Study of cytotoxic, genotoxic and DNA-protective effects of selected plant essential oils on human cells cultured in vitro.
OBJECTIVE
To investigate cytotoxic, genotoxic and DNA-protective effects of carvacrol and thymol on human hepatoma HepG2 and colonic Caco-2 cells cultured in vitro.


RESULTS
Cytotoxicity testing was performed by the trypan blue exclusion technique. Level of DNA lesions induced in human cells with carvacrol, thymol or their combinations with hydrogen peroxide (H(2)O(2)) were measured by alkaline single cell gel electrophoresis (comet assay). The trypan blue exclusion technique showed that though the metabolically more competent human hepatoma HepG2 cells were more sensitive to the toxic effects of carvacrol or thymol than colonic Caco-2 cells, which contained lower levels of metabolizing enzymes, the observed differences were not very expressive. The comet assay technique showed that at concentrations <IC(50) the compounds studied did not induce DNA strand breaks either in hepatoma HepG2 or in colonic Caco-2 cells. On the other side, 24-h incubation of cells in the presence of carvacrol or thymol led to a significant protection of the cells studied toward DNA damage induced by H(2)O(2).


CONCLUSIONS
Based on our results it can be concluded that the cytotoxic effects of selected components of essential plant oils on human hepatoma HepG2 and colonic Caco-2 cells were not associated with a DNA-damaging effect. Carvacrol and thymol reduced the level of DNA lesions induced by H(2)O(2). We assume that the observed DNA-protective effects of these plant volatiles can be associated with their antioxidative activity.
Horváthová
Eva
E
Cancer Research Institute, Slovak Academy of Sciences, Bratislava, Slovakia. eva.horvathova@savba.sk
Sramková
Monika
M
Lábaj
Juraj
J
Slamenová
Darina
D
D018938:Caco-2 Cells; D002478:Cells, Cultured; D000081007:Cymenes; D003603:Cytotoxins / Q000494:pharmacology; D004247:DNA / Q000187:drug effects*; D004249:DNA Damage; D006801:Humans; D039821:Monoterpenes / Q000494:pharmacology / Q000633:toxicity; D009152:Mutagenicity Tests; D010938:Plant Oils / Q000494:pharmacology* / Q000633:toxicity*; D020011:Protective Agents / Q000494:pharmacology; D013943:Thymol / Q000494:pharmacology
D000081007:Cymenes; D003603:Cytotoxins; D039821:Monoterpenes; D010938:Plant Oils; D020011:Protective Agents; D013943:Thymol; D004247:DNA; C073316:carvacrol