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PubMed2003

Pyrene metabolism in the springtail Orchesella cincta L. (Collembola, Entomobryidae).

A novel, solvent-free spiking method was used to contaminate foodstuff (Desmococcus spp. algae) with pyrene for bioassays with the springtail Orchesella cincta L. (Collembola, Entomobryidae). The primary metabolite 1-hydroxypyrene and two conjugates (pyrene-1-glucoside and one tentatively identified as pyrene-1-glucosidemalonate) were quantified in the insects by high-performance liquid chromatography (HPLC) with fluorescence detection. Individuals from an unpolluted site (SUS population) were capable of rapid metabolism of pyrene, reaching an apparent steady state after 24 h with a composite assimilation/transformation rate of approximately 25 pmol pyrene x g(-1) fresh weight x h(-1) at an exposure level of approximately 18 microg pyrene x g(-1) dry weight algae. A cadmium (Cd)-tolerant population (TOL), genetically distinct from SUS, was exposed in parallel and the populations' pyrene metabolism compared in order to gain insight into any potential cost of Cd-tolerance. The TOL animals assimilated and/or performed phase 1 transformation of pyrene approximately twice as fast as SUS (approximately 56 pmol x g(-1) x h(-1)), but there was no significant difference in the elimination rate constants between SUS and TOL animals. Attributing this difference to any specific cost of Cd-tolerance requires more work and may he coincidental to metal tolerance, but pyrene metabolism in these distinct genotypes, subjected to different selection pressures, was nevertheless significantly different.

Adaptation, Physiological↗
PubMed2005

Uptake and accumulation of phenanthrene and pyrene in spiked soils by Ryegrass (Lolium perenne L.).

Phytoremediation has long been recognized as a cost-effective method for the removal of polycyclic aromatic hydrocarbons (PAHs) from soil. A study was conducted to investigate the uptake and accumulation of PAHs in root and shoot of Lolium perenne L. Pot experiments were conducted with series of concentrations of 3.31-378.37 mg/kg for phenanthrene and those of 4.22-365.38 mg/kg for pyrene in a greenhouse. The results showed that both ryegrass roots and shoots did take up PAHs from spiked soils, and generally increased with increasing concentrations of PAH in soil. Bioconcentration factors (BCFs) of phenanthrene by shoots and roots were 0.24--4.25 and 0.17-2.12 for the same treatment. BCFs of pyrene by shoots were 0.20--1.5, except for 4.06 in 4.32 mg/kg treatment, much lower than BCFs of pyrene by roots (0.58--2.28). BCFs of phenanthrene and pyrene tended to decrease with increasing concentrations of phenanthrene and pyrene in soil. Direct uptake and accumulation of these compounds by Lolium perenne L. was very low compared with the other loss pathways, which meant that plant-promoted microbial biodegradation might be the main contribution to plant-enhanced removal of phenanthrene and pyrene in soil. However, the presence of Lolium perenne L. significantly enhanced the removal of phenanthrene and pyrene in spiked soil. At the end of 60 d experiment, the extractable concentrations of phenanthrene and pyrene were lower in planted soil than in non-planted soil, about 83.24%--91.98% of phenanthrene and 68.53%-84.10% of pyrene were removed from soils, respectively. The results indicated that the removal of PAHs in contaminated soils was a feasible approach by using Lolium perenne L.

Analysis of Variance↗
PubMed1989

Benzo(a)pyrene metabolism by murine spleen microsomes.

The immunosuppressive actions of benzo(a)pyrene have been proposed to be mediated by reactive metabolites rather than the parent compound. Reactive metabolites which suppress splenic humoral immune responses are thought to be generated within the spleen rather than in distant tissues. Although the spleen has been shown to be capable of metabolizing benzo(a)pyrene, the relative amounts and types of metabolites generated have not been determined. In this study, high-pressure liquid chromatography was used to separate benzo(a)pyrene metabolites generated by splenic microsomes. The major metabolites generated by the splenic microsomal preparations of untreated female B6C3F1 mice were found to be the 9,10- and 7,8-dihydrodiols and 9-, 7-, and 3-hydroxy benzo(a)pyrene. The 1,3-, 3,6-, and 6,12-diones and 4,5-dihydrodiol constituted only a small fraction of the metabolites generated. The generation of all metabolites were inhibited by alpha-naphthoflavone and antiserum to NADPH-cytochrome P-450 reductase, whereas SKF 525-A had only a minimal effect. Dihydrodiol production was completely inhibited by the epoxide hydrolase inhibitor, trichloropropylene oxide. Benzo(a)pyrene pretreatment of mice produced a dramatic increase in the amount of metabolites formed; however, the pattern of metabolites remained similar to that generated by splenic microsomes of untreated mice. The role of prostaglandin synthetase in generating these metabolites was also examined. The addition of arachidonic acid in place of NADPH resulted in the formation of only quinones. Dihydrodiols and phenols were undetectable. The results of this study indicate that splenocytes may be capable of generating the 7,8-dihydrodiol, the precursor to the highly reactive 7,8-dihydrodiol-9,10-epoxide. Furthermore, the addition of the 7,8-dihydrodiol-9,10-epoxide to splenocyte cultures resulted in a decreased in vitro antibody forming cell response to sheep red blood cells. Thus, benzo(a)pyrene-induced immunosuppression may be mediated by the dihydrodiol-epoxide generated within the spleen. Since benzo(a)pyrene exposure was found to increase its own metabolism, immunosuppression produced by the administration of benzo(a)pyrene over several days may be the result of an increased production of immunosuppressive metabolites. The pattern of metabolites generated and the effects of the two types of cytochrome P-450 inhibitors suggests that the major isozyme of cytochrome P-450 that mediates the metabolism of benzo(a)pyrene within the spleen of untreated mice may be similar to the isozyme induced in the liver upon pretreatment with polycyclic aromatic hydrocarbons.

Animals↗
PubMed1987

Inducible high-affinity binding site for benzo(a)pyrene in cytosol from rat liver.

By the use of the dextran-coated charcoal method the presence of a high-affinity binding site for benzo(a)pyrene in the cytosol from rat liver (R strain) has been demonstrated. This binder was saturable by ligand concentration and by time. Sucrose density gradient analysis after charcoal treatment revealed one major peak of radioactivity sedimenting at 4.4 S which was displaceable by a 100-fold molar excess of nonlabeled benzo(a)pyrene. Benzo(a)pyrene binding to liver cytosol was sensitive to protease treatment of the cytosol suggesting that the binder was a protein. Saturation and Scatchard plot analysis of benzo(a)pyrene binding indicated a high-affinity (Kd = 4.7 nmol) and a relatively low binding capacity (Bmax = 379 fmol/mg cytosolic protein), allowing, to denote this binder as a receptor for benzo(a)pyrene. Competition studies showed that this cytosolic receptor was distinct from steroid hormone receptors since benzo(a)pyrene binding was partially inhibited by aromatic carcinogens 3-methylcholanthrene and benz(a)anthracene but not by estradiol, progesterone or cortisol. R strain rats used in these experiments were sensitive to induction with 3-methylcholanthrene which produced the increase of cytochrome Pl-450 content in liver microsomes, enhanced the glutathione S-transferase activity in hepatic cytosol and produced liver hypertrophy in stimulated animals. All these effects were related to the dose of 3-methylcholanthrene used for the induction. Also, the cytosolic binding capacity for benzo(a)pyrene was increased in animals stimulated with 3-methylcholanthrene in a dose-dependent fashion. The 3-methylcholanthrene-induced binder displayed identical sedimentation velocity and kinetic parameters (Kd) to those characteristic for the benzo(a)pyrene receptor in hepatic cytosol from unstimulated animals. Conclusively, our results demonstrated that benzo(a)pyrene was bound to a receptor protein in rat liver cytosol which was inducible by the classical inducer 3-methylcholanthrene. The mechanism of induction of this receptor and its role in cell response to aromatic carcinogens still need to be elucidated.

Animals↗
PubMed1987

Toxicity of polycyclic aromatic hydrocarbons. II. Effect of NO2-nitrated phenanthrene and pyrene on blood chemistry in rats.

Male Sprague-Dawley rats were treated with a single ip injection of dimethyl sulfoxide (DMSO), phenanthrene, nitrated products of phenanthrene, pyrene, or nitrated products of pyrene. Phenanthrene, pyrene and their nitrated products were dissolved in DMSO. Phenanthrene produced a significant elevation of serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels relative to DMSO-injected rats 24 hr after injection. Gamma-glutamyl transpeptidase (GGTP) levels were significantly increased for groups treated with phenanthrene when compared with the DMSO group 72 hr after injection. Nitrated products of phenanthrene produced a significant elevation of serum AST, ALT, sorbitol dehydrogenase (SDH), and GGTP levels when compared with groups treated with DMSO and phenanthrene 24 hr after injection. Four of six rats in the nitrated phenanthrene treatment group died between 48 and 72 hr after the injection. Injection of pyrene caused no significant increases in serum enzyme activities. Significant changes in the serum AST, SDH and LDH levels were observed with the nitrated products of pyrene at 24 hr. Only SDH levels were significantly different when pyrene and its nitrated products were compared. No significant differences were detected at 72 hr with the nitrated products of pyrene. As supported by serum chemistry, this study suggests that the products of the reaction of NO2 with two model polynuclear aromatic hydrocarbons (PAH) are hepatotoxic. Both pyrene and phenanthrene form nitrated products that are more toxic than the parent PAH, but the nitrated products of phenanthrene appear to be more toxic than the nitration products of pyrene.

Animals↗
PubMed1982

Benzo(a)pyrene metabolism in primary cultures of mouse epidermal cells and untransformed and transformed epidermal cell lines.

The metabolism of [3H]benzo(a)pyrene [B(a)P] by cultures of primary mouse epidermal cells and untransformed and transformed epidermal cell lines was investigated. All three cell types effectively metabolized [3H]B(a)P. The major organic solvent-extractable metabolites found intracellularly in primary cultures were trans-7,8-dihydro-7,8-dihydroxybenzo(a)pyrene and 3-hydroxybenzo(a)pyrene, although quantities of 9-hydroxybenzo(a)pyrene, trans-9,10-dihydro-9,10-dihydroxybenzo(a)pyrene, and quinones also were present. The major organic solvent-soluble metabolites found in the extracellular medium were trans-9,10-dihydro-9,10-dihydroxybenzo(a)pyrene and trans-7,8-dihydro-7,8-dihydroxybenzo(a)pyrene, with smaller quantities of unconjugated phenols and quinones. The major water-soluble metabolites found in the extracellular medium were conjugated with glucuronic acid [primarily 3-hydroxybenzo(a)pyrene and several quinones]. No sulfate conjugates of [3H]B(a)P metabolites were detected. [3H]B(a)P metabolism was similar in cultures of untransformed and transformed epidermal cell lines but differed from the primary cultures. The major intracellular and extracellular organic solvent-soluble metabolites were diols. Little or no unconjugated phenols were detected. Both the untransformed and transformed epidermal cell lines converted [3H]B(a)P to water-soluble metabolites, primarily glucuronide conjugates. In contrast to the primary cells, a major pathway of trans-7,8-dihydro-7,8-dihydroxybenzo(a)pyrene metabolism in the untransformed and transformed cell lines was a glucuronide conjugate. Primary mouse epidermal cells provide an important model system for studying factors affecting the activation and detoxification of hydrocarbon carcinogens.

Animals↗
PubMed1993

The adjuvant activity of pyrene in diesel exhaust on IgE antibody production in mice.

In this communication, it is shown that pyrene has an adjuvant activity on IgE antibody production when mice are immunized by an intraperitoneal injection of ovalbumin (OA) or Japanese cedar pollen allergen (JCPA) with pyrene. The effects of pyrene on IgE antibody production in mice were investigated to clarify the relation between pollen allergy and the adjuvanticity of the chemical compounds contained in diesel-exhaust particulates (DEP). In the first experiment, three groups of mice were immunized intraperitoneally six times at 2-week intervals with 1 microgram of OA alone, 1 microgram of OA plus 1 mg of pyrene, and 1 microgram of OA plus 1 mg of DEP, respectively. The IgE antibody responses to OA in mice immunized with OA plus pyrene or OA plus DEP were extremely enhanced as compared with those in mice immunized with OA alone, and the highest responses were observed in mice immunized with OA plus DEP. In the second experiment, mice were immunized with 10 micrograms of JCPA alone or 10 micrograms of JCPA plus 5 mg of pyrene in the same way. The IgE antibody responses to JCPA in mice immunized with JCPA plus pyrene were higher than those in mice immunized with JCPA alone. The intraperitoneal macrophages of the mice also clearly stimulated in vitro by pyrene on chemiluminescence assay. These results suggest that pyrene contained in DEP acts as an adjuvant in IgE antibody production when mice are immunized with antigens.

Adjuvants, Immunologic↗
PubMed1978

Carcinogenicity and metabolic profiles of 6-substituted benzo[a]pyrene derivatives on mouse skin.

The ability was tested of appropriate substituents of benzo[a]pyrene (BP) at C-6 to decrease or suppress the carcinogenic activity for these BP derivatives relative to the parent compound. 8-week-old female Swiss mice in 9 groups of 30 were treated on the back with 0.2 mumol of compound in acetone 4 times weekly for 20 weeks. The following compounds were administered: BP, 6-methylbenzo[a]pyrene (BP-6-CH3), 6-hydroxymethylbenzo[a]pyrene (BP-6-CH2OH), benzo[a]pyrene-6-carboxaldehyde (BP-6-CHO), benzo[a]pyrene-6-carboxylic acid, 6-methoxybenzo[a]pyrene, 6-acetoxybenzo[a]pyrene, 6-bromobenzo[a]pyrene, and 6-iodobenzo[a]pyrene. Two additional groups received BP or BP-6-CH3 twice weekly for 20 weeks at a total dose 25% of that above. In addition, the metabolism of selected 6-substituted BP derivatives was studied, using mouse skin homogenates in vitro and mouse skin in vivo. Only four compounds were carcinogenic; the order of potency was BP greater than BP-6-CH3 greater than BP-6-CH2OH and BP-6-CHO. The difference in carcinogenicity between BP-6-CH2OH and BP-6-CHO could not be assessed by this experiment. In a further tumorigenesis experiment the carcinogenicity of BP-6-CH2OH was compared to that of BP-6 CHO, BP-6-CH3 and 6-hydroxymethylbenzo[a]pyrere sulfate ester (BP-6-CH2OSO3Na) on mouse skin. 9-week-old female Swiss mice in groups of 28 were treated at three dose levels with 0.8, 0.2 and 0.05 mumol of compounds in dioxane--dimethyl sulfoxide (75 : 25) twice weekly for 40 weeks. After 40 experimental weeks BP-6-CH2OSO3Na proved to be a more potent carcinogen than BP-6-CH2OH, which, in turn was more active than BP-6-CHO. The greater carcinogenicity of BP-6-CH3 relative to BP-6-CH2OH and BP-6-CHO is confirmed, suggesting that BP-6-CH2OH is not a proximate carcinogenic metabolite for BP-6-CH3. Since BP-6-CHO is a weaker carcinogen than BP-6-CH2OH and is efficiently reduced metabolically to BP-6-CH2OH, the latter compound may be a common proximal carcinogenic metabolite. The stronger potency of BP-6-CH2OSO3Na, compared to its alcohol, suggests that an ester of BP-6-CH2OH might be the ultimate alkylating compound reacting with cellular nucleophiles.

Animals↗
PubMed1988

Ca2+-induced conformational changes in cardiac troponin C as measured by N-(1-pyrene)maleimide fluorescence.

Bovine cardiac troponin C was modified by N-(1-pyrene)maleimide at Cys-35 and Cys-84; the Ca2+-induced conformational changes were followed by measuring pyrene fluorescence. In isolated troponin C, the saturation of Ca2+, Mg2+-sites leads to a simultaneous increase in the pyrene monomer as well as to a decrease in the pyrene excimer fluorescence, whereas the saturation of Ca2+-specific sites results in a slight decrease in the fluorescence of pyrene monomer. Troponin T does not influence the dependence of pyrene-troponin C fluorescence on Ca2+ concentration. Within the equimolar complex of troponin C and troponin I, the saturation of Ca2+, Mg2+-sites has no effect on pyrene fluorescence, whereas the saturation of Ca2+-specific sites leads to a simultaneous decrease of both pyrene monomer and pyrene excimer fluorescence. It is supposed that troponin I diminishes the conformational changes in troponin C that are induced by the saturation of Ca2+, Mg2+-sites and enhances the conformational changes induced by the saturation of Ca2+-specific sites of troponin C.

Animals↗
PubMed1981

The effects of modulation of microsomal epoxide hydrolase activity on microsome-catalyzed activation of benzo[alpha]pyrene and its covalent binding to DNA.

The effects of modulation of microsomal epoxide hydrolase activity on the binding of calf thymus DNA of benzo[alpha]pyrene metabolically activated by rat liver microsomes were investigated. In systems where microsomal epoxide hydrolase levels were not manipulated, 2 major bound species, one derived from 9-hydroxybenzo[alpha]pyrene and the other derived from benzo[alpha]pyrene 7,8-dihydrodiol, were found in approximately equivalent amounts. When epoxide hydrolase levels were increased, either by addition in vitro of purified enzyme or by induction in vivo by trans-stilbene oxide, the binding of the benzo[alpha]pyrene 7,8-dihydrodiol product was increased, while the binding of the 9-hydroxybenzo[alpha]pyrene product was practically eliminated. When microsomal epoxide hydrolase activity was decreased by selective inhibition with low concentrations of 1,1,1-trichloropropene 2,3-oxide, the binding of the species derived from 9-hydroxybenzo[alpha]pyrene was increased several-fold, while that of the species derived from benzo[alpha]pyrene 7,8-dihydrodiol was greatly decreased. The results indicate that the binding species derived from 9-hydroxybenzo[alpha]pyrene is formed through a metabolic pathway leading to an epoxide which is a substrate of microsomal epoxide hydrolase and that microsomal epoxide hydrolase is important in regulating the pattern of binding of individual microsomally-formed benzo[alpha]pyrene metabolites to DNA.

Animals↗
PubMed1994

Predominance of glucuronidation over sulfation in metabolism of 1-hydroxybenzo[a]pyrene by isolated rat hepatocytes.

This study shows that 1-hydroxybenzo[a]pyrene glucuronide and 1-hydroxybenzo[a]pyrene sulfate are formed in isolated rat hepatocytes. Formation of these conjugates by hepatocytes incubated with 1-acetoxy-[G-3H]benzo[a]pyrene (100 microM) as a source of intracellular 1-hydroxy-[G-3H]benzo[a]pyrene was documented by comparison of the spectra of metabolites separated by HPLC with the spectra of 1-hydroxybenzo[a]pyrene glucuronide and 1-hydroxybenzo[a]pyrene sulfate standards. The rates of 1-hydroxybenzo[a]pyrene glucuronidation and sulfation were 7.72 +/- 1.03 and 0.68 +/- 0.02 nmol x mg dry wt.-1 x 30 min-1, respectively. The rate of 1-hydroxybenzo[a]pyrene glucuronide production by intact cells corresponded well with the total activity of UDP-glucuronosyltransferase(s) determined in permeabilized hepatocytes. Cryopreserved hepatocytes fully retained a high capacity to glucuronidate the benzo[a]pyrene phenol.

Animals↗
PubMed1965

Benzo[a]pyrene uptake by bacteria and yeast.

Moore, B. G. (Oak Ridge National Laboratory, Oak Ridge, Tenn.), and Arthur P. Harrison, Jr. Benzo[a]pyrene uptake by bacteria and yeast. J. Bacteriol. 90:989-1000. 1965.-Various Enterobacteriaceae and yeast incubated in a medium containing 25 mug/ml of H(3)-benzo[a]pyrene (30% serum in the medium dissolves the hydrocarbon) retain radioactivity after washings with fresh 30% serum-medium. This radioactivity is defined as bound and represents intact benzo[a]pyrene. Factors relating to the binding of benzo[a]pyrene (benzo[a]pyrene uptake) have been studied in detail with Escherichia coli Ma, a triple auxotroph requiring l-leucine, uracil, and thymine. In defined medium, benzo[a]pyrene uptake by normally growing cells is 10(-10) to 2 x 10(-10) mug per cell. Uptake is the same in suspensions lacking leucine and containing chloramphenicol where there is neither measurable protein synthesis nor cell division. Uptake is diminished, but not eliminated, by autoclaving the cells; thus, some uptake occurs in the absence of enzymatic activity. Uptake is enhanced by heat shock, thymine deprivation, uracil deprivation, and exposure to penicillin. Thus, uptake is affected by the physiological state of the cells. Either the cells play a direct (enzymatic) role in uptake, or they affect uptake indirectly by increasing or altering the benzo[a]pyrene-binding structure. Physical fractionation of cells demonstrates that this structure is associated with the cell wall-membrane complex. All but 1% of the bound radioactivity is extracted with ethyl alcohol-ether. This residual radioactivity is defined as fixed, and may be associated with cell protein. The extracted radioactivity is identified as benzo[a]pyrene. Very little hydrocarbon is metabolized. Adverse photodynamic effects, increase in mutation, and dimunition in bacteriophage replication (in whole cells) have not been observed in the benzo[a]pyrene cultures.

Benzopyrenes↗
PubMed1976

Changes in biochemical and physiological indices in animals produced by the combined effect of benz [a] pyrene and phenol.

Early energy changes in lungs, liver, and kidneys during the introduction of a benz a pyrene and phenol (as the possible carcinogen activator) were studied. It was observed that 10 days after a single instance introduction of 5 mg benz a pyrene per 0.9% NaCl (60 rats), oxidative phosphorylation in the lungs and livers is disturbed in the test rats, accompanied by a reduction of adenine nucleotides in these tissues. It is assumed that at this stage, the detoxication of benz a pyrene is intensified by free oxidation systems and by the respiratory chain of mitochondria. A chronic 3-month exposure to benz a pyrene and phenol (150 rats, each 5 mg of benz a pyrene per month intratracheally and 0.4 mg/m3 of phenol round-the-clock) results in greater disturbances of the energy exchange in the lungs, liver and kidneys. Benz a pyrene and phenol, individually and in combination, inhibit oxidative phosphorylation in the lungs. This significantly decreases the content of adenine nucleotides in this tissue. Activation of anaerobic glycolysis (twofold) and of aerobic glycolysis (eightfold) does not make up for the energy insufficiency in the tissue. The effect of benz a pyrene and phenol in the liver also results in suppressing oxidative phosphorylation and in the activation of glycolysis (anaerobic 2.5 times, the aerobic 3.7 times). Changes in the bioenergy of the kidneys are not as great. Phenol in its combined effect with benz[a]pyrene intensifies the effect of the latter, as shown primarily to the greater activation of anaerobic and aerobic glycolysis in the lungs and livers of test rats. The observed disturbances as concern the weight dynamics of the animals (weight loss in test rats), vitamin metabolism (their decrease in the organs in in urine) and hemopoiesis of red blood cells (erythropenia) attest to the toxic effect of benz a pyrene phenol on the organism, which is greater in the case of the combined action of the studied agents. No changes were discerned in the morphology of white blood cells.

Adenine Nucleotides↗
PubMed1985

Labeling of a thiol residue in sarcoplasmic reticulum ATPase by pyrene maleimide. Solvent accessibility studied by fluorescence quenching.

Sarcoplasmic reticulum ATPase was specifically labeled by the fluorescent probe N-(1-pyrene)maleimide which modified 1 mol of a highly reactive thiol residue per mol of ATPase under appropriate conditions, when the probe concentration was varied in the range 0.1-1.5 microM. Addition of inorganic phosphate to the labeling medium increased both the rate of labeling and the number of modified thiol residues. Addition of ATP gave a marked kinetic protection from labeling, suggesting that the label was attached to a protein domain which is sensitive to changes at the catalytic site. Quenching of pyrene fluorescence emission of labeled ATPase by acrylamide and cesium chloride gave linear Stern-Volmer plots. The Stern-Volmer quenching constants of pyrene-ATPase fluorescence were 10 times lower than the constant obtained for acrylamide quenching of the fluorescent adduct of pyrene-maleimide-cystein used as a control, indicating that the pyrene moiety of the probe was considerably shielded from the medium solvent when covalently attached to the ATPase. The efficiency of quenching of pyrene-ATPase fluorescence increased by a significant amount upon addition of 100 microM Ca2+, when compared to the quenching in the presence of a Ca2+ chelator. It suggests that occupancy of the high affinity Ca2+ sites of the ATPase increases the accessibility of medium solvent into hydrophobic domains of the enzyme. The fluorescence lifetime of the solubilized pyrene-ATPase emission was 144-149 ns. The fluorescence polarization of pyrene-ATPase solubilized by nonionic detergent C12E8 was rho = 0.10 and it increased with an increase in the viscosity of the medium yielding a linear Perrin plot. The rotational correlation time for the soluble ATPase was 532 ns, corresponding to the overall rotation of a detergent-pyrene-ATPase particle with radius of 87A.

Acrylamide↗
PubMed1978

Skin tumor-initiating activities of the twelve isomeric phenols of benzo(a)pyrene.

The skin tumor-initiating activities of the 12 isomeric phenols of benzo(a)pyrene (BP) were determined in mice by use of a two-stage system of tumorigenesis. 11-Hydroxybenzo(a)pyrene was moderately active, whereas 2-hydroxybenzo(a)pyrene and BP were strong tumor initiators when applied topically to CD-1 mice and followed by twice-weekly applications of the promoter 12-O-tetradecanoylphorbol-13-acetate. 1-, 3-, 4-, 5-, 6-, 7-, 8-, 9-, 10-, and 12-hydroxybenzo(a)pyrene had less than 5% of the tumor-initiating activity of BP when the data were expressed as papillomas per mouse. After 30 weeks of promotion, the number of papillomas per mouse was 8.4, 8.5, and 2.8, respectively, for the animals treated with BP, 2-hydroxybenzo(a)pyrene, and 11-hydroxybenzo(a)pyrene. A 5-week latency period before the appearance of the first tumor was observed after the application of either 2-hydroxybenzo(a)pyrene or BP, whereas a slightly longer latency period of 7 weeks was observed following application of 11-hydroxybenzo(a)pyrene. The time required for 50% of the animals to develop tumors was 13 weeks for animals treated with BP and 15 weeks for animals treated with 2- or 11-hydroxybenzo(a)pyrene.

Animals↗
PubMed1977

Comparison of the tumor-initiating activities of benzo(a)pyrene arene oxides and diol-epoxides.

The ability of arene oxides, and diol epoxides of benzo(a)pyrene to initiate skin tumors in mice was determined by using a two-stage system of tumorigenesis. (+/-)-7beta,8alpha-Dihydroxy-9alpha, 10alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene was a more effective tumor initiator than was (+/-)-7beta,8alpha-dihydroxy-9beta,10beta-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene when applied topically to CD-1 mice and then followed by twice-weekly applications of the promotor 12-O-tetradecanoylphorbol-13-acetate. (+/-)-7beta,8alpha-Dihydroxy-9alpha,10alpha-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene was approximately 20 to 30% as active as benzo(a)pyrene was as a tumor initiator. (+/-)-7beta,8alpha-Dihydroxy-7beta,8beta-epoxy-7,8,9,10-tetrahydrobenzo(a)pyrene, benzo(a)pyrene, 9,10-oxide, and benzo(a)pyrene 11, 12-oxide, possessed about 1, 2, and 10%, respectively, of the tumor-initiating activity of benzo(a)pyrene.

Animals↗
PubMed1995

Inhibitory effect of hemin, chlorophyllin and related pyrrole pigments on the mutagenicity of benzo[a]pyrene and its metabolites.

Hemin and chlorophyllin are known to inhibit strongly the mutagenicity of benzo[a]pyrene in the Salmonella assay. To further investigate this phenomenon, a series of these pyrrole pigments including pure samples of Cu- and Fe-chlorins were tested for their potency to inhibit the mutagenicity of benzo[a]pyrene and its metabolites, benzo[a]pyrene-7,8-diol, benzo[a]pyrene-4,5-epoxide, and benzo[a]pyrene-7,8-diol-9,10-epoxide. Hemin was the most potent among the pigments tested for these inhibitions. Both hemin and Cu-chlorin accelerated efficiently the degradation of benzo[a]pyrene-7,8-diol-9,10-epoxide, and this acceleration seemed to be the predominant mechanism by which these pigments inhibit the overall mutagenicity of benzo[a]pyrene in Salmonella. Based on spectroscopic evidence, we speculate that a complex formation between hemin and benzo[a]pyrene-7,8-diol-9,10-epoxide takes place and that this complexing is the cause of the accelerated degradation.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗
PubMed1994

Comparison of DNA adduct formation in mice fed coal tar or benzo[a]pyrene.

Coal tar is a complex mixture containing hundreds of compounds, including the carcinogenic polycyclic aromatic hydrocarbon, benzo[a]pyrene. In order to compare the metabolic activation of a single carcinogen versus a complex mixture containing the carcinogen, we determined the DNA adduct profiles in B6C3F1 mice fed doses of coal tar or benzo[a]pyrene at concentrations corresponding to the amount of benzo[a]pyrene found in the respective coal tar treatments. DNA adduct formation was quantified in liver, lungs and forestomach by 32P-postlabeling and was found to increase as a function of dose in each tissue with both coal tar and benzo[a]pyrene. In mice fed benzo[a]pyrene, a major adduct was detected with the same elution characteristics by TLC and HPLC as the major adduct, 10 beta-(deoxyguanosin-N2-yl)-7 beta, 8 alpha, 9 alpha-trihydroxy-7,8,9,10- tetrahydrobenzo[a]-pyrene (dG-N2-BPDE), obtained from reacting (+/-)-antibenzo[a]pyrene-7,8- dihydrodiol-9,10-epoxide (BPDE) with DNA. DNA binding was in the order forestomach > or = liver > lung, except at the highest dose group where the order was liver > forestomach > lung. In mice fed coal tar, a diagonal zone of radioactivity with a number of discrete adducts was observed. One area of radioactivity contained the major BPDE adduct, dG-N2-BPDE, based on co-elution by TLC and HPLC with the synthesized adduct. Total DNA binding was greater in the coal tar-fed mice than in the mice fed benzo[a]pyrene, and the adduct levels were in the order lung > liver > forestomach. These results indicate that there are tissue-specific differences in the activation of coal tar components when compared to a representative carcinogen contained within the mixture.

7,8-Dihydro-7,8-dihydroxybenzo(a)pyrene 9,10-oxide↗