The Dong research group is interested in harnessing the power of transition metal catalysis to transform simple molecules and reagents (such as carbon monoxide, hydrogen gas, olefins, and C–H and C–O bonds) into valuable products (such as functionalized heterocycles, chiral carbonyl compounds and natural products). This thesis will describe our continual effort to achieve this goal. Part I describes the Pd-catalyzed functionalization of sp2 and sp3 C–H bonds. Carbon monoxide is used as a stoichiometric reductant in the cyclization of diarylnitroalkenes to afford biologically relevant 3-arylindoles and other N-containing heterocycles with carbon dioxide as the only stoichiometric byproduct. Also, an aryl sulfoxide moiety is shown to direct the arylation of sp3 C–H bonds to afford beta-functionalized amides. Part II describes the Ru-catalyzed sp3 C–O bond activation of alkoxypyridines and related heterocycles. In this transformation, an O- to N-alkyl migratory rearrangement occurs to afford N-alkylated pyridones which are structures found in many natural products and pharmaceutical agents. Part III describes our pursuit of metal-catalyzed asymmetric synthesis. Readily available benzylic bromides are carbonylated with carbon monoxide in alcoholic solvent mixtures. The resulting medicinally relevant 2-arylpropionic esters are obtained with moderate to good enantioselectivities. Preliminary results for the asymmetric hydrogenation of gem-diarylethylenes and novel ligand development are also disclosed. Part IV describes our efforts towards the total synthesis of 6-deoxyerythronolide B. Our retrosynthetic analysis of the macrolide antibiotic involves disconnections at the lactone linkage and between C7 and C8. The two equally complex fragments were prepared via reliable aldol, hydroboration, crotylation and redox chemistry. Rather than the typical macrolactonization method to form the 14-membered ring, we propose an alternative strategy where we plan to cyclize with a metal-catalyzed ring-closing metathesis event. Currently, this step is under investigation by other members in the group.

The Dong research group is interested in harnessing the power of transition metal catalysis to transform simple molecules and reagents (such as carbon monoxide, hydrogen gas, olefins, and C–H and C–O bonds) into valuable products (such as functionalized heterocycles, chiral carbonyl compounds and natural products). This thesis will describe our continual effort to achieve this goal. Part I describes the Pd-catalyzed functionalization of sp2 and sp3 C–H bonds. Carbon monoxide is used as a stoichiometric reductant in the cyclization of diarylnitroalkenes to afford biologically relevant 3-arylindoles and other N-containing heterocycles with carbon dioxide as the only stoichiometric byproduct. Also, an aryl sulfoxide moiety is shown to direct the arylation of sp3 C–H bonds to afford beta-functionalized amides. Part II describes the Ru-catalyzed sp3 C–O bond activation of alkoxypyridines and related heterocycles. In this transformation, an O- to N-alkyl migratory rearrangement occurs to afford N-alkylated pyridones which are structures found in many natural products and pharmaceutical agents. Part III describes our pursuit of metal-catalyzed asymmetric synthesis. Readily available benzylic bromides are carbonylated with carbon monoxide in alcoholic solvent mixtures. The resulting medicinally relevant 2-arylpropionic esters are obtained with moderate to good enantioselectivities. Preliminary results for the asymmetric hydrogenation of gem-diarylethylenes and novel ligand development are also disclosed. Part IV describes our efforts towards the total synthesis of 6-deoxyerythronolide B. Our retrosynthetic analysis of the macrolide antibiotic involves disconnections at the lactone linkage and between C7 and C8. The two equally complex fragments were prepared via reliable aldol, hydroboration, crotylation and redox chemistry. Rather than the typical macrolactonization method to form the 14-membered ring, we propose an alternative strategy where we plan to cyclize with a metal-catalyzed ring-closing metathesis event. Currently, this step is under investigation by other members in the group.

Biologically active peptides are important for many physiological functions in the human body and therefore serve as interesting starting points in drug discovery processes. In this work the neuropeptide substance P 1–7 (SP1–7, H-Arg-Pro-Lys-Pro-Gln-Gln-Phe-OH), which has been demonstrated to reduce neuropathic pain and attenuate opioid withdrawal symptoms in animal models, has been addressed in a medicinal chemistry program with the overall aim of transforming this bioactive peptide into more drug-like compounds. Specific binding sites for this neuropeptide have been detected in the brain and the spinal cord. Interestingly, the smaller neuropeptide endomorphin-2 (EM-2, H-Tyr-Pro-Phe-Phe-NH2) also interacts with these binding sites, although 10-fold less efficient. In this work the structure–activity relationship of SP1–7 and EM-2, regarding their affinity to the SP1–7 binding site was elucidated using alanine scans, truncation, and terminal modifications. The C-terminal part of both peptides, and especially the C-terminal phenylalanine, was crucial for binding affinity. Moreover, the C-terminal functional group should preferably be a primary amide. The truncation studies finally resulted in the remarkable discovery of H-Phe-Phe-NH2 as an equally good binder as the heptapeptide SP1–7. This dipeptide amide served as a lead compound for further studies. In order to improve the drug-like properties and to find a plausible bioactive conformation, a set of rigidified and methylated dipeptides of different stereochemistry, and analogs with reduced peptide character, were synthesized and evaluated regarding binding, metabolic stability and absorption. Small SP1–7 analogs with retained affinity and substantially improved permeability and metabolic stability were identified. Beside peptide chemistry the synthetic work included the development of a fast and convenient microwave-assisted protocol for direct arylation of imidazoles. Furthermore, microwave-assisted aminocarbonylation using Mo(CO)6 as a solid carbon monoxide source was investigated in the synthesis of MAP amides and for coupling of imidazoles with amino acids. In a future perspective the present findings, together with the fact that some of the SP1–7 analogs discovered herein have been shown to reproduce the biological effects of SP1-7 in animal studies related to neuropathic pain and opioid dependence, can ultimately have an impact on drug discovery in these two areas.

Palladium-catalysed carbonylative multicomponent reactions have proven useful for the synthesis of structurally diverse compounds. Carbon monoxide serves as an atom-efficient, one-carbon building block, which allows for further structural elaboration of the carbonyl compound. By varying the components of the carbonylative multicomponent reaction, considerable product diversity can readily be attained. However, due to the reluctance to use toxic CO gas, considerable efforts have been directed at exploring non-gaseous approaches. The work described in this thesis has mainly focused on the development of palladium(0)-catalysed, carbonylative multicomponent synthetic methodology, using the non-gaseous CO source molybdenum hexacarbonyl, in the synthesis of heterocycles and other biologically relevant functional groups. The first part of this work describes the development of a non-gaseous carbonylative Sonogashira cross-coupling of bifunctional ortho-iodoanilines and terminal alkynes. Where 4-quinolones were synthesised via a carbonylation/cyclisation sequence. Using a similar synthetic strategy, three different N-cyanobenzamide intermediates were prepared by palladium-catalysed carbonylative couplings of various aryl halides and bromides and cyanamide. The formed intermediates provided a basis for further chemical transformations. First, ortho-iodoanilines were carbonylatively coupled with cyanamide and subsequently cyclised to yield heterocyclic 2-aminoquinazolinones. Next, building on those findings, the same synthetic strategy was applied to ortho-halophenols to provide a highly convenient domino carbonylation/cyclisation method for the preparation of benzoxazinones. The developed method was used to evaluate the efficiency of various non-gaseous CO sources. Third, the palladium-catalysed carbonylative synthesis of N-cyanobenzamides, was used to produce biologically relevant N-acylguanidines with considerable product diversity. Finally, one of the developed carbonylative methodologies was used in the preparation of potential NDH-2 inhibitors based on a quinolinyl pyrimidine scaffold. The prepared compounds were biologically evaluated in terms of inhibition of oxidoreductase NDH-2 and antibacterial activity on Gram-negative bacteria, S. aureus and Mtb. The biological evaluation revealed that some of the quinolinyl pyrimidines exerted inhibitory activity on the NDH-2 enzyme and possessed antibacterial properties. The work described in this thesis has been devoted to the development of non-gaseous one-pot, multicomponent carbonylation/cyclisation and carbonylation/amination reactions. The described methods offer highly attractive synthetic strategies that can be of great value to synthetic and medicinal chemists.

This thesis deals with the development of new reaction methodology as well as stereochemical investigations. The first part concerns the investigation of 1,2- and merged 1,2- and 1,3- asymmetric induction in Mukaiyama aldol additions to α-heteroatom and α,β- heteroatom substituted aldehydes respectively. In particular, the unexpected 1,2-syn selectivity obtained in the addition of sterically hindered nucleophiles to α-chloroaldehydes is examined, and an explanation for the observed stereochemical trends is proposed. The second part describes the development of a novel entry to α-amino-β- hydroxy esters by a 1,3-dipolar cycloaddition reaction of aldehydes and azomethine ylides, generated by thermolysis of aziridines. The third part deals with our efforts to develop a novel entry to vicinal all- carbon quaternary centers, based on an intramolecular domino Heck- carbonylation reaction using tetrasubstituted olefins. / QC 20120611

Protein carbonylation, a marker of excessive oxidative stress, has been studied in the context of multiple human diseases related to oxidative stress. The variety of post-translational carbonyl modifications (carbonyl PTMs) and their low concentrations in plasma challenge their reproducible identification and quantitation. However, carbonyl-specific biotinylated derivatization tags (e.g., aldehyde reactive probe, ARP) allow for targeting carbonyl PTMs by enriching proteins and peptides carrying these modifications. In this study, an oxidized human serum albumin protein model (OxHSA) and plasma from a healthy donor were derivatized with ARP, digested with trypsin, and enriched using biotin-avidin affinity chromatography prior to nano reversed-phase chromatography coupled online to electrospray ionization tandem mass spectrometry with travelling wave ion mobility spectrometry (nRPC-ESI-MS/MS-TWIMS). The presented workflow addresses several analytical challenges by using ARP-specific fragment ions to reliably identify ARP peptides. Furthermore, the reproducible recovery and relative quantitation of ARP peptides were validated. Human serum albumin (HSA) in plasma was heavily modified by a variety of direct amino acid oxidation products and adducts from reactive carbonyl species (RCS), with most RCS modifications being detected in six hotspots, i.e., Lys10, Lys190, Lys199, Lys281, Lys432, and Lys525 of mature HSA.

Traumatic Brain Injury (TBI) is the major cause of death or cognitive deficits in industrialized countries. Although studies have indicate that the oxidative stress and functional deficits after TBI are connected events, the mechanisms that outline the development of these cognitive deficits are, still, limited. In this context, we investigated the involvement of oxidative stress markers (thiobarbituric acid reactive species; TBARS and protein carbonylation) and the Na+,K+-ATPase enzyme activity on the spatial learning after one and three months from a fluid percussion injury (FPI) in rats. The results revealed that FPI increase the latency of escape and the number of the errors on the Barnes Maze Test one and three months after FPI. We also found an increase of TBARS and protein carbonylation in parietal cortex after one and three months FPI. In addition, statistical analysis revealed a decrease of the Na+,K+- ATPase enzyme activity in the parietal cortex after FPI (time-dependent). These results suggest that cognitive impairment following FPI may result, at least in part, from increase of two oxidative stress markers, protein carbonylation and TBARS that occurs concomitantly to a decrease in Na+,K+-ATPase activity. Physical exercise, despite the involvement on the generation of the reactive oxygen species (ROS), is used on the rehabilitation of TBI. However, although the favorable effects of physical exercise on traumatic brain injury (TBI) patients is well known, the specific mechanisms involved in this protection after TBI has been limited. Thus, we investigated whether physical training protects against oxidative damage (measured by protein carbonylation and TBARS) and neurochemical alterations represented by immunodetection of alpha subunit and activity of Na+,K+-ATPase after FPI in cerebral cortex of rats. The results revealed that physical training protected against oxidative damage induced by FPI. In addition, physical training was effective against Na+,K+- ATPase enzyme activity inhibition and α subunit level decrease after FPI. The Pearson correlation showed that the decrease of the catalytical levels of the Na+,K+- ATPase enzyme α subunit is related with the increasing on oxidative stress markers. Moreover, the physical activity-related protection against free radicals induced by FPI links with maintenance of α subunit immunocontent. These results suggest that the effective protection stimulated by physical exercise on the neuronal damage induced by TBI has connection with the protection of the specific targets from the free radicals action, like Na+,K+-ATPase enzyme. / O Traumatismo crânio-encefálico (TCE) é uma das maiores causas de morte ou déficits cognitivos nos países industrializados. Apesar de os estudos indicarem que o estresse oxidativo e os déficits funcionais que ocorrem após TCE serem eventos interrelacionados, os mecanismos que delineiam o desenvolvimento destes déficits cognitivos são, ainda, limitados. Neste contexto nós investigamos o envolvimento de marcadores de estresse oxidativo (espécies reativas ao ácido tiobarbitúrico; TBARS e carbonilação protéica) e a atividade da enzima Na+,K+-ATPase no aprendizado espacial um e três meses após um dano de percussão por fluído (FPI) em ratos. Os resultados revelaram que o FPI aumentou o tempo de latência e o número de erros no teste do labirinto de Barnes em um e três meses após FPI. Também encontramos aumento no conteúdo de TBARS e proteína carbonil no córtex parietal em um e três meses após FPI. Além disso, a análise estatística revelou uma diminuição na atividade da enzima Na+,K+-ATPase no córtex cerebral após FPI tempo dependente, sugerindo que o déficit cognitivo induzido pelo FPI se deva pela perda de funcionabilidade de enzimas presentes na células como Na+,K+-ATPase. Perda esta induzida pelo aumento na geração de radicais livres após TCE. Apesar de estar envolvido no aumento da produção de espécies reativas ao Oxigênio (ERO), exercício físico tem sido utilizado na reabilitação de após TCE. Por outro lado, ainda são escassos na literatura estudos que evidenciam a especificidade dos mecanismos envolvidos na proteção induzida pelo exercício físico após TCE. Desta forma, investigamos se o treinamento físico protege contra o dano oxidativo bem como das alterações neuroquímicas representadas pela imunodetecção da subunidade α e da atividade da enzima Na+,K+-ATPase no córtex cerebral de ratos. Os resultados revelaram que o treinamento físico protegeu contra o dano oxidativo induzido por FPI. Além disso, o treinamento físico foi efetivo contra a inibição da enzima Na+,K+-ATPase e a diminuição dos níveis da sua subunidade α após FPI. A correlação de Pearson revelou que a diminuição dos níveis catalíticos da subunidade α da enzima Na+,K+-ATPase se correlaciona com o aumento dos marcadores de estresse oxidativo. Além disso, a proteção exercida pela atividade física contra os radicais livres induzidos por FPI tem relação com a manutenção do imunoconteúdo da subunidade α. A partir destes achados, sugere-se que a efetiva proteção exercida pelo exercício físico no dano neuronal causado induzido pelo TCE se deva pela proteção de alvos específicos a ação de radicais livres, como a enzima Na+, K+-ATPase.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-05-04T12:42:14Z No. of bitstreams: 1 angelinamariadealmeida.pdf: 23133254 bytes, checksum: 7560d658fe12ed7f6166fc99ab314157 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-17T13:30:51Z (GMT) No. of bitstreams: 1 angelinamariadealmeida.pdf: 23133254 bytes, checksum: 7560d658fe12ed7f6166fc99ab314157 (MD5) / Made available in DSpace on 2017-05-17T13:30:51Z (GMT). No. of bitstreams: 1 angelinamariadealmeida.pdf: 23133254 bytes, checksum: 7560d658fe12ed7f6166fc99ab314157 (MD5) Previous issue date: 2016-07-29 / CAPES - Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Os valores terapêuticos do ouro são conhecidos desde a China antiga e, atualmente, complexos de ouro são empregados no tratamento da artrite reumatóide. Outras propriedades biológicas relativas aos complexos de ouro(I) vêm sendo reportadas na literatura, como atividade antitumoral, antibacteriana, antiviral e antifúngica. A primeira parte dessa tese descreve a síntese de novos complexos lipofílicos de ouro(I) contendo núcleo 1,3,4-oxadiazol-2-tiona ou 1,3-tiazolidina-2-tiona, além de serem constituídos por fosfinas terciárias, como trifenilfosfina ou trietilfosfina. Após caracterização através de métodos espectroscópicos usuais (RMN de 1H, 13C, 31P, IV e EMAR), foram realizadas avaliações biológicas in vitro para todos os complexos de ouro(I) e seus respectivos ligantes orgânicos. Os resultados citotóxicos frente a linhagens tumorais (CT26WT e B16F10) e normais (BHK21) indicam acentuada atividade antitumoral devido aos baixos valores de IC50 quando comparados aos valores obtidos para os ligantes orgânicos e para a Cisplatina. A atividade antibacteriana dos complexos de ouro(I) contra as bactérias Gram-positivas Staphylococcus aureus e Staphylococcus epidermidis também mostrou-se satisfatória, uma vez que os complexos exibem baixos valores de CIM comparados aos resultados obtidos para os ligantes orgânicos e cloranfenicol. O desenvolvimento de metodologias de catálise por metais de transição, em especial o uso de paládio, tem atraído considerável atenção no meio acadêmico e industrial. Assim, a segunda parte do trabalho aborda o desenvolvimento de um método geral de preparação de ésteres ativos via alcoxicarbonilação catalisada por paládio e o acoplamento carbonilativo entre haletos de arila, cianato de potássio, álcoois e monóxido de carbono catalisada por paládio. Em ambos os casos, verifica-se a generalidade dos protocolos devido à diversidade e aos bons rendimentos do escopo obtido a partir de diferentes nucleófilos e haletos aromáticos e heteroaromáticos. / Therapeutic gold values are known since ancient China and gold complexes are currently employed in the treatment of rheumatoid arthritis. Other biological properties relative to the complexes of gold(I) have been reported in the literature, such as antitumor activity, antibacterial, antiviral and antifungal. The first part of this thesis describes the synthesis of novel lipophilic complexes of gold(I) containing core 1,3,4-oxadiazol-2-thione or 1,3-thiazolidine-2-thione, and they are constituted by tertiary phosphines, such as triphenylphosphine or triethylphosphine. After characterization using usual analythical methods (NMR 1H, 13C, 31P, IR and HRMS) the biological evaluations were performed in vitro for all complexes of gold(I) and their organic ligands. The cytotoxic results against tumor cells (CT26WT and B16F10) and normal cells (BHK21) show pronounced antitumor activity due to low IC50 values compared to the values obtained for the corresponding ligands and Cisplatin. The antibacterial activity for the complexes of gold(I) against Gram-positive bacteria Staphylococcus aureus and Staphylococcus epidermidis also proved to be satisfactory, since the complexes exhibit low MIC values compared to the results obtained for the ligands and chloramphenicol. The development of catalytic methodologies by transition metals, in particular the use of palladium, has attracted considerable attention in the academia and industry. Thus, the second chapter covers the development of a general method for preparation of active esters via palladium catalyzed alkoxycarbonilation and carbonilative coupling of aryl halides, potassium cyanate, alcohols and carbon monoxide. In both cases the generality of the protocols is confirmed by the diversity and good yields obtained to the scope from different nucleophiles and aromatic and heteroaromatic halides.

Beneath glycation, oxidation reactions may take place at cereal proteins during production of malt. The extent of oxidative chemical changes at malt proteins has not yet been studied. In the present short communication, malt protein was characterized by the determination of free thiol groups and degree of methionine oxidation as well as the sites that are reactive to covalent modification by 2,4-dinitrophenylhydrazine (DNPH, “protein carbonylation”). Protein carbonylation in pale malts was around 1.5 nmol/mg protein and increased with increasing malt colour. Investigations on the protein pellet isolated for determination of carbonylation revealed that solubility and colour may disturb the quantification of carbonyl sites in roasted malts. Free thiols decreased with increasing malt colour already in pale malts (EBC < 10). The formation of methionine sulfoxide (MetSO) was intensified with increasing malt colour. An amount of 7–20% of methionine was converted to MetSO in pale and dark malt, whereas nearly 60% of methionine was oxidized to MetSO in roasted malts. The formation of methionine sulfone was negligible. This study shows that malt proteins suffer from oxidation during kilning, and future studies will have to show whether this supports the pro- or antioxidant activity of malt.

No description available.