Determination of cytotoxic and genotoxic effects of naphthalene, 1-naphthol and 2-naphthol on human lymphocyte culture

Abstract

Naphthalene, a bicyclic aromatic hydrocarbon, has toxic effects on animals and humans. Although recent studies stressed on the genotoxic and cytotoxic effects of naphthalene and its metabolites on eukaryotic cells, there is a big controversy among the results of these studies. The aim of this study is to investigate the effects of naphthalene and its metabolites on the cytotoxicity and genotoxicity in the human lymphocytes in the culture. The genotoxic and cytotoxic effects of naphthalene and its metabolites, 1-naphthol and 2-naphthol, were studied using cytotoxicity test (lactate dehydrogenase and cell proliferation (WST-1) assays) and DNA fragmentation assay (terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay). Naphthalene and its metabolites had no significant cytotoxic effect on treated samples when compared with untreated ones. This result was also confirmed by WST-1 assay. In the TUNEL assay, DNA fragmentation was induced significantly by all concentrations of naphthalene and 2-naphthol and 50 and 100 mM concentrations of 1-naphthol (p < 0.05 or 0.001). In the DNA fragmentation, the most effective dose of 2-naphthol (63%) was 100 mM, when compared with negative control group (13%). These results suggest that naphthalene and its metabolites, 1naphthol and 2-naphthol, may cause DNA damage on human lymphocytes.

Hypothesis-based weight-of-evidence evaluation and risk assessment for naphthalene carcinogenesis

“… Kapuci et al (2012) reported that naphthalene, 1-naphthol, and 2-naphthol all induced DNA fragmentation, as measured by the terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay, at concentrations that were not cytotoxic in human lymphocytes in culture. These authors found that the genotoxic effect occurred in the presence of 10–100 μM naphthalene or 2-naphthol, and in the presence of 50–100 μM 1-naphthol.…”

“…The human lymphoblast micronucleus assay employed by Recio et al (2012) has high predictivity for genotoxicity in vivo ( Pfuhler et al 2011 ). The TUNEL assay used by Kapuci et al (2012) is generally used to measure DNA fragmentation that occurs during apoptosis, not to specifically evaluate genotoxic events ( Morley et al 2006 ), and has a high degree of false positives as an apoptosis assay ( Ribble et al 2005 ). Therefore, it is likely that the genotoxicity at low doses in the Kapuci et al (2012) study is due to problems with the assay and should not necessarily be attributed to naphthalene.…”

“…The TUNEL assay used by Kapuci et al (2012) is generally used to measure DNA fragmentation that occurs during apoptosis, not to specifically evaluate genotoxic events ( Morley et al 2006 ), and has a high degree of false positives as an apoptosis assay ( Ribble et al 2005 ). Therefore, it is likely that the genotoxicity at low doses in the Kapuci et al (2012) study is due to problems with the assay and should not necessarily be attributed to naphthalene. This would explain the inconsistencies between results from Kapuci et al (2012) and the Recio et al (2012) and Karagiannis et al (2012) studies.…”

A complete map of the ion chemistry of the naphthalene radical cation? DFT and RRKM modeling of a complex potential energy surface

“…5,6 In the atmosphere, most naphthalene is in the gas phase, 1 and since it absorbs UV radiation, 7 photolysis can be an important transformation, 8 resulting in a complex and not completely understood chemistry. In this context, the gasphase chemistries of naphthalene, its ions, radicals, and decomposition products are important for different fields of knowledge, especially when these species are generated by UV radiation.…”

Environmental and health impact assessment of Liquid Organic Hydrogen Carrier (LOHC) systems – challenges and preliminary results

“…Aromatic forms of LOHC structures presented here generally do not possess structural features that are considered to hinder biodegradability (high degree of halogenation, more than 3 aromatic rings, excessive branching etc. 58 The higher the quantity of a given chemical circulating on the markets the more data has to be gathered for its risk assessment. 53 The heteroatom itself is usually not very problematic unless it is substituted like in the case of N-ethylcarbazole.…”