Fig. 6. (a) Effects of LmEO on the viability of RAW 264.7 cells determined by MTT assay. The cells were treated with different concentrations of LmEO for 24 h. (C−): negative control values were obtained in the absence of components. None of the tested concentrations of LmEO showed significant detrimental effects. (b) Effects of LmEO on nitric oxide production (NO) in lipopolysaccharide-stimulated macrophages. Cells were treated with lipopolysaccharide and different concentrations of LmEO for 24 h. The supernatants of the cultured cells were examined for NO levels by the Griess method. (C−): negative control values were obtained in the absence of lipopolysaccharide and the essential oil. (C+): the positive control was lipopolysaccharide-only treated cells. Data represent mean ± SEM of three independent experiments.*P < 0.05 compared with the LPS-only treatment group, **P < 0.01 vs. the positive control. Ctrl = control.