| 1. |
- Lagerlund, Olof
(författare)
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Design and Synthesis of Novel Glutamine Synthetase Inhibitors and Development of Palladium(0)-Catalyzed Aminocarbonylation
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tuberculosis (TB) is a major infectious disease, killing about 2 million people annually throughout the world. Today's TB treatment is a lengthy procedure involving a combination of antibiotics. No new TB drug has been introduced onto the market in the past 40 years, and the emergence of multi- and extensively drug-resistant TB calls for new drugs. Finding new drug targets is important and one such target is the Mycobacterium tuberculosis enzyme glutamine synthetase (GS), which catalyses the formation of glutamine from glutamic acid. In this work, novel GS inhibitors and new Pd(0)-catalyzed methods have been developed. A microwave-enhanced Pd(0)-catalyzed α-arylation reaction was developed using water as solvent, and a phenylglycine scaffold was identified using structure-based design. A series of α-arylated phenylglycine derivates was produced at moderate to good yields. Some of these were biologically evaluated against GS. A novel scaffold, 3-amino-imidazo[1,2-a]pyridine, was identified by high-throughput screening directed towards GS. This type of compound could be easily produced via a Ugi-type, microwave-promoted multi-component reaction in 20 min. The scaffold was investigated by changing one substituent at a time, and in an experimental design where 8 factors were varied in the same design. Several potent inhibitors were identified; amongst them the most potent inhibitor to date (IC50 = 0.38 µM). Two discrete structure-activity relationships were established, and one of the inhibitors was co-crystallized. The first general aminocarbonylation of aryl chlorides and the first aminocarbonylation of alkenyl phosphates were developed. Alkenyl chlorides, bromides and triflates were investigated in the same transformation utilizing Mo(CO)6 as a solid carbon monoxide source. Two different Pd(0)-based catalytic systems were developed. A wide variety of aryl chlorides and amines could be transformed into the corresponding amides with good yields. The alkenyl substrates produced low to good yields.
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| 2. |
- Nordqvist, Anneli, 1978-
(författare)
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Hit Identification and Hit Expansion in Antituberculosis Drug Discovery : Design and Synthesis of Glutamine Synthetase and 1-Deoxy-D-Xylulose-5-Phosphate Reductoisomerase Inhibitors
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Since the discovery of Mycobacterium tuberculosis (Mtb) as the bacterial agent causing tuberculosis, the permanent eradication of this disease has proven challenging. Although a number of drugs exist for the treatment of tuberculosis, 1.7 million people still die every year from this infection. The current treatment regimen involves lengthy combination therapy with four different drugs in an effort to combat the development of resistance. However, multidrug-resistant and extensively drug-resistant strains are emerging in all parts of the world. Therefore, new drugs effective in the treatment of tuberculosis are much-needed. The work presented in this thesis was focused on the early stages of drug discovery by applying different hit identification and hit expansion strategies in the exploration of two new potential drug targets, glutamine synthetase (GS) and 1-deoxy-D-xylulose-5-phosphate reductoisomerase (DXR). A literature survey was first carried out to identify new Mtb GS inhibitors from compounds known to inhibit GS in other species. Three compounds, structurally unrelated to the typical amino acid derivatives of previously known GS inhibitors, were then discovered by virtual screening and found to be Mtb GS inhibitors, exhibiting activities in the millimolar range. Imidazo[1,2-a]pyridine analogues were also investigated as Mtb GS inhibitors. The chemical functionality, size requirements and position of the substituents in the imidazo[1,2-a]pyridine hit were investigated, and a chemical library was designed based on a focused hierarchical design of experiments approach. The X-ray structure of one of the inhibitors in complex with Mtb GS provided additional insight into the structure–activity relationships of this class of compounds. Finally, new α-arylated fosmidomycin analogues were synthesized as inhibitors of Mtb DXR, exhibiting IC50 values down to 0.8 µM. This work shows that a wide variety of aryl groups are tolerated by the enzyme. Cinnamaldehydes are important synthetic intermediates in the synthesis of fosmidomycin analogues. These were prepared by an oxidative Heck reaction from acrolein and various arylboronic acids. Electron-rich, electron-poor, heterocyclic and sterically hindered boronic acids could be employed, furnishing cinnamaldehydes in 43–92% yield.
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| 3. |
- Nurbo, Johanna, 1979-
(författare)
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Peptidomimetic Enzyme Inhibitors : Targeting M. tuberculosis Ribonucleotide Reductase and Hepatitis C Virus NS3 Protease
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis focuses on the design and synthesis of inhibitors targeting Mycobacterium tuberculosis ribonucleotide reductase (RNR) and hepatitis C virus (HCV) NS3 protease; enzymes that have been identified as potential drug targets for the treatment of tuberculosis and hepatitis C, respectively. Small peptides have been recognized as inhibitors of these enzymes. However, the use of peptides as drugs is limited due to their unfavorable properties. These can be circumvented by the development of less peptidic molecules, often referred to as peptidomimetics. When this work was initiated, only a few inhibitors targeting M. tuberculosis RNR had been identified, whereas the HCV NS3 protease was an established drug target. Therefore, early peptidomimetic design strategies were applied to inhibitors of RNR while the NS3 protease inhibitors were subjected to modifications in a later stage of development. It has previously been shown that peptides derived from the C-terminus of the small subunit of M. tuberculosis RNR can compete for binding to the large subunit, and thus inhibit enzyme activity. To investigate the structural requirements of these inhibitors, different series of peptides were evaluated. First, peptides from an N-terminal truncation, an alanine scan and a designed library were synthesized and evaluated to examine the importance of the individual amino acid residues. Then, a set of N-terminally Fmoc-protected peptides was evaluated, and it was found that the N-terminal group improved the affinity of the peptides even when the length of the compounds was reduced. Furthermore, potential inhibitors of less peptidic character were generated by the introduction of a benzodiazepine-based scaffold. To further reduce the peptidic character and investigate the binding properties of HCV NS3 protease inhibitors, a series of tripeptides incorporating a β-amino acid was synthesized. Inhibition was evaluated and docking studies were performed to understand how the structural changes affected inhibitory potency. The results illustrated the importance of preserving the hydrogen bonding network and retaining electrostatic interactions in the oxyanion hole between inhibitor and protein.
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| 4. |
- Andersson, Hanna, 1979-
(författare)
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Design and Synthesis of Angiotensin IV Peptidomimetics Targeting the Insulin-Regulated Aminopeptidase (IRAP)
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Peptidomimetics derived from the bioactive hexapeptide angiotensin IV (Ang IV, Val1-Tyr2-Ile3-His4-Pro5-Phe6) have been designed and synthesized. These peptidomimetics are aimed at inhibiting the insulin-regulated amino peptidase (IRAP), also known as the AT4 receptor. This membrane-bound zinc-metallopeptidase is currently under investigation regarding its potential as a target for cognitive enhancers. The work presented herein was based on stepwise replacement of the amino acid residues in Ang IV by natural and unnatural amino acids, non-peptidic building blocks, and also on the introduction of conformational constraints. Initially, we focused on the introduction of secondary structure mimetics and backbone mimetics. The C-terminal tripeptide His-Pro-Phe was successfully replaced by a γ-turn mimetic scaffold, 2-(aminomethyl)phenylacetic acid (AMPA), which was coupled via an amide bond to the carboxyl terminus of Val-Tyr-Ile. Substitution of Val-Tyr-Ile, Val-Tyr, Tyr-Ile and Tyr, respectively, by 4-hydroxydiphenylmethane scaffolds comprising a 1,3,5-substituted benzene ring as a central moiety unfortunately rendered peptidomimetics that were less potent than Ang IV. The subsequent approach involved the introduction of conformational constraints into Val-Tyr-Ile-AMPA by replacing Val and Ile by amino acid residues appropriate for disulfide cyclization or ring-closing metathesis. Chemically diverse structures encompassing an N-terminal 13- or 14-membered macrocyclic tripeptide and a C-terminal non-peptidic moiety were developed. Tyr2 and AMPA were modified to acquire further knowledge about the structure-activity relationships and, in addition, to improve the metabolic stability and reduce the polarity. Several of the compounds displayed a high capacity to inhibit IRAP and exhibited Ki values in the low nanomolar range. Hence, the new compounds were more than ten times more potent than the parent peptide Ang IV. Enhanced selectivity over the closely related aminopeptidase N (AP-N) was achieved, as well as improved stability against proteolysis by metallopeptidases present in the assays. However, additional investigations are required to elucidate the bioactive conformation(s) of the relatively flexible N-terminal macrocycles. The compounds presented in this thesis have provided important information on structure-activity relationships regarding the interaction of Ang IV-related pseudopeptides and peptidomimetics with IRAP. The best compounds in the series constitute important starting points for further discovery of Ang IV peptidomimetics suitable as tools in the investigation of IRAP and other potential targets for Ang IV. The literature presents strong support for the hypothesis that drug-like IRAP inhibitors would serve as a new type of future cognitive enhancers with potential use in the treatment of cognitive disorders, e.g. Alzheimer’s disease.
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| 5. |
- Arvela, Riina K
(författare)
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Palladium-Catalysed Carbon–Carbon Coupling Reactions : Focusing on Microwave Heating, Low Catalyst Concentrations, Aqueous Conditions, Regioselectivity and Medicinal Chemistry Applications
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- It is widely accepted that palladium is one of the most useful catalysts in organic chemistry, and many palladium(0)-catalysed carbon–carbon bond-forming reactions have been developed over the years. In addition, the ever-growing need for more environmentally benign processes in the chemical industry has driven scientists to look for greener options while developing new methodologies for organic synthesis. This thesis describes a series of studies on Suzuki and Heck coupling reactions in water and the application of palladium(0) catalysis to the development of new HIV-1 integrase inhibitors. The previously described 'transition-metal-free Suzuki-type coupling' reaction was shown to take place due to sub-ppm levels of palladium contaminants present in the commercially available sodium carbonate base. Based on this finding, a new, microwave-assisted Suzuki protocol utilizing ppb/ppm levels of palladium in water was developed. This methodology was adapted to terminal Heck coupling, although the scope of the protocol was found to be rather limited. Finally, both Suzuki and Heck reaction processes were successfully scaled up to 100 mmol using an automated batch stop-flow microwave apparatus. As the methodologies utilizing ultralow palladium concentrations were not applicable to aryl chlorides, attention was shifted towards palladium on carbon. This simple catalyst, together with microwave heating employing simultaneous cooling, was found to be beneficial in the Suzuki coupling of aryl chlorides with phenylboronic acid in water. Ligand-controlled internal arylation of ethylene glycol vinyl ether with aryl halides was shown to be possible in water alone without any additives. Reactions were run under air, using conventional heating and the products formed were isolated as aryl methyl ketones in good to excellent yields. The electron-rich (dippp)2Pd complex was shown to be beneficial for the microwave-assisted internal arylation of some aryl chlorides. Furthermore, the active role of the hydroxyl group of ethylene glycol vinyl ether in the formation of a cationic intermediate leading to internal Heck coupling product was elucidated. Finally, to demonstrate the usefulness of palladium(0) catalysis in the development of new pharmaceutical entities, a series of HIV-1 integrase inhibitors was synthesised and evaluated in strand transfer assays and in vitro. Based on the results and docking studies performed, valuable information related to the structure–activity relationship was obtained.
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| 6. |
- Beckman Rehnman, Jeannette, 1969-
(författare)
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New methods to evaluate the effect of conventional and modified crosslinking treatment for keratoconus
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Background: Today corneal crosslinking with ultraviolet-A photoactivation of riboflavin is an established method to halt the progression of keratoconus. In some cases, when the refractive errors are large and the visual acuity is low, conventional corneal crosslinking may not be sufficient. In these cases it would be desirable with a treatment that both halts the progression and also reduces the refractive errors and improves the quality of vision.Aims: The aims of this thesis were to determine whether mechanical compression of the cornea during corneal crosslinking for keratoconus using a sutured rigid contact lens could improve the optical and visual outcomes of the treatment, and also to find methods to evaluate the effect of different corneal crosslinking treatment regimens.Methods: In a prospective, open, randomized case-control study, 60 eyes of 43 patients with progressive keratoconus, aged 18-28 years, planned for routine corneal crosslinking, and a corresponding age- and sex-matched control group was included. The patients were randomized to conventional corneal crosslinking (CXL; n=30) or corneal crosslinking with mechanical compression of the cornea during the treatment (CRXL; n=30).Biomicroscopy, autorefractometry, best spectacle corrected visual acuity, axial length measurement, Pentacam® HR Scheimpflug photography, pachymetry, intraocular pressure measurements and corneal biomechanical assessments were performed before treatment (baseline) and at 1 month and 6 months after the treatment.One of the articles evaluated and compared the optical and visual outcomes between CXL and CRXL, while the other three articles focused on methods to evaluate treatment effects. In Paper I, the corneal light scattering was manually quantified from Scheimpflug images throughout the corneal thickness at 8 measurements points, 0.0 to 3.0 mm from the corneal centre, in patients treated with CXL. In Paper IV the corneal densitometry (light scattering) was measured with the Pentacam® HR software, in 4 circular zones around the corneal apex and at 3 different depths of the corneal stroma, in both CXL and CRXL treated corneas. Paper III quantified the biomechanical effects of CXL in vivo.Results: Corneal light scattering after CXL showed distinctive spatial and temporal profiles and Applanation Resonance Tonometry (ART) -technology demonstrated an increased corneal hysteresis 1 and 6 months after CXL. When comparing the refractive and structural results after CXL and CRXL, CRXL failed to flatten the cornea, and the treatment did not show any benefits to conventional CXL treatment, some variables even indicated an inferior effect. Accordingly, the increase in corneal densitometry was also less pronounced after CRXL.Conclusions: Analysis of corneal light scattering/densitometry shows tissue changes at the expected treatment location, and may be a relevant variable in evaluating the crosslinking effect. ART -technology is an in vivo method with the potential to assess the increased corneal hysteresis after CXL treatment. By refining the method, ARTmay become a useful tool in the future. Unfortunately, CRXL does not improve the optical and visual outcomes after corneal crosslinking. Possibly, stronger crosslinking would be necessary to stabilize the cornea in a flattened position.
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| 7. |
- Datta, Gopal K., 1975-
(författare)
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Heck Reactions with Aryl Chlorides : Studies of Regio- and Stereoselectivity
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Homogeneous palladium-catalyzed Heck vinylation of aryl chlorides was investigated under air using Herrmann’s palladacycle and the P(t-Bu)3-liberating salt [(t-Bu)3PH]BF4. Based on the results, controlled microwave heating was utilized to accelerate model Heck reactions with aryl chlorides down to 30 min employing an electron-poor olefin and a mixture of an ionic liquid and 1,4-dioxane as solvent.For the first time, a highly regioselective general protocol has been developed for palladium-catalyzed terminal (β-) arylation of acyclic vinyl ethers using inexpensive aryl chlorides as starting materials and the preligand [(t-Bu)3PH]BF4 as the key additive. This swift and straightforward protocol exploits non-inert conditions and controlled microwave heating to reduce handling and processing times, and aqueous DMF or environmentally friendly PEG-200 as the reaction medium. Somewhat higher selectivity for the linear β-product was observed in PEG-200. DFT calculations were performed at the B3LYP level of theory for the regioselectivity-determining insertion step in the Heck reaction following the neutral pathway. A series of para-substituted phenylpalladium(II) complexes was investigated in the computational study. The calculations support a ligand-driven selectivity rationale, where the electronic and steric influence of the bulky P(t-Bu)3 ligand provides improved β-selectivity. The preparative methodology was used to synthesize the β-adrenergic blocking agent Betaxolol.Highly stereoselective Pd(0)-catalyzed β-arylation and β-vinylation of a tetra-substituted cyclopentenyl ether have been accomplished using a chiral, pyrrolidine-based and substrate-bound palladium(II)-directing group under neutral reaction conditions. To the best of the author’s knowledge, this P(t-Bu)3-mediated method represents the first examples of the successful utilization of aryl and vinyl chlorides in asymmetric Heck reactions. The Heck arylation products formed were hydrolyzed and isolated as the corresponding quaternary 2-aryl-2-methyl cyclopentanones in good to moderate two-step yields with excellent stereoselectivity (90-96% ee). Inclusion of vinyl triflates under neutral reaction conditions and one aryl triflate equipped with a strongly electron-withdrawing para-cyano substituent under cationic conditions increased the preparative usefulness of the methodology.Furthermore, diastereoselective Heck arylation of both five- and six-membered cyclic vinyl ethers with aryl bromides, using the identical chiral auxiliary and suitable Pd sources, was performed. Arylated products from the tetra-substituted cyclopentenyl ether were also in this case hydrolyzed to the corresponding 2-aryl-2-methyl cyclopentanones with high to excellent enantioselectivity (85-94% ee). Despite low reaction rates and relatively modest yields, arylation reactions with the tri-substituted cyclohexenyl ether were found to be highly diastereoselective (94-98% de).Thus, an attractive supplement to direct Pd(0)-catalyzed α-arylation protocols, particularly when the use of organic chlorides, aryl bromides, and milder reaction conditions are of great importance, have been developed.
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| 8. |
- Hallberg, David, 1978-
(författare)
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Lifelong learning : The social impact of digital villages as community resource centres on disadvantaged women
- 2014
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The overall aim of this research was to enhance the understanding of what affects the social impact of ICT in lifelong learning on disadvantaged women.In contributing to the field of social informatics, this research employs behavioural theories as strategy and analytic possibilities. This research mainly used the Kenyan digital villages as CRCs as settings but did also look beyond such establishments to provide a more solid picture. The studies were located in Kenya with complementary studies in Bolivia, Cameroon, Sri Lanka, and Sweden. The main strategies and methods used were case study, comparative education approaches, and observations and interviewing techniques.The findings suggest that ICT and CRCs have the potential to support disadvantaged women and their lifelong learning. However, the positive social impacts are limited because the arrangement of them generally does not favour vernacular languages, illiterate users, female owners and users, or non-students. In general, the use of ICT was sometimes perceived as forced, which is both a barrier and a stressor in the use of ICT in lifelong learning. It also emerged from the comparative studies that discussions among the participants in the CRCs largely covered issues in respect to 1) family and reproduction and 2) self-esteem, i.e. what settles the matter of the social impact of ICT in lifelong learning depends on change attitude among men and women. With minimal if not zero self-esteem a change that would make the difference or break a woman’s “legendary status quo” in order for a woman to feel that she can reach her goal or ambitions in lifelong learning would be difficult. Hence the lack of self-esteem is a stressor in itself.This research is valuable for stakeholders delving into issues of development and learning using ICTs, not only in Kenya but in a broader, global perspective.
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| 9. |
- Wallinder, Charlotta, 1976-
(författare)
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Design, Synthesis and Biological Evaluation of Selective Nonpeptide AT2 Receptor Agonists and Antagonists
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The G protein-coupled receptors (GPCRs) are important targets in drug discovery. In several cases, the endogenous ligands that activate the GPCRs of pharmaceutical interest are peptides. Unfortunately, peptides are in general not suitable as drugs, since the peptide structure is associated with several disadvantages, such as low oral bioavailability, rapid degradation and low receptor subtype selectivity. Thus, there is a strong need for drug-like nonpeptide ligands to peptide-activated GPCRs. However, to discover nonpeptide ligands that mimic the effect of the endogenous peptide, i.e. peptidomimetics, is a tremendous challenge. In fact, morphine and the related opioids were the only known examples of peptidomimetics before 1995 and these ligands were known long before the native endogenous peptide ligands were discovered. The main objective of the work described in this thesis was to design, synthesize and biologically evaluate selective nonpeptide agonists to the peptide-activated GPCR AT2. The AT2 receptor belongs to the renin–angiotensin system, where the octapeptide angiotensin II (Ang II) is the major effector peptide. Ang II mediates its effects through the two GPCRs AT1 and AT2. The AT1 receptor is already an established target in the treatment of hypertension. The physiological role of the AT2 receptor, which is up-regulated in certain pathological conditions, is not fully understood but it seems to include positive effects such as vasodilatation, tissue repair, tissue regeneration and neuronal differentiation. In the current investigation we started from the nonpeptide and nonselective (AT1/ AT2) compound L-162,313. This ligand is a known AT1 receptor agonist but its effect on the AT2 receptor was unknown at the start of this project. We were able to show that it acts as an agonist also at the AT2 receptor. Furthermore, stepwise synthetic modifications of L-162,313 led to the identification of the first selective nonpeptide AT2 receptor agonist. Following the discovery of this compound several selective nonpeptide AT2 receptor agonists were identified. It was also revealed that a minor structural alteration of one of these compounds interconverted the functional activity from agonism to antagonism. The structural requirement for agonism vs antagonism was therefore studied. The functionality switch was suggested, at least partly, to be due to the spatial relationship between the methyleneimidazole group and the isobutyl side chain of the compounds. To further investigate the bioactive conformation(s) of this series of compounds enantiomerically pure analogues with conformationally constrained isobutyl chains were prepared. This study revealed that the direction of the isobutyl side chain determine whether the compounds act as agonists or antagonists at the AT2 receptor. Further investigations are required to fully elucidate the bioactive conformation(s) of these nonpeptide AT2 receptor agonists.We believe that the selective nonpeptide AT2 receptor agonists and antagonists identified in this thesis will serve as important research tools in the continuing investigation of the physiological role of the AT2 receptor. We also believe that these drug-like compounds might provide potential leads in drug discovery processes.
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| 10. |
- Ax, Anna, 1975-
(författare)
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Cyclic Sulfamide HIV-1 Protease Inhibitors : Design, Synthesis and Modelling
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ten years ago, the first protease inhibitor targeting the human immunodeficiency virus (HIV) was approved for clinical use. Highly active antiretroviral therapy (HAART), which combined protease and reverse transcriptase inhibitors, quickly became the standard therapy for treating patients infected with HIV and Acquired Immune Deficiency Syndrome (AIDS). Nevertheless, last year the AIDS pandemic reached its highest level ever. Many infected patients, mainly in the developing countries, are still without treatment. Among those patients who receive treatment, an increase in drug resistance and new-infection with drug-resistant strains are seen. To come to terms with these problems, new drugs that are efficient against resistant strains and can be produced at low cost are needed.In this study, we have focused our research efforts on cyclic sulfamides active as HIV-1 protease inhibitors. Distinctive to this compound class, as compared to the inhibitors so far approved for clinical use, was the incorporation of a water mimic that displaces the structural water (W301) observed in the X-ray crystal co-complexes. The first part of the study was aimed at understanding the rationale behind the nonsymmetric binding mode that the inhibitor adopted when bound to the enzyme. Symmetric and nonsymmetric inhibitors were synthesized and the structure-activity relationships and preferable binding modes were rationalized with the help of Comparative Molecular Field Analysis (CoMFA).In the second part of the study, an attempt was made to reduce the size of these inhibitors. As a result, the traditional P1/P1' substituents were removed, while the P2/P2' substituents were elongated in an attempt to reach between the binding sites. The design hypothesis was shown to be successful and inhibitors possessing nanomolar activity were identified.
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| 11. |
- Enquist, Per-Anders, 1974-
(författare)
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Novel Metal-Mediated Organic Transformations : Focusing on Microwave Acceleration and the Oxidative Heck Reaction
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Transition metals have played an important role in synthetic organic chemistry for more than a century, and offer catalytic transformations that would have been impossible with classical chemistry. One of the most useful and versatile of the transition metals is palladium, which over the years has catalyzed many important carbon-carbon forming reactions. Popular cross-coupling reactions such as the Suzuki, Stille and the Heck reaction are all catalyzed by palladium, or more correctly, by palladium in its ground state, Pd(0). Recently, interest in palladium(II)-catalyzed transformations has started to grow, partly due to the development of the vinylic substitution reaction, commonly called the oxidative Heck reaction, presented in this thesis. This Pd(II)-catalyzed, ligand-modulated reaction occurs under air at room temperature, and for the first time a general protocol employing a wide range of olefins and arylboronic acids was obtained. Ligand screening showed that the bidentate nitrogen ligand, 2,9-dimethyl-1,10-phenanthroline (dmphen), was the most suitable ligand. Dmphen is believed to facilitate regeneration of active Pd(II), increase catalytic stability and improve the regioselectivity in the reaction. A mechanistic investigation was conducted using electrospray ionization mass spectrometry (ESI-MS), making it possible to observe cationic intermediates in a productive oxidative Heck arylation. The results obtained are in agreement with the previously proposed catalytic cycle.The emerging discipline of high-speed synthesis is making contributions to society’s growing demand for new chemical entities. This inspired the development of two ultrafast, microwave-accelerated carbonylation reactions with dicobalt octacarbonyl acting both as an in situ carbon monoxide supplier and reaction mediator. A wide range of symmetrical benzophenones was produced in only 6 to 10 s, using aryl iodides as the substrate. The second carbonylation reaction provided symmetrical and unsymmetrical ureas in process times ranging from 10 s to 40 minutes using primary and secondary amines.
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| 12. |
- Örtqvist, Pernilla, 1978-
(författare)
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On the Design and Synthesis of Hepatitis C Virus NS3 Protease Inhibitors : From Tripeptides to Achiral Compounds
- 2010
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Infection by the hepatitis C virus (HCV) leads to inflammation of the liver, i.e. hepatitis. The acute infection often progresses to a chronic phase during which the liver function is gradually impaired. Approximately 20% of these chronic cases develop liver cirrhosis, with an ensuing increased risk of liver cancer. Global estimates of the total number of chronic cases range from 123–170 million. Yet, neither specific anti-HCV drugs nor vaccines are available. When drugs become available for daily clinical use, rapid development of drug-resistant strains is expected, making resistance an important issue. One of the most studied targets for specific anti-HCV drugs is the NS3 protease. The main objectives of the work presented in this thesis were to design and synthesise peptidomimetic inhibitors of this enzyme, and to establish the structure–activity relationships (SARs) regarding the inhibition of the wild type as well as of the known resistant variants A156T and D168V. Substituted prolines are common P2 residues in HCV NS3 protease inhibitors. To decrease the peptide character of the inhibitors, the non-coded phenylglycine was evaluated as a proline replacement in combination with known and novel P3 and P1 residues and P2 substituents. The results confirmed that phenylglycine is a promising P2 scaffold, with a possible π-stacking interaction with histidine 57 of the active site. However, to benefit from its full potential, additional optimisation is required. A 2(1H)-pyrazinone-based scaffold was introduced as P3 residue. Utilising the scope of the method developed for the pyrazinone scaffold synthesis, the phenylglycine side-chain was transferred to the scaffold. In combination with an aromatic P1 building-block, this design yielded achiral, peptidomimetic inhibitors, three times more potent than the tripeptide lead. The SARs for the inhibition of the resistant variants A156T and D168V were investigated for compounds based on either P2 proline or phenylglycine. It was concluded that the vulnerability of the inhibitors to alterations in the enzyme depends on the P2 and the P1 residue, not only on the P2 as previously suggested. These results provide important information for the design of a new generation of inhibitors with improved properties.
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| 13. |
- Arefalk, Anna, 1974-
(författare)
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New Methods for the Synthesis of 3-Substituted 1-Indanones : A Palladium-Catalyzed Approach
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- In medicinal chemistry, there is a constant need for new preparative methods, both to make the synthesis process more effective, and to increase the accessibility to a wide variety of compounds. A number of different approaches can be used to attain these goals. Transition metal catalysis is generally performed under mild conditions, providing both regio- and chemoselective reactions. Thus, it offers an attractive means of preparation of complex drug candidates. Two additional methodologies used to increase the preparative efficiency are one-pot protocols and controlled microwave heating. One-pot and multi-component reactions are less time consuming than step-by-step reactions, and microwave heating has been used to considerably shorten the reaction times. This thesis describes a new palladium-catalyzed, one-pot reaction producing racemic acetal-protected 3-hydroxy-1-indanones from ethylene glycol vinyl ether and triflates of salicylic aldehydes. The triflates were prepared using controlled microwave heating. The reaction sequence starts with a regioselective internal Heck coupling, followed by an annulation cascade. By including secondary amines in the reaction mixture, the reaction was further developed into a three-component reaction delivering racemic acetal-protected 3-amino-1-indanones. This new method was utilized for the synthesis of primary, secondary and tertiary aminoindanones. Finally, by using enantiopure t-butyl sulfinyl imines, derived from salicylic aldehyde triflates and ethylene glycol vinyl ether as starting materials in a closely related type of palladium coupling–annulation sequence, a stereoselective protocol providing enantiomerically pure 3-amino-1-indanones was developed. To demonstrate an application in medicinal chemistry, the enantiopure 3-amino-1-indanones were incorporated as P2 and/or P2´ substituents into active HIV-1 protease inhibitors.
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| 14. |
- Candefjord, Stefan, et al.
(författare)
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Combining scanning haptic microscopy and fibre optic Raman spectroscopy for tissue characterization
- 2012
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Ingår i: Journal of Medical Engineering & Technology. - : Taylor & Francis. - 0309-1902 .- 1464-522X. ; 36:6, s. 319-327
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Tidskriftsartikel (refereegranskat)abstract
- The tactile resonance method (TRM) and Raman spectroscopy (RS) are promising for tissue characterization in vivo. Our goal is to combine these techniques into one instrument, to use TRM for swift scanning, and RS for increasing the diagnostic power. The aim of this study was to determine the classification accuracy, using support vector machines, for measurements on porcine tissue and also produce preliminary data on human prostate tissue. This was done by developing a new experimental set-up combining micro-scale TRMscanning haptic microscopy (SHM)for assessing stiffness on a micro-scale, with fibre optic RS measurements for assessing biochemical content. We compared the accuracy using SHM alone versus SHM combined with RS, for different degrees of tissue homogeneity. The cross-validation classification accuracy for healthy porcine tissue types using SHM alone was 6581%, and when RS was added it increased to 8187%. The accuracy for healthy and cancerous human tissue was 6770% when only SHM was used, and increased to 7277% for the combined measurements. This shows that the potential for swift and accurate classification of healthy and cancerous prostate tissue is high. This is promising for developing a tool for probing the surgical margins during prostate cancer surgery.
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| 15. |
- Ekegren, Jenny, 1976-
(författare)
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Design and Synthesis of Novel HIV-1 Protease Inhibitors Comprising a Tertiary Alcohol in the Transition-State Mimic
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- HIV-1 protease inhibitors are important in the most frequently used regimen for the treatment of HIV/AIDS, the highly active antiretroviral therapy (HAART). For patients with access to this treatment, an HIV infection is no longer lethal, but rather a manageable, chronic infection. However, the HIV-1 protease inhibitors are generally associated with serious shortcomings such as adverse events, development of drug resistance and poor pharmacokinetic properties. Most of the approved inhibitors suffer from high protein binding, rapid metabolism and/or low membrane permeability. In this project, novel HIV-1 protease inhibitors comprising a rarely used tertiary alcohol in the transition-state mimic were designed, synthesized and evaluated. The rationale behind the design was to achieve ‘masking’ of the tertiary alcohol by for example, intramolecular hydrogen bonding, which was believed could enhance transcellular transport. A reliable synthetic protocol was developed and a series of highly potent inhibitors was obtained exhibiting excellent membrane permeation properties in a Caco-2 cell assay. However, the cellular antiviral potencies of these compounds were low. In an attempt to improve the anti-HIV activity, microwave-accelerated, palladium-catalyzed cross-coupling reactions and aminocarbonylation of aryl bromide precursors were employed to produce P1'-extended test compounds. Inhibitors demonstrating up to six times higher antiviral effect were obtained, the best derivatives having para 3- or 4-pyridyl elongations in P1'.Fast metabolic degradation was observed in liver microsome homogenate, which is believed, at least partly, to be attributable to benzylic oxidation of the indanol P2 group of the inhibitors. To enable facile variation of the P2 side chain a new synthetic route was developed using an enantiomerically pure, benzyl-substituted epoxy carboxylic acid as the key intermediate. Cyclic and amino-acid-residue-derived P2 groups were evaluated, and inhibitors equipotent to the series containing an indanol moiety were produced.
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| 16. |
- Georgsson, Jennie, 1975-
(författare)
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Design and Synthesis of Novel AT2 Receptor Ligands : From Peptides to Drug-Like Molecules
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Many peptide receptors are of pharmaceutical interest and there is thus a need for new ligands for such receptors. Unfortunately, peptides are not suitable as orally administrated drugs since they are associated with poor absorption, rapid metabolism and low sub-receptor selectivity. One approach that should allow identification of more drug-like ligands is to use the structural information of the endogenous ligand to develop peptidomimetic compounds.The main objective of the work described in this thesis was to convert angiotensin II (Ang II, Asp-Arg-Val-Tyr-Ile-His-Pro-Phe) to small drug-like compounds with retained bioactivity at the AT2 receptor. The study was performed step-wise via incorporation of well-defined secondary structure mimetics and repeated truncation of the peptide. Five scaffolds, comprising a benzene ring as a central element, suitable as a γ-turn or dipeptide mimetics were designed and synthesized. In order to decorate the scaffolds, a method of microwave-assisted alkoxycarbonylation was developed. After incorporation of the scaffolds into Ang II-related peptides or peptide fragments, the affinities for both the AT1 and the AT2 receptor were determined.In the first series of ligands, two tyrosine-related scaffolds were introduced as γ-turn mimetics in Ang II. All five pseudopeptides exhibited good affinities for the AT2 receptor. One compound was chosen for functional studies and was shown to act as an AT2 receptor agonist. After truncation of Ang II it was shown that C-terminal pentapeptide analogs were AT2 receptor selective agonists. A series of pseudopeptides comprising tyrosine-related scaffolds, derived from the pentapeptides, displayed high AT2 receptor affinities. Two compounds had agonistic effect at the AT2 receptor.This study revealed that the N-terminal part was of less importance while a C-terminal Ile residue was a key element for enhanced AT2 receptor affinity. In the final set of compounds, the peptide was truncated to tripeptide C-terminal fragments. After replacing His-Pro by a histidine-related scaffold small drug-like peptidomimetic compounds with nanomolar affinity for the AT2 receptor were identified.
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| 17. |
- Hallberg, Per, 1965-
(författare)
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Applanation Resonance Tonometry for Intraocular Pressure Measurement
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Elevated intraocular pressure (IOP) is one of the major risk factors for glaucoma. Since glaucoma is a leading cause of blindness, reliable methods for measuring the IOP are important. This doctoral dissertation presents a new method, applanation resonance tonometry (ART), for measurement of IOP. The method is based on resonance sensor technology combined with the novel multipoint analysis of continuously sampled data of both contact force and contact area. The ART was evaluated in in vitro porcine-eye studies as well as in clinic on both healthy volunteers and patients. A new symmetric probe with a larger sensor tip and improved aligning light was developed and evaluated in vitro. It showed that the error from off-centring was highly reduced. The new ART probe, used as a biomicroscope device (ARTBiom) and as a handheld device (ARTHand), was further evaluated in a clinical study designed in accordance with the International Standard Organisation’s (ISO) requirement. Both the ARTBiom and the ARTHand met the precision set by the requirements. Laser surgery is a common way to correct vision. The biomechanical effect of photorefractive keratectomy (PRK) on IOP measurements was evaluated using Goldmann applanation tonometry (GAT) and ART in an in vitro study. Both methods were affected, but to a different extent. The flat contact probe of GAT, as compared with the convex tip of ART, and single point vs. multipoint approach, provide explanation to the ART advantage regarding measurement error of IOP after PRK. In conclusion, resonance sensor technology has made it possible to introduce a new multipoint method for measuring IOP, and the method is relevant for measuring IOP in humans. It may be possible to reduce errors in the clinical measurement of IOP with this new method, especially after corneal surgery. The ART has the potential to become a useful clinical instrument for IOP measurement.
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| 18. |
- Le Grevès, Madeleine, 1966-
(författare)
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CNS Targets for GH and IGF-1 : Emphasis on Their Regulation in Relation to Cognitive Processes
- 2005
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The interest for the growth hormone/insulin-like growth factor-1 (GH/IGF-1) axis and its role in the central nervous system (CNS) has grown during the past decade. GH has been associated with psychological functions as sleep, mood, general well-being and learning and memory. The present thesis is a contribution to clarify the functions and mechanisms involved in the actions of GH and IGF-1 in the CNS. A variant of the GH receptor (GHR) gene transcript lacking exon 3 (GHR3-) was cloned from ovine choroid plexus epithelial cells and tissue. The GHR3- transcript has previously only been identified in human tissue. Further, an anatomical study of the localization of GHR mRNA in the rat brain stem and spinal cord was carried out by the use of in situ hybridization. High densities of GHRs were found in areas associated with the regulation of food intake, sleep and nociception, functions known to be influenced by the GH/IGF-1 axis. The interaction with the opioid system was studied by an acute treatment with morphine. The levels of the transcripts for GHR and GHBP in the rat hippocampus and spinal cord were decreased 4 h after the injection of the opiate and restored to normal levels after 24 h. Young and aged rats injected with GH or IGF-1 showed differential gene regulation of subunits of the NMDA subtype of glutamate receptor in the hippocampus. This indicates an age-related difference in the sensitivity to GH/IGF-1 mediated effects on memory functions. Moreover, hypophysectomized rats treated with GH showed improved performance in the Morris water maze, a spatial memory task. The effect was accompanied with an increase in transcripts for NMDA receptor subunits and its associated membrane anchoring PSD-95 protein. Taken together, the results suggest that GH and/or IGF-1 play important roles in mechanisms associated with cognitive functions.
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| 19. |
- Nilsson, Peter, 1971-
(författare)
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Selectivity in Palladium- and Enzyme-Catalyzed Reactions : Focusing on Enhancement of Reactivity
- 2003
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Catalysis has a profound impact on all living species on the earth. Nature’s catalysts, the enzymes, have the ability to selectively promote a specific bio-chemical transformation, given the required substrate. As well as being highly selective, enzymes enhance the speed of these reactions, helping them to run at temperatures much lower than normally required, i.e. at body temperature. In comparison, reactions used in the production of new materials such as polymers, medicines, fragrances, petrochemicals, etc. are often catalyzed by transition metals. This thesis describes how the selectivity and activity of these catalysts can be influenced via two conceptually different methods: chelation control and microwave heating. The thesis primarily focuses on regio- and stereochemical aspects of the palladium-catalyzed arylation of olefins, i.e. the Heck reaction. Reaction rate enhancement of both palladium and enzyme (polymerase chain reaction [PCR]) catalysis by microwave heating is also discussed. Novel chelation-controlled palladium-catalyzed multi- and asymmetric arylations of vinyl ethers were performed, resulting in tetra-substituted olefins as well as chiral quaternary carbon centers with excellent optical purity. In addition, a new synthetic route to diarylated ethanals, relying on a double chelation-controlled regioselective arylation followed by hydrolysis, has been discovered. High temperature conditions, using microwave heating, substantially reduce the reaction time for ligand-controlled asymmetric Heck arylations, while retaining levels of enantioselectivity in most cases. In addition, a potentially useful fast synthetic protocol for the employment of aryl boronic acids in oxidative Heck arylation was developed. Finally, microwave-assisted PCR was described for the first time; this method allows reductions in the run time of 50%.
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| 20. |
- Rosenström, Ulrika, 1972-
(författare)
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Design and Synthesis of AT2 Receptor Selective Angiotensin II Analogues Encompassing β- and γ-Turn Mimetics
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Important information on the bioactive conformation of biologically active peptides may be obtained by studies of rigid peptides or well-defined secondary structure mimetics incorporated into pseudopeptides. The structural requirements for the interaction of angiotensin II (Ang II, Asp-Arg-Val-Tyr-Ile-His-Pro-Phe) with its AT1 and AT2 receptors were the subject of this study. The main objectives of this work were to synthesize secondary structure mimetics and incorporate these into Ang II. Ang II has been suggested to adopt a turn conformation around Tyr4 when interacting with its AT1 receptor. Therefore, two γ- and one β-turn mimetic scaffolds based on the benzodiazepine structure were synthesized and decorated with side chains. The scaffolds replaced the turn region around Tyr4. Most of the pseudopeptides obtained after incorporation into Ang II exhibited high AT2/AT1 selectivity and nanomolar affinity to the AT2 receptor. One pseudopeptide encompassing a β-turn mimetic also displayed AT1 receptor affinity. We hypothesized that the position of the guanidino group of the arginine residue and the N-terminal end, in relation to the tyrosine side chain, was critical for AT2 receptor affinity. Conformational evaluation of the pseudopeptides revealed that in all the compounds with AT2 receptor affinity the arginine side chain and the N-terminal end could reach common regions, not accessible to the inactive compound. It is proposed that Ang II has a more extended bioactive conformation when binding to the AT2 receptor than when binding to the AT1 receptor. Furthermore, in a Gly scan of Ang II only replacement of the arginine residue reduced the affinity for the AT2 receptor considerably. Some N-terminal modified Ang II analogues were also synthesized and it was concluded that truncated Ang II analogues interact with the AT2 receptor differently than Ang II. Three of the synthesized pseudopeptides were evaluated in AT2 receptor functional assays and were found to act as agonists.
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