Evaluation of the mutagenicity and genotoxic potential of carvacrol and thymol using the Ames Salmonella test and alkaline, Endo III- and FPG-modified comet assays with the human cell line Caco-2

• Carvacrol has showed a mutagenic potential by bacterial assay, being more active in presence of the metabolic fraction.
• Carvacrol produced oxidative DNA damage in purine bases at 460 μM by FPG modified-comet assay.
• Thymol did not showed mutagenic (Ames test) and genotoxic effects (comet assays) at concentrations up to 250 μM.

Currently, direct antimicrobial and antioxidant additives derived from essential oils are used in food packaging and are perceived by consumers as low-health-risk compounds. In this study, we investigated the potential mutagenicity and genotoxicity of carvacrol and thymol, major compounds in several essential oils, using the Ames Salmonella test and the alkaline, Endo III- and formamidopyrimidine glycosylase (FPG)-modified comet assays, respectively. Thymol did not show any mutagenic activity at any concentration assayed (0–250 μM), whereas carvacrol exhibited mutagenic potential, displaying greater activity in presence of the metabolic fraction (29–460 μM). The genotoxic effects were evaluated in the human colon carcinoma cell line Caco-2, and the standard comet assay revealed that neither carvacrol (0–460 μM) nor thymol (0–250 μM) had any affects at 24 and 48 h. The FPG-modified comet assay showed that the highest concentration of carvacrol (460 μM) caused DNA damage, indicating damage to the purine bases. These results should be used to identify the appropriate concentrations of carvacrol and thymol as additives in food packaging. Moreover, further studies are necessary to explore the safety and/or the toxicity mechanisms of these compounds.