p-Cymene Modulate Oxidative Stress and Inflammation in Murine 
Macrophages: Potential Implication in Atherosclerosis

BACKGROUND: p-Cymene (p-CYM) is a common chemical used in air fresheners. OBJECTIVE: The study was designed to investigate the molecular effect of p-CYM on macrophages. MATERIALS AND METHODS: Macrophages (RAW 264.7) were treated with p-CYM (50 uM/L, 150 uM/L and 250 uM/L) for 6 hours, and 24 hours). Gene involved in inflammation, such as the Tumor Necrosis Factor-alpha (TNF-α), and the Monocyte Chemoattractant Protein-1 (MCP-1) and other genes known for their antioxidant activity such as the Paraoxonase 1 (PON-1) were analyzed. RESULTS: Cells treated with p-CYM have shown 30% up-regulation of MCP-1 after 24 hour of exposure; and also a differential up-regulation of TNF-α. However, treatment with p-CYM has resulted in a considerable (37%) dose-dependent downregulation of PON-1 after 24 hours of exposure. PON-1 is known for its antioxidant properties protecting High-Density Lipoproteins (HDL) from oxidation. CONCLUSION: Our findings demonstrate that exposure to p-CYM over time promotes oxidative stress by downregulating antioxidants genes as shown in PON-1 and also stimulates inflammation, a key process during the initiation and progression of atherosclerosis.