Genotoxicity evaluation of kaurenoic acid

Thalidomide: lack of mutagenic activity across phyla and genetic endpoints

Genotoxicity studies on licorice flavonoid oil (LFO)

A series of seven 1-aryl-3.3-dialkyltriazenes, including 1-phenyl-3.3-dimethyltriazene (DMPT), 1-phenyl-3.3-di-(trideuteromethyl)-triazene (DMPT-ds), 1-p-methylphenyl-3.3-dimethyltriazene (DMpMPT), 1-p-nitrophenyl-3.3-dimethyltriazene (DMpNPT), 1-phenyl-3.3-diethyltriazene (DEPT), 1-phenyl-3.3-di-n-propyltriazene (DnPrPT) and 1-phenyl-3.3-diisopropyltriazene (DiPrPT) and 1.3-diphenyl-3-methyltriazene (DPMT), was synthesized and characterized by UV/VIS, IR and 1H-NMR spectroscopy. Chemical half-life was determined in phosphate buffer at 37 degrees using UV/VIS spectroscopy. With the exception of DMpNPT, which was stable, the triazenes underwent pH-dependent hydrolytic decomposition (acid catalysis). By means of UV/VIS spectra, TLC and HPLC, phenol, aniline and secondary azocoupling products were identified after complete hydrolytic cleavage of the parent compounds. Pathways of spontaneous hydrolysis are proposed and discussed. Genotoxic activity of the triazenes was assayed by measurement of sister chromatid exchanges (SCE) in V79-E cells without and with rat liver S9 mix as an exogenous metabolizing system. In the direct SCE assay (without S9 mix), all triazenes except DMpNPT exerted a toxic action (cell cycle delay) in a narrow concentration range between no effect and overt cytotoxicity. This non-specific toxicity depended on the pH of the incubation system and was inversely proportional to chemical half-life. The toxicity of these agents is most likely due to the arenediazonium cation which is a relatively stable intermediate. In a sublethal concentration range most triazeness induced significant increases of SCE rates. These are interpreted as an indirect consequence of cytotoxicity. Upon metabolic activation, the compounds were genotoxic in a dose-dependent fashion. Their SCE-inducing capacity depended on the nature of the alkylating species generated, i.e., the alkyldiazonium cation, and on chemical stability. Surprisingly, no deuterium isotope effect was observed in DMPT-d6. The order of genotoxic activity among the aryldialkyltriazenes was DMpNPT much greater than DMPT = DMPT-ds greater than DMpMPT much greater than DEPT greater than DnPrPT greater than or equal to DiPrPT. DPMT was a marginal SCE inducer but very toxic upon metabolic activation. As monooxygenation of DPMT, like spontaneous hydrolysis, should generate a phenyldiazonium cation, the results suggest that arylation of DNA causes a very low SCE induction, if any.

Cytotoxic effects of trimethyltin chloride on human peripheral blood lymphocytes in vitro.

Streptococcus agalactiae or Group B Streptococcus (GBS) remains a leading cause of neonatal infections worldwide; and the maternal vaginal-rectal colonization increases the risk of vertical transmission of GBS to neonates and development of infections. This study reports the in vitro antibacterial effect of the oleoresin from Copaifera officinalis Jacq. L. in natura (copaiba oil) and loaded into carbomer-hydrogel against planktonic and sessile cells of GBS. First, the naturally extracted copaiba oil was tested for the ability to inhibit the growth and metabolic activity of planktonic and sessile GBS cells. The time-kill kinetics showed that copaiba oil exhibited a dose-dependent bactericidal activity against planktonic GBS strains, including those resistant to erythromycin and/or clindamycin [minimal bactericidal concentration (MBC) ranged from 0.06 mg/mL to 0.12 mg/mL]. Copaiba oil did not inhibit the growth of different Lactobacillus species, the indigenous members of the human microbiota. The mass spectral analyses of copaiba oil showed the presence of diterpenes, and the kaurenoic acid appears to be one of the active components of oleoresin from C. officinalis related to antibacterial activity against GBS. Microscopy analyses of planktonic GBS cells treated with copaiba oil revealed morphological and ultrastructural alterations, displaying disruption of the cell wall, damaged cell membrane, decreased electron density of the cytoplasm, presence of intracellular condensed material, and asymmetric septa. Copaiba oil also exhibited antibacterial activity against established biofilms of GBS strains, inhibiting the viability of sessile cells. Low-cost and eco-friendly carbomer-based hydrogels containing copaiba oil (0.5% – CARB-CO 0.5; 1.0% – CARB-CO 1.0) were then developed. However, only CARB-CO 1.0 preserved the antibacterial activity of copaiba oil against GBS strains. This formulation was homogeneous, soft, exhibited a viscoelastic behavior, and showed good biocompatibility with murine vaginal mucosa. Moreover, CARB-CO 1.0 showed a slow and sustained release of the copaiba oil, killing the planktonic and sessile (established biofilm) cells and inhibiting the biofilm formation of GBS on pre-coated abiotic surface. These results indicate that carbomer-based hydrogels may be useful as topical systems for delivery of copaiba oil directly into de vaginal mucosa and controlling S. agalactiae colonization and infection.

Effects of the formaldehyde releasing preservatives dimethylol urea and diazolidinyl urea in several short-term genotoxicity tests

This study was designed to assess the toxicity of capsaicin-containing (CP) pharmacopunture using an in vitro chromosomal aberrations in Chinese hamster lung (CHL/IU) cells. In order to determine the high dose level in the main study of this study, a dose range finding study was conducted first. The high dose was selected at 10.0% of CP pharmacopuncture extract, and then diluted sequentially to produce lower dose levels of 5.00, 2.50, 1.25, 0.625 and 0.313% by applying a geometric ratio of 2. As a result, the cytotoxicity and precipitation of the CP pharmacopuncture as a test substance were not evident at any dose level during short-time treatment with and without metabolic activation and continuous treatment without metabolic activation. Therefore, the dose levels for this study were chosen as 10.0, 5.0, and 2.5%., and the treatment volume was 1.3 mL. In addition, negative and positive controls were set. In main study, the frequency of cells with chromosome aberrations in CP treated groups was less than 5% in short-time treatment with and without metabolic activation and continuous treatment without metabolic activation. In addition, there was no statistically significant difference when compared to the negative control group. The frequency of cells with structural chromosomal aberrations in the positive control group was more than 10% compared to the negative control group, and it increased statistically significantly. In conclusion, under the conditions of this study, CP pharmacopuncture did not show the possibility of causing chromosome aberrations.

Chromosome damage by dothistromin in human peripheral blood lymphocyte cultures: a comparison with aflatoxin B 1

Genotoxic and antigenotoxic effects of Hemidesmus indicus R. Br. root extract in cultured lymphocytes

Assessment of genetic damage induced by gadolinium-based radiocontrast agents

Computational screening is suggested as a way to set priorities for further testing of high production volume (HPV) chemicals for mutagenicity and other toxic endpoints. Results are presented for batch screening of 2484 HPV chemicals to predict their mutagenicity in Salmonella typhimurium (Ames test). The chemicals were tested against 15 databases for Salmonella strains TA100, TA1535, TA1537, TA97 and TA98, both with metabolic activation (using rat liver and hamster liver S9 mix test) and without metabolic activation. Of the 2484 chemicals, 1868 are predicted to be completely nonmutagenic in all of the 15 data modules and 39 chemicals were found to contain structural fragments outside the knowledge of the expert system and therefore suggested for further evaluation. The remaining 616 chemicals were found to contain different biophores (structural alerts) believed to be linked to mutagenicity. The chemicals were ranked in descending order according to their predicted mutagenic potential and the first 100 chemicals with highest mutagenicity scores are presented. The screening result offers hope that rapid and inexpensive computational methods can aid in prioritizing the testing of HPV chemicals, save time and animals and help to avoid needless expense.

In this work, we examined the genotoxic effect of the antibiotic preparation ipronidazol (Gastrogal 10). An experiment was performed in vitro on human peripheral blood lymphocytes using the chromosome aberration and sister chromatid exchange tests. Clastogenic effects of ipronidazol were examined at three experimental concentrations (25 (g/ml, 50 (g/ml i 100 (g/ml) in eight experimental cycles. The results demonstrate that Gastrogal 10 has the ability to change the human lymphocyte kariotype, i.e. it induces numerical aberrations (aneuploidies and polyploidies), as well as chromosome gaps and breaks. Moreover, Gastrogal 10 induces a significant increase of sister chromatid exchange in human lymphocytes. The obtained results demonstrate that the examined preparation exhibits a certain genotoxic potential.

In this study, the influence of anthropogenic pollution on the aquatic environment of Plitvice Lakes National Park (PLNP) was investigated during 2011-2012 using a combination of chemical and cytogenetic analyses. Four groups of major contaminants [(volatile organic compounds: benzene, toluene, ethylbenzene, and xylenes (BTEX); persistent organochlorine pollutants: organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs); major and trace elements; anthropogenic radionuclides (90Sr, 134Cs, and 137Cs)] were determined in three aquatic compartments (water, sediment, fish). Mass fractions of inorganic constituents in different compartments reflected the geological background of the area, indicating their origin from predominantly natural sources. Levels of volatile and persistent organic compounds in water and fish, respectively, were very low, at levels typical for remote pristine areas. Analysis of anthropogenic radionuclides in water and sediment revealed elevated activity concentrations of 137Cs in water, and measurable 134Cs in the upper sediment layers from April 2011, possibly as a consequence of the Fukushima nuclear accident in March 2011. The potential genotoxicity of river and lake water and lake sediment was assessed under laboratory conditions using the alkaline comet assay on human peripheral blood lymphocytes, and measured levels of primary DNA damage were within acceptable boundaries. The results showed that despite the protected status of the park, anthropogenic impact exists in both its terrestrial and aquatic components. Although contaminant levels were low, further monitoring is recommended to make sure that they will not rise and cause potentially hazardous anthropogenic impacts.

Aniline (in the form of its hydrochloride) has been shown to induce a rather rare spectrum of tumors in the spleen of Fischer 344 rats. The dose levels necessary for this carcinogenic activity were in a range where also massive effects on the blood and non-neoplastic splenotoxicity as a consequence of methemoglobinemia were to be observed. This review aimed at clarifying if aniline itself or one of its metabolites has a genotoxic potential which would explain the occurrence of the spleen tumors in rats as a result of a primary genetic activity. The database for aniline and its metabolites is extremely heterogeneous. With validated assays it ranges from a few limited Ames tests (o- and m-hydroxyacetanilide, phenylhydroxylamine, nitrosobenzene) to a broad range of studies covering all genetic endpoints partly with several studies of the same or different test systems (aniline, p-aminophenol, p-hydroxyacetanilide). This makes a direct comparison rather difficult. In addition, a varying number of results with as yet not validated systems are available for aniline and its metabolites. Most results, especially those with validated and well performed/documented studies, did not indicate a potential of aniline to induce gene mutations. In five different mouse lymphoma tests, where colony sizing was performed only in one test, aniline was positive. If this indicates a peculiar feature of a point mutagenic potential or does represent a part of the clastogenic activity for which there is evidence in vitro as well as in vivo remains to be investigated. There is little evidence for a DNA damaging potential of aniline. The clastogenic activity in vivo is confined to dose levels, which are close to lethality essentially due to hematotoxic effects. The quantitatively most important metabolites for experimental animals as well as for humans (p-aminophenol, p-hydroxyacetanilide) seem to have a potential for inducing chromosomal damage in vitro and, at relatively high dose levels, also in vivo. This could be the explanation for the clastogenic effects that have been observed after high doses/concentrations with aniline. They do not induce gene mutations and there is little evidence for a DNA damaging potential. None of these metabolites revealed a splenotoxic potential comparable to that of aniline in studies with repeated or long-term administration to rats. The genotoxicity database on those metabolites with a demonstrated and marked splenotoxic potential, i.e. phenylhydroxylamine, nitrosobenzene, is unfortunately very limited and does not allow to exclude with certainty primary genotoxic events in the development of spleen tumors. But quite a number of considerations by analogy from other investigations support the conclusion that the effects in the spleen do not develop on a primary genotoxic basis. The weight of evidences suggests that the carcinogenic effects in the spleen of rats are the endstage of a chronic high-dose damage of the blood leading to a massive overload of the spleen with iron, which causes chronic oxidative stress. This conclusion, based essentially on pathomorphological observations, and analogy considerations thereof by previous authors, is herewith reconfirmed under consideration of the more recently reported studies on the genotoxicity of aniline and its metabolites, on biochemical measurements indicating oxidative stress, and on the metabolism of aniline. It is concluded that there is no relationship between the damage to the chromosomes at high, toxic doses of aniline and its major metabolites p-aminophenol/p-hydroxyacetanilide and the aniline-induced spleen tumors in the rat.

A mutagenicity test was conducted for 1,4-pentadiene-3-ol, 2,4-hexadiene, isoprene, cis- and trans-piperylene in the bacterial mutation assay using Salmonella typhimurium (S. typhimurium) strain TA 100, TA98, TA1535 and Escherichia coli (E. coli) WP2uvrA/pKM101 with and without metabolic activation by S9 mix in the preincubation method. The mutagenicity of 1,3-butadiene was tested by the gas exposure method. Mutagenicity was weakly positive for 1,4-pentadiene-3-ol in TA 100 with S9 mix and was pseudopositive for WP2uvrA/pKM101 without S9 mix. Mutagenicity was very clear for 1,3-butadiene in 10 fold concentrated TA1535 with S9 mix. The 2,4-hexadiene, isoprene, cis-piperlylene and trans-piperlylene were not mutagenic on S. typhimurium TA98, TA100, TA1535 or E. coli WP2uvrA/pKM101 with or without metabolic activation. It can be concluded from these results, that chemicals, containing double bond carbon (C=C) chemical generally tend to show weak mutagenicity in the presence of the metabolic activation system.