Antioxidant activities of major thyme ingredients and lack of (oxidative) DNA damage in V79 Chinese hamster lung fibroblast cells at low levels of carvacrol and thymol

The leafy parts of thyme and its essential oil have been used in foods for the flavour, aroma and preservation and also in folk medicines. In the present study the genotoxicity of thymol and carvacrol was examined using comet assay. In V79 Chinese hamster lung fibroblast cells treated with 1, 5, 25 μM thymol and carvacrol, only 25 μM thymol caused some clastogenic DNA damage. For detection of oxidative DNA damage, the comet assay with formamido pyrimidine glycosylase (Fpg) protein was used: When V79 cells were treated with 1, 5, 25 μM thymol and carvacrol and post-treated with Fpg enzyme, no significant increase of Fpg-sensitive sites was observed at all concentrations studied. Reactive oxygen species (ROS) generation decreased slightly in the presence of thymol (1–100 μM) and carvacrol (5 μM) between 1 and 4 h, yet increased at the highest 100 μM concentration of carvacrol after 24 h. Thymol and carvacrol displayed a concentration dependent antioxidant capacity, whilst γ-terpinene which lacks a phenolic group did not show any antioxidant capacity in the trolox equivalent antioxidant capacity (TEAC) assay. The results of this study indicate a lack of clastogenic activity for thymol and carvacrol at biologically relevant concentrations, and a moderate antioxidant activity in vitro.