In vitro anti-inflammatory activity of terpenes via suppression of superoxide and nitric oxide generation and the NF-κB signalling pathway

Background and aims: Terpenes are considered the main components of essential oils and an important source for the identification of novel lead molecules. This study aimed to investigate the in vitro anti-inflammatory activity of L-carveol, L-carvone, and m-cimene (monoterpenes) and of valencene and guaiene (Sesquiterpenes).

Methods: The influence on intracellular nitric oxide (NO) and pro- and anti-inflammatory cytokine (TNF-α, IL-1α and IL-10) production and on nuclear factor kappa B (NF-κB) activity was determined using Griess reagent, immunoenzymatic assay kits (ELISA) and chemiluminescence measurements in cell-based assays, respectively. Antioxidant activity was assayed through the protective effect against cellular oxidative damage produced by superoxide anion production (O ₂ ^·- ) and hydrogen peroxide on macrophages and by the quenching activity of the NO radical.

Results and discussion: Terpenes reduced the pro-inflammatory cytokines TNF-α and IL-1α and increased the production of IL-10. In addition, the terpenes, especially guaiene (53.3 ± 2.4%) and m-cymene (38.1 ± 0.6%), significantly inhibited NO production in a macrophage cell culture-based assay, whereas no effect was observed in the scavenging activity of this radical. L-carveol and m-cymene significantly inhibited O ₂ ^·- production with reductions of approximately 68.6 ± 2.2% and 48.2 ± 4.2%, respectively, at a concentration of 10 μM. Moreover, these terpenes were verified to suppress NF-κB activity. The results indicate that these terpenes have therapeutic potential and may be used to suppress inflammatory diseases or as a leading compounds.