Inhibition of nitric oxide production and nitric oxide synthase gene expression in LPS activated RAW 264 .7 macrophages by thyme oleoresin from thymus vulgaris

Objective: To evaluate the effect of Thyme oleoresin on nitric oxide production and nitric oxide synthase gene expression in RAW264.7 macrophage cell lines. Methods: The efficacy of Thyme oleoresin at different concentrations (3.175-150µg/ml) was determined on nitric oxide production in RAW264.7 cells macrophages. The optical density was measured at 540 nm with a microplate reader. RT - PCR was used to examine the expression of the iNOS gene in activated macrophages. The Statistical analysis of the data was carried out by Dunnett's following one way ANOVA and Posthoc comparisons in Graph pad Prism 5.0 software version. Results: Thyme oleoresin at its tested concentrations exhibited dose - dependent decrease in the production of NO. The IC₅₀ value was 24.24 µg/ml. LPS stimulated RAW macrophages strongly up regulated the iNOS gene expression levels. Thyme oleoresin at three different concentration, 12.5µg/ml, 25µg/ml and 50µg/ml, significantly suppressed the iNOS levels compared to that of LPS treatment only. Conclusion: Thyme oleoresin extract may be used for its anti-inflammatory effect as it could significantly suppress the iNOS gene expression as well as the production of NO.