Antioxidant and Anti-Inflammatory Activities of Essential Oils: A Short Review

Miguel, Maria Graça

α-Thujone, β-thujone, camphor, and caryophyllene were the main components of Artemisia fukudo oil that were able to inhibit the release of TNF-α, IL-1β, and IL-6 in LPS-treated RAW 264.7 cells [116] . The mixture of stereoisomers geranial (E-isomer) and neral (Z-isomer), known as citral, constitutes the main components of Cymbopogon citratus (DC) Stapf. (lemongrass) essential oil. This essential oil revealed to be capable to suppress IL-1β and IL-6 in LPS-stimulated peritoneal macrophages of normal mice [117] . The same authors attributed similar properties to the eugenol, the main component present in the essential oil of Syzygium aromaticum (L.) Merr. et Perry (clove) [118] . Other authors also found that eugenol on human macrophages (U937) under the stimulation of LPS blocked the release of IL-1β, TNF-α and PGE 2 [119] . Whether some essential oils are able to inhibit the production of pro-inflammatory cytokines such as TNF-α, some of them, particularly lemongrass, geranium and spearmint and their main components (citral, geraniol, citronellol, and carvone), can also suppress TNF-α-induced neutrophil adherence responses [120] . According to these authors, those essential oils or their major components do not affect TNF-α but do affect the neutrophil function to suppress their adhesion. Therefore and concerning lemongrass and citral and as reported above, they can also suppress IL-1β and IL-6 pro-inflammatory cytokines [117] . In other work, Lin et al. (2008) [121] Therefore, the hepatoprotective activity of myristicin might be, at least in part, due to the inhibition of TNF-α release from macrophages, according to the same authors [122] .