Oregano Essential Oil Attenuates RAW264.7 Cells from Lipopolysaccharide-Induced Inflammatory Response through Regulating NADPH Oxidase Activation-Driven Oxidative Stress

Abstract

Oregano is an aromatic plant widely distributed throughout the Mediterranean area and in Asia. Recent studies have revealed that the anti-inflammatory effect of essential oil in this plant. However, the mechanisms underlying the therapeutic potential have not been well elucidated. This study determined whether oregano essential oil (OEO) exerts an anti-inflammatory effect on lipopolysaccharide (LPS)-treated murine macrophage cells (RAW264.7 cells) in vitro and elucidated the possible underlying molecular mechanisms. The results showed that OEO (2.5–10 μg/mL) inhibited the expression and secretion of interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α) in RAW264.7 cells treated with LPS (1 μg/mL). Consistent with the pro-inflammatory gene expression, the OEO treatment efficiently reduced the LPS-induced activation of mitogen-activated protein kinase, protein kinase B, and nuclear factor κB in RAW264.7 cells. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibition in Nox2 protein-silenced cells attenuated the mRNA expression of IL-1β, IL-6, and TNF-α in the LPS-induced RAW264.7 cells. The OEO inhibited the LPS-induced elevation of NADPH oxidase and oxidative stress. This result suggests that LPS induces RAW264.7 cell inflammation through the NADPH oxidase-mediated production of reactive oxygen species (ROS). In conclusion, OEO protects against the LPS-induced RAW264.7 cell inflammatory response through the NADPH oxidase/ROS pathway.

New Tricks for Old Guys: Recent Developments in the Chemistry, Biochemistry, Applications and Exploitation of Selected Species from the Lamiaceae Family

“…Oregano EO protects against the LPS-induced cell inflammatory response through the NADPH oxidase/ROS pathway. [362] Similarly, the results of the anti-inflammatory tests on sage essential oils using murine macrophages indicate that these oils significantly (p < 0.05) reduced nitric oxide (NO), and NF-κB production in murine macrophage cells. [363] The antiinflammatory activity of rosemary EO is mainly attributed to its main compounds 1,8-cineole, αpinene, and camphor.…”

“…Specifically, for our five essential oils, the anti‐inflammatory activity has been recently reported for oregano essential oil on lipopolysaccharide (LPS)‐treated murine macrophage cells. Oregano EO protects against the LPS‐induced cell inflammatory response through the NADPH oxidase/ROS pathway . Similarly, the results of the anti‐inflammatory tests on sage essential oils using murine macrophages indicate that these oils significantly ( p <0.05) reduced nitric oxide (NO), and NF‐ κ B production in murine macrophage cells .…”

Lipopolysaccharide and inflammatory cytokines levels decreased after sleeve gastrectomy in Chinese adults with obesity

“…Previous studies demonstrated levels of IL-6, IL-8, and TNF-α were significantly elevated in participants with obesity [32,33]. Cheng et al [34] found that secretion of IL-1β, IL-6, and TNF-α was increased in LPS-treated murine macrophage cells in vitro through the activation of NF-κB pathway. Circulating levels of IL-6 were significantly higher in diet-induced obese mice than in Lean mice.…”

Editorial to Special Issue—Anti-Inflammatory Activity of Natural Products

“…In this cellular system, the oregano essential oil was able to inhibit the expression and secretion of IL-1β, IL-6 and TNF-α and to reduce the activation of MAPK, IκB and NF-κB. Moreover, oregano essential oil also inhibited the LPS-induced RAW264.7 cell inflammation through the NADPH oxidase-mediated production of reactive oxygen species (ROS) [18].…”

“…In LPS-stimulated RAW 264.7 cells, the butenolide derivative n-butyl bracteanolide A showed higher NO inhibitory production than bracteanolide A isolated from the plant [17]. Essential oils have been described as possessing in vitro and in vivo anti-inflammatory activities [18]. The authors studied the effect of the essential oil of oregano-mainly constituted by carvacrol-on the NADPH oxidase mediated oxidative stress and the anti-inflammatory activity using LPS-induced RAW264.7 macrophages.…”