Aristolochic acids (AA) are carcinogenic and nephrotoxic alkaloids from Aristolochia species. Aristolochic acid I (AAI), the major component of AA, causes the development of Aristolochic acid nephropathy (AAN) and Balkan endemic nephropathy (BEN). These two diseases cause total renal failure and urothelial malignancies. The fact that these diseases have not been developed in all persons, who have been exposed to their action, might be causd by different activities and protein levels of the enzymes metabolizing AAI. Thus, the identification of enzymes involved in the metabolism, and detailed knowledge of their expression and catalytic specifities is a major importance. Aristolochic acid I (AAI) can be metabolized by several types of reactions. Like most nitroaromatics, the main activation pathway of AAI is reduction of its nitro group to form a cyclic acylnitrenium ion, which can bind to the purine bases, thereby forming AAI-DNA adducts. The detoxication pathway of AAI is its oxidative demethylation by cytochromes P450 forming detoxication metabolite 8-hydroxyaristolochic acid Ia (AAIa). In the present thesis, using rat and human enzymes and as well as several mice models, the metabolism of AAI in vitro and in vivo was investigated. The first model has deleted gene for NADPH:cytochrome P450...

6 Abstract Ellipticine (5,11-dimethyl-6H-pyrido[4,3-b]carbazole), an alkaloid isolated from Apocynaceae plants, exhibits significant antitumor and HIV activity. This antitumor agent binds to DNA and forms covalent DNA adducts. Enzymes, which are involved in its enzymatic activation, are cytochromes P450 (CYP) and peroxidases. To elucidate the effect of ellipticine on the expression and enzymatic activity of the individual components of the microsomal mixed function oxidase system in different tissues, we used rat model. Simultaneously, the effect of ellipticine and its cytotoxicity on different tumor cell lines was also investigated. Another part of the presented work was targeted on preparation of anti-peptide antibody against orphan cytochrome P450 2S1, which is highly expressed in many human tumours of the epithelial origin, for its detection in these tissues. For better understanding how CYP2S1 can contribute to the metabolism of xenobiotics, the protein was prepared by heterologous expression in E. coli. Furher, its role in metabolism of an antitumor drug ellipticine, a carcinogenic environmental pollutant benzo[a]pyrene (BaP) and its derivate BaP-7,8-dihydrodiol was examined. Utilizing a mouse model, the impact of pulmonary inflammation on the metabolism of an environmental carcinogen was...

As espécies reativas são associadas a processos toxicológicos e fisiopatológicos, agindo como importantes mediadores, por exemplo, na sinalização celular. Diversas classes de compostos têm sido utilizadas como possíveis biomarcadores de estresse redox, destacando-se os aldeídos &#945;,&#946;-insaturados, capazes de alquilar biomoléculas como o DNA. Para evitar efeitos deletérios, estes aldeídos são detoxificados por glutationilação e posterior metabolização a derivados mercaptúricos. Contudo, avaliar o estado redox em sistemas biológicos ainda é tarefa bastante complexa, sendo a dificuldade em quantificar de forma prática e acurada os efeitos de sinalização e/ou dano molecular o maior problema dos estudos redox. Assim, o objetivo deste trabalho foi desenvolver métodos acurados e sensíveis de análise de potenciais biomarcadores de estresse redox, isto é: nucleosídeos modificados, aldeídos endógenos e exógenos, glutationa e produtos de glutationilação, e avaliá-los em sistemas modelos, celular e animal, e em humanos. A avaliação dos níveis urinários de três nucleosídeos modificados por metodologia de HPLC-MS/MS desenvolvida pelo grupo em moradores da cidade de São Paulo - região com poluição atmosférica - demonstrou aumento significativo de 1,N2-propanodGuo comparado aos moradores de região não poluída. Ademais, comprova-se pela primeira vez que células deficientes em reparo de ligações cruzadas apresentam níveis basais elevados de 1,N2-propanodGuo, em duas linhagens independentes, colocando este aduto como potencial mediador de carcinogênese em pacientes portadores de Anemia de Fanconi. Utilizando cérebro de ratos SOD1G93A (modelo de Esclerose Lateral Amiotrófica - ELA), verificou-se aumento de 50% nos níveis de 1,N2-propanodGuo e de 100% nos de 1,N6-&#949;dAdo em fase sintomática, sugerindo influência do conteúdo lipídico cerebral, levando a comprometimento do metabolismo neuronal e morte celular. O perfil de aldeídos determinado em cérebro de ratos SOD1G93A demonstrou aumento de trans-hexa-2-enal e trans,trans-hexa-2,4-dienal em fase assintomática e de trans,trans-deca-2,4-dienal em fase sintomática, não sendo observada nenhuma alteração na medula. Conhecer estas variações permite direcionar estudos de modificações em biomoléculas, além de a metodologia per se corroborar com as áreas de análises lipidômicas. Técnicas distintas e o preparo de amostras refletiram nos níveis de glutationa reduzida (GSH) e oxidada (GSSG) relatados. A técnica de espectrometria de massas mostrou-se mais precisa que a detecção eletroquímica; e a alquilação do grupo tiol minimizou interferências de matriz. Por análise de HPLC-UV/Vis-ESI-MS/MS, a quantificação de trans-4-hidroxi-2-nonenal (HNE) e crotonaldeido conjugados com GSH demonstrou não haver alterações em cérebro e medula de ratos SOD1G93A. Contudo, há formação esteroespecífica dos adutos de HNE in vivo. Ressalta-se que a metodologia desenvolvida é extremamente sensível e específica e permite análise simultânea de GSH, GSSG, cisteína, cistina e dos adutos supracitados, servindo para análise de outros adutos de glutationilação de aldeídos que possam ser importantes em doenças associadas a estresse redox. / Free radicais and oxidant species are associated with toxicological and pathophysiological processes. It has been demonstrated that production of reactive oxygen species may be involved in cell signaling and regulation. Several biomarkers of redox processes have been used, including adducts formed through the reaction of &#945;,&#946;-unsaturated aldehydes with biomolecules such as DNA. In order to avoid these deleterious effects, aldehydes are detoxified through glutathionylation and further metabolized to mercapturic derivatives. However, assessing the redox status in biological systems is still a very complex task, and the difficulty in practical and accurate quantification of signaling effects and/or molecular damage is a major problem in redox studies. The objective of this work was to develop accurate and sensitive methods for analysis of potential biomarkers of redox stress, i.e., modified nucleosides, endogenous and exogenous aldehydes, glutathione and glutathionylation products, and their evaluation in cell, animal model and humans. Evaluation of urinary levels of 1,N2-propano-2\'-deoxyguanosine (1,N2-propanodGuo), 1,N2-etheno-2\'-deoxyguanosine and 8-oxo-7,8-dihydro-2\'-deoxyguanosine in residents of São Paulo City - polluted region - showed a significant increase (p<0.05) in 1,N2-propanodGuo levels compared to residents of an unpolluted region by a HPLC-MS/MS methodology developed by the group. Moreover, it was proven, for the first time, that repair deficient cells have basal levels of 1,N2-propanodGuo higher than proficient cells in two independent strains, placing 1,N2-propanodGuo as a potential mediator of carcinogenesis in Fanconi Anemia patients. In an Amyotrophic Lateral Sclerosis (ALS) animal model (SOD1G93A rat) , a 50% increase in the levels of 1,N2-propanodGuo and 100% in the 1,N6-etheno-2\'-deoxyadenosine in brain tissue in the symptomatic phase was observed, suggesting that the high brain lipid content may play a role, leading to impairment of cell metabolism and neuronal cell death. There is an increase of trans-hex-2-enal and trans,trans-hexa-2,4-dienal in asymptomatic SOD1G93A rats brain and of trans,trans-deca-2,4-dienal in symptomatic ones. However, no alteration was observed in spinal cord. Our approach contributes to a better understanding of the aldehyde status in vivo and allows us to predict biomolecule modifications. The developed methodology can contribute to lipidomic studies. The use of different techniques and sample preparation reflected in the reported levels of reduced (GSH) and oxidized glutathione (GSSG). The mass spectrometry technique proved to be more accurate than the electrochemical one, and the use of thiol alkylating agent minimizes matrix interference. No changes were observed in the levels of the GSH conjugates of trans-4-hydroxy-2-nonenal (HNE) and crotonaldehyde in brain and spinal cord of SOD1G93A rats quantified by HPLC-UV/Vis-ESI-MS/MS compared to controls. However, it was observed stereospecific HNE adducts formation in vivo. Note that this methodology is extremely sensitive and specific and allows simultaneous analysis of GSH, GSSG, Cys, cystine and the aforementioned adducts, serving for analysis of other aldehyde-glutathionylation adducts that may be important in pathologies associated with stress redox.

CI Disperse Blue 291 (CI DB 291) é um corante dinitrobromoaminoazobenzeno com atividade mutagênica para S. typhimurium, aumentada na presença de nitrorredutase, o-acetiltransferase e enzimas microssomais (S9). Neste estudo foram isolados e caracterizados quatro produtos da redução de DB 291 com ditionito de sódio (in vitro), sendo denominados 2- fenilbenzotriazóis não clorados (não-ClPBTAs). Os espectros de absorbância não apresentam o pico correspondente à ligação azo (?&#955;=613 nm), indicando a redução dessa ligação. Espectros de massas e 1H RMN mostram que os produtos são dois pares de tautômeros com m/z 465 [M+H]+ e m/z 449 [M+H]+. Esses produtos foram acetilados com piridina/anidrido acético e espectros de massas desses produtos indicam adição de grupamento acetil na molécula e formação de produtos com m/z 507 [M+H]+ e m/z 491 [M+H]+. Esses compostos foram reagidos com dGuo e obtivemos dois produtos com m/z 632 [M+H]+ e m/z 683 [M+H]+, sendo os possíveis adutos. A partir do composto não clorado com m/z 449 obtido após redução com ditionito de sódio, sintetizamos o análogo clorado (PBTA) após reação de cloração. Espectros de massa confirmam a formação do composto clorado com m/z 483 [M+H]+. Também incubamos o corante CI DB 291 com nitrorredutase/NADH. Análises por HPLC/ESI/MS indicam a formação de não-ClPBTA (m/z 449). Uma vez que não-ClPBTAs são mais mutagênicos para linhagens de S. typhimurium (com fração S9) que seus dinitrofenilazo corantes precursores, a conversão enzimática do corante para não-ClPBTAs pode ser uma via importante para sua bioativação. / C.I. Disperse Blue 291 (C.I. DB 291) is a dinitrobromoaminoazobenzene dye with mutagenic activity to S. typhimurium, that is increased in the presence of nitroreductase, o-acetyltransferase and microsomal enzymes (S9). In this study were isolated and characterized four products of the reduction of DB 291 with sodium dithionite (in vitro), named non- chlorinated 2- phenylbenzotriazoles (non-ClPBTAs). The absorbance spectra do not present the peak corresponding to the band of azo bond (&#955;= 613 nm), indicating that the reduction of this bond occured. Mass spectra and 1H NMR show that the products are two pairs of tautomers with m/z 465 [M+H]+ and m/z 449 [M+H]+. These compounds were acetylated with pyridine/acetic anhydride and their mass spectra indicate the addition of an acetyl group to the molecules and formation of products with m/z 507 [M+H]+ e m/z 491 [M+H]+. After reaction of these compounds with dGuo we have got two products with m/z 632 [M+H]+ and m/z 683 [M+H]+, which are possible adducts. Starting from the non chlorinated compound with m/z 449, obtained through the dye reduction with sodium dithionite, we have synthesized the chlorinated analogous (PBTA) after chlorination reaction. Mass spectrum confirms formation of the chlorinated product with m/z 483 [M+H]+. The DB 291 dye was also incubated with nitroreductase NADH. HPLC/ESI/MS analyses indicate the formation of a non chlorinated PBTA (m/z 449). Since non- chlorinated PBTAs are more mutagenic to S. typhimurium strains (with S9 mix) than the parent phenylbenzotriazole dye, enzymatic conversion of this type of dye non chlorinated PBTAs may be an important way for its bioactivation.

A produção de radicais de carbono \"in vivo\" durante a biotransformação da hidrazina foi demonstrada por ressonância para magnética eletrônica, utilizando o método do captador de spin. Eritrócitos de rato também oxidaram a hidrazina, formando radicais de carbono e nitrogênio, além de espécies reativas de oxigênio. Todas estas espécies, possivelmente formadas \"in vivo\", são potencialmente causadoras de dano a macromoléculas. Podem, por exemplo, iniciar reações secundárias formando radicais de componentes celulares, como ocorreu com a hemoglobina que foi oxidada a radicais tiil-hemoglobina em eritrócitos tratados com hídrazina. Radicais de carbono formados durante a biotransformação da hidrazina em animais expostos provêm necessariamente de substâncias endógenas e podem ser direta ou indiretamente responsáveis pela modificação ( alquilação ) de bases no DNA \"in vivo\". A hidrazona do formaldeído é descrita na literatura como um intermediário da alquilação induzida por hidrazina \"in vivo\". Células L 1210, catalase ou oxihemoglobina de rato foram capazes de formar radicais de carbono durante a oxidação da hidrazona do formaldeído. A oxidação da hidrazona do formaldeído pela catalase foi estudada \"in vítro\" e os radicais de carbono formados, identificados como radicais metila. A base modificada C8 -metil-guanina foi formada em animais expostos, como demonstrado por cromatografia líquida de alta eficiência associada à detecção eletroquímica, sugerindo que ocorreu alquilação do DNA por radicais metila durante a biotransformação da hidrazina \"in vivo\". / The production of carbon-centered radicais during hydrazine biotransformation \"in vivo\" was demonstrated by electron paramagnetic resonance ( EPR ) spin trapping technique. Rat red blood cells also oxidized hydrazine, forming carbon and nitrogen centered radicais, besides oxygen reactive speties. Ali these species, possibly formed \"in vivo\", are potentially harmful to macromolecules. For example, they can initiate secondary reactions in which the radicais from cell components are formed, as it occurred with hemoglobin, forming thiyl-hemoglobin radicais in the red blood cells treated with hydrazine. Carbon-centered radicais produced during the biotransformation of hydrazine in exposed animais must be derived from endogenous sources and may be directly or indirectly responsible for the modificaton ( alkylation ) of DNA bases \"in vivo\". The formaldehyde hydrazone is reported in the literature as an intermediate of hydrazine-induced alkylation \"in vivo\". L1210 cells, catalase and rat hemoglobin were able to produce carbon-centered radicais during the oxidation of the formaldehyde hydrazone. The oxidation of formaldehyde hydrazone by catalase was studied \"in vitro\" and the generated carbon-centered radicais were identified as methyl radicais. The modified base C8 -methylguanine was formed in exposed animais, as demonstrated by high performance liquid chromatography with electrochemical detection, suggesting that DNA alkylation by methyl radicais occurred during hydrazine biotransformation \"in vivo.\"

Exposição a Hidrocarbonetos policíclicos aromáticos (HPAs) está relacionada com o aumento de risco de câncer. Esses carcinógenos dependem da sua ativação para intermediários eletrofílicos para causar danos em biomoléculas. As vias de ativação melhor estudadas incluem (i) a formação de diol-epóxido nas regiões de baía ou fjord dos HPAs através de epoxidações catalisadas pela citocromo P450 (CYP450), com uma hidrólise intermediária pela epóxido hidrolase e (ii) oxidação (CYP450 ou peroxidases) levando à formação de um cátion radical reativo. Outras vias incluem a formação de derivados metilados, quinonas e metabólitos de anel aberto cujas contribuições para a carcinogênese ainda são pouco estudadas, assim como o papel do estresse oxidativo na toxicidade dos HPAs. Neste trabalho foi investigado a citotoxicidade e genotoxicidade do indeno[1,2,3-cd]pireno, trifenileno e coroneno e seus produtos de oxidação (quinonas e hidroquinonas). Linhagens de carcinoma hepatocelular humano (HepG2) e de hepatócitos humanos normais (THLE-2) foram incubadas com os HPAs e suas respectivas quinonas e hidroquinonas acetiladas para análise de viabilidade celular (MTT) em diferentes condições de cultivo (por 16 horas, de 20 a 200 uM). Células HepG2 foram incubadas por 16 horas com indeno[1,2,3-cd]pireno (50 &#181;M), coroneno (20 &#181;M), trifenileno (10 uM) ou seus produtos de oxidação (quinonas e hidroquinonas acetiladas) para análise de dano oxidativo em DNA e peroxidação lipídica. Nas concentrações descritas acima, esses HPAs estruturalmente diferentes e seus produtos de oxidação são citotóxicos e levam ao aumento dos níveis de 7,8- dihidro-8-oxo-2\'-desoxiguanosina e malonaldeído. Tais danos podem contribuir para o aumento do risco de desenvolvimento de doenças, como o câncer, na população exposta. / Exposure to Polycyclic Aromatic Hydrocarbons (PAH) is related to the increase in the risk of cancer. These carcinogens depend on their activation by electrophilic intermediates to cause damage on biomolecules. The best understood activation pathways include (i) the formation of diol-epoxide in the bay and fjord regions of the PAH through epoxidations catalyzed by cytochrome P450 (CYP450), with an intermediate hydrolysis by epoxide hydrolase and (ii) oxidation (CYP450 or peroxidases) leading to the formation of a reactive cationic radical. Other pathways include the formation of methylated derivatives, quinones and open-ring metabolites whose contributions to carcinogenesis, as well as the role of oxidative stress on PAH toxicity, have not been extensively studied yet. This work investigated the cytotoxicity and genotoxicity of indene[1,2,3-cd]pyrene, triphenylene and coronene and their oxidation products (quinones and hydroquinones). Strains of human hepatocellular carcinoma (HepG2) and of normal human hepatocytes (THLE-2) were incubated with PAH and their respective quinones and acetylated hydroquinones and afterwards analyzed for cell viability (MTT) under different culture conditions (for 16 hours, 20 to 200 BM). HepG2 cells were incubated for 16 hours with indene[1,2,3-cd]pyrene (50 BM), coronene (20 BM), triphenylene (10 BM) or their oxidation products (quinones and acetylated hydroquinones) and afterwards analyzed for oxidative damage on DNA and lipid peroxidation. In the mentioned concentrations, these structurally different PAHs and their oxidation products are cytotoxic and lead to an increase in the levels of 7,8-dihydro-8-oxo-2\'-deoxyguanosine and malonaldehyde. Such damages may contribute to increase the risk of diseases like cancer in the exposed population.

CI Disperse Blue 291 (CI DB 291) é um corante dinitrobromoaminoazobenzeno com atividade mutagênica para S. typhimurium, aumentada na presença de nitrorredutase, o-acetiltransferase e enzimas microssomais (S9). Neste estudo foram isolados e caracterizados quatro produtos da redução de DB 291 com ditionito de sódio (in vitro), sendo denominados 2- fenilbenzotriazóis não clorados (não-ClPBTAs). Os espectros de absorbância não apresentam o pico correspondente à ligação azo (?&#955;=613 nm), indicando a redução dessa ligação. Espectros de massas e 1H RMN mostram que os produtos são dois pares de tautômeros com m/z 465 [M+H]+ e m/z 449 [M+H]+. Esses produtos foram acetilados com piridina/anidrido acético e espectros de massas desses produtos indicam adição de grupamento acetil na molécula e formação de produtos com m/z 507 [M+H]+ e m/z 491 [M+H]+. Esses compostos foram reagidos com dGuo e obtivemos dois produtos com m/z 632 [M+H]+ e m/z 683 [M+H]+, sendo os possíveis adutos. A partir do composto não clorado com m/z 449 obtido após redução com ditionito de sódio, sintetizamos o análogo clorado (PBTA) após reação de cloração. Espectros de massa confirmam a formação do composto clorado com m/z 483 [M+H]+. Também incubamos o corante CI DB 291 com nitrorredutase/NADH. Análises por HPLC/ESI/MS indicam a formação de não-ClPBTA (m/z 449). Uma vez que não-ClPBTAs são mais mutagênicos para linhagens de S. typhimurium (com fração S9) que seus dinitrofenilazo corantes precursores, a conversão enzimática do corante para não-ClPBTAs pode ser uma via importante para sua bioativação. / C.I. Disperse Blue 291 (C.I. DB 291) is a dinitrobromoaminoazobenzene dye with mutagenic activity to S. typhimurium, that is increased in the presence of nitroreductase, o-acetyltransferase and microsomal enzymes (S9). In this study were isolated and characterized four products of the reduction of DB 291 with sodium dithionite (in vitro), named non- chlorinated 2- phenylbenzotriazoles (non-ClPBTAs). The absorbance spectra do not present the peak corresponding to the band of azo bond (&#955;= 613 nm), indicating that the reduction of this bond occured. Mass spectra and 1H NMR show that the products are two pairs of tautomers with m/z 465 [M+H]+ and m/z 449 [M+H]+. These compounds were acetylated with pyridine/acetic anhydride and their mass spectra indicate the addition of an acetyl group to the molecules and formation of products with m/z 507 [M+H]+ e m/z 491 [M+H]+. After reaction of these compounds with dGuo we have got two products with m/z 632 [M+H]+ and m/z 683 [M+H]+, which are possible adducts. Starting from the non chlorinated compound with m/z 449, obtained through the dye reduction with sodium dithionite, we have synthesized the chlorinated analogous (PBTA) after chlorination reaction. Mass spectrum confirms formation of the chlorinated product with m/z 483 [M+H]+. The DB 291 dye was also incubated with nitroreductase NADH. HPLC/ESI/MS analyses indicate the formation of a non chlorinated PBTA (m/z 449). Since non- chlorinated PBTAs are more mutagenic to S. typhimurium strains (with S9 mix) than the parent phenylbenzotriazole dye, enzymatic conversion of this type of dye non chlorinated PBTAs may be an important way for its bioactivation.

Exposição a Hidrocarbonetos policíclicos aromáticos (HPAs) está relacionada com o aumento de risco de câncer. Esses carcinógenos dependem da sua ativação para intermediários eletrofílicos para causar danos em biomoléculas. As vias de ativação melhor estudadas incluem (i) a formação de diol-epóxido nas regiões de baía ou fjord dos HPAs através de epoxidações catalisadas pela citocromo P450 (CYP450), com uma hidrólise intermediária pela epóxido hidrolase e (ii) oxidação (CYP450 ou peroxidases) levando à formação de um cátion radical reativo. Outras vias incluem a formação de derivados metilados, quinonas e metabólitos de anel aberto cujas contribuições para a carcinogênese ainda são pouco estudadas, assim como o papel do estresse oxidativo na toxicidade dos HPAs. Neste trabalho foi investigado a citotoxicidade e genotoxicidade do indeno[1,2,3-cd]pireno, trifenileno e coroneno e seus produtos de oxidação (quinonas e hidroquinonas). Linhagens de carcinoma hepatocelular humano (HepG2) e de hepatócitos humanos normais (THLE-2) foram incubadas com os HPAs e suas respectivas quinonas e hidroquinonas acetiladas para análise de viabilidade celular (MTT) em diferentes condições de cultivo (por 16 horas, de 20 a 200 uM). Células HepG2 foram incubadas por 16 horas com indeno[1,2,3-cd]pireno (50 &#181;M), coroneno (20 &#181;M), trifenileno (10 uM) ou seus produtos de oxidação (quinonas e hidroquinonas acetiladas) para análise de dano oxidativo em DNA e peroxidação lipídica. Nas concentrações descritas acima, esses HPAs estruturalmente diferentes e seus produtos de oxidação são citotóxicos e levam ao aumento dos níveis de 7,8- dihidro-8-oxo-2\'-desoxiguanosina e malonaldeído. Tais danos podem contribuir para o aumento do risco de desenvolvimento de doenças, como o câncer, na população exposta. / Exposure to Polycyclic Aromatic Hydrocarbons (PAH) is related to the increase in the risk of cancer. These carcinogens depend on their activation by electrophilic intermediates to cause damage on biomolecules. The best understood activation pathways include (i) the formation of diol-epoxide in the bay and fjord regions of the PAH through epoxidations catalyzed by cytochrome P450 (CYP450), with an intermediate hydrolysis by epoxide hydrolase and (ii) oxidation (CYP450 or peroxidases) leading to the formation of a reactive cationic radical. Other pathways include the formation of methylated derivatives, quinones and open-ring metabolites whose contributions to carcinogenesis, as well as the role of oxidative stress on PAH toxicity, have not been extensively studied yet. This work investigated the cytotoxicity and genotoxicity of indene[1,2,3-cd]pyrene, triphenylene and coronene and their oxidation products (quinones and hydroquinones). Strains of human hepatocellular carcinoma (HepG2) and of normal human hepatocytes (THLE-2) were incubated with PAH and their respective quinones and acetylated hydroquinones and afterwards analyzed for cell viability (MTT) under different culture conditions (for 16 hours, 20 to 200 BM). HepG2 cells were incubated for 16 hours with indene[1,2,3-cd]pyrene (50 BM), coronene (20 BM), triphenylene (10 BM) or their oxidation products (quinones and acetylated hydroquinones) and afterwards analyzed for oxidative damage on DNA and lipid peroxidation. In the mentioned concentrations, these structurally different PAHs and their oxidation products are cytotoxic and lead to an increase in the levels of 7,8-dihydro-8-oxo-2\'-deoxyguanosine and malonaldehyde. Such damages may contribute to increase the risk of diseases like cancer in the exposed population.

Alkylierte polyzyklische aromatische Kohlenwasserstoffe werden in vielen Matrizes wie Fahrzeugabgasen und Tabakrauch und auch als Kontaminanten in Nahrungsmitteln neben rein aromatischen Kongeneren gefunden. Alkylierte PAK können über die Alkylseitenkette über benzylische Hydroxylierung und nachfolgende Sulfonierung katalysiert über Sulfotransferasen (SULT) zu reaktiven Schwefelsäureestern umgesetzt werden. Die SULT-vermittelte Bioaktivierung zu einem genotoxischen Schwefelsäureester wurde für den benzylischen Alkohol 1-Hydroxymethylpyren des Hepatokanzerogens 1-Methylpyren in früheren Arbeiten gezeigt. In der vorliegenden Arbeit wurde überprüft, ob die benzylischen Alkohole weiterer alkylierter PAK über Sulfonierung zu genotoxischen Schwefelsäureestern umgesetzt werden. Hierzu wurde eine Gruppe von 17 Modellsubstanzen ausgewählt, um die Ableitung von Struktur-Aktivitäts-Beziehungen zu ermöglichen. Das genotoxische Potenzial authentischer benzylischer Schwefelsäureester der Modellsubstanzen wurde zunächst in vitro über DNA-Adduktbildung im zellfreien System und Mutagenität im Salmonella-Rückmutationstest untersucht. Die Sulfate zeigten große Reaktivitätsunterschiede in Abhängigkeit von der Struktur des aromatischen Systems und der Position der Alkylseitenkette, wobei die Endpunkte DNA-Adduktbildung und Mutagenität gut korrelierten. Des Weiteren wurde der Salmonella-Mutagenitätstest mit den benzylischen Alkoholen der untersuchten alkylierten PAK und gentechnisch veränderten S. typhimurium-Stämmen, die SULT-Formen des Menschen heterolog exprimieren, durchgeführt. Bis auf die Alkohole 2- und 4-HMP zeigten alle untersuchten benzylischen Alkohole deutliche mutagene Effekte in einem oder mehreren humane SULT exprimierenden Stämmen. Die durchgeführten in vitro-Versuche zeigten das Potenzial der benzylischen Metabolite alkylierter PAK für genotoxische Wirkungen. Nachfolgend musste geklärt werden, welche Relevanz die beobachteten Effekte für die komplexere in vivo-Situation haben. Nach Verabreichung verschiedener benzylischer Schwefelsäureester und Alkohole an männliche Ratten konnten DNA-Addukte in den untersuchten Organen detektiert werden, was im Fall der Schwefelsäureester deren systemische Bioverfügbarkeit und im Fall der benzylischen Alkohole deren Umsatz durch SULT der männlichen Ratte zeigte. Da im Gegensatz zum Menschen die SULT-Expression in der Ratte auf die Leber fokussiert ist, musste ein Großteil des Umsatzes zu genotoxischen Sulfaten in der Leber stattgefunden haben. DNA-Addukte wurden jedoch auch in extrahepatischen Organen gefunden, was über einen hepatischen Export der gebildeten reaktiven Sulfate und deren Transport über den Blutkreislauf zu diesen Geweben erklärt werden kann. Für die weiterführenden in vivo-Studien wurden die benzylischen Alkohole 1-HMP und 1-HM-8-MP ausgewählt, die trotz großer struktureller Ähnlichkeit toxikodynamische Unterschiede zeigten. Zur Untersuchung der Bedeutung des SULT-vermittelten Toxifizierungsweges als auch konkurrierender detoxifizierender oxidativer Stoffwechselprozesse, wurden für 1-HMP und 1-HM-8-MP in vivo-Inhibitionsstudien mit SULT-Inhibitoren und für 1-HM-8-MP auch mit ADH/ALDH-Inhibitoren durchgeführt. Eine Vorbehandlung mit dem SULT-Hemmstoff Pentachlorphenol führte zu einer Reduktion der DNA-Adduktniveaus in Organen 1-HMP- und 1-HM-8-MP-behandelter Tiere. Die Verabreichung von Quercetin hatte keine Auswirkung auf die DNA-Adduktniveaus. Die Hemmung der DNA-Adduktbildung bei Verabreichung von Pentachlorphenol verdeutlichte jedoch, dass benzylische Alkohole alkylierter PAK in vivo über Sulfonierung bioaktiviert werden. Eine Vorbehandlung mit dem ADH-Inhibitor 4-Methylpyrazol und dem ADH-Substrat Ethanol führte zu erhöhten DNA-Adduktniveaus in Organen 1-HM-8-MP-behandelter Tiere. Den gleichen Effekt, jedoch in geringerem Ausmaß, hatte auch die Vorbehandlung mit dem ALDH-Inhibitor Disulfiram. Dies deutet darauf hin, dass oxidative Modifikationen an der Seitenkette des 1-HM-8-MP einen Detoxifizierungsmechanismus darstellen. Nach Verabreichung benzylischer Metabolite alkylierter PAK wurden oftmals hohe Adduktniveaus in der Niere detektiert. Als mögliche Ursache hierfür wurde eine Transporter-vermittelte renale Sekretion reaktiver Sulfate postuliert, die über Vorbehandlung mit Probenecid vor Verabreichung von 1-HMP und 1-HM-8-MP überprüft wurde. Der Haupteffekt der Probenecid-Behandlung wurde jedoch nicht in der Niere, sondern in der Leber beobachtet, die stark erhöhte Adduktniveaus zeigte. Eine mögliche Erklärung hierfür ist die Hemmung des Exportes in der Leber gebildeter reaktiver Sulfate über Inhibition hepatischer organischer Anionentransporter. / Alkylated polycyclic aromatic hydrocarbons are found besides purely aromatic congeners in numerous matrices like car engine exhausts and tobacco smoke and as contaminants in foods. Alkylated PAH can be converted at the alkyl side chain to reactive sulfuric acid esters via benzylic hydroxylation and subsequent sulfonation catalysed by sulfotransferases (SULT). The SULT-mediated bioactivation to a genotoxic sulfuric acid ester was shown for the benzylic alcohol 1-hydroxymethylpyrene of the hepatocarcinogen 1-methylpyrene in previous studies. In the thesis at hand it was studied if the benzylic alcohols of further alkylated PAH are converted to genotoxic sulfuric acid esters via sulfonation. For this purpose a group of 17 model substances was chosen to allow for deduction of structure activity relationships. The genotoxic potential of authentic benzylic sulfuric acid esters of the model substances was initially investigated in vitro via DNA adduct formation in a cell free system and mutagenicity in the Salmonella reverse mutation test. The sulfates showed large differences in reactivity depending on the structure of the aromatic system and the position of the alkyl side chain whereupon the endpoints DNA adduct formation and mutagenicity correlated well. Furthermore, the Salmonella mutagenicity test was carried out with the benzylic alcohols of the alkylated PAH studied and S. typhimurium strains genetically engineered for the heterologous expression of human SULT forms. Except for the alcohols 2- and 4-HMP all benzylic alcohols studied showed clear mutagenic effects in one or more SULT-expressing strains. The studies performed in vitro demonstrated the potential of benzylic metabolites of alkylated PAH for genotoxic effects. Consecutively, the relevance of the observed effects for the more complex in vivo situation had to be clarified. After administration of different benzylic sulfuric acid esters and alcohols to male rats DNA adducts were detected in the organs studied, in case of the sulfuric acid esters showing their systemic bioavailability and in case of the benzylic alcohols demonstrating their conversion to the corresponding reactive benzylic sulfuric acid esters by SULT of the male rat. Since in contrast to man SULT expression in the rat is focused on the liver, a large part of the conversion to genotoxic sulfates must have been taken place in the liver. However, DNA adducts were also found in extrahepatic tissues which can be attributed to a hepatic export of the reactive sulfates formed and their transport to these tissues via circulation. For the continuative in vivo studies the benzylic alcohols 1-HMP and 1-HM-8-MP were chosen that demonstrated toxicodynamic differences in spite of their great structural resemblance. To investigate the importance of the SULT-mediated toxification pathway as well as competing detoxifying oxidative metabolic pathways, in vivo inhibition studies with SULT inhibitors were performed for 1-HMP and 1-HM-8-MP and with ADH/ALDH inhibitors also for 1-HM-8-MP. A pretreatment with the SULT inhibitor pentachlorophenol led to a reduction of DNA adduct levels in organs of animals treated with 1-HMP and 1-HM-8-MP. Administration of quercetin had no impact on the DNA adduct levels. However, inhibition of DNA adduct formation at administration of pentachlorophenol demonstrated that benzylic alcohols of alkylated PAH are bioactivated via sulfonation in vivo. A pretreatment with the ADH inhibitor 4-methylpyrazole and the ADH substrate ethanol led to increased DNA adduct levels in organs of animals treated with 1-HM-8-MP. The same effect but to a lesser extent was caused by a pretreatment with the ALDH inhibitor disulfiram. This indicates that oxidative modifications at the side chain of 1-HM-8-MP represent a detoxification mechanism. After administration of benzylic metabolites of alkylated PAH often high DNA adduct levels were detected in kidney. A transporter-mediated renal secretion was postulated as possible cause which was investigated using a pretreatment with probenecid before administration of 1-HMP and 1-HM-8-MP. However, the main effect of the treatment with probenecid was not observed in kidney but in liver that showed strongly increased adduct levels. A possible explanation for this effect is the inhibition of the export of reactive sulfates formed in liver via inhibition of hepatic organic anion transporters.

Small molecule Zn(II) complexes containing N- and S- donor environments may serve as appropriate models for mimicking Zn protein sites, and thus, their reactions with heavy metal ions such as Pt(II) and W(0) may provide insight into possible adduct formation and zinc displacement. To study such possible interactions between zinc finger proteins and platinum-bound DNA, the ZnN2S2 dimeric complex, N,N?-bis(2- mercaptoethyl)-1,4-diazacycloheptane zinc (II), [Zn-1?]2, has been examined for Znbound thiolate reactivity in the presence of Pt(II) nitrogen ? rich compounds. The reactions yielded Zn/Pt di- and tri- nuclear thiolate-bridged adducts and metalexchanged products, which were initially observed via ESI-mass spectrometry (ESI-MS) analysis of reaction solutions, and ultimately verified by comparison to the ESI-MS analysis, 195Pt NMR spectroscopy, and X-ray crystallography of directly synthesized complexes. The isolation of Zn-(?-SR)-Pt-bridged [(Zn(bme-dach)Cl)(Pt(dien))]Cl adduct from these studies is, to our knowledge, the first Zn-Pt bimetallic thiolatebridged model demonstrating the interaction between Zn-bound thiolates and Pt(II). Additional derivatives involving Pd(II) and Au(III) have been explored to parallel the experiments executed with Pt(II). The [Zn-1?]2 was then modified by cleavage with Na+[ICH2CO2]- to produce (N- (3-Thiabutyl)-N?-(3-thiapentaneoate)-1,4-diazacycloheptane) zinc(II), Zn-1?-Ac or ZnN2SS?O, and 1,4-diazacycloheptane-1,4-diylbis(3-thiapentanoato) zinc(II), Zn-1?-Ac2 or ZnN2S?2O2, monomeric complexes (where S = thiolate, S? = thioether). The [Zn-1?]2 di- and Zn-1?-Ac mono-thiolato complexes demonstrated reactivity towards labile-ligand tungsten carbonyl species, (THF)W(CO)5 and (pip)2W(CO)4, to yield, respectively, the [(Zn-1?-Cl)W(CO)4]- complex and the [(Zn-1?-Ac)W(CO)5]x coordination polymer. With the aid of CO ligands for IR spectral monitoring, the products were isolated and characterized spectroscopically, as well as by X-ray diffraction and elemental analysis. To examine the potential for zinc complexes (or zinc-templated ligands) to possibly serve as a toxic metal remediation agents, Zn-1?-Ac and Zn-1?-Ac2 were reacted with Ni(BF4)2. The formation of Zn/Ni exchanged products confirmed the capability of ?free? Ni(II) to displace Zn(II) within the N-, S-, and O- chelate environment. The Zn/Ni exchanged complexes were analyzed by ESI-MS, UV-visible spectroscopy, IR spectroscopy of the acetate regions, and X-ray crystallography. They serve as foundation molecules for more noxious metal exchange / zinc displacement products.