as reactive oxygen species (ROS) production. Taken together, the inhibition of LPS-induced NO and PGE(2) production might be due to the suppression of NF-κB and p38 MAPK signal pathway and, at least in part, by inhibiting the generation of ROS. Hence, these effects of dieckol might assist therapeutic treatment for neurodegenerative diseases that are accompanied by microglial activation.

The Anti-Inflammatory Effects of Persicaria thunbergii Extracts on Lipopolysaccharide-Stimulated RAW264.7 Cells

“…NF-κB is one of the principal factors for the expression of COX-2 and iNOS as mediated by the LPS or pro-inflammatory cytokines [11]. The present study identified that NF-κB is responsible for the maintenance of iNOS expression [9].…”

Antidiabetic effect of polyphenols from brown algaEcklonia kuromein genetically diabetic KK-Aymice

“…conclusion From our finding in addition to little toxicity of phlorotannins and those main components (Nagayama et al, 2002;Jung et al, 2009;Kim et al, 2009;Shim et al, 2009;, we suggest that E. kurome polyphenol (KPP) consumption might be useful to prevent DM-II and diabetes-related complications.…”

Potential Targets for Anti-Inflammatory and Anti-Allergic Activities of Marine Algae: An Overview

“…These inhibitory effects may cause a reduction in the synthesis and release of leukotoriene and prostaglandin [34]. Further, dieckol from E. cava was shown as a neuroprotective agent due to alleviation of iNOS and COX-2 expression in BV2 microglia [35]. Similarly, dieckol from E. cava, diphlorethohydroxycarmalol from Ishige okamurae, and phlorofucofuroeckol A from Ecklonia stolonifera also displayed potent down-regulation on iNOS and COX-2 expression in human umbilical vein endothelial cells and RAW 264.7 macrophage cells [36][37][38].…”