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PubMed1994

Ubiquitous presence of mutagenic and antimutagenic components in air-borne particulates of two Japanese cities.

Previous studies on several samples of urban air-borne particulates showed that the long-chain fatty acids present in these samples can interfere with the measurement of mutagenicity of the particulates with the Salmonella assay. To explore whether this phenomenon is a general, fatty acid contents and the mutagenicity (with Salmonella typhimurium TA98 without S9) were measured for 34 particulate samples collected in the cities of Okayama and Tokyo over a period of 1 year. Palmitic, stearic, oleic and linoleic acids were found in all these samples in this order of amount, and their interference on mutagenicity measurement was eminent, particularly at high doses of the sample. With the use of blue cotton extraction, the mutagenic components can be freed from most of these antimutagenic factors. Significant correlation was found between the number of particulates and the mutagenicity per unit volume of the air. Eight polycyclic aromatic hydrocarbon compounds, including benzo[alpha]pyrene were quantified for these 34 particulate samples. Their contents were too small to account for the observed mutagenicity, suggesting that other polycyclic compounds, possibly involving nitro aromatics, were responsible for the mutagenicity observed. No remarkable differences were noted between Okayama and Tokyo in fatty acid contents, mutagenicity or polycyclic aromatic-hydrocarbon contents of the samples.

Air Pollutants↗
PubMed1988

Determination of polynuclear aromatic compounds in composted municipal refuse and compost-amended soils by a simple clean-up procedure.

A rapid and reproducible procedure suitable for the analysis of polycyclic aromatic compounds (PACs) in sludges and soil samples has been developed. The PACs are isolated by ultrasonic extraction with methyl chloride, redissolution of the crude extract in isooctane and clean-up of the PAC-containing fraction by chromatography on alumina micro-columns. After separation and quantitative determination of the various PACs by capillary gas chromatography/mass spectrometry, more than 50 PAC compounds which cover a wide range of concentrations were detected in the sludge samples. The most abundant compounds were mono-, di- and trimethyl derivatives of naphthalene, phenanthrene, fluorene, dibenzethiophene and naphthothiophene. No accumulation of PAC in an agricultural soil after an experiment of compost application over three years was observed.

Fatty Acids↗
PubMed1988

CASE, the computer-automated structure evaluation method, correctly predicts the low mutagenicity for Salmonella of nitrated cyclopenta-fused polycyclic aromatic hydrocarbons.

Recently Goldring et al. [Mutation Res., 187 (1987) 67-77] reported the synthesis and purification of a series of nitro-substituted cyclopenta-fused polycyclic aromatic hydrocarbons. On the basis of expected charge distributions, these chemicals were predicted to be potent mutagens and, yet, contrary to expectation, they were found to be only weakly mutagenic for Salmonella. In their discussion, the authors suggest that application of CASE, an artificial intelligence system recently developed in these laboratories, would also not predict the low mutagenicity of this group of chemicals. In the present report, it is shown that CASE, in fact, correctly predicts the low mutagenicity of nitro-substituted cyclopenta-fused polycyclic aromatic hydrocarbons.

Mutagenicity Tests↗
PubMed1978

Direct-acting mutagens in automobile exhaust.

Particulate matter in city air contains chemicals which are mutagenic in the Ames Salmonella typhimurium assay. In residential urban areas, the principal mutagens in air do not require liver enzymes to be activated. The source of these liver independent (direct-acting) mutagens may be automobile exhaust because (1) the mutagenic activities were correlated to the lead content or air, (2) the mutagens were found exhaust samples from automobiles and from an experimental CFR single-cylinder gasoline engine, and (3) these mutagens were not found in fuel or unused motor oil, but were found in used motor oil. The strain specificity and the fact that liver enzymes were not required for activation indicated that the exhaust and airborne mutagens were not unsubstituted polycyclic aromatic hydrocarbons (PAH), aromatic amines, alkylnitrosamines or aliphatic epoxides, peroxides and hydroepoxides. A number of nitro-substituted aromatic compounds are direct-acting mutagens in the Ames test, and it is possible that nitration of PAH in exhaust may form the compounds observed here. We synthesized 6-nitrobenzo [a] pyrene and found it to be a potent, direct-acting mutagen with activity comparable to that of benzo-[a] pyrene.

Animals↗
PubMedDate not supplied

Computer-assisted studies of molecular structure and carcinogenic activity.

Both quantitative and qualitative studies of the structure-activity relationships (SAR) of carcinogenic compounds are discussed. Using the ADAPT software system, examples are given of (1) predicting the gas and liquid chromatographic retention behavior of polycyclic aromatic compounds, (2) predicting the carcinogenicity of N-nitrosamines, and (3) predicting the mutagenic behavior of pesticides and other compounds in short-term test systems. It is concluded that the complexity and lack of understanding of the carcinogenic response should not prevent scientists from searching for useful empirical relationships between molecular structure and carcinogenicity. Computer generated molecular descriptors and statistical and pattern recognition techniques can be useful tools in this research.

Animals↗
PubMed1991

Contaminated sediments from tributaries of the Great Lakes: chemical characterization and carcinogenic effects in medaka (Oryzias latipes).

Sediments from four inshore industrial sites and a reference site in the Great Lakes were extracted with organic solvents to produce a crude extract, which was separated on alumina into two fractions: predominantly polycyclic aromatic hydrocarbons; and predominantly nitrogen-containing polycyclic aromatic compounds. Crude extracts were redissolved in acetone and analyzed by gas chromatography and gas chromatography-mass spectrometry. The acetone-redissolved crude extracts from the four industrialized sites contained 5.6-313.3 micrograms total polycyclic aromatic compounds/g sediment and 3.0-36.4 micrograms other compounds/g sediment. In addition to the typical EPA priority pollutants, a substantial amount (228.7 micrograms/g sediment) of alkyl-polycyclic-aromatic compounds was detected in sediments from one of the industrialized sites. Extracts from the reference site contained 1.55 micrograms total polycyclic aromatic compounds/g sediment. Medaka (Oryzias latipes) were exposed to multiple pulse doses of acetone-redissolved extracts and fractions. Medaka were also exposed to a known carcinogen, methylazoxymethanol acetate, to verify that chemicals produced tumors in the test fish. Acetone-redissolved extracts and fractions from contaminated sediments were toxic to medaka. Fin erosion and non-neoplastic liver abnormalities were more prevalent in medaka after exposure to acetone-redissolved extracts and fractions from contaminated sediments. Neoplasms previously associated with chemical exposure in wild fishes were induced in medaka exposed to acetone-redissolved extracts and fractions from two of the contaminated sites, but not from the reference site or controls. These findings further support the hypothesis that chemical contaminants in sediments are involved in epizootics of neoplasms in wild fishes at contaminated sites.

Animals↗
PubMed2004

Towards organo-click chemistry: development of organocatalytic multicomponent reactions through combinations of aldol, Wittig, Knoevenagel, Michael, Diels-Alder and Huisgen cycloaddition reactions.

Here we report on our studies on combinations of amino acids and copper(I) for catalyzing multicomponent reactions (MCRs). We aimed to prepare both diene and dienophiles simultaneously, under very mild and environmentally friendly conditions, thus giving the constituents for a stereocontrolled Diels-Alder reaction, which in turn yields compounds 4 to 8. A diversity-oriented synthesis of polysubstituted spirotriones 4 to 6 were assembled from simple substrates like 1-(triphenylphosphanylidene)-propan-2-one, two aldehydes, and cyclic-1,3-diketones through Wittig/Knoevenagel/Diels-Alder and aldol/Knoevenagel/Diels-Alder reaction sequences in one pot under stereospecific organocatalysis. Chemical diversity libraries of polysubstituted spirotrione-1,2,3-traizoles 8 were assembled from simple substrates by means of Wittig/Knoevenagel/Diels-Alder/Huisgen cycloaddition reaction sequences in one pot under stereospecific organo/Cu(I) catalysis. Functionalized dispirolactones such as 6 are biologically active antioxidants and radical scavengers, and spirotrione-1,2,3-traizoles 8 have found wide applications in chemistry, biology, and materials science. Experimentally simple and environmentally friendly, organocatalytic, asymmetric four-component Diels-Alder (AFCDA) reactions of 1-(triphenylphosphanylidene)- propan-2-one, two different aldehydes, and cyclic-1,3-diketones produced diastereospecific and highly enantioselective substituted spirotriones 4 by means of a Wittig/Knoevenagel/Diels-Alder reaction sequence in one pot. Additionally we have developed an organocatalytic, asymmetric three-component Michael (ATCM) reaction of 1-(triphenylphosphanylidene)-propan-2-one, aldehyde, and cyclic-1,3-diketones that produced Michael adducts 15, 16 through a Wittig/Michael reaction sequence in a highly enantioselective one-pot process.

Amino Acids↗
PubMed1986

Comparative effects of topically applied nitrated arenes and their nonnitrated parent arenes on cutaneous and hepatic drug and carcinogen metabolism in neonatal rats.

The effect of a single topical application of several nitroarenes (1-nitropyrene, nitropyrenes mixture, nitrobenzo(ghi)perylene mixture, 3-nitrofluoranthene, nitrofluoranthene mixture, and nitroperylene mixture) and their corresponding parent arenes to neonatal rats on hepatic and cutaneous drug and carcinogen metabolism was studied. Topical application of each nitroarene (10 mg/kg) resulted in significant induction of aryl hydrocarbon hydroxylase (AHH), 7-ethoxyresorufin O-deethylase (ERD), and 7-ethoxycoumarin O-deethylase (ECD) activities in both skin (1.5- to 14.6-fold) and liver (1.3- to 41.9-fold). The induction of these enzymes by each of the nitroarenes was significant when compared to control or to their corresponding parent arenes. Among the nitroarenes studied, 1-nitropyrene was the least effective in inducing enzyme activities. The inducibility in both skin and liver by different nitroarenes tested was in the following order: nitrofluoranthenes mixture greater than 3-nitrofluoranthene greater than nitroperylenes mixture greater than nitrobenzo(ghi)perylenes mixture greater than nitropyrenes mixture greater than 1-nitropyrene. The nitrofluoranthenes mixture and the nitroperylenes mixture were almost as effective as 3-methylcholanthrene (3-MC). Parent arenes were either ineffective or significantly less effective than nitrated arenes in inducing hepatic and/or cutaneous monooxygenase activities. Hepatic and/or cutaneous benzphetamine N-demethylase (BPD), NADPH cytochrome c reductase, NADH ferricyanide reductase activities, and the levels of cytochrome P-450 and cytochrome b5, remained unchanged following treatment with either topically applied nitroarenes or arenes. However, a shift of approximately 1 nm to the blue region in the absorption maximum of hepatic cytochrome P-450 was observed in animals treated with nitroarenes. This shift was not evident in the case of 1-nitropyrene. Analysis of benzo(a)pyrene metabolites by high-pressure liquid chromatography revealed a significant enhancement in the production of metabolites by nitroarene-treated rat skin and liver microsomes. Our studies suggest that nitroarenes are inducers of hepatic and cutaneous monooxygenases in neonatal rats after topical administration and that they resemble the 3-MC type of inducers in this regard.

7-Alkoxycoumarin O-Dealkylase↗
PubMed1995

Biochemical biomarkers in ecotoxicology--some recent developments.

Biochemical biomarkers measure the exposure of organisms to environmental chemicals. They can also provide measures of toxic effect, e.g. where they are based on molecular mechanisms which underly toxicity. Ideally, biomarkers should be sensitive, specific, simple to use and suitable for the assay of material obtained by non-destructive sampling procedures (e.g. of blood). Recently, there has been encouraging progress in the development of several different types of biomarker assays: (1) The measurement of inhibition of serum 'B' esterases to monitor exposure of birds to organophosphorus insecticides. (2) The measurement of DNA damage caused by aromatic hydrocarbons. DNA adduct formation has been studied using the 32P-postlabelling technique. Several other techniques are currently under investigation. (3) The measurement of disturbances to the transthyretin-retinol binding protein complex caused by a metabolite of 3,4,3',4',tetrachlorobiphenyl. (4) The measurement of precursors of clotting proteins in blood following the inhibition of the Vitamin K cycle by anticoagulant rodenticides. Of these examples, the first is only a biomarker of exposure but the remaining three examples are, in principle, biomarkers of toxic effect since they all represent measures of molecular mechanisms which underly toxicity. Biochemical biomarkers have considerable potential for measuring effects of chemicals under field conditions--especially where carefully selected combinations of them are used.

Animals↗
PubMed1984

Covalent hydration: a possible mechanism for aza-arene carcinogenesis.

It is hypothesized that differences in the carcinogenicity of certain aza-arenes and their carbocyclic analogs may originate from the ability of the former to form covalent hydrates. The hypothesis is primarily based on a comparison of the carcinogenicity of several aza-arenes with that of corresponding carbocyclic compounds and of aromatic amines which are structurally related to the hydrated aza-arenes. Additional evidence is provided by the regiochemistry of cytochrome P-450 catalyzed oxidation of quinoline.

Amines↗
PubMed2002

Biomimetic synthesis of (-)-longithorone A.

An enantioseletive, biomimetic synthesis of (-)-longithorone A has been achieved using an intermolecular/transannular Diels-Alder sequence which provides some support for the proposed biosynthesis. The cycloaddition precursors were two [12]-paracyclophanes that were constructed with atropisomer control during ene-yne metathesis macrocyclizations.

Biological Factors↗
PubMedDate not supplied

Synthesis and mutagenicity of trans-dihydrodiol metabolites of benzo[b]naphtho[2,1-d]thiophene.

The syntheses of potentially important metabolites of benzo[b]naphtho[2,1-d]thiophene ([2,1]BNT)--trans-1,2-dihydroxy-1,2-dihydrobenzo[b]naphtho[2,1- d]thiophene ([2,1]BNT-1,2-diol) and trans-3,4-dihydroxy-3,4-dihydrobenzo[b]naphtho[2,1-d]thiophene ([2,1]BNT-3,4-diol)--are described. The syntheses involved preparation of the appropriate 1-(3-benzo[b]-thiopheneyl)-2-(methoxyphenyl)ethylenes followed by photocyclization to methoxy-[2,1]BNTs, hydrolysis to hydroxy-[2,1]BNTs, oxidation to [2,1]BNT-diones, and NaBH4 reduction. The dihydrodiols were tested for mutagenicity in Salmonella typhimurium TA 100 with activation; [2,1]BNT-3,4-diol, which can form a bay region diol epoxide, was as mutagenic as [2,1]BNT whereas [2,1]BNT-1,2-diol was inactive. These results suggest that the metabolic activation of [2,1]BNT proceeds partially via formation of a bay region diol epoxide.

Carcinogenicity Tests↗
PubMed2001

Immunotoxicity in invertebrates: measurement and ecotoxicological relevance.

Concern is growing regarding the impact of chemicals suspected of altering the function of the immune system in humans and wildlife. There are numerous examples of links between pollution and increased susceptibility to disease in wildlife species, including immunosuppression in harbour seals feeding on fish from contaminated sites, altered immune function in riverine fish and decreased host resistance in birds exposed to pollutants. Laboratory tests have identified potential immunological hazards posed by a range of anthropogenic chemicals in mammals and higher vertebrates. However, few reports have considered the ecological relevance of pollution-induced immunosuppression in invertebrate phyla, which constitute around 95% of all animal species and occupy key structural and functional roles in ecosystems. In this paper effects of chemicals on immune function in invertebrates are briefly reviewed and biomarkers of immunotoxicity are identified. Examples of new approaches for the measurement of immunological inflammatory reactions and stress in molluscan haemocytes are detailed. The relevance of defining the immune system as a target organ of toxicity in invertebrates is discussed and an integrated approach for the use of immunological biomarkers in environment management is proposed, combining measures of immune function and organismal viability at the biochemical, cellular and population level.

Animals↗