Pyrene characterization

Heitkamp MA, W Franklin, CE Cerniglia (1988b) Microbial metabolism of polycyclic aromatic hydrocarbons isolation and characterization of a pyrene-degrading bacterium. Appl Environ Microbiol 54 2549-2555. 

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). 

Siess, M. H., Le Bon, A. M., Canivenc-Lavier, M. C., Amiot, M. ]., Sabatier, S., Yaubert, S. Y., and Suschetet, M. (1996). Flavonoids of honey and propolis Characterization and effects on hepatic drug-metabolizing enzymes and benzoja] pyrene-DNA.. Agric. Food Chem. 44, 2297-2301. 

Mayer, E., Valis, L., Huber, R., Amann, N. and Wagenknecht, H. A. (2003). Preparation of pyrene-modified purine and pyrimidine nucleosides via Suzuki-Miyaura cross-couplings and characterization of their fluorescent properties. Synthesis 2335-2340. 

The reaction of metabolically generated polycyclic aromatic diol epoxides with DNA Ua vivo is believed to be an important and critical event in chemical carcinogenesis Cl,2). In recent years, much attention has been devoted to studies of diol epoxide-nucleic acid interactions in aqueous model systems. The most widely studied reactive intermediate is benzo(a)pyrene-7,8-diol-9,10-epoxide (BaPDE), which is the ultimate biologically active metabolite of the well known and ubiquitous environmental pollutant benzo(a)pyrene. There are four different stereoisomers of BaPDE (Figure 1) which are characterized by differences in biological activities, and reactivities with DNA (2-4). In this review, emphasis is placed on studies of reaction mechanisms of BPDE and related compounds with DNA, and the structures of the adducts formed. 

The pyrene-like aromatic chromophore of BaPDE is characterized by a prominent and characteristic absorption spectrum in the A 310-360 nm spectral region, and a fluorescence emission in the X 370-460 nm range. These properties are sensitive to the local microenvironment of the pyrenyl chromophore, and spectroscopic techniques are thus useful in studies of the structures of the DNA adducts and in monitoring the reaction pathways of BaPDE and its hydrolysis products in DNA solutions. 

Site I is characterized by a relatively large red shift of 10 nm in the absorption maxima (relative to the aqueous solution spectra), exhibiting maxima at 337 and 354 nm, and a negative AA spectrum all of these properties are consistent with an intercalation-complex geometry in which the planar pyrene ring-system is nearly parallel to the planes of the DNA bases. 

Site II is characterized by a relatively small 2-3 nm red shift in the absorption spectrum and a positive AA spectrum. In this conformation, the planes of the pyrene moeities tend to align parallel rather than perpendicular to the axis of the DNA helix. 

The site I adducts are characterized by a near-parallel (within 25°) average orientation of the planar pyrene residue with the planes of the DNA bases, and a relatively strong interaction between the TT-electrons of the pyrene residues and the DNA bases. 

The well characterized reactions of carcinogens such as benzols] pyrene and aflatoxin B with DNA (39-50) suggested to us that an analysis of the kinds of mutations these agents induced could shed light on the contribution of specific DNA lesions to mutagenesis. 

Sachleben J, Chefetz B, Deshmukh A, Hatcher P (2004) Solid state NMR characterization pyrene-cuticular matter interactions. Environ Sci Technol 38 4369-4376. 

In the present work, we have examined poly(N-vinylcarbazole) (abbreviated hereafter as PVCz) and pyrene-doped poly(aethyl methacrylate) (PMMA) films by using a tine-resolved fluorescence spectroscopic aethod. Fluorescence spectra and their dynanic behavior of the forner fila were elucidated with a high intensity laser pulse and a streak camera, which nakes it possible to neasure dynaaics just upon laser ablation. This aethod reveals aolecular and electronic aspects of laser ablation phenomena (17). For the latter fila a laser pulse with weak intensity was used for characterizing the ablated and Basked areas. On the basis of these results, we demonstrate a high potential of fluorescence spectroscopy in aolecular studies on laser ablation and consider its mechanism. Experimental... 

The competition between ET and 5n2 processes in the reaction between radical anions of various aromatic compounds, e.g. anthracene, pyrene, (E)-stilbene, and m- and / -cyanotoluene, and substrates such as RHal (where R = Me, Et, Bu, 2-Bu, neopentyl, and 1-adamantyl) or various methanesulfonates has been studied in DMF as solvent. The reaction mechanism could be characterized electrochemically in many of the systems indicated above. The presence of an 5n2 component is related not only to the steric requirements of the substrate, but also to the magnitude of the driving force for the ET process. 

Characterization of Inverted Micelles of Calcium Alkarylsulfonates by Some Pyrene Fluorescence Probes... 

The nitration of PAHs by N02/HN03 also occurs under laboratory conditions approximating plume gases, that is, higher concentrations of gases and deposition on coal fly ash as a substrate. Thus, Hughes and co-workers (1980) reported that BaP and pyrene reacted with 100 ppm of NOz the presence of nitric acid (possibly on the surface of the fly ash) enhanced the rate of reaction. Reactions proceeded more rapidly on silica gel than fly ash substrates, and for pyrene, both mono and dinitro isomers were formed. At the 100 ppm plume gas level, neither NO nor S02 reacted with BaP or pyrene on the substrates studied both PAHs reacted with SO, but products were not characterized. 

Phenanthrene, fluoranthene, and pyrene—the three abundant parent PAHs identified by GC—were confirmed by MS. The major GC peaks between phenanthrene and fluoranthene were characterized as methyl- and dimethylphenanthrene/anthracene. Four compounds, each having a nominal mass of 192 amu were dejected. Small fragment ions at masses corresponding to (M-l), (M-27)+ and M", were detected. A general feature of these spectra was loss of a methyl group from the parent ion. The spectral features are characteristic of dimethyl or ethylphenanthrene/anthracene. 

The peak with the parent ion of m/e 226 was assigned benzo[ghi]flu granthene. The reference standard was not available, but its retention index was in agreement with that reported (389.6) by Lee et al. (6). The presence of benzo[b,j k]fluoranthenes was also confirmed. They appeared as one broad peak, but the presence of all three was established by their GC retention time in the HPLC subfraction S1-C2C. Benzo[ejpyrene and benzo[a]pyrene were also characterized by MS. PAHs with higher ring systems were not detected in this sample. 

GC-MS examination of the PAH fraction of sample S2 (S2-C2) gave very similar results the total ion chromatogram is shown in Figure 5. Major constituents were phenanthrene, fluoranthene, pyrene, and methyl, dimethyl/ethylphenanthrene/anthracene. Relative abundance of some C2-alkylphenanthrenes/anthracenes were higher in this sample than in S1-C2. Smaller quantities of benzo[ghi]fluoranthene, chrysene, benzo[ajanthracene, tripheny-lene, benzo[b,j, k]fluoranthenes, and benzo[e aJpyrenes and were characterized by MS. In addition, most compounds listed in Table 1 were also detected in this sample. 

As noted earlier, the limiting lifetime of pyrene excimer fluorescence from concentrated solutions in PS and PMMA glasses was found to be the same as that of pyrene in cyclohexane solution. There have been no similar studies of naphthyl compounds in rigid glasses. Values of k and Q for the [2,6]-naphthalenophanes have not yet been determined for any solvent system. The bis(2-naphthyl) compounds have not been quantitatively characterized in rigid matrices, probably because excimer fluorescence is weak and difficult to detect under such conditions. Given such limited data, it can only be assumed that the values of QD and kD of 2-naphthyl excimers remain the same in rigid solution as in fluid solution. 

Ghosh, D. K., Dutta, D., Samanta, T. B. Mishra, A. K. (1983). Microsomal benzo[a]pyrene hydroxylase in Aspergillus ochraceus TS Assay and characterization of the enzyme system. Biochemistry and Biophysics Research Communications, 113, 497-505. 

On the other hand, pyrenyl-L-alanine 184 has also been used as a conformational probe in the characterization of an artificial 4-a-helix bundle protein.11,121 The 53-residue peptide 186 incorporating one residue of 184 in each of two different helical segments was synthesized by solid-phase synthesis using a segment condensation strategy and the oxime resin. Boc-pyrenyl-L-alanine 191 was coupled just like any other amino acid by the BOP/HOBt method in DMF. CD and fluorescence studies demonstrated that the two pyrene groups were in close proximity forming an excimer complex, which is possible only when the polypeptide chain folds into a 4-a-helix bundle structure. 

---