A (-)- grandisina (GRA) é um produto natural da classe das lignanas e é encontrada em muitas espécies de plantas das regiões Norte e Nordeste do Brasil. Por apresentar diversas propriedades biológicas, como atividade tripanocida, anti-inflamatória, antinociceptiva, e principalmente atividade antileucêmica e antitumoral contra tumores de Ehrlich, a GRA pode ser considerada um potencial candidato a fármaco. Porém, para que a GRA se torne um fármaco são necessárias diversas etapas de estudos, incluindo estudos pré-clínicos de interações medicamentosas (DDI). As DDI ocorrem principalmente devido a inibições diretas e tempo-dependentes das enzimas do citocromo P450 (CYP450), uma superfamília de enzimas responsável por metabolizar cerca de 75% dos fármacos em uso. Os estudos pré-clínicos de DDI envolvem o conhecimento do potencial inibitório do candidato a fármaco sobre essas enzimas e esses estudos podem ser realizados empregando diversos modelos in vitro, como, por exemplo, microssomas hepáticos de humanos (HLM). Assim, nesse estudo foi avaliado o efeito inibitório da GRA sobre a atividade das principais isoformas do CYP450 e também foram determinadas as isoformas que contribuem para a formação dos metabólitos da GRA. Os resultados demonstraram que múltiplas isoformas participam da formação dos metabólitos da GRA, com destaque para a CYP2C9, que participa da formação de todos os metabólitos. Em relação aos estudos de inibição, foi possível concluir que a GRA é um inibidor fraco da CYP1A2 e CYP2D6, com valores de IC50 maiores do que 200 µM e 100 µM, respectivamente, e um inibidor moderado e competitivo da CYP2C9, com IC50 igual a 40,85 µM e Ki igual a 50,60 µM. Para a CYP3A4 o potencial inibitório da GRA foi avaliado utilizando dois substratos distintos. A GRA demonstrou ser tanto um inibidor dose-dependente moderado e competitivo dessa isoforma, quanto um inibidor tempo-dependente baseado em mecanismo com potencial de inativação equiparável ao do irinotecano, inibidor baseado em mecanismo clinicamente significativo. Utilizando a nifedipina como substrato os valores de IC50 e Ki foram 78,09 µM e 48,71 µM, respectivamente. Já os valores dos parâmetros cinéticos de inativação foram KI= 6,40 µM, kinact= 0,037 min-1 e Clinact= 5,78 mL min-1 µmol-1. Para os ensaios empregando o midazolam os valores de IC50 e Ki foram 48,87 µM e 31,25 µM, respectivamente, e os valores dos parâmetros cinéticos de inativação foram KI= 31,53 µM, kinact= 0,049 min-1 e Clinact= 1,55 mL min-1 µmol-1. Com relação a CYP2E1, por sua vez, foi possível observar que a GRA tem capacidade de aumentar a atividade dessa isoforma significativamente a partir da concentração de 4 µM. Portanto, conclui-se que não há risco da GRA apresentar interações medicamentosas com fármacos metabolizados pela CYP1A2 e CYP2D6, enquanto que para a CYP2C9, apesar da GRA ser um inibidor moderado dessa isoforma, o risco é baixo. Já para medicamentos metabolizados pela CYP2E1 e CYP3A4 o risco de DDI existe e isso deve ser cuidadosamente monitorado in vivo, principalmente porque a CYP3A4 é a isoforma responsável por catalisar o metabolismo da maioria dos fármacos. / (-)-grandisin (GRA) is a lignanic natural product found in many species of plants from North and Northeast of Brazil. This compound has several biological properties, such as trypanocide, anti-inflammatory, antinociceptive, antileukemia activity and antitumor activity against Ehrlich tumor. Because of these biological properties, GRA is considered a potential drug candidate, however, before becoming a new drug, GRA has to undergo various tests, including preclinical drug-drug interactions (DDI) studies. Most of the times, DDI occur because of direct and time-dependent inhibitions of cytochrome P450 (CYP450) enzymes, an enzyme superfamily responsible for metabolizing the vast majority of drugs administered. Preclinical drug-drug interactions studies involve the evaluation of the potential of a drug candidate to inhibit this superfamily of enzymes and these studies can be conducted using in vitro models, such as human liver microsomes (HLM). Therefore, in this project, the inhibitory effect of GRA on the activity of some CYP450 isoforms was evaluated and the isoforms that catalyze the formation of GRA\'s metabolites were also determined. Results showed that multiple CYP450 isoforms participate in the GRA\'s metabolites formation, highlighting CYP2C9, which catalyzes the formation of all metabolites. The inhibition studies showed that GRA is a weak inhibitor of CYP1A2 and CYP2D6, with IC50 values greater than 200 µM and 100 µM, respectively, and a moderate and competitive inhibitor of CYP2C9, with IC50 value equal to 40.85 µM and Ki value equal to 50.60 µM. The capability of GRA to inhibit CYP3A4 was evaluated using two different substrates. GRA showed to be a moderate and competitive dose- dependent inhibitor of this isoform and also a mechanism-based time-dependent inhibitor with potential of inactivation comparable to irinotecan, a clinically significant mechanism-based inhibitor. IC50 and Ki values obtained using nifedipine as substrate were 78.09 µM and 48.71 µM, respectively, and inactivation kinetics parameters were KI= 6.40 µM, kinact= 0,037 min-1 e Clinact= 5.78 mL min-1 µmol-1. On the other hand, IC50 and Ki values using midazolam as substrate were 48.87 µM and 31.25 µM, respectively, and the values of inactivation kinetics parameters were KI= 31.53 µM, kinact= 0,049 min-1 and Clinact= 1.55 mL min-1 µmol-1. With respect to CYP2E1, it was observed that GRA increases its activity significantly from a concentration of 4 µM. Therefore, it is possible to conclude that there is no risk of DDI between GRA and drugs metabolized by CYP1A2 and CYP2D6, while for CYP2C9, although GRA is a moderate inhibitor of this isoform, the risk is low. Finally, for drugs metabolized by CYP3A4 and CYP2E1 there is risk of DDI and this should be carefully monitored in humans, mainly because CYP3A4 is an isoform responsible for catalyzing the metabolism of most drugs in use.

O gênero Piper pertencente à família Piperaceae, encontra-se distribuído nas regiões tropicais e subtropicais do globo. Estudos químicos têm demonstrado diversidade de metabólitos secundários com atividade biológica. Os alcalóides são metabólitos característicos. A piplartina, (E)-1-(3-(3,4,5-trimetoxifenil)acriloil)-5,6- diidropiridin-2(1H)-ona, é um alcalóide encontrado em muitas espécies. Tem atividade citotóxica contra células de linhagem tumoral, ansiolítica, antidepressiva, antifúngica e antiagregação plaquetária, sendo dessa forma, uma molécula candidata a um novo fármaco. O conhecimento do metabolismo de um candidato a fármaco é um fator importante na avaliação da sua segurança e eficácia. Ensaios in vitro estão crescentemente sendo utilizados como screening e os microssomas hepáticos representam o sistema in vitro mais utilizado. Dessa forma, o presente trabalho tem como objetivo determinar os parâmetros cinéticos enzimáticos in vitro da piplartina utilizando microssomas de fígado de ratos, bem como a determinação dos possíveis metabólitos formados. Para tanto, foi desenvolvido um método de quantificação da piplartina utilizando cromatografia líquida de alta eficiência. Como condição de análise, empregou-se uma coluna C18, fase móvel acetonitrila:água (40:60, v/v) e vazão de 1 mL min-1. Para extração da piplartina dos microssomas hepático de ratos foi empregado a extração líquido-líquido utilizando 4,0 mL de hexano como solvente extrator. Após otimização da extração, o método foi validado, mostrando-se linear na faixa de 2,4-157,7 ?M, obtendo-se uma equação da reta y= 0,0934x + 0,0027, (r= 0,99) e limite de quantificação de 2,4 ?M. A recuperação média foi de 85%. A precisão e exatidão apresentaram resultados dentro do recomendável pela ANVISA. A piplartina manteve-se estável até 50 minutos em condições de incubação, e até 6h sob a bancada. Após validação da metodologia, estabeleceram-se as condições lineares para a quantidade de proteínas microssomais: 0,28 mg mL-1 e para o tempo de incubação: 16 minutos no consumo da piplartina no meio microssomal, e então efetuou-se a determinação dos parâmetros cinéticos enzimáticos da piplartina empregando as condições de V0. Nesse estudo foi observado um Vmax= 4,74 ± 0,26 ?M/?g mL-1/min, h= 2,53 ± 0,37, S50= 44,69 ± 0,32 ?M e CLmax= 0,054 ?L/min/mg proteina, um perfil cinético indicativo de cooperatividade. Um estudo qualitativo para determinação dos possíveis metabólitos foi feito utilizando-se a espectrometria de massas, por meio da qual foi possível identificar a formação de dois produtos hidroxilados. Deste modo, os microssomas mostraram-se uma ferramenta útil, rápida e simples para determinação da cinética enzimática, e na condução dos estudos preliminares de metabolismo in vitro. / The genus Piper belongs to the Piperaceae family and includes species that are widely distributed throughout the tropical and subtropical regions of the world. Chemical studies have shown diversity of secondary metabolites with biological activity. The alkaloids are characteristic metabolites. The piplartine, (E)-1-(3-(3,4,5- trimethoxyphenyl)acryloyl)-5,6-diidropiridin-2(1H)-one is an alkaloid found in many species. It shows cytotoxic activity against tumor cell lines, anxiolytic, antidepressant, antifungal, and antiplatelet therapy, thus being a drug candidate. The knowledge regarding the oxidative metabolism is an important tool in assessing the safety and efficacy of a drug candidate. In vitro assays are increasingly being used as a screening tool and liver microsomes represent the most widely in vitro system used for that. This study aims to determine the in vitro enzymatic kinetic parameters for piplartine by cytochrome P450 enzymes (CYP) present in the rat liver microsomes, and the determination of possible metabolites. To accomplish, it was developed a method to quantify the piplartine using high performance liquid chromatography. The analysis was carried out employing a C18 column, mobile phase: acetonitrile: water (40:60, v/v) at a flow rate of 1 ml min-1. To extract piplartine from rat liver microsomes it was employed the liquid-liquid extraction (4.0 mL of hexane). The method was validated and proved to be linear in the range of 2.4 to 157.7 ?M, the equation for calibration curve was: y= 0.0934x + 0.0027 (r = 0.99), and a limit of quantification of 2.4 ?M. The mean recovery was 85%. The precision and accuracy were in agreement with ANVISA guidelines. The piplartine remained stable until 50 minutes of incubation conditions, and until 6 hours under the bench. Once validated, it was set the conditions for the linear amount of microsomal protein: 0.28 mg mL-1 and to the incubation time: 16 minutes, then it was performed the determination of enzymatic kinetic parameters, that revealed a sigmoidal profile with Vmax = 4.74 ± 0.26 ?M/mg mL-1/min, h = 2.53 ± 0.37, S50 = 44.69 ± 0.32 ?M, and CLmax = 0.054 ?L/min/mg protein, indicating a cooperativity behavior. A qualitative study to determine possible metabolites carried out using mass spectrometry, through which it was possible to identify the formation of two hydroxylated products. To conclude, the microsomes showed to be a useful, fast and simple tool to determination of enzymatic kinetics and in vitro metabolism studies.

Phosphodiesterase 2A (PDE2A) is highly expressed in distinct areas of the brain, which are known to be related to neuropsychiatric diseases. The development of suitable PDE2A tracers for Positron Emission Tomography (PET) would permit the in vivo imaging of the PDE2A and evaluation of disease-mediated alterations of its expression. A series of novel fluorinated PDE2A inhibitors on the basis of a Benzoimidazotriazine (BIT) scaffold was prepared leading to a prospective inhibitor for further development of a PDE2A PET imaging agent. BIT derivatives (BIT1–9) were obtained by a seven-step synthesis route, and their inhibitory potency towards PDE2A and selectivity over other PDEs were evaluated. BIT1 demonstrated much higher inhibition than other BIT derivatives (82.9% inhibition of PDE2A at 10 nM). BIT1 displayed an IC50 for PDE2A of 3.33 nM with 16-fold selectivity over PDE10A. This finding revealed that a derivative bearing both a 2-fluoro-pyridin-4-yl and 2-chloro-5-methoxy-phenyl unit at the 8- and 1-position, respectively, appeared to be the most potent inhibitor. In vitro studies of BIT1 using mouse liver microsomes (MLM) disclosed BIT1 as a suitable ligand for 18F-labeling. Nevertheless, future in vivo metabolism studies are required.

TRPC6, the sixth member of the family of canonical transient receptor potential (TRP) channels, contributes to a variety of physiological processes and human pathologies. This study extends the knowledge on the newly developed TRPC6 blocker SH045 with respect to its main target organs beyond the description of plasma kinetics. According to the plasma concentration-time course in mice, SH045 is measurable up to 24 h after administration of 20 mg/kg BW (i.v.) and up to 6 h orally. The short plasma half-life and rather low oral bioavailability are contrasted by its reported high potency. Dosage limits were not worked out, but absence of safety concerns for 20 mg/kg BW supports further dose exploration. The disposition of SH045 is described. In particular, a high extravascular distribution, most prominent in lung, and a considerable renal elimination of SH045 were observed. SH045 is a substrate of CYP3A4 and CYP2A6. Hydroxylated and glucuronidated metabolites were identified under optimized LC-MS/MS conditions. The results guide a reasonable selection of dose and application route of SH045 for target-directed preclinical studies in vivo with one of the rare high potent and subtype-selective TRPC6 inhibitors available

No / Cytochrome P450 (CYP) is one of the most important drug-metabolizing enzyme families, which participates in the biotransformation of many endogenous and exogenous compounds. Quantitative analysis of CYP expression levels is important when studying the efficacy of new drug molecules and assessing drug-drug interactions in drug development. At present, chemical probe-based assay is the most widely used approach for the evaluation of CYP activity although there are cross-reactions between the isoforms with high sequence homologies. Therefore, quantification of each isozyme is highly desired in regard to meeting the ever-increasing requirements for carrying out pharmacokinetics and personalized medicine in the academic, pharmaceutical, and clinical setting. Herein, an absolute quantification method was employed for the analysis of the seven isoforms CYP1A2, 2B6, 3A4, 3A5, 2C9, 2C19, and 2E1 using a proteome-derived approach in combination with stable isotope dilution assay. The average absolute amount measured from twelve human liver microsomes samples were 39.3, 4.3, 54.0, 4.6, 10.3, 3.0, and 9.3 (pmol/mg protein) for 1A2, 2B6, 3A4, 3A5, 2C9, 2C19, and 2E1, respectively. Importantly, the expression level of CYP3A4 showed high correlation (r = 0.943, p < 0.0001) with the functional activity, which was measured using bufalin-a highly selective chemical probe we have developed. The combination of MRM identification and analysis of the functional activity, as in the case of CYP3A4, provides a protocol which can be extended to other functional enzyme studies with wide application in pharmaceutical research.

En raison de la diffusion incontrôlée sur le e-commerce, la sécurité et l’alternative légale aux stupéfiants habituels, les nouvelles substances psychoactives (NPS), d’apparition récente (2008), sont au cœur des phénomènes récents d’addiction et de décès mal expliqués. Au-delà des différents défis dans nos sociétés (prévention, législation), la capacité d’identifier les NPS dans des échantillons biologiques pour caractériser leur utilisation, présente de nombreux challenges analytiques. L’objectif principal de cette thèse a été de collecter des échantillons biologiques (sang, urine, cheveux) provenant de cas d’exposition à des NPS et d’y caractériser les substances présentes à l’aide de méthodes analytiques originales, dans le but d’enrichir les librairies de spectres de masse et d’améliorer, en conséquence, la détection de la consommation de NPS. En particulier, il s’agissait d’augmenter la fenêtre de détection de la prise de NPS en se focalisant sur les métabolites qui sont, le plus souvent, les produits majeurs d’élimination. Le développement analytique, par chromatographie liquide ultra haute performance couplée à la spectrométrie de masse en tandem (UHPLC-MS/MS), a demandé plusieurs mois d’optimisation afin d’obtenir une méthode robuste, exhaustive et sensible. Actuellement, la librairie de spectres MS comporte 114 NPS et est mise à jour régulièrement. A la suite de ce développement, ma thèse a porté sur l’étude de cas d’intoxication vus au service des urgences du CHU de Strasbourg, mais aussi en médecine légale, avec des situations de décès et d’identification de produits inconnus provenant de saisies (poudres et cristaux). Il a également été nécessaire de développer des outils analytiques complémentaires, tels que la caractérisation de métabolite(s) par étude sur microsomes hépatiques humains (HLMs), et l’utilisation de la spectroscopie par résonance magnétique nucléaire (RMN) afin d’identifier avec certitude certains composés et de déterminer leur degré de pureté. Les outils analytiques développés et la stratégie mise en place ont permis la rédaction de 18 publications, ainsi que l’agencement de nombreuses collaborations. / Due to the uncontrolled spread on the Internet and their legal alternative to usual drugs, the new psychoactive substances (NPS), recently appeared (2008), are at the center of recent phenomena of addiction and badly explained deaths. Beyond different challenges in our societies (prevention, legislation), the ability to identify NPS in biological samples, in order to characterize their use, presents many analytical challenges. The main objective of this thesis was to collect biological samples (blood, urine, hair) from cases of exposure to NPS and to characterize the substances present using original analytical methods, in order to enlarge the libraries of mass spectra and improve, as a result, the detection of NPS consumption. In particular, it was intended to increase the detection sensitivity of NPS intake by focusing on the metabolites that are often the major products of elimination. This analytical development, by ultra-high liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS), required several months of optimization in order to obtain a robust, exhaustive and sensitive method. At present, the mass spectra database has 114 NPS and is regularly updated. Thereafter, ma thesis focused on the study of cases of intoxication observed in the emergency department of Strasbourg, but also in legal medicine with situations of deaths and identification of unknown products collected from seizures (powders and crystals). It has also been necessary to implement complementary analytical tools, such as the characterization of metabolites by human liver microsomes (HLMs), and the use of nuclear magnetic resonance (NMR) spectroscopy to accurately identify the compounds and establish their purity degrees. The analytical tools developed, and the strategy adopted, allowed the writing of 18 publications, as well as the setting up of numerous collaborations.

Indiana University-Purdue University Indianapolis (IUPUI) / Fatty acid elongation is the extension of de novo synthesized fatty acids through a series of four reactions analogous to those of fatty acid synthase. ELOs catalyze the first reaction in the elongation pathway through the condensation of an acyl group with a two carbon unit derived from malonyl-CoA. This study uses the condensing enzyme, EloA, from the cellular slime mold, Dictyostelium discoideum as a model for the family of ELOs. EloA has substrate specificity for monounsaturated and saturated C16 fatty acids and catalyzes the elongation of 16:1Δ9 to 18:1Δ11. Site-directed mutagenesis was used to change residues highly conserved among the ELO family to examine their potential role in the condensation reaction. Mutant EloAs were expressed in yeast and fatty acid methyl esters prepared from total cellular lipids were analyzed by gas chromatography/mass spectrometry. Sixteen out of twenty mutants had a decrease in 18:1Δ11 production when compared to the wild-type EloA with little to no activity observed in ten mutants, four mutants had within 20% of wild-type activity, and six mutants had 10-60% of wild-type activity. Immunoblot studies using anti-EloA serum were used to determine if the differences in elongation activity were related to changes in protein expression for each mutant. Analysis of immunoblots indicated that those mutants with little to no activity, with the exception of T130A and Q203A, had x comparable protein expression to the wild-type. Further research included the solubilization of the His6-ELoA fusion protein and preliminary work toward the isolation of the tagged protein and the use of a radiolabeled condensation assay to determine the activity of the eluted protein. Preliminary results indicated that the protein was solubilized but the eluted protein showed no activity when examined by a condensation assay. The work presented here contributes to a better understanding of the role of certain amino acid residues in the activity of EloA and serves as a stepping-stone for future EloA isolation work.

No / Here we report the identification and approximate quantification of cytochrome P450 (CYP) proteins in human liver microsomes as determined by nano-LC-MS/MS with application of the exponentially modified protein abundance index (emPAI) algorithm during database searching. Protocols based on 1D-gel protein separation and 2D-LC peptide separation gave comparable results. In total, 18 CYP isoforms were unambiguously identified based on unique peptide matches. Further, we have determined the absolute quantity of two CYP enzymes (2E1 and 1A2) in human liver microsomes using stable-isotope dilution mass spectrometry, where microsomal proteins were separated by 1D-gel electrophoresis, digested with trypsin in the presence of either a CYP2E1- or 1A2-specific stable-isotope labeled tryptic peptide and analyzed by LC-MS/MS. Using multiple reaction monitoring (MRM) for the isotope-labeled tryptic peptides and their natural unlabeled analogues quantification could be performed over the range of 0.1-1.5 pmol on column. Liver microsomes from four individuals were analyzed for CYP2E1 giving values of 88-200 pmol/mg microsomal protein. The CYP1A2 content of microsomes from a further three individuals ranged from 165 to 263 pmol/mg microsomal protein. Although, in this proof-of-concept study for CYP quantification, the two CYP isoforms were quantified from different samples, there are no practical reasons to prevent multiplexing the method to allow the quantification of multiple CYP isoforms in a single sample.

No / We identify cytochrome P450 1A1 (CYP1A1) as a target for tumor-selective drug development in bladder cancer and describe the characterization of ICT2700, designed to be metabolized from a prodrug to a potent cytotoxin selectively by CYP1A1. Elevated CYP1A1 expression was shown in human bladder cancer relative to normal human tissues. RT112 bladder cancer cells, endogenously expressing CYP1A1, were selectively chemosensitive to ICT2700, whereas EJ138 bladder cells that do not express CYP1A1 were significantly less responsive. Introduction of CYP1A1 into EJ138 cells resulted in 75-fold increased chemosensitivity to ICT2700 relative to wild-type EJ138. Negligible chemosensitivity was observed in ICT2700 in EJ138 cells expressing CYP1A2 or with exposure of EJ138 cells to CYP1B1- or CYP3A4-generated metabolites of ICT2700. Chemosensitivity to ICT2700 was also negated in EJ138-CYP1A1 cells by the CYP1 inhibitor alpha-naphthoflavone. Furthermore, ICT2700 did not induce expression of the AhR-regulated CYP1 family, indicating that constitutive CYP1A1 expression is sufficient for activation of ICT2700. Consistent with the selective activity by CYP1A1 was a time and concentration-dependent increase in gamma-H2AX protein expression, indicative of DNA damage, associated with the activation of ICT2700 in RT112 but not EJ138 cells. In mice-bearing CYP1A1-positive and negative isogenic tumors, ICT2700 administration resulted in an antitumor response only in the CYP1A1-expressing tumor model. This antitumor response was associated with detection of the CYP1A1-activated metabolite in tumors but not in the liver. Our findings support the further development of ICT2700 as a tumor-selective treatment for human bladder cancers.