DNA binding metabolites

A. Luch, S. Kishiyama, A. Seidel, J. Doehmer, H. Greim, W. M. Baird, The K-Region //z/ .v-8.9-Diol Does not Significantly Contribute as an Intermediate in the Metabolic Activation of Dibenzo[a,Z]pyrene to DNA-Binding Metabolites by Human Cytochrome P450 1A1 or 1B1 , Cancer Res. 1999, 59, 4603 - 4609. 

Hydroquinone forms DNA adducts in the peroxidase-containing promyelocytic HL-60 cell line this process is enhanced by addition of hydrogen peroxide or cumene hydroperoxide (Levay Bodell, 1996), presumably because the hydroquinone is oxidized by a cellular peroxidase to a reactive, DNA-binding metabolite. 

The approach has been used in a short, asymmetric synthesis of y-butyrol-actone 155 [23], a moderate DNA-binding metabolite isolated from Strepto-myces GT61115, starting from aldehyde 154 (Scheme 35). 

Species Cell line PAH Evidence of Metabolite formation Cytotoxic metabolites DNA-binding metabolites References... 

Smolarek, T.A., S.L. Morgan and W.M. Baird. Temperature-induced alterations in the metabolic activation of benzo[a Jpyrene to DNA-binding metabolites in the Blue gill cell line BF-2. Aquat. Toxicol. 13 89-98, 1988. 

H38. Hesse, S Jernstrom, B., Martinez, M Moldeus, P., Christodoulides, L., and Ketterer, B., Inactivation of DNA-binding metabolites of benzo(a)pyrene and benzo(a)pyrene-7,8-dihydro-diol by glutathione and glutathione S-transferases. Carcinogenesis (London) 3, 757-760 (1982). 

E., and Hayes, M. A., Protective activity of different hepatic cytosolic glutathione S-trans-ferases against DNA-binding metabolites of aflatoxin Bj. Toxicol. Appl. Pharmacol. lOS, 351-363 (1990). 

The direct mutagenicity of the reaction mixture was shown to be caused by the presence of the benzo(a)pyrene-4,5-epoxide in small yield (Pitts et al. (70)). This compound is a photosensitive intermediate of the ozonolysis and is known as a DNA-binding metabolite in biological systems (Grover and Sims (95a). 

Maul, C. Sattler, I. ZerUn, M. Hinze, C. Koch, C. Maier, A. Grabley, S. Thiericke, R. Biomolecular-chemical screening A novel screening approach for the discovery of biologically active secondary metabolites—III. New DNA-binding metabolites. J. Antibiot. 1999, 52, 1124-1134. 

Moorthy B, Miller KP, Jiang W, Williams ES, Kondraganti SR, Ramos KS Role of cytochrome P4501B1 in benzo[a]pyrene bioactivation to DNA-binding metabolites in mouse vascular smooth muscle cells evidence from 32P-postlabeling for formation of 3-hydroxybenzo[a]pyrene and benzo[a]pyrene-3,6-quinone as major proximate genotoxic intermediates. J Pharmacol Exp Ther 2003,305 394-401. 

Two types of DNA binding sites. Two different spectroscopically distinct types of binding sites have been identified utilizing absorption, fluorescence and linear dichroism data on non-covalent (6), and covalent (7) pyrene-like metabolite model compound-DNA complexes. 

The major goals of recent studies of the physical binding to DNA of BP and DMBA metabolites and metabolite models are to determine (1) the magnitudes of the binding constants, (2) the conformations of physical complexes which are formed and the nature of DNA binding sites, (3) how DNA structure and environment influence physical binding, (4) how the structure of hydrocarbon metabolites influences physical binding properties, (5) whether the... 

Most studies of the physical binding of hydrocarbon metabolites and metabolite model compounds have measured the effect of DNA binding on hydrocarbon fluorescence intensities, fluorescence lifetimes and UV absorption spectra Radioactive labelling has also been used, but less frequently. Spectroscopic methods are particularly convenient. These methods, especially fluorescence methods, are also very sensitive. All of the hydrocarbons in Figure 1 except the epoxides have high fluorescence quantum yields, which permit routine detection in the 10 -10 7 M concentration range. 

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. 

Vamvakas S, Muller DA, Dekant W, et al. 1988b. DNA-binding of sulfur-containing metabolites from S-(pentachlorobutadienyl)-L-cysteine in bacteria and isolated renal tubular cells. Drug Metabolic Interact 6 349-358. 

DFBcPh and its dihydrodiol were subjected to metabolism, and the extent of DNA binding in human breast cancer MCF-7 cells was assessed." The extent of DNA binding was then compared with that for BcPh and its dihydrodiol and the potent carcinogen BaP. The 1,4-DFBcPh series 2 (anti) DE-derived DNA adducts were also compared with those arising from intracellular oxidation of the dihydrodiol with subsequent DNA binding. These experiments showed that increased molecular distortion decreased metabolic activation to the terminal metabolites but the DE metabolites formed were the DNA-damaging species. 

Amifostine is a cytoprotective adjuvant used to reduce the incidence of neutropenia-related fever and infection induced by DNA-binding chemotherapeutic agents. It is an organic thiophosphate prodrug which is dephosphorylated to the active cytoprotective thiol metabolite. The elimination half-life of the... 

Carbon tetrachloride is metabolized by CYP2 enzymes several reactive metabolites have been postulated, including radicals and phosgene. In vitro, DNA binding of carbon tetrachloride is observed in several cellular systems no such binding in vivo has been reported. 

Schlosser, M.J., Shurina, R.D. Kalf, EG (1990) Prostaglandin H synthase catalyzed oxidation of hydroquinone to a sulfhydryl-binding and DNA-damaging metabolite. Chem. Res. Toxicol., 3, 333-339... 

These studies demonstrated that DNA-binding can be a reliable probe of metabolic activation. In contrast to studies of metabolites per se, which usually involve large numbers of metabolite intermediates, DNA-binding monitors only chemically reactive metabolites. Also, if there is no selective repair of specific adducts, DNA-binding monitors the cumulative production of metabolites over time, while direct measurement of metabolites can show the metabolite spectrum only at the time observed. This can be particularly critical for studies of activation of complex chemicals such as polycyclic aromatic hydrocarbons whose primary metabolites are subject to secondary and tertiary metabolism (8). 

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