Eucalyptol

In a concentration-dependent manner, 1,8-Cineol (Eucalyptol) reduces LPS-induced Egr-1 expression in nuclei and in whole cell of THP-1 cells, but shows no effect on NF-κB expression. 1,8-Cineol significantly inhibits cytokine production in human unselected lymphocytes of TNF-α, IL-1β, IL-4, IL-5, and in lipopolysaccharide (LPS)-stimulated monocytes of TNF-α, IL-1β, IL-6, and IL-8^[1]. 1,8-Cineol significantly stimulates the transactivation of liver X receptor modulator LXR-α and LXR-β. The mRNA and protein expression of LXRs and their target genes, including ABCA1 and ABCG1, are significantly increased in macrophages stimulated with cineole. This leads to the subsequent removal of cholesterol from the cells^[2].

The THP-1 cells are incubated with serial doses of 1,8-cineol (1, 10, and 100 mg/L, 30 min) before being stimulated with LPS (1 mg/L, 30 min). The localization of Egr-1 in the THP-1 cells is detected by immunofluorescence and a laser scanning confocal microscope. The expression of Egr-1 in the nuclei and whole cell, and NF-κB in the nuclei, are measured by Western blot analysis.

In rats, it depresses myocardial contractility in a concentration-dependent way while increasing extracellular Ca2+ concentration. i.v. treatment of both anesthetized and conscious rats with 1,8-cineole lowers blood pressure, probably through an active vascular relaxation rather than withdrawal of sympathetic tone. 1,8-Cineole is also found to relax rat and guinea-pig (nonsensitized and ovalbumin-sensitized) airway smooth muscle by a nonspecific mechanism^[2].