The fungal metabolism of 7-methylbenz[a]anthracene (7-MBA) and 7-hydroxymethylbenz[a]anthracene (7-OHMBA) was studied. 7-MBA was metabolized by Cunninghamella elegans to form 7-OHMBA-trans-8,9-dihydrodiol and 7-OHMBA-trans-3,4-dihydrodiol as the predominant metabolites. Other metabolites were identified as 7-OHMBA, 7-MBA-trans-8,9-dihydrodiol and 7-MBA-trans-3,4-dihydrodiol, and 7-MBA-8,9,10,11-tetraol. Incubation of 7-OHMBA with C. elegans cells indicated that 7-OHMBA-trans-8,9-dihydrodiol and 7-OHMBA-trans-3,4-dihydrodiol were major metabolites. The metabolism of 7-MBA by rat liver microsomes from 3-methylcholanthrene-treated rats showed that the metabolites were qualitatively similar to those formed by C. elegans, except additional dihydrodiol metabolites were formed at the 5,6 and 10,11 positions. The metabolites formed were isolated by high-performance liquid chromatography and identified by comparing their chromatographic, UV-visible absorption and mass spectral properties with those of reference compounds.
7-Methylbenz[a]anthracene (7-MBA) was metabolized stereoselectively by rat liver microsomes to form five optically active dihydrodiols as the predominant metabolites. The dihydrodiols were purified by a combination of reversed-phase and normal-phase high performance liquid chromatography (HPLC). By comparison of their circular dichroism (CD) spectra with the corresponding benz[a]anthracene (BA) dihydrodiols of known absolute stereochemistry, the major dihydrodiol enantiomers of 7-MBA have been determined to have 1R,2R-, 3R,4R- and 10R , 11R - absolute configurations, respectively. Due to their quasi- diaxial conformations, the absolute configuration of trans-5,6- and trans-8,9-dihydrodiols, the two most abundant metabolites of 7-MBA, could not be determined by simple comparisons of their circular dichroism spectra with those of the quasidi -equatorial BA 5R, 6R - and 8R , 9R -dihydrodiols. The major enantiomers of the quasi- diaxial trans-5,6- and trans-8,9-dihydrodiol metabolites of 7-MBA were determined by comparison to the CD spectrum of 7-bromo-BA 5R, 6R -dihydrodiol and by the exciton chirality method to have R,R absolute stereochemistry. This study also revealed that the circular dichroism Cotton effects of an enantiomeric dihydrodiol of polycyclic aromatic hydrocarbons can be drastically altered if the conformation (quasi- diaxial vs. quasi di-equatorial ) of the dihydrodiol is changed.
The metabolism of 7-ethyl (7-EBA) and 7-methylbenz[a]anthracene (7-MBA) to dihydrodiols has been compared in incubations with hepatic microsomal fractions prepared from untreated rats. Although both hydrocarbons were found to be metabolized to similar extents, the relative proportions of their diols that were detected differed. For 7-MBA, the principal diols identified were the 8,9- and 5,6-derivatives, whereas for 7-EBA the 8,9- and 1,2-diols predominated; the 5,6-diol was only present as a minor product. These results imply that the presence of the sterically bulky ethyl group at position seven in the benz[a]anthracene ring system may, when compared to the analogous methyl derivative, enhance diol formation on the angular 1,2,3,4 benzo-ring, at the expense of metabolism at the K-region.
The carcinogen 7-methylbenz[a]anthracene (7-MBA) is considered to be metabolically activated via its bay-region dihydrodiol-epoxide, trans-3,4-dihydro-3,4-dihydroxy-7-methyl-benz[a]anthracene 1,2-oxide (7-MBA-3,4-diol 1,2-oxide). When tested on mouse skin, a target tissue for polycylic aromatic hydrocarbon carcinogenesis, 7-ethylbenz[a]anthracene (7-EBA) was much less active than 7-MBA, and this difference may be due to differences in the pathways by which the two compounds are metabolized and activated. In the present work, the metabolism by mouse-skin microsomes of both hydrocarbons to dihydrodiols has been examined. Both were metabolized to a similar extent with the 8,9-dihydrodiols being detected as the predominant metabolites. The 3,4-, 5,6-and 10,11-dihydrodiols of 7-MBA and the 3,4- and 10, 11-dihydrodiols of 7-EBA, were also detected. 7-MBA was found to bind covalently to microsomal protein at 10 times the level of 7-EBA. The covalent binding of benz[a]anthracene (BA), 7-EBA and 7-MBA to DNA in mouse skin following topical application was determined using the 32P-postlabelling assay. The results correlated with the relative carcinogenic activities of the compounds with 7-MBA binding at five and nine times the level of 7-EBA and BA respectively. For all three hydrocarbons, the major hydrocarbon: 32P-labelled nucleoside bisphosphate, eluted in the same area of the TLC maps, suggesting the involvement of a common type of bay-region dihydrodiol-epoxide intermediate.
IDENTIFICATION AND USE: 7-Methylbenz(a)anthracene (7-MBA) is a solid. It can be formed from incomplete combustion of organic materials. it is used mostly in biochemical research. HUMAN EXPOSURE AND TOXICITY: There are no data available. ANIMAL STUDIES: DNA adducts formed in mouse epidermis following topical application of 7-MBA. In other experiment, mice received sc administration of 230 ug of 7-MBA three times per week for 12 months (100 mg/single dose). Out of 35 mice, 13 had carcinomas. The 12 possible monomethylbenz[a]anthracenes (MBAs) were examined for their tumor-initiating activity in the classical two-stage initiation-promotion experiment. Based on the average number of tumors/mouse, 7-MBA was the most tumorigenic compound of the series causing 4.9 papillomas/mouse at an initiating dose of 400 nmol/mouse. When given to newborn male and female mice 7-MBA gave rise to sc sarcomata at injection site, and multiple lung tumors and liver tumors. Dihydrodiol dehydrogenase decreased the mutagenicity of 7-MBA in Salmonella typhimurium TA 100 with metabolic activation. There appeared to be little quantitative correspondence between carcinogenic and mutagenic potency in this group of chemicals.
In S. typhimurium TA98 (in presence of rat liver postmitochondrial supernatant), 1,1,1-trichloropropene 2,3-oxide, an inhibitor of epoxide hydratase, incr microsome-mediated mutagenicity of 7-methylbenz(a)anthracene.
Immediate First Aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR if necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Aromatic hydrocarbons and related compounds/
Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... . Monitor for shock and treat if necessary ... . Anticipate seizures and treat if necessary. ... For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... . Do not use emetics. For ingestion, rinse mouth and administer 5 mL/kg up to 200 L of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool. Administer activated charcoal ... . /Aromatic hydrocarbons and related compounds/
Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag-valve-mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start IV administration of D5W TKO /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam (Valium) or lorazepam (Ativan) ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Aromatics hydrocarbons and related compounds/
Rhodium(III)-Catalyzed Directed <i>peri</i>-C–H Alkenylation of Anthracene Derivatives
作者:Jaganathan Karthikeyan、Naohiko Yoshikai
DOI:10.1021/ol501926b
日期:2014.8.15
coupling reactions of anthracene-9-carboxylic acid derivatives with electron-deficient olefins are reported. A cationic rhodium(III) catalyst, in combination with a copper(II) oxidant, promotes selective monoalkenylation of anthracene-9-carboxamide, affording 1-alkenylanthracene-9-carboxamide in moderate to good yields. A similar catalytic system also promotes the reaction of anthracene-9-carboxylic
Substituent Effects in Benz[<i>a</i>]anthracene Carbocations: A Stable Ion, Electrophilic Substitution (Nitration, Bromination), and DFT Study
作者:Kenneth K. Laali、Maria A. Arrica、Takao Okazaki、Ronald G. Harvey
DOI:10.1021/jo070936r
日期:2007.8.31
computed relative energies by DFT. Charge delocalization paths in the resulting carbocations were deduced based on the magnitude of Δδ13C values. For the thermodynamically more stable C-12 protonated carbocations, the charge delocalization path is analogous to those derived based on computed NPA charges for the benzylic carbocations formed by 1,2-epoxide (bay-region) and 5,6-epoxide (K-region) ring opening
在FSO 3 H / SO 2 ClF中通过低温质子化作用,由异构的单烷基化和二烷基化的苯并[ a ]蒽(BAs)生成了一系列新型的碳正离子化反应。C-7具有单烷基衍生物(5-甲基,6-甲基,7-甲基和7-乙基)以及D环甲基化类似物(9-甲基,10-甲基和11-甲基),或在所有情况下均观察到C-12质子化的碳正离子(作为唯一或主要的碳正离子)。12-甲基衍生物的质子化(9)得到C-7质子化的碳正离子(9H +)作为动能种类和本位-protonated碳阳离子(9AH +)作为热力学阳离子。与12-乙基衍生物(10),在箱式区域空间张力的浮雕大大有利于本位-protonation(10AH +)。具有3,9-二甲基(14),C-7质子化(14H +)(C-12质子化<10%)受到强烈青睐,在1,12-二甲基(15)的情况下,观察到的唯一物质是C-7质子化的碳正离子化(15H +)。对于7-甲
Optically active N-hydroxytartrimides for enantioselective peptide synthesis
Preparations of opticallyactive N-hydroxytartrimides were achieved. 1,3,4-Trihydroxysuccinimide ester of Z-L-alanine and 1-hydroxy-3,4-diacetoxysuccinimide ester of Z-D-alanine were allowed to react with D,L-alaninate to produce L-L form and D-D form of Z-Ala-Ala-OEt respectively (optical yield 100%).
A novel synthesis of 3-methylcholanthrene is described which is operationally sipmler than the method in current use and is potentially applicable to the synthesis ofa wide range of other polycyclic hydrocarbons and their cracinogenic metabolites.
Aldimine-Directed Branched-Selective Hydroarylation of Styrenes
作者:Pin-Sheng Lee、Naohiko Yoshikai
DOI:10.1002/anie.201207958
日期:2013.1.21
Branching out: A simple and inexpensive cobalt/triarylphosphine catalyst promotes aldimine‐directed hydroarylation of styrene with high branched regioselectivity to afford 1,1‐diarylethane derivatives in good yields under mild reaction conditions. The ortho‐formyl group in the hydroarylation products is amenable to dehydrative cyclization, to give fused polycyclic aromatic hydrocarbons, as well as