Selected components of plant essential oils and intact Rosmarinus officinalis oil (RO) were investigated for their antioxidant, iron-chelating, and DNA-protective effects. Antioxidant activities were assessed using four different techniques. DNA-protective effects on human hepatoma HepG2 cells and plasmid DNA were evaluated with the help of the comet assay and the DNA topology test, respectively. It was observed that whereas eugenol, carvacrol, and thymol showed high antioxidative effectiveness in all assays used, RO manifested only antiradical effect and borneol and eucalyptol did not express antioxidant activity at all. DNA-protective ability against hydrogen peroxide (H2O2)-induced DNA lesions was manifested by two antioxidants (carvacrol and thymol) and two compounds that do not show antioxidant effects (RO and borneol). Borneol was able to preserve not only DNA of HepG2 cells but also plasmid DNA against Fe(2+)-induced damage. This paper evaluates the results in the light of experiences of other scientists.

Since the earliest agricultural attempts, humankind has been trying to improve crop quality and yields, as well as protect them from adverse conditions. Strategies to meet these goals include breeding, the use of fertilisers, and the genetic manipulation of crops, but also an interesting phenomenon called priming or adaptive response. Priming is based on an application of mild stress to prime a plant for another, mostly stronger stress. There are many priming techniques, such as osmopriming, halopriming, or using physical agents. Non-thermal plasma (NTP) represents a physical agent that contains a mixture of charged, neutral, and radical (mostly reactive oxygen and nitrogen species) particles, and can cause oxidative stress or even the death of cells or organisms upon interaction. However, under certain conditions, NTP can have the opposite effect, which has been previously documented for many plant species. Seed surface sterilization and growth enhancement are the most-reported positive effects of NTP on plants. Moreover, some studies suggest the role of NTP as a promising priming agent. This review deals with the effects of NTP treatment on plants from interaction with seed and cell surface, influence on cellular molecular processes, up to the adaptive response caused by NTP.

Experimental evidences suggest that most essential oils possess a wide range of biological and pharmacological activities that may protect tissues against oxidative damage. In this study, we investigated DNA-protective effect of borneol, a component of many essential oils, against oxidative DNA damage induced in primary cultures of rat hepatocytes. Borneol was added to drinking water of Sprague-Dawley rats and DNA resistance against oxidative agents was compared in hepatocytes originated from control and borneol-treated rats. Oxidative stress induced by visible light-excited methylene blue (MB/VL) or 2,3-dimethoxy-1,4-naphthoquionone (DMNQ) resulted in increased levels of DNA lesions measured by the modified single cell gel electrophoresis. Borneol (17 or 34 mg/kg body weight) added to drinking water of rats for 7 days reduced the level of oxidative DNA lesions induced in their hepatocytes by MB/VL or DMNQ. To explain the increased resistance of DNA towards oxidative stress, we measured the base-excision repair (BER) capacity in liver cell extracts of control and borneol-supplemented rats on DNA substrate of HepG2 cells containing oxidative damage. Our results showed that administration of borneol in drinking water had no effect on incision activity of hepatocytes isolated from supplemented rats. The spectrophotometric assessment of enzymatic antioxidants superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and the flow cytometric assessment of total intracellular glutathione (iGSH) in primary hepatocytes of borneol-supplemented rats showed no changes in SOD and GPx activities but higher iGSH content particularly in hepatocytes of higher borneol dose (34 mg/kg) supplemented rats in comparison to control animals. Despite the fact that borneol had no effect either on BER of oxidative DNA damage or on the levels of antioxidant enzymes and manifested no reducing power and radicals scavenging activity, it increased significantly the level of non-enzymatic antioxidant iGSH which could reduce the oxidative DNA lesions induced by MB/VL or DMNQ.

The potential genotoxicity and antigenotoxicity of non-photoactivated hypericin was investigated in five experimental models. Hypericin was non-mutagenic in the Ames assay, with and without metabolic activation. It did not exert a protective effect against mutagenicity induced by 9-aminoacridine. In a yeast (Saccharomyces cerevisiae) assay, hypericin did not increase the frequency of mitotic crossovers or total aberrants at the ade(2) locus, the number of convertants at the trp5 locus, or the number of revertants at the ilv1 locus. In combined application with 4-nitroquinoline-1-oxide, it significantly enhanced the number of revertants at the ilv1 locus at the highest concentration used. Hypericin was not mutagenic in the alga Chlamydomonas reinhardtii. However, in combined application with methyl methane sulfonate, toxicity and mutagenicity were slightly reduced. In a chromosome aberration assay using three mammalian cell lines, hypericin did not alter the frequency of structural chromosome aberrations, and in the DPPH radical scavenging assay, it did not exert any antioxidant effects.

Climate change, environmental pollution and pathogen resistance to available chemical agents are part of the problems that the food industry has to face in order to ensure healthy food for people and livestock. One of the promising solutions to these problems is the use of cold atmospheric pressure plasma (CAPP). Plasma is suitable for efficient surface decontamination of seeds and food products, germination enhancement and obtaining higher yields in agricultural production. However, the plasma effects vary due to plasma source, treatment conditions and seed type. In our study, we tried to find the proper conditions for treatment of barley grains by diffuse coplanar surface barrier discharge, in which positive effects of CAPP, such as enhanced germination or decontamination effects, would be maximized and harmful effects, such as oxidation and genotoxic potential, minimized. Besides germination parameters, we evaluated DNA damage and activities of various germination and antioxidant enzymes in barley seedlings. Plasma exposure resulted in changes in germination parameters and enzyme activities. Longer exposures had also genotoxic effects. As such, our findings indicate that appropriate plasma exposure conditions need to be carefully optimized in order to preserve germination, oxidation balance and genome stability, should CAPP be used in agricultural practice.