Effects of borneol on the level of DNA damage induced in primary rat hepatocytes and testicular cells by hydrogen peroxide.

The aim of this paper was to evaluate genotoxic effects of borneol and its ability to change DNA-damaging effects of H2O2 in rat hepatocytes and testicular cells. Both in vitro and ex vivo approaches were used in the case of hepatocytes. Testicular cells were tested only ex vivo, i.e. shortly after isolation from rats supplemented by borneol. Cytotoxicity of borneol increased in in vitro conditions in a concentration-dependent manner and it was associated with DNA-damaging effects at toxic concentrations. While non-toxic concentrations of borneol applied in vitro protected cells against H2O2-induced DNA damage and interfered only partly with rejoining of H2O2-induced DNA strand breaks, cytotoxic concentrations of borneol manifested synergy with H2O2, i.e. enhanced DNA-damaging effects of H2O2. On the other side, borneol given to rats in drinking water decreased the level of DNA damage induced by H2O2 in both hepatocytes and testicular cells. Our results show that though at higher concentrations (2-h treatment with >2 mM borneol >0.3084 mg/ml) borneol acts cytotoxically and genotoxically on primary hepatocytes cultured in vitro, if given to rats during 7 days in a daily concentration of 17.14 or 34.28 mg/kg it reduces genotoxicity of H2O2 in both hepatocytes and testicular cells.

Carvacrol given to rats in drinking water reduces the level of DNA lesions induced in freshly isolated hepatocytes and testicular cells by H(2)O(2).

Carvacrol represents a very frequent constituent of essential oils and occurs in many kinds of plants. Though human beings comequite often into close contact with this phenol derivative, its biological effects are not sufficiently known. In this paper we investigated the influence of carvacrol given to rats in drinking water on resistance of their liver and testicular DNA against the oxidative agent hydrogen peroxide H(2)O(2). Carvacrol was dissolved in tap water and given to rats either in concentrations of 30 and 60 mg/1 kg/day during 7 days or in concentrations of 15 and 30 mg/1 kg/day during 14 days. Control animals were given tap water only. After the given time the rats were sacrificed and hepatocytes and testicular cells were isolated and treated with different concentrations of H(2)O(2) (0-250 microM, 5 min, on ice). Then the level of DNA lesions was detected by single cell gel electrophoresis. The results of both types of application of carvacrol showed that DNA of cells isolated from carvacrol-treated animals was significantly more resistant to damaging effects of hydrogen peroxide than DNA of control animals. We assume that the observed DNA-protective effects of carvacrol, which was given to rats during a short time of their life, could be associated with an increase of antioxidant activity of liver and testicular cells in these animals.

DNA-protective effects of two components of essential plant oils carvacrol and thymol on mammalian cells cultured in vitro.

Many components of essential volatile oils show antioxidant activity and may serve e.g. as a natural replacement of synthetic antioxidant food additives. However, it is important to evaluate such compounds also for their pro-oxidant and toxic properties as their plant origin doesn't secure their safety for living beings, including humans. The aim of this study was therefore to investigate cytotoxic, genotoxic and DNA-protective effects of the long-term (24 h) incubation of mammalian cells with two components of essential plant oils (carvacrol and thymol) in in vitro conditions. Cytotoxicity testing was in all cell lines (human hepatoma cells HepG2, human colonic cells Caco-2 and hamster lung cells V79) performed on the basis of trypan blue exclusion. Plating efficiency was evaluated only in V79 cells which manifest a high colony forming ability. The amount of DNA lesions induced in cells treated with hydrogen peroxide, carvacrol, thymol or combinations of carvacrol or thymol with hydrogen peroxide was measured by standard alkaline single cell gel electrophoresis in human cells HepG2 and Caco-2. Trypan blue exclusion test showed that carvacrol was mildly more cytotoxic than thymol and that Caco-2 cells were mildly more resistant to both carvacrol and thymol than HepG2 and V79 cells. At concentrations = IC20-40, the compounds studied did not induce DNA strand breaks either in human cells HepG2 or in cells Caco-2. Incubation of HepG2 and Caco- 2 cells in the presence of the whole scale of concentrations of carvacrol or thymol led in both cases to a significant protection of the cells studied toward DNA strand breaks induced by a potent oxidant hydrogen peroxide.