Assessment of the potential in vivo genotoxicity of fluoranthene (original) (raw)
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Aquatic Toxicology, 2012
The fluoranthene (Fluo) is one of the most abundant polycyclic aromatic hydrocarbons (PAHs) in human food and in marine compartments. However, the existing data on its genotoxicity is poor and controversial. The aim of this study was to assess in vitro the potential genotoxicity of Fluo in sole and its possible effect on CYP450 modulation. Freshly isolated hepatocytes were exposed for 24 h to a range of Fluo concentrations from 0.5 to 50 M in both culture flasks and microplate wells. The ethoxyresorufin-O-deethylase (EROD) activity was measured as an indicator of the activity of the cytochrome P450 1A1 (CYP1A1). The genotoxic effects were evaluated by measuring both DNA strand breaks and DNA adducts by the alkaline comet assay and the postlabeling technique respectively. Calf thymus DNA was also exposed to Fluo in the presence of sole liver microsomes in order to check for Fluo DNA adduct formation. In sole hepatocytes, Fluo was shown to induce a decrease in the EROD activity in a concentrationdependent manner. A significant genotoxic effect was observed in terms of DNA strand breakage from an exposure concentration of 5 M: despite a concentration-dependent effect was observed, it did not follow a linear dose-response. The response was similar whatever the way of exposure in flasks or in wells. One reproducible adduct was detected in the hepatocytes exposed to the highest concentrations of Fluo. The formation of Fluo adducts was confirmed by the detection of one reproducible adduct following in vitro exposure of calf thymus DNA to 100 and 200 M of Fluo in the presence of sole microsomes. These results demonstrate the potential of sole hepatocytes to metabolize Fluo in 24 h into reactive species, able to induce genotoxicity by DNA strand breakage and DNA adduct formation. Moreover, a miniaturized cell exposure system was validated for further experiments using fewer amounts of hepatocytes and contaminants, and allowing exposure to PAH metabolites.
Journal of Organic Chemistry, 1984
The syntheses of the two major hepatic microsomal dihydrodiol metabolites of the environmental carcinogen, benzo[b]fluoranthene, are described. 1,2-Dihydro-1,2-dihydroxybenzo[b]fluoranthene was prepared from 11Hbenzo[ blfluorene-11-carboxylic acid. The key intermediate was l-oxo-1,2,3,3a-tetrahydrobenzo[ b] fluoranthene which was prepared by regiospecific cyclization of llH-benzo[ blfluorene-11-propionic acid chloride. 11,12-Dihydro-11,12-dihydroxybenzo[b]fluoranthene was synthesized from 2-methylfluoranthene via 12-oxo-9,10,11,12-tetrahydrobenzo[ blfluoranthene. Both dihydrodiols were mutagenic toward Salmonella typhimurium TA 100, but their activities were less than that of benzo[b]fluoranthene.
Mutagenesis, 1999
Chlorohydroxyfuranones (CHFs) are mutagenic disinfection by-products found in chlorine-treated drinking water. In the current study, the genotoxicity of four CHFs, 3,4-dichloro-5-hydroxy-2(5H)-furanone (MCA), 3-chloro-4-methyl-5-hydroxy-2(5H)-furanone (MCF), 3-chloro-4-(chloromethyl)-5-hydroxy-2(5H)-furanone (CMCF) and 3-chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), was determined. Two in vitro assays, the microscale micronucleus assay on L5178Y mouse lymphoma cells and the unscheduled DNA synthesis assay on a hepatocyte primary culture from Fisher F344 rats, were carried out. All four CHFs demonstrated genotoxic effects in both assays. In the two systems used, CMCF was the most genotoxic compound, followed by MCA, MX and MCF, respectively. This work was the first study of the DNA damaging properties of all four CHFs in two in vitro genotoxicity tests. These new data expand the range of genetic damages induced by this group of compounds.
Acute and subchronic oral toxicity of fluoranthene in F-344 rats
Ecotoxicology and Environmental Safety, 2004
We have studied the acute and subchronic oral toxicity of fluoranthene (FLA) in male and female F-344 rats. Single acute FLA doses of 0, 1000, 2000, and 3000 mg/kg body weight (BW) dissolved in peanut oil were administered daily by oral gavage. Subchronic doses of 0, 150, 750, and 1500 mg FLA/kg BW/day were administered for 90 days in the rats' diet. The toxicological endpoints examined included rat body and organ weights, as well as histopathological examinations of liver, kidney, stomach, prostate, testes, and ovaries; hematological parameters including red blood cell (RBC) counts, white blood cell (WBC) counts, hemoglobin (Hgb) concentration, hematocrit (Hct) concentration, mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC); blood chemistry including alanine amino transferase (ALT), aspartate amino transferase (AST), blood urea nitrogen (BUN); and urine chemistry including glucose, bilirubin, specific gravity, pH, protein, urobilinogen, nitrite, occult blood, and leukocytes. In acute toxicity studies, WBC counts were significantly decreased and MCHC was significantly increased in both males and females at all doses. In the subchronic study, several of the blood cell parameters were significantly decreased in males and females after 90 days; RBCs (p12%), WBCs (p40%), Hct (p9%), and Hgb (p12%). Only BUN in males was significantly increased in the high-dose group (1500 mg FLA/kg BW/day) at the 90-day time point. None of the other clinical chemistry parameters were affected. The histopathological examinations showed significant abnormalities (tubular casts) only in the male kidney at the two highest doses after 90 days. We propose a subchronic oral noobserved-adverse-effect level (NOAEL) of 150 mg/kg BW/day for FLA in rats, based on the hematological and renal changes. Overall, our findings indicate that FLA affects specific hematological parameters and kidneys, and has a greater effect on males than females.
Evaluation of Flutamide Genotoxicity in Rats and in Primary Human Hepatocytes
Pharmacology & Toxicology, 2008
Flutamide, an effective competitive inhibitor of the androgen receptor used orally for palliative treatment of prostatic carcinoma and regulation of prostatic hyperplasia was evaluated for its genotoxic effects in the intact rat and in primary cultures of human hepatocytes. Negative responses were obtained in all the in vivo assays as well as in the in vitro assay. In rats given a single oral dose of 500 mg/kg flutamide, fragmentation and repair of liver DNA were absent, and no increase was observed in the frequency of micronucleated hepatocytes. In the liver of rats given flutamide as initiating agent at the dose of 500 mg/kg/week for 6 successive weeks, g-glutamyltraspeptidase-positive foci were detected only in 3 of 10 rats. There was no evidence of a promoting effect on the development of aberrant crypt foci in rats given 100 mg/ kg flutamide on alternate days for 8 successive weeks. In primary cultures of human hepatocytes from one male and one female donor DNA fragmentation as measured by the Comet assays, and DNA repair synthesis as revealed by quantitative autoradiography, were absent after a 20 hr exposure to flutamide concentrations ranging from 18 to 56 mM. Taken as a whole, our results seem to indicate that flutamide is a non-genotoxic drug.
Mutagenicity and tumor initiating activity of methylated benzo[k]fluoranthenes
Cancer Letters, 1985
The biological activities of benzo(a)pyrene, cycbopenta (c,d)pyrene, and i 2 other structurally related compounds were assessed by mutagenicity studies with bacterial and mamma han cells and/or skin tumonigenicity studies with mice. The ability of the parent hydrocarbons to be metabolically activated to mutagenic products was examined in strains TA98 and TAi 00 of Salmonella typhimurium, using 3 experimental pro tocols. In each case, cycbopenta(c,d)pyrene was metabolically activated to products mutagenic to the bacteria to a greater extent than was benzo(a)pynene. However, 7,8-dihydro benzo(a)pyrene and 9, i 0-dihydrobenzo(e)pyrene were the best substrates for metabolic activation to bacterial mutagens. Highly purified epoxide hydnaseadded to a purified and recon stituted monooxygenase system readily abolished the muta genic activity observed in strain TA100 of S. typhimurium when cycbopenta(c,d)pyrene was the substrate, but not when benzo(a)pyrene was the substrate. Inherent mutagenicity of several epoxides of the hydrocarbons generally paralleled the ability of their potential metabolic precursors to be activated to mutagens. 1-Pyrenyboxirane and i 0, i i-dihydrocycboheptapy rene 8,9-oxide were highly mutagenic in strains TA98 and TA100 of S. typhimurium, and in the former strain these activ ities were comparable to that observed with 9,i 0-epoxy 7,8,9,i 0-tetrahydrobenzo(a)pyrene. 4-Pyrenyboxirane was sig nificantly less mutagenic than was i-pyrenyboxirane in both strains of bacteria and in mammalian cells. Benzo(a)pyrene was over 20 times more turnonigenic than was cycbopenta (c,d)pyrene, and it was the most potent of the i i compounds tested for tumor-initiating activity in 2-stage initiation-promo tion experiments on the skin of mice. Cycbopenta(c,d)py rene had tumor-initiating activity comparable to that of benzo (a)anthracene, but it was significantly less active than chry sene. Thus, contrary to inferences made from its high muta genic activity, cycbopenta(c,d)pyrene is a weak tumor initiator on mouse skin.
Carcinogenesis, 1996
Ki-ras proto-oncogene in DNA from B[6]F-induced tumors. Mice were given i.p. injections of 0,10, 50,100 or 200 mg/kg body wt and lung adenomas were scored after 8 months. B[Z»]F induced significant numbers of mouse lung adenomas in a dose-related fashion, with the highest dose (200 mg/kg) yielding 6.95 adenomas/ mouse, with 100% of the mice exhibiting an adenoma. In mice given tricaprylin, the vehicle control, there were 0.60 adenomas/mouse, with 55% of the mice exhibiting an adenoma. Based on dose, B[Z>]F was less active than benzo[a]pyrene. DNA adducts were analyzed qualitatively and quantitatively by 32 P-post-labeling in lungs of strain A/J mice 1, 3, 5, 7, 14 and 21 days after i.p. injection. Maximal levels of adduction occurred 5 days after treatment with the 200 mg/kg dose group, producing 1230 amol B[6]F-DNA adducts/ug DNA. The major B[A]F-DNA adduct was identified by co-chromatography as trans-9,10dihydroxy-a/ifi-11,12-epoxy-5-hydroxy-9,10,11,12-tetrahydro-B[A]F-deoxyguanosine. Approximately 86% of the tumors had a mutation in codon 12 of the Ki-ras oncogene, as determined by direct DNA sequencing of PCR-amplified exon 1 and single-stranded conformation polymorphism analysis. Analysis of the Ki-ras mutation spectrum in 25 of 29 B[Z>]F-induced tumors revealed the predominant mutation to be a G->T transversion in the first or second base of codon 12, congruous with the DNA adduct data. Our data are consistent with previous reports in mouse skin implicating a phenolic diol epoxide as the proximate carcinogenic form of that binds to guanine.