A comparative evaluation of antioxidant and anticancer activity of essential oil from Origanum onites (Lamiaceae) and its two major phenolic components

The objectives of the present study were to determine the effects of essential oil from Turkish oregano (Origanum lutes L.) and its 2 major phenolic components, carvacrol and thymol, on cell viability, and to investigate their cytoprotective (antioxidant) effects against hydrogen peroxide-induced cytotoxicity and membrane damage in hepatoma G2 (Hep G2) cells. Their antioxidant properties were also evaluated with 2 in vitro complementary test systems: DPPH radical scavenging activity and linoleic acid oxidation inhibition. The aerial parts of the essential oil were isolated using a Clevenger-type apparatus (hydrodistillation) and its components were analyzed by gas chromatography/mass spectrometry (GC/MS). The essential oil of O. onites decreased cancer cell viability at higher concentrations. The essential oil was found to be less cytototoxic (IC50: 149.12 mu g/mL) than carvacrol and thymol (IC50: 53.09 and 60.01 mu g/mL, respectively) for Hep G2 cells. On the other hand, with the O. onites essential oil, carvacrol and thymol protected the cells against H2O2-induced cytotoxicity when the cells were preincubated with the oil and its components at a lower concentration (