Adverse Phototoxic Effect of Essential Plant Oils on NIH 3T3 Cell Line after UV Light Exposure.

AIM: Natural or artificial substances have become an inseparable part of our lives. It is questionable whether adequate testing has been performed in order to ensure these substances do not pose a serious health risk. The principal aim of our research was to clarify the potential risk of adding essential oils to food, beverages and cosmetic products. METHODS: The toxicity of substances frequently employed in cosmetics, aromatherapy and food industry (bergamot oil, Litsea cubeba oil, orange oil, citral) were investigated using cell line NIH3T3 (mouse fibroblasts) with/without UV irradiation. The MTT assay was used to estimate the cell viability. Reactive oxygen species (ROS) which are products of a number of natural cellular processes such as oxygen metabolism and inflammation were measured to determine the extent of cellular stress. DNA damage caused by strand breaks was examined by comet assay. RESULTS: MTT test determined EC50 values for all tested substances, varying from 0.0023% v/v for bergamot oil to 0.018% v/v for citral. ROS production measurement showed that UV radiation induces oxidative stress to the cell resulting in higher ROS production compared to the control and non-irradiated samples. Comet assay revealed that both groups (UV, without UV) exert irreversible DNA damage resulting in a cell death. CONCLUSIONS: Our findings suggest that even low concentrations (lower than 0.0464% v/v) of orange oil can be considered as phototoxic (PIF value 8.2) and probably phototoxic for bergamot oil (PIF value 4.6). We also found significant changes in the cell viability, the ROS production and the DNA after the cells were exposed to the tested chemicals. Even though these substances are widely used as antioxidants it should be noted that they present a risk factor and their use in cosmetic and food products should be minimized.

The effect of silver nanoparticles and silver ions on mammalian and plant cells in vitro.

Silver nanoparticles (AgNPs) are the most frequently applied nanomaterials. In our experiments, we tested AgNPs (size 27 nm) manufactured by the Tollens process. Physico-chemical methods (TEM, DLS, AFM and spectrophotometry) were used for characterization and imaging of AgNPs. The effects of AgNPs and Ag(+) were studied in two experimental models (plant and mammalian cells). Human keratinocytes (SVK14) and mouse fibroblasts (NIH3T3) cell lines were selected to evaluate the cytotoxicity and genotoxicity effect on mammalian cells. Higher sensitivity to AgNPs and Ag(+) was observed in NIH3T3 than in SVK14 cells. AgNPs accumulated in the nucleus of NIH3T3 cells, caused DNA damage and increased the number of apoptotic and necrotic cells. Three genotypes of Solanum spp. (S. lycopersicum cv. Amateur, S. chmielewskii, S. habrochaites) were selected to test the toxicity of AgNPs and Ag(+) on the plant cells. The highest values of peroxidase activity and lipid peroxidation were recorded after the treatment of S. habrochaites genotype with AgNPs. Increased ROS levels were likely the reason for observed damaged membranes in S. habrochaites. We found that the cytotoxic and genotoxic effects of AgNPs depend not only on the characteristics of nanoparticles, but also on the type of cells that are treated with AgNPs.

Phthalocyanine-mediated Photodynamic Treatment of Tumoural and Non-tumoural cell lines.

This study deals with the use of cationic far-red absorbing photosensitizers (λ(max) ~740 nm) from the group of the phthalocyanines, in photodynamic therapy. The photosensitizers differed in their central atom, bearing either hydrogen, zinc or magnesium. These photosensitizers were tested in vitro on the tumour cell line HeLa (cervical cancer) and non-tumour cell line NIH3T3 (mouse fibroblast). The following tests were performed: measurement of reactive oxygen species production, viability testing, Comet assay and cell type detection (apoptotic, necrotic and living cells). The best results were achieved with zinc derivative at relatively low half-maximum inhibitory concentration (0.04 µM) and a total radiation dose of 15 J cm(-2).