Pyrene formation

Cerniglia CE, DT Gibson (1980b) Fungal oxidation of (-l-/-)-9,10-dihydroxy-9-10-dihydrobenzo[a]pyrene formation of diastereomeric benzo[a]pyrene 9,10-diol-7,8-epoxides. Proc Natl Acad USA 77 4554-4558. 

Compared to the extensive data that have been obtained on the mutagenicity of nitro PAHs in S. typhimurium, relatively little is known about the metabolism of these compounds in this organism. Messier et al. (67) reported that incubation of 1-nitropyrene with S. typhimurium TA98 yielded 1-aminopyrene and 1-acetylaminopyrene as major and minor metabolites, respectively. The reduction of 1-nitropyrene was slow and was accompanied by a slow formation of DNA adducts. When incubations were conducted with the nitroreductase-deficient strain, TA100 F50, both the extent of 1-amino-pyrene formation and DNA binding decreased. Howard ej al. (71,115) also found reduction of 1-nitropyrene to 1-aminopyrene in strains TA98, TA1538 and ATCC 14028. 

Cerniglia, C. E., Mahaffey, W. Gibson, D. T. (1980c). Fungal oxidation of benzo(a)pyrene formation of (-)-rranr-7,8-dihydroxy-7,8-dihydrobenzo(a)pyrene by Cunninghamella elegans. Biochemistry and Biophysics Research Communications, 94, 226-32. 

Noncovalent functionalization with derivatives of pyrene, formation of micelles with various surfactants, wrapping in polymers (including starch, peptides)... 

Patterson, J.M., N.F. Haidar, W.T. Smith Jr, J.F. Benner, H.R. Burton, and D. Burton Benzo[a]pyrene formation in the pyrolysis of selected amino acids, amines, and maleic hydrazide J. Agr. Food Chem. 26 (1978) 268-270. 

A strong pyrene (3.129) emission was observed when certain block, alternate and random styrene-butadiene rubber films were subjected to intense UV irradiation in vacuum. The proposed mechanism for pyrene formation is [8] ... 

A large number of other sensitizers has been investigated for use in photolytic de-diazoniation. The excited states of these compounds (S ) react either by direct electron transfer (Scheme 10-97), as for pyrene, or by reaction with an electron donor with formation of a sensitizer anion radical which then attacks the diazonium ion (Scheme 10-98). An example of the second mechanism is the sensitization of arenedi-azonium ions by semiquinone, formed photolytically from 1,4-benzoquinone (Jir-kovsky et al., 1981). 

The pollutant (xenobiotic) forms a stable covalent bond with its target. Examples include the phosphorylation of cholinesterases by the oxon forms of OPs, the formation of DNA adducts by the reactive epoxides of benzo[a] pyrene and other PAHs, and the binding of organomercury compounds to... 

Photochemical transformation of pyrene in aqueous media produced the 1,6- and 1,8-quinones as stable end products after initial formation of 1-hydroxypyrene (Sigman et al. 1998). 

Considerable attention has been directed to the formation of nitroarenes that may be formed by several mechanisms (a) initial reaction with hydroxyl radicals followed by reactions with nitrate radicals or NO2 and (b) direct reaction with nitrate radicals. The first is important for arenes in the troposphere, whereas the second is a thermal reaction that occurs during combustion of arenes. The kinetics of formation of nitroarenes by gas-phase reaction with N2O5 has been examined for naphthalene (Pitts et al. 1985a) and methylnaphthalenes (Zielinska et al. 1989) biphenyl (Atkinson et al. 1987b,c) acephenanthrylene (Zielinska et al. 1988) and for adsorbed pyrene (Pitts et al. 1985b). Both... 

The metabolic activity of other white-rot fungi including Phanerochaete chrysosporium and Pleurotus ostreacus has been discussed in the context of polycyclic aromatic hydrocarbons. For example, the mineralization potential of the manganese peroxide system fmmNematolomafrowardii for a number of substrates has been demonstrated (Hofrichter et al. 1998) the formation of CO2 from labeled substrates ranged from 7% (pyrene) to 36% (pentachlorophenol), 42% (2-amino-4, 6-dinitrotoluene), and 49% (catechol). 

Egaas E, U Varanasi (1982) Effects of polychlorinated biphenyls and environmental temperature on in vitro formation of benzo[a]pyrene metabolites by liver of trout (Salmo gairdneri). Biochem Pharmacol 31 561-566. 

Stroomberg GJ, C Reuther, I Konin, TC van Brummelen, CAM van Gestel, C Gooijer, WP Cofino (1996) Formation of pyrene metabolites by the terrestrial isopod Porcello scaber. Chemosphere 33 1905-1914. 

The bacterial aerobic degradation of pyrene is initiated by the formation of cfi-pyrene-4,5-dihydrodiol. Analysis for this metabolite was used to demonstrate the biodegradability of pyrene in an environment in which there was continuous input of the substrate, when it was not possible to use any diminution in its concentration as evidence for biodegradation (Li et al. 1996). The corresponding metabolite from naphthalene—cfi-naphthalene-1,2-dihydrodiol—has been used to demonstrate biodegradation of naphthalene both in site-derived enrichment cultures and in leachate from the contaminated site (Wilson and Madsen 1996). 

Cerniglia CE, DT Gibson (1980a) Fungal oxidation of benzo[a]pyrene and (+/-)-fra s-7,8-dihydroxy-7,8-dihydrobenzo[a]pyrene evidence for the formation of a benzo[a]pyrene 7,8-diol-9,10-epoxide. J Biol Chem 255 5159-5163. 

Lange B, Kremer S, Sterner O, Anke H (1995) Indnction of secondary metabolism by environmental pollutants metabolism of pyrene and formation of 6,8-dihydroxy-3-methylisocoumarin by Crinipellis stipitaria JK 364. ZNaturforsch 50c 806-812. 

It is worth drawing attention to the significance of other issues. In natural ecosystans, other microorganisms including bacteria are almost always present and it has been shown that, in experiments using [7,10- C]benzo[a]pyrene, incubation for 215 d mth Bjerkandera sp. strain BOS55 alone resulted in the formation of 13.5% C02 and 61% of labeled metabolites in the... 

P 32] Pyrene (20 mM), 1,4-dicyanobenzene (40 mM) and sodium cyanide (1 M) were reacted in propylene carbonate and water. A 100 pi solution of pyrene (20 mM), 1.4-dicyanobenzene (40 mM) in propylene carbonate and a 100 pi solution of sodium cyanide (1 M) in water were fed by programmable dual-syringe pumps via fused-silica capillary tubes into a micro-channel chip [29]. Both solutions were fed with equal flow velocity. A 300 W high-pressure mercury lamp was used as light source. After passing an optical filter made of a CUSO4 solution, the whole chip was irradiated after formation of a stable oil/water interface inside. The oil phase was collected at the exit. 

Figure 8.2e shows the dependence of the fluorescence intensity on the excitation power of the NIR light for the microcrystals measured with a 20x objective. In this plot, both axes are given in logarithmic scales. The slope of the dependence for the perylene crystal is 2.8, indicating that three-photon absorption is responsible for the florescence. On the other hand, slopes for the perylene and anthracene crystals are 3.9 for anthracene and 4.3 for pyrene, respectively. In these cases, four-photon absorption resulted in the formation of emissive excited states in the crystals. These orders of the multiphoton absorption are consistent with the absorption-band edges for each crystal. The four-photon absorption cross section for the anthracene crystal was estimated to be 4.0 x 10 cm s photons by comparing the four-photon induced fluorescence intensity of the crystal with the two-photon induced fluorescence intensity of the reference system (see ref. [3] for more detailed information). 

Graceffa, P. and Weitzman, S.A. (1987). Asbestos catalyzes the formation of 6-oxobenzo(a)pyrene radical from 6-hydroxybenzo(a)pyrene. Arch. Biochem. Biophys. 257, 481-484. 

Each plant tissue tends to have an obviously distinctive profile of flavonoids. The flavonoid content can reach about 0.5% in pollen, 10% in propolis, and about 6 mg/kg in honey. Havonoid aglycones appear to be present only in propolis and honey, while pollen contains flavanols in herosidic forms. The flavonoids in honey and propolis have been identified as flavanones and flavanones/flavanols (Campos et ah, 1990). The antimi-crobially active flavanone pinocembrine was foimd to be a major flavonoid in honey (Bogdanov, 1989). Amiot et ah (1989) studied two blossom and two honeydew Swiss honey samples and foimd that pinocembrine was the main flavonoid. Pinocembrine concentration varied between 2 and 3 mg/kg (Bogdanov, 1989). Berahia et ah (1993) analyzed sunflower honey samples and detected six flavone/flavols, four flavanone/ flavols, and pinocembrin, of which pinocembrin is the main flavonoid. The flavonoids in sunflower honey and propolis were characterized and assessed for their effects on hepatic drug-metabolizing enzymes and benzo [fl]pyrene-DNA adduct formation (Sabatier et ah, 1992 Siess et ah, 1996). 

Additional support for this disassembly mechanism was obtained by monitoring the release of the pyrene tail units by fluorescence spectroscopy. The confined proximity of the pyrene units in the dendritic molecule results in formation of excimers. The excimer fluorescence generates a broad band at a wavelength of 470 nm in the emission spectrum of dendron 31 (Fig. 5.25). Upon the release of the pyrene units from the dendritic platform, the 470 nm band disappeared from... 

Although the aromatic polycyclic hydrocarbons are usually associated with tar and soot formation, in a firing or roasting process, compounds such as fluoranthrene and pyrene have also been found in green... 

Langenegger SM, Haner R (2004) Excimer formation by interstrand stacked pyrenes. Chem Commun 2792-2793... 

---