A New Synthesis of trans-3,4-Dihydroxy-anti-1,2-epoxy-1,2,3,4-tetrahydro-7,12-dimethylbenz(a) anthracene

A facile synthesis of trans-3,4-dihydroxy-anti-1,2-epoxy-1,2,3,4-tetrahydro-7,12-dimethylbenz(a) anthracene 1 ; a highly carcinogenic metabolite of 7,12-dimethylbenz(a) anthracene (DMBA) have been described.     

Simultaneous determination of retinol,retinyl palmitate and β-carotene in rat serum treated with 7,12-dimethylbenz[a]anthracene and <Emphasis Type="Italic">Hypericum Perforatum</Emphasis> L. by high-performance liquid chromatography with diode-array detection

A new and simple high-performance liquid chromatography method was developed and validated for the simultaneous determination of retinol, retinyl palmitate and β-carotene in rat serum treated with Hypericum Perforatum L. and 7,12-dimethylbenz[a]anthracene. Furthermore, vitamin C was determined spectrophotometrically. High-performance liquid chromatography analysis was performed utilizing an Inertsil ODS3 reversed phase column with methanol-acetonitrile-tetrahydrofuran (65:30:5, v/v/v) as mobile phase, at a flow rate of 1.5 mL min⁻¹ and 40°C. Diode-array detection was conducted at 325 and 450 nm for retinol and retinyl palmitate, and β-carotene, respectively with a running time of 26 min. The high-performance liquid chromatography assay and extraction procedure proposed are simple, rapid, sensitive and accurate. This method was then applied to determine the amounts of retinol, retinyl palmitate and β-carotene in rat serum. Results of this study demonstrated that at 60^th day in the 7,12-dimethylbenz[a]anthracene-treated group there was a significant decrease (p<0.001), (p<0,01), (p<0.05) in levels of retinol, retinyl palmitate and vitamin C, respectively compared to the control group levels. A significant decrease (p<0.01) in retinyl palimitate was observed in the 7,12 dimethylbenz[a] anthracene + Hypericum Perforatum L. treated group compared to the control group..     

The syntheses of 4b,5a-dihydro-5H-benzo[3,4]-phenanthro[1,2-b]azirine and 1a,11b-dihydro-6,11-dimethyl-1H-benz[3,4]anthra[1,2-b]azirine

The syntheses of the K-imine derivatives of carcinogenic benzo[c]phenanthrene and 7,12-dimethylbenz-[a]anthracene are described. Treatment of trans-5-azido-5,6-dihydrobenzo[c]phenanthren-6-ol ( 3 ) and trans-6-azido-5,6-dihydrobenzo[c]phenanthren-5-ol ( 5 ) with thionyl chloride yielded the corresponding β-chloro azides, which in turn, were reacted with lithium aluminium hydride to give 4b,5a-dihydro-5H-benzo[3,4]-phenanthro[1,2-b]azirine ( 2 ). In a similar manner trans-5-azido-5,6-dihydro-7,12-dimethylbenz[a]anthracen-6-ol ( 11 ) and trans-6-azido-5,6-dihydro-7,12-dimethylbenz[a]anthracen-5-ol ( 13 ) were transformed to the respective chloro azides and, converted into 1a,11b-dihydro-6,11-dimethyl-1H-benz[3,4]anthra[1,2-b]azirine ( 10 ).     

Separation of aromatic isomers on cyclophane-bonded stationary phases

A cyclophane (CP66)-bonded silica gel stationary phase (CP66-SP) was prepared and the retention of water-insoluble hydrophobic compounds on it was investigated in comparison with that on the CP44-bonded stationary phase (CP44-SP) reported previously. Like CP44-SP, it retained aromatic compounds more strongly than the corresponding alicyclic compounds, as was expected by the cavity size of the cyclophane. The CP66-SP also showed isomer-selectivity for monosubstituted and disubstituted naphthalenes, but its selectivity was perfectly reversed to that of the CP44-SP. On the CP66-SP, isomers having methyl and ethyl groups at beta-position were eluted prior to those having groups at alpha-position, whereas on the CP44-SP beta-substituted naphthalenes were retained more strongly than alpha-substituted ones. Isomers of three- and four-ring aromatic compounds were also separated on these cyclophane-bonded stationary phases. The retention order on the CP66-SP was almost opposite to that on the CP44-SP; on the CP66-SP, the retention order was phenanthrene > anthracene, and chrysene > 1,2-benzanthracene > 2,3-benzanthracene, whereas on the CP44-SP, anthracene > phenanthrene, and 2,3-benzanthracene > chrysene > 1,2-benzanthracene. The retention mechanism of aromatic compounds is discussed on the basis of the structure of the cyclophane-involved complex.     

Isomer differentiation in 7, 12-dimethylbenz[a]anthracene-pyridine adducts by fast atom bombardment tandem mass spectrometry

Three isomeric 7,12-dL-nethylbenz[α]anthracene-pyridine adduct salts, namely.. the 5-N-pyridinium-7,12-dimethylbenz[α]anthracene perchlorate, the 7-N-pyridiniummethylene-12methylbenz[ α]anthracene picrate, and the 7-methyl-12-N-pyridiniummethylenebenz[ α]anthracene picrate, were studied by fast atom bombardment tandem mass spectrometry using high energy collisional-activated dissociation (CAD). The CAD mass spectra of the molecular cations and the (M – pyridine)⁺ ions allow one to distinguish positional isomers on the basis of daughter ion peak height ratios. The differences in the CAD mass spectra of the (M – pyridine)⁺ ions are probably due in part to formation of isomer-specific fused-ring tropyliumions.     

Synthesis of the o-quinones and other oxidized metabolites of polycyclic aromatic hydrocarbons implicated in carcinogenesis

Efficient new syntheses of the o-quinone derivatives of benzo[a]pyrene (BPQ), 7,12-dimethylbenz[a]anthracene (DMBAQ), and benz[a]anthracene (BAQ), implicated as active carcinogenic metabolites of the parent polycyclic aromatic hydrocarbons (PAHs), are reported. These PAH quinones also serve as starting compounds for the synthesis of the other active metabolites of these PAHs thought to be involved in their mechanism(s) of carcinogenesis. The latter include the corresponding o-catechols, trans-dihydrodiols, and the corresponding anti- and syn-diol epoxides.     

1H NMR study of the interaction between ethidium bromide and self-complementary and self-complementary deoxytetranucleotide 5′-d(CpGpCpG) in an aqueous solution

Complexation of the ethidium bromide (3,8-diamino-6-phenyl-5-ethylphenanthridine) dye with self-complementary deoxytetraribonucleoside triphosphate 5′-d(CpGpCpG) in a water-salt solution is studied by one- and two-dimensional¹H NMR spectroscopy (500 MHz). Two-dimensional PMR spectroscopy (2D-COSY and 2D-NOESY) is used for the full assignment of proton signals of the molecules in the solution and for the qualitative analysis of the interaction between ethidium bromide and the tetranucleotide. The concentration dependences of the proton chemical shifts of the molecules at a fixed temperature (T=308 K) are measured. Different schemes of the formation of the dye complexes with the tetranucleotide, taking into account various molecular associations in the solution are considered. The equilibrium constants of the reactions and the limiting chemical shifts of ethidium bromide protons in the complexes are determined. The relative contents of different complexes in the solution are analyzed, and the dynamic equilibrium is studied as a function of the dye-tetranucleotide ratio in the solution. The data obtained suggest that ethidium bromide (like the acridine dye proflavine) is intercalated predominantly into the pyrimidine-purine sections (CG sites) of the tetranucleotide duplex. However, ethidium bromide is intercalated on the side of the narrow slot of the duplex, while proflavine intercalation occurs through the broad slot of the double helix. The most likely structures of the 1∶2 and 2∶2 dye-tetranucleotide complexes in the solution are constructed using the calculated values of the induced chemical shifts of ethidium bromide protons and 2D NOESY spectroscopy data. Sevastopol State Technical University. Berkbeck College, London University. Translated fromZhurnal Strukturnoi Khimii, Vol. 37, No. 1, pp. 75–87, January–February, 1996. Translated by I. Izvekova     

A comparison of eight commercial reverse-phase (ODS) columns for the separation of hydroxylated derivatives of 7,12-dimethylbenz(a)anthracene

This paper presents an evaluation of a number of commercially available octadecylsilane columns. The separation of four 7,12-dimethylbenz(a)anthracene (DMBA) derivatives namelycis- andtrans-5,6-dihydroxy DMBA,trans-8,9-dihydro-8,9-dihydroxy DMBA, and 7,12-dihydroxymethyl benz(a)anthracene (BA) was compared under identical conditions comprising of a concave gradient (No. 4) from 20 to 70% acetonitrile/water for 75 minutes at flow rate of 1ml/min. A direct correlation between percent carbon loading and retention behavior was observed for bonded phases prepared from silica particles with similar surface areas. Other column performance parameters, such as capacity factors, separation ratios and resolution between peaks for the solutes examined were also calculated and are discussed.     

1H NMR study of complexation of ethidium bromide with single-stranded noncomplementary desoxytetranucleotide 5′-d(GpApApG) in aqueous solution

Complication of the ethidium bromide dye (3,8-diamino-6-phenyl-5-ethylphenanthridine) with single-stranded noncomplementary desaxytetranucleotide 5′-d(GpApApG) in aqueous salt solution was studied by one- and two-dimensional¹H NMR (500 and 600 MHz). The concentration dependences of the proton chemical shifts of the reactant molecules were measured at different temperatures (T₁ = 298 K, T₂ = 308 K). Investigations of self-association of the tetranucleotide showed that duplices can hardly form in solution. Therefore, dye complexes with single-stranded tetranucleotide play a major role in the equilibrium in solution; this makes it possible to analyze the specifics of interactions of aromatic ligands with single-stranded DNA. Various schemes of complexation are discussed; the equilibrium constants and the limiting values of the proton chemical shifts of ethidium bromide in the complexes are determined. The constants of dye binding to the single-stranded tetranucleotide 5′-d(GAAG) involving only purine bases is approximately an order of magnitude lower than the constants of ethidium bromide complexation with desaxytetranucleotide monomers whose sequences contain alternating types of base in the chain. The relative contents of complexes of different types are analyzed, and peculiarities of dynamic equilibrium, depending on the ratio of concentrations between the dye and the tetranucleotide, are revealed. Based on the data obtained it is concluded that the binding between ethidium bromide and the single-stranded nucleotide is sequence-specific. The estimated values of the induced chemical shifts of the dye protons are used to establish the most probable structures of the 1:1 and 2:1 complexes of ethidium bromide with single-stranded desaxytetranucleotide. Translated fromZhumal Struktumoi Khimii, Vol. 39, No. 5, pp. 808–820, September–October, 1998. This work was supported by INTAS grant NUD 7200.     

Analysis of the interaction of ethidium bromide with a DNA octamer 5’-d(GpApCpApTpGpTpC) in aqueous solution using1H NMR data

Complexation of a phenanthridine dye ethidium bromide with a desoxyoligonucleotide 5’-d(GpApCpAp-TpGpTpC) in aqueous salt solution is studied by one- and two-dimensional¹H NMR spectroscopy. Two-dimensional correlated homonuclear PMR spectroscopy (2D-TOCSY and 2D-N0ESY) was used for complete assignment of the proton signals of molecules in solution and for qualitative analysis of the character of interaction between ethidium bromide and desoxyoctanucleotide. The concentration dependences of the proton chemical shifts of the molecules were measured at three temperatures (T₁ = 298 K, T₂ = 308 K, and T₃ = 318 K); the temperature dependences were measured in the temperature range 278–358 K. Different schemes of dye complexation with an octamer duplex involving different molecular associates in solution are considered. The equilibrium constants of the reactions, the corresponding thermodynamic parameters (δH⁰, δS₀), and the limiting values of the chemical shifts of ethidium bromide protons in the complexes are determined. The relative contents of complexes of different types in solution (dye complexes with desoxyoctanucleotide in duplex form) are analyzed, and peculiarities of the dynamic equilibrium depending on the ratio of dye and octamer concentrations and temperature are established. The most probable structures of the 1:2 and 2:2 intercalated complexes corresponding to dye intercalation into the pyrimidine-purine sites of the desoxyoctanucleotide duplex are derived using the calculated values of the induced proton chemical shifts of ethidium bromide and two-dimensional PMR data. Translated fromZhurnal Strukturnoi Khimii, Vol.40, No. 2, pp. 265–275, March–April, 1999.     

USE OF THE DYE HOECHST 33258 IN A MODIFICATION OF THE BROMODEOXYURIDINE PHOTOLYSIS TECHNIQUE FOR THE ANALYSIS OF DNA REPAIR

Abstract— A modification of the bromodeoxyuridine photolysis technique is described in which the cells are treated with the fluorescent dye Hoechst 33258 to enhance the bromodeoxyuridine photolysis produced by 365 nm or by black light. Use of the modified assay overcomes several difficulties encountered in the original 313 nm photolysis technique and demonstrates that excision repair of damage produced in the DNA by 7,12-dimethylbenz(fl)anthracene 5,6-oxide takes place by a long patch type of repair pathway.     

Acridine dyes in the triplet state as reagents for the selective luminescence determination of polycyclic aromatic hydrocarbons

The possibility of the selective determination of several polycyclic aromatic hydrocarbons (PAH) by sensitized room-temperature phosphorescence (SRTP) in sodium dodecylsulfate (SDS) micelles was studied. Acridine dyes (trypaflavine, acridine yellow, and acridine orange) were used as triplet-energy donors. It was found that the presence of external heavy atoms of thallium(I) is a prerequisite to SRTP in the system of an acridine dye (donor) and a PAH (acceptor). The linear concentration ranges, detection limits, and selectivity factors for the determination of pyrene, anthracene, and 1,2-benzanthracene by fluorimetry, room-temperature phosphorescence (RTP), and proposed SRTP were compared.     

The synthesis of a potential bisintercalating ethidium bromide analog

The synthesis of diethyl-1,3,4,13b-tetrahydro-13b-phenyl-2H-pyrimido[1,2-f]phenanthridine-7,12-dicarba-mate and N,N′-3,3′[5,5′-Bis(3,8-biscarbethoxyamino-6-phenyl)phenanthridinium]propylglutarylamide dichloride are reported starting from 3,8-biscarbethoxyamino-5-(3′-bromopropyl)-6-phenylphenanthridinium bromide.     

The Regioselective Methylation of Polycyclic Aromatic Hydrocarbons through Tricarbonylchromium Coordination

Deprotonation, methylation, and air oxidation of polycyclic arenes coordinated to chromium(0), (η⁶-arene)Cr(CO)₃, produced ring-methylated products with high selectivity and in good yield. This procedure gave 3-methylbenz[a]anthracene from (η⁶-benz[a]anthracene)Cr(CO)₃, 3-methylphenanthrene from (η⁶-phenanthrene)Cr(CO)₃, 2-acetyl-6-methylphenanthrene from (η^6?2-acetylphenanthrene)Cr(CO)₃, and 3,7,12-trimethylbenz[a]anthracene from (η^6?7,12-dimethylbenz[a]anthracene)Cr(CO)₃.     

Studies on shape selectivity of RP C18-columns

Summary Stationary phases with octadecyl groups have been prepared with different carbon content without and in the presence of water and characterized for their selectivity for the shape of various polyaromatic hydrocarbons. It is shown that both a high hydrocarbon content and a good accessibility of the bonded groups within the pores is required to achieve shape recognition for PAH. High carbon content alone is not sufficient. The two tests for shape selectivity proposed by Sander and Wise as well as by Tanaka are compared. In most cases the results are similar: A low selectivity with the Sander and Wise test (α TBN/BaP<1) corresponds to a high value with the Tanaka test (α TRI/o-TER>3). However, not in all cases the tests give corresponding answers. Further studies on molecular recognition are required.     

Determination of selected chlorohydrocarbons and polyaromatic hydrocarbons by gas chromatography-mass spectrometry in soils in Southwest Louisiana

The use of gas chromatography-mass spectrometry for the determination of selected polyaromatic hydrocarbons (PAHs) (anthracene and pyrene) and chlorohydrocarbons (hexachlorobutadiene and 1, 2, 4-trichlorobenzene) in soils from five areas in Southwest Louisiana was investigated. No detectable concentrations (below the detection limits) were found on or near the surface. However, trace levels of the PAHs were found at a depth in the 2 to 3 ft range below the surface levels.     

Determination of iodide and bromide by flow methods with amperometric detection

Determination of bromide and iodide in real samples (water, pharmaceutical preparations, and biological material) was performed using modified flow injection analyses (FIA) with amperometric detection on platinum electrode. As an additional confirmation of FIA experiments, cyclic voltammetry was employed. Iodide was determined by the kinetic method, its limit of detection was 1.0 nM, and the linearity was 0.1–100 μM. The limit of detection for bromide determination was 50.0 nM and the calibration was linear for 2.5–100 μM and 0.1–10 mM. The relative standard deviation for 1 μM of iodide was 3.03% and, for 5 μM of bromide, it was 1.23% (n = 6). Both methods enable 60 analyses per hour to be performed. The text was submitted by the authors in English.     

Comparative Assessment of the Solvating Powers of Solvents of Different Nature with Respect to Condensed Aromatic Hydrocarbons

The solubilities of anthracene, tetracene, 1,2-benzanthracene, chrysene, pyrene, perylene, ,'-dinaphtyl, rubrene, and decacyclene in solvents of different nature and polarity (hydrocarbons and halogenated hydrocarbons, alcohols, ketones, ethers, and esters) were determined at 20±1°C. The distribution of benzene and naphthalene in the organic solvent-water system was studied. The Gibbs energy of transfer of aromatic hydrocarbons from n-octane to organic solvents was calculated.     

Photoinitiation. II. Kinetics of the acrylonitrile polymerization photoinitiated by aromatic hydrocarbons

The kinetics of acrylonitrile polymerization photoinitiated by aromatic hydrocarbons have been studied. For the acrylonitrile polymerization photoinitiated by naphthalene the rate of polymerization depends on the square root of incident light intensity, on the square root of naphthalene concentration, and on the 1.5 power of acrylonitrile concentration. In the system acrylonitrile-1-methoxynaphthalene the rate of acrylonitrile polymerization depends on the first power of acrylonitrile concentration. The monoradical character of this polymerization process has been established. For the interpretation of experimental results a reaction mechanism involving the formation of the exciplex between the first singlet or triplet of aromatic hydrocarbon and acrylonitrile in the ground state as a precursor of polymerization reactions is suggested. The photoinitiating efficiency of various aromatic hydrocarbons in acrylonitrile polymerization increases in the order: fluoranthene (zero efficiency) ? pyrene < phenanthrene, fluorene ≈ 2-methoxynaphthalene ≈ biphenyl < anthracene < 2-methylnaphthalene < 1-methoxynaphthalene < 2,3,6-trimethylnaphthalene < 2,3-dimethylnaphthalene ≈ naphthalene < 1-methylnaphthalene < 2,6-dimethylnaphthalene < p-terphenyl < acenaphthene, provided that the systems absorb the same amount of the incident light. The explanation of this result ensues from the study of the effect of concentration on the rate of polymerization and from the quenching of hydrocarbon fluorescence by acrylonitrile. The photoinitiating efficiency of a given aromatic hydrocarbon is mainly determined by the value of the rate constant k_q for the formation of exciplex as well as the self-quenching efficiency of aromatic hydrocarbon. By using the literature data for the lifetime of fluorescence τ the values of k_q were calculated from the Stern-Volmer equation expressing the quenching of hydrocarbon fluorescence by acrylonitrile. The order of aromatic hydrocarbons according to increasing values of k_q is as follows: pyrene < phenanthrene < anthracene ≈ naphthalene < 2-methylnaphthalene ≈ 1-methylnaphthalene ≈ 2,3-dimethylnaphthalene < 2,6-dimethylnaphthalene < acenaphthene < p-terphenyl < 1-methoxynaphthalene. The study of the concentration effect reflecting the self-quenching of aromatic hydrocarbons during polymerization has given the following sequence for decreasing self-quenching efficiency of aromatic hydrocarbons: 2-methoxynaphthalene ≈ pyrene > anthracene > 1-methoxynaphthalene > fluorene > 2,6-dimethylnaphthalene, phenanthrene, acenaphthene > 2,3,6-trimethylnaphthalene > 2,3-dimethylnaphthalene > 1-methylnaphthalene > naphthalene. It has been shown that the photoinitiating efficiency of a given aromatic hydrocarbon in the polymerization of acrylonitrile can be roughly predicted from the position of that aromatic hydrocarbon in the above-mentioned sequences.     

Superoxide chemical transformation of diolepoxide polyaromatic hydrocarbon DNA adducts. Determination of benzo[a]pyrene-r-7,t-8,9,c-10-tetrahydrotetrol by gas chromatography.

Benzo[a]pyrene-r-7,t-8,9,c-10-tetrahydrotetrol (100 pg, 342 fmol) was measured using the following sequence of steps: (1) chemical transformation with potassium superoxide to 2,3-pyrenedicarboxylic acid; (2) electrophore derivatization with pentafluorobenzyl bromide; (3) sample clean-up by high-performance liquid chromatography and (4) measurement by gas chromatography with electron-capture detection and by gas chromatography with electron-capture negative-ion mass spectrometry. The overall, absolute yields obtained by the two procedures were 69% and 60%, respectively. This work completes the first stage towards the establishment of a general method for detecting diolepoxide polyaromatic hydrocarbon DNA adducts by gas chromatography.