New reductive addition of hard nucleophiles to 6,7-bis(methylsulfanyl)-1,4-dihydro-1,4-methanonaphthalene-5,8-dione

A new reaction mode of 6,7-bis(methylsulfanyl)-1,4-dihydro-1,4-methanonaphthalene-5,8-dione 1 with the hard nucleophiles sodium benzene- or methane-sulfinate and cyanide, in DMSO, at room temperature, leads to the unexpected hydroquinonoid products 3a-c. All the data are in agreement with a mechanistic pathway involving the initial attack of the hard nucleophile onto the hard carbonyl group, followed by a symbiotic re-attack of the oxygen on the incoming group. In the case of soft nucleophiles, reaction on the olefinic carbon of the enedione system is preferential.

Degradação da manipueira utilizando reator de lodo ativado em batelada sequencial com elevado tempo de paralisação intermitente da aeração

Conselho Nacional de Desenvolvimento em Pesquisa (CNPq)

Maternal protein restriction increases respiratory and sympathetic activities and sensitizes peripheral chemoreflex in male rat offspring

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influência do tratamento superficial 3IP na vida em fadiga dos aços ABNT 4340 e 15-5PH para aplicação aeronáutica

Pós-graduação em Engenharia Mecânica - FEG

Chemoreflex and baroreflex alterations in Parkinsonism induced by 6-OHDA in unanesthetized rats

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Composição físico-química e propriedades tecnológicas da farinha de folhas de mandioca

Cassava leaves can be considered an important nutritional source when compared to other commonly consumed vegetables leaves. Cassava leaves have high levels of protein, fiber and minerals, and arestill underexplored due to the lack of information regarding the use of them as afood product, as well as, their use as an industrial raw material. The consumption of cassava leaves in fresh form is impractical due to the presence of cyanide, thereby it is required a pretreatment to be performed to reduce this component. The objective of this study was to produce and characterize the four made with cassava leaves as its chemical composition, color, indices of absorption and water solubility, and pasting properties, aiming to provide information of interest for possible application as an ingredient in the food industry. Cassava leaf flour showed low moisture content (6.6 %)and significant amounts of fiber (30.68 %), protein (23.00 %), and total carbohydrate (22.27%). Drying and milling processes allowed to obtain a flour with a low content of total cyanide (0.3 mg 100g-1 ), and the presence of vitamin C (56.6 mg 100g-1 ) and β –carotene (38 mg 100g- 1 ). The color analysis of cassava leaf flour showed low lightness with, predominantly, green and yellow pigments. The cassava leaf flour presented good solubility (14.85 %) and water absorption (6.87 g gel. g-1 ). Pasting properties showed a low peak of viscosity and a higher final viscosity with a retrogradation tendency, indicating a low capacity of this flour to form gel. The flour of cassava leaves can be a good source of nutrition when used as a food ingredient in soups and pasta. However, it is not indicated to products that require high gel formation.

Hypotensive and vasorelaxing effects of the new NO-donor [Ru(terpy)(bdq)NO+](3+) in spontaneously hypertensive rats

Drugs that release nitric oxide (NO) usually have limitations due to their harmful effects. Sodium nitroprusside (SNP) induces a rapid hypotension that leads to reflex tachycardia, which could be an undesirable effect in patients with heart disease, a common feature of hypertension. The nitrosyl ruthenium complex [Ru(terpy)(bdq)NO+](3+) (TERPY) is a NO donor that is less potent than SNP in denuded aortic rings. This study evaluated the hypotension and vasorelaxation induced by this NO donor in Wistar (W) and spontaneously hypertensive rats (SHR) and compared to the results obtained with SNP. Differently from the hypotension induced by SNP, the action of TERPY was slow, long lasting and it did not lead to reflex tachycardia in both groups. The hypotension induced by the NO-donors was more potent in SHR than in W. TERPY induced relaxation with similar efficacy to SNP, although its potency is lower in both strains. The relaxation induced by TERPY is similar in W and SHR, but SNP is more potent and efficient in SHR. The relaxation induced by TERPY is partially dependent on guanylate cyclase in SHR aorta. The NO released from the NO donors measured with DAF-2 DA by confocal microscopy shows that TERPY releases similar amounts of NO in W and SHR, while SNP releases more NO in SHR aortic rings. (c) 2012 Elsevier Inc. All rights reserved.

Structural, spectral and potentiometric characterization, and antimicrobial activity studies of [Zn(phen)(2)(cnge)(H2O)](NO3)(2)∙H2O

An octahedral Zn complex with o-phenanthroline (o-phen) and cyanoguanidine (cnge) has been synthesized and characterized. The crystal structural data show the formation of a ZnN5O core where the metal coordinates to two mutually perpendicular o-phenanthrolines as bidentate ligands [Zn-N bond lengths in the 2.124(2)-2.193(2) angstrom range], the cyanide nitrogen of a cnge [d(Zn-N) = 2.092(2) angstrom, angle(Zn-N-C) = 161.1(2)degrees], and a water molecule [d(Zn-Ow) = 2.112(2) angstrom]. Spectral data (FT-IR, Raman, and fluorescence) and speciation studies are in agreement with the structure found in the solid state and the one proposed to exist in the solution. To evaluate the changes in the microbiological activity of Zn, antibacterial studies were carried out by observing the changes in minimum inhibitory concentration of the complex, the ligands, and the metal against five different bacterial strains. The antibacterial activity of Zn improved upon complexation in three of the tested strains.

Organocatalytic asymmetric mannich-type reactions: an easy approach to optically active amine derivatives

The topics I came across during the period I spent as a Ph.D. student are mainly two. The first concerns new organocatalytic protocols for Mannich-type reactions mediated by Cinchona alkaloids derivatives (Scheme I, left); the second topic, instead, regards the study of a new approach towards the enantioselective total synthesis of Aspirochlorine, a potent gliotoxin that recent studies indicate as a highly selective and active agent against fungi (Scheme I, right). At the beginning of 2005 I had the chance to join the group of Prof. Alfredo Ricci at the Department of Organic Chemistry of the University of Bologna, starting my PhD studies. During the first period I started to study a new homogeneous organocatalytic aza-Henry reaction by means of Cinchona alkaloid derivatives as chiral base catalysts with good results. Soon after we introduced a new protocol which allowed the in situ synthesis of N-carbamoyl imines, scarcely stable, moisture sensitive compounds. For this purpose we used α-amido sulfones, bench stable white crystalline solids, as imine precursors (Scheme II). In particular we were able to obtain the aza-Henry adducts, by using chiral phase transfer catalysis, with a broad range of substituents as R-group and excellent results, unprecedented for Mannich-type transformations (Scheme II). With the optimised protocol in hand we have extended the methodology to the other Mannich-type reactions. We applied the new method to the Mannich, Strecker and Pudovik (hydrophosphonylation of imines) reactions with very good results in terms of enantioselections and yields, broadening the usefulness of this novel protocol. The Mannich reaction was certainly the most extensively studied work in this thesis (Scheme III). Initially we developed the reaction with α-amido sulfones as imine precursors and non-commercially available malonates with excellent results in terms of yields and enantioselections.3 In this particular case we recorded 1 mol% of catalyst loading, very low for organocatalytic processes. Then we thought to develop a new Mannich reaction by using simpler malonates, such as dimethyl malonate.4 With new optimised condition the reaction provided slightly lower enantioselections than the previous protocol, but the Mannich adducts were very versatile for the obtainment of β3-amino acids. Furthermore we performed the first addition of cyclic β-ketoester to α-amido sulfones obtaining the corresponding products in good yield with high level of diastereomeric and enantiomeric excess (Scheme III). Further studies were done about the Strecker reaction mediated by Cinchona alkaloid phase-transfer quaternary ammonium salt derivatives, using acetone cyanohydrin, a relatively harmless cyanide source (Scheme IV). The reaction proceeded very well providing the corresponding α-amino nitriles in good yields and enantiomeric excesses. Finally, we developed two new complementary methodologies for the hydrophosphonylation of imines (Scheme V). As a result of the low stability of the products derived from aromatic imines, we performed the reactions in mild homogeneous basic condition by using quinine as a chiral base catalyst giving the α-aryl-α-amido phosphonic acid esters as products (Scheme V, top).6 On the other hand, we performed the addition of dialkyl phosphite to aliphatic imines by using chiral Cinchona alkaloid phase transfer quaternary ammonium salt derivatives using our methodology based on α-amido sulfones (Scheme V, bottom). The results were good for both procedures covering a broad range of α-amino phosphonic acid ester. During the second year Ph.D. studies, I spent six months in the group of Prof. Steven V. Ley, at the Department of Chemistry of the University of Cambridge, in United Kingdom. During this fruitful period I have been involved in a project concerning the enantioselective synthesis of Aspirochlorine. We provided a new route for the synthesis of a key intermediate, reducing the number of steps and increasing the overall yield. Then we introduced a new enantioselective spirocyclisation for the synthesis of a chiral building block for the completion of the synthesis (Scheme VI).

Oligosilyl- und Stannylderivate des Kupfers

Benzyltris(trimethylsilyl)silan konnte durch Reaktion mit Lithiummethanid oder Alkalimetall-tert-butanolaten (M-OtBu, M = Na, K, Rb, Cs) in die entsprechenden Alkalimetall-benzylbis(trimethylsilyl)silanide (M-Bnz, Bnz = Si(SiMe3)2CH2Ph) überführt werden. Die Strukturen dieser Verbindungen weisen viele Gemeinsamkeiten mit den entsprechenden Hypersilylverbindungen (Hypersilyl bzw. Hyp = Si(SiMe3)3) auf. Mit Ausnahme der Lithiumverbindung weisen die Natrium-, Kalium- und Rubidiumverbindungen jedoch noch intramolekulare Wechselwirkungen des Benzylrestes mit den Alkalimetallkationen auf. Die Benzylbis(trimethylsilyl)silanide der Alkalimetalle eignen sich zur Darstellung von Kupfersilylverbindungen. So konnten heteroleptische Cuprate (Bnz-Cu-OtBu-, Bnz-Cu-Hyp-) und monoleptische Cuprate (CuBnz2-), aber auch das ungeladene Kupfer-benzyl-bis(trimethylsilyl)silanid hergestellt werden. Auf analoge Weise wurde versucht, Alkalimetall- und Kupferverbindungen des Phenylbis(trimethylsilyl)silanides herzustellen. Da aber bereits bei der Synthese der Alkalimetallverbindungen die entsprechenden Hypersilanide als schwer abtrennbare Nebenprodukte entstanden, konnten keine ausführlichen Untersuchungen angestellt werden. Es konnten die Natrium- und Kaliumsalze des Dihypersilylcuprates hergestellt und strukturell charakterisiert werden. Die Natriumverbindung wurde nur als Nebenprodukt einer Reaktion von Kupfer(I)-cyanid mit Natriumhypersilanid erhalten, die entsprechende Kaliumverbindung ließ sich jedoch mit guten Ausbeuten gezielt aus Kupfer(I)-tert-butanolat herstellen. Beide Verbindungen weisen ein hantelförmiges Hyp-Cu-Hyp-Anion auf, die THF- bzw. THP-koordinierten Kationen liegen isoliert vom Anion vor. Eine neue Klasse von Kupfersilylverbindungen konnten durch Reaktion von Kupfer(I)-cyanid mit Alkalimetallhypersilaniden erzeugt werden. Dabei entstehen heteroleptische Cyano-hypersilyl-cuprate. Großen Einfluss auf die Strukturen üben die Alkalimetallkationen und Lösungsmittelmoleküle aus. So findet man bei den Lithiumverbindungen zweikernige Kupferkomplexe, die je nach Lösungsmittelgehalt unterschiedliche Anordnungen der Cyanid- und Hypersilanidanionen aufweisen. Lediglich die Kaliumverbindung weist lineare Cyanid-Kupfer-Hypersilanid-Einheiten auf, wie man sie analog von Organyl-cyano-cupraten kennt. Trotz vieler Gemeinsamkeiten vieler Silyl- und entsprechender Stannylverbindungen bezüglich Struktur und Reaktivität, erwies sich die Darstellung von Kupferstannyl-verbindungen schwieriger als erwartet. Zwar konnte in einer mehrstufigen Reaktion Kupfer-tris(trimethylsilyl)stannanid erhalten werden, auftretende Zwischen- und Nebenprodukte weisen jedoch auf das Auftreten von Umlagerungen und Redoxprozesse hin, die bei entsprechenden Kupfersilylverbindungen nicht beobachtet wurden.

Sintesi di molecole biologicamente attive con tecniche chemoenzimatiche:beta-lattami, profeni e alfa-amminoacidi non naturali

Il progetto di ricerca di questa tesi è stato focalizzato sulla sintesi di tre classi di molecole: β-lattami, Profeni e α-amminonitrili, utilizzando moderne tecniche di sintesi organica, metodologie ecosostenibili e strategie biocatalitiche. I profeni sono una categoria di antiinfiammatori molto diffusa e in particolare abbiamo sviluppato e ottimizzato una procedura in due step per ottenere (S)-Profeni da 2-arilpropanali raceme. Il primo step consiste in una bioriduzione delle aldeidi per dare i relativi (S)-2-Aril Propanoli tramite un processo DKR mediato dall’enzima Horse Liver Alcohol Dehydrogenase. Il secondo, l’ossidazione a (S)-Profeni, è promossa da NaClO2 e TEMPO come catalizzatore. Con lo scopo di migliorare il processo, in collaborazione con il gruppo di ricerca di Francesca Paradisi all’University College Dublino abbiamo immobilizzato l’enzima HLADH, ottenendo buone rese e una migliore enantioselettività. Abbiamo inoltre proposto un interessante approccio enzimatico per l’ossidazione degli (S)-2-Aril Propanoli utilizzando una laccasi da Trametes Versicolor. L’anello β-lattamico è un eterociclo molto importante, noto per essere un interessante farmacoforo. Abbiamo sintetizzato nuovi N-metiltio beta-lattami, che hanno mostrato un’attività antibatterica molto interessante contro ceppi resistenti di Staphilococcus Aureus prelevati da pazienti affetti da fibrosis cistica. Abbiamo poi coniugato gruppi polifenolici a questi nuovi β-lattami ottenendo molecule antiossidanti e antibatteriche, cioè con attività duale. Abbiamo poi sintetizzato un nuovo ibrido retinoide-betalattame che ha indotto differenziazione si cellule di neuroblastoma. Abbiamo poi sfruttato la reazione di aperture dell’anello monobattamico tramite enzimi idrolitici, con lo scopo di ottenere β-amminoacidi chirali desimmetrizzati come il monoestere dell’acido β–amminoglutammico. Per quando riguarda gli α-amminonitrili, è stato sviluppato un protocollo di Strecker. Le reazioni sono state molto efficienti utilizzando come fonte di cianuro l’acetone cianidrina in acqua, utilizzando differenti aldeidi e chetoni, ammine primarie e secondarie. Per mettere a punto una versione asimmetrica del protocollo, abbiamo usato ammine chirali con lo scopo di ottenere nuovi α-amminonitrili chirali.

Additions- und Umlagerungsreaktionen des Lewis-aciden Dihypersilylplumbandiyls in Umsetzungen mit monodenten und ambidenten Lewis-Basen

Die chemische Reaktivität des Dihypersilylplumbylens Pb[Si(Si(CH3)3)3]2 wird durch seine besondere elektronische Struktur bestimmt. Im Unterschied zu Carbenen (Triplett-Grundzustand) liegen Plumbylene im Grundzustand als Singulett vor, mit einem energetisch hochliegenden HOMO (freies Elektronenpaar mit hohem s-Charakter) und einem tiefliegenden LUMO (näherungsweise: freies p-Orbital des Pb-Atoms). Daraus resultiert das amphotere Lewis-Säure/Lewis-Base-Verhalten der Verbindung, mit der Besonderheit, dass sich die beiden Lewis-Zentren am selben Atom befinden. rnIn Umsetzungen mit monodenten und ambidenten Lewis-Basen wurden die Lewis-aciden Eigenschaften des Dihypersilylplumbandiyls Pb[Si(Si(CH3)3)3]2 untersucht. Reaktionen mit den sterisch anspruchsvollen O-Nucleophilen KOtBu (Kalium-tert-Butanolat) und KOiPrPh (4-Kaliumisopropylphenolat) führten bei tiefen Temperaturen zur primären Adduktbildung. Die aus der Strukturanalyse erhaltenen Bindungsdaten zeigen die extreme sterische Überfrachtung des zentralen Blei-Atoms. Der Abbau der sterischen Spannung ist möglicherweise die Ursache für offensichtlich stattfindende Umlagerungsfolgereaktionen (bei Reaktionsführungen bei T>-60°C), die aufgrund spektroskopische Untersuchungen zu vermuten sind.rnEingehender wurden diese Umlagerungsreaktionen in Umsetzungen des Pb[Si(Si(CH3)3)3]2 mit ambidenten Lewis-Basen untersucht. In Übereinstimmung und Erweiterung mit früheren Ergebnissen von Klinkhammer (K. Klinkhammer, Polyhedron, 2002, 21, 587) konnte beispielsweise die Migration einer (mit der ambidenten Lewis-Base tert-Butylisonitril) bzw. beider Hypersilylgruppen (mit p-Tolylisocyanat) unter Bildung hetero- bzw. homoleptischer Plumbylene nachgewiesen werden.rnReaktionen des Pb[Si(Si(CH3)3)3]2 mit den anorganischen ambidenten Salz-Ionen CN-, OCN-, SCN-, N3-, NO2- führen zur Bildung salzartiger Plumbanide der Zusammensetzung Me{Pb[Si(Si(CH3)3)3]2}Nu (Me: Na bzw. K, Nu: CN, OCN, SCN, N3, NO2). Die Verbindungen liegen im Kristall monomer als Kontaktionenpaar vor. Auf diese Weise gelang erstmalig die gezielte Synthese eines Blei(II)cyanids sowie die Darstellung eines Blei(II)isocyanats. rn

Reaktionen monovalenter Münzmetalle in flüssigem Ammoniak

Im Rahmen dieser Arbeit konnten erstmals eine Reihe von Ammoniakaten von Münzmetallhalogeniden (M(I)Hal) und Pseudohalogeniden aus flüssigem Ammoniak in einkristalliner Form isoliert und strukturell charakterisiert werden. Mit dem Ammoniakat des Gold(I)-iodids wurden Metathesen in flüssigem Ammoniak durchgeführt, die die Isolierung einiger sehr thermolabiler, teilweise explosiver Alkoholate des Golds ermöglichten. Die Bestimmung der Kristallstruktur eines Gold(I)-phenolates erlaubte erste Einblicke in deren Aufbau.rnIn der Reihe der Ammoniakate der M(I)Hal mit Ausnahme von Silberiodid, werden keine direkten Metall-Halogen-Kontakte ausgebildet. Die Ammoniakate der Chloride und Bromide des Kupfers und Silbers sowie des Kupferiodids besitzen isotype Strukturen. Sie liegen als Trisammoniakate [M(NH3)3]Hal vor. Im Ammoniakat von Silberiodid besitzen die Silberionen durchgängig die Koordinationszahl 4. Neben Ag•••NH3- findet man auch direkte Kationen-rnAnionen-Kontakte und sehr kurze Ag(I)-Ag(I)-Abstände. Das Goldkation im Ammoniakat von Goldiodid besitzt die Koordinationszahl 2 und wird ausschließlich durch Ammoniakmoleküle koordiniert. Die gebildeten H3N-NH3-Hanteln werden über aurophile Wechselwirkungen verknüpft.rn rnDie Ammoniakate der Cyanide von Silber und Gold, enthalten molekulare Baueinheiten des Typs:(H3N)nMCN [(n= 1 für M= Au und n= 2 für M= Ag].rnrnAnders als bei den solvatfreien Homologen wird eine Ausbildung von Polymerketten nicht beobachtet. Das linear aufgebaute Ammoniakat von Goldcyanid ermöglicht die Ausbildung von aurophilen Wechselwirkungen. Metallophile Wechselwirkungen zwischen dem als Dimer vorliegenden Ammoniakat von AgCN scheinen nicht ausgebildet zu werden.rnrnMetatheseversuche von Goldiodid mit einem Amid und diversen Alkanolaten lieferten teilweise explosive Produkte. Es ist davon auszugehen, dass mit zunehmender Basizität der eingesetzten Anionen, die an das Gold(I)-ion koordinierten Ammoniakmoleküle deprotoniert werden und explosives Goldamid gebildet wird. Der als zweites Produkt entstehende Alkohol kann ebenfalls ein Ammoniakat bilden. Im Fall von Li-Fencholat wird ein solches in Form sehr tiefschmelzender Einkristalle erhalten.rnrnDa die Deprotonierung der an Gold koordinierten Ammoniakmoleküle unweigerlich zu explosiven oder sehr instabilen Produkten führt, wurde die geringere Basizität der Phenolate ausgenutzt, um dies zu umgehen. Im Falle der Umsetzung von AuI mit Li-2,6-di-tert.-butylphenolat gelang tatsächlich die Isolierung eines kristallinen Gold(I)-phenolats.rn

Therapeutic protein transduction of mammalian cells and mice by nucleic acid-free lentiviral nanoparticles

The straightforward production and dose-controlled administration of protein therapeutics remain major challenges for the biopharmaceutical manufacturing and gene therapy communities. Transgenes linked to HIV-1-derived vpr and pol-based protease cleavage (PC) sequences were co-produced as chimeric fusion proteins in a lentivirus production setting, encapsidated and processed to fusion peptide-free native protein in pseudotyped lentivirions for intracellular delivery and therapeutic action in target cells. Devoid of viral genome sequences, protein-transducing nanoparticles (PTNs) enabled transient and dose-dependent delivery of therapeutic proteins at functional quantities into a variety of mammalian cells in the absence of host chromosome modifications. PTNs delivering Manihot esculenta linamarase into rodent or human, tumor cell lines and spheroids mediated hydrolysis of the innocuous natural prodrug linamarin to cyanide and resulted in efficient cell killing. Following linamarin injection into nude mice, linamarase-transducing nanoparticles impacted solid tumor development through the bystander effect of cyanide.

Functional and structural characterization of a prokaryotic peptide transporter with features similar to mammalian PEPT1

The ydgR gene of Escherichia coli encodes a protein of the proton-dependent oligopeptide transporter (POT) family. We cloned YdgR and overexpressed the His-tagged fusion protein in E. coli BL21 cells. Bacterial growth inhibition in the presence of the toxic phosphonopeptide alafosfalin established YgdR functionality. Transport was abolished in the presence of the proton ionophore carbonyl cyanide p-chlorophenylhydrazone, suggesting a proton-coupled transport mechanism. YdgR transports selectively only di- and tripeptides and structurally related peptidomimetics (such as aminocephalosporins) with a substrate recognition pattern almost identical to the mammalian peptide transporter PEPT1. The YdgR protein was purified to homogeneity from E. coli membranes. Blue native-polyacrylamide gel electrophoresis and transmission electron microscopy of detergent-solubilized YdgR suggest that it exists in monomeric form. Transmission electron microscopy revealed a crown-like structure with a diameter of approximately 8 nm and a central density. These are the first structural data obtained from a proton-dependent peptide transporter, and the YgdR protein seems an excellent model for studies on substrate and inhibitor interactions as well as on the molecular architecture of cell membrane peptide transporters.