New Insights into the Structure-Activity Relationship and Neuroprotective Profile of Benzodiazepinone Derivatives of Neurounina-1 as Modulators of the Na+/Ca2+Exchanger Isoforms

Due to the neuroprotective role of the Na+/Ca2+ exchanger (NCX) isoforms NCX1 and NCX3, we synthesized novel benzodiazepinone derivatives of the unique NCX activator Neurounina-1, named compounds 1-19. The derivatives are characterized by a benzodiazepinonic nucleus linked to five- or six-membered cyclic amines via a methylene, ethylene, or acetyl spacer. The compounds have been screened on NCX1/NCX3 isoform activities by a high-throughput screening approach, and the most promising were characterized by patch-clamp electrophysiology and Fura-2AM video imaging. We identified two novel modulators of NCX: compound 4, inhibiting NCX1 reverse mode, and compound 14, enhancing NCX1 and NCX3 activity. Compound 1 displayed neuroprotection in two preclinical models of brain ischemia. The analysis of the conformational and steric features led to the identification of the molecular volume required for selective NCX1 activation for mixed NCX1/NCX3 activation or for NCX1 inhibition, providing the first prototypal model for the design of optimized isoform modulators

The synthesis of heterocyclic systems for use in biological imaging

The first research project described in this thesis is the development of new SPECT and PET imaging agents for group II metabotropic glutamate receptors (mGluR2/3). Investigation of these receptors is of great interest as they have been implicated in many psychiatric disorders. A small library of 1,5-benzodiazepinones were synthesised with potential radiolabelling sites incorporated in the 7- and 8-positions around the benzodiazepinone core. Once synthesised the binding affinity of the compounds with mGluR2 was determined using the [35S]GTPγS binding assay, which revealed them to be highly potent. Physicochemical properties were also investigated to determine whether compounds were likely to be brain penetrant. The 8-trifluoromethyl-7-methoxy and 8-iodo substituted compounds were found to have the required properties to be progressed. Work then focused on the synthesis of radiolabelling precursors of the hit compounds. The second research project outlined in thesis involves the synthesis of novel heterocycle containing α-amino acids. Previous work in the Sutherland group achieved the synthesis of enone containing amino acids from L-aspartic acid. Building upon this, such enones were employed to form a small library of phenylpyrazole containing amino acids. The fluorescence properties of these compounds were then investigated which revealed the naphthalene and nitrophenyl substituted analogues to be fluorescent and thus have potential to be used as peptide labels for fluorescence imaging

Plasmodium falciparum heat shock proteins as antimalarial drug targets: An update.

Global efforts to eradicate malaria are threatened by multiple factors, particularly the emergence of antimalarial drug resistant strains of Plasmodium falciparum. Heat shock proteins (HSPs), particularly P. falciparum HSPs (PfHSPs), represent promising drug targets due to their essential roles in parasite survival and virulence across the various life cycle stages. Despite structural similarities between human and malarial HSPs posing challenges, there is substantial evidence for subtle differences that could be exploited for selective drug targeting. This review provides an update on the potential of targeting various PfHSP families (particularly PfHSP40, PfHSP70, and PfHSP90) and their interactions within PfHSP complexes as a strategy to develop new antimalarial drugs. In addition, the need for a deeper understanding of the role of HSP complexes at the host-parasite interface is highlighted, especially heterologous partnerships between human and malarial HSPs, as this opens novel opportunities for targeting protein-protein interactions crucial for malaria parasite survival and pathogenesis

development of qsar models for predicting anti hiv 1 activity using the monte carlo method

AbstractAbstract The CORAL software (http://www.insilico.eu/coral/) has been examined as a tool for modeling anti-HIV-1 activity by quantitative structure — activity relationships (QSAR) for three different sets: (i) TIBO derivatives (n=82) (ii) anti-HIV-1 activity of 2-amino-6-arylsulfonylbenzonitriles and their congeners (n=64), and (iii) the measured binding affinity for fullerene-based HIV-1 PR inhibitors (n=48). A new global invariant ATOMPAIR of the molecular structure which can be calculated with the simplified molecular input line entry system (SMILES) was studied. The ATOMPAIR is an indicator of the joint presence of pairs of chemical elements (F, Cl, Br, N, O, S, and P) and three types of bonds (double covalent bond, triple covalent bond, and stereo chemical bond). Six random splits into sub-training, calibration, and test set were examined for each set. For the three aforementioned sets, the use of ATOMPAIR in the modeling process improves the predictive potential of the models for six random splits. Graphical abstrac

Design and synthesis of diazepine inhibitors as novel anti-cancer agents

Cancer is a new growth that arises from abnormal and uncontrolled division of cells that may go on to invade and destroy surrounding tissues. The eukaryotic cell cycle consists of a complex sequence of events that regulates cell division and responses to DNA damage. These processes rely upon several key enzymes, including the cyclin dependent kinases (CDKs), checkpoint kinases (Chk2) and poly(ADP-ribose)polymerase-l (PARP-1). CDKs are a family of protein kinases that control progression of the cell cycle, and are themselves regulated by a complex network of activating and inhibitory mechanisms. The vital importance of CDKs in regulating of the cell cycle, emphasise their importance as anti-cancer drug targets. CDKs inhibitors compete with the natural substrate ATP in a competitive manner. Hymenialdisine and kenpaullone have been identified as novel and potent CDK inhibitors both containing an unusual azepinone scaffold. Checkpoint kinase 2 (Chk2) is a novel target for anti-cancer drug design. The enzyme mediates cell proliferation in response to DNA damage by inducing cell cycle arrest, which facilitates the DNA repair pathways. Chk2 inhibition has been recognised as a potential target for the chemopotentiation of current anti-cancer treatments. Few Chk2 inhibitors are known, kenpaullone has been identified as a novel and selective ATP competitive Chk2 inhibitor (IC₅₀ = 0.8 µM). Debromohymenialdisine (DBH) also containing an azepinone scaffold has also been reported to inhibit Chk2. Poly(ADP-ribose)polymerase-l (PARP-1) is activated in response to DNA damage, and inhibition can potentiate cancer chemotherapy and radiotherapy. A PARP-1 inhibitor in combination with a cytotoxic agent should enhance drug activity by blocking the repair capabilities of PARP-1 in cancer cells. Although many types of inhibitors have been identified for each of these three enzymes, compounds containing a seven-membered lactam ring have been identified as key inhibitors for CDKs/Chk2/PARP-l. This study is entered upon developing the synthesis for a series of novel inhibitors of these three enzymes containing the essential lactam pharmacophore in their structures. The compounds synthesised in this study were assessed by a number of biological assays showing moderate or good growth or catalytic inhibitory activity against CDKs and PARP-1 respectively, while assays against Chk2 showed no inhibition.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Design and synthesis of diazepine inhibitors as novel anti-cancer agents

Cancer is a new growth that arises from abnormal and uncontrolled division of cells that may go on to invade and destroy surrounding tissues. The eukaryotic cell cycle consists of a complex sequence of events that regulates cell division and responses to DNA damage. These processes rely upon several key enzymes, including the cyclin dependent kinases (CDKs), checkpoint kinases (Chk2) and poly(ADP-ribose)polymerase-l (PARP-1). CDKs are a family of protein kinases that control progression of the cell cycle, and are themselves regulated by a complex network of activating and inhibitory mechanisms. The vital importance of CDKs in regulating of the cell cycle, emphasise their importance as anti-cancer drug targets. CDKs inhibitors compete with the natural substrate ATP in a competitive manner. Hymenialdisine and kenpaullone have been identified as novel and potent CDK inhibitors both containing an unusual azepinone scaffold. Checkpoint kinase 2 (Chk2) is a novel target for anti-cancer drug design. The enzyme mediates cell proliferation in response to DNA damage by inducing cell cycle arrest, which facilitates the DNA repair pathways. Chk2 inhibition has been recognised as a potential target for the chemopotentiation of current anti-cancer treatments. Few Chk2 inhibitors are known, kenpaullone has been identified as a novel and selective ATP competitive Chk2 inhibitor (IC 50 = 0.8 µM). Debromohymenialdisine (DBH) also containing an azepinone scaffold has also been reported to inhibit Chk2. Poly(ADP-ribose)polymerase-l (PARP-1) is activated in response to DNA damage, and inhibition can potentiate cancer chemotherapy and radiotherapy. A PARP-1 inhibitor in combination with a cytotoxic agent should enhance drug activity by blocking the repair capabilities of PARP-1 in cancer cells. Although many types of inhibitors have been identified for each of these three enzymes, compounds containing a seven-membered lactam ring have been identified as key inhibitors for CDKs/Chk2/PARP-l. This study is entered upon developing the synthesis for a series of novel inhibitors of these three enzymes containing the essential lactam pharmacophore in their structures. The compounds synthesised in this study were assessed by a number of biological assays showing moderate or good growth or catalytic inhibitory activity against CDKs and PARP-1 respectively, while assays against Chk2 showed no inhibition.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Design and synthesis of diazepine inhibitors as novel anti-cancer agents.

Cancer is a new growth that arises from abnormal and uncontrolled division of cells that may go on to invade and destroy surrounding tissues. The eukaryotic cell cycle consists of a complex sequence of events that regulates cell division and responses to DNA damage. These processes rely upon several key enzymes, including the cyclin dependent kinases (CDKs), checkpoint kinases (Chk2) and poly(ADP-ribose)polymerase-l (PARP-1). CDKs are a family of protein kinases that control progression of the cell cycle, and are themselves regulated by a complex network of activating and inhibitory mechanisms. The vital importance of CDKs in regulating of the cell cycle, emphasise their importance as anti-cancer drug targets. CDKs inhibitors compete with the natural substrate ATP in a competitive manner. Hymenialdisine and kenpaullone have been identified as novel and potent CDK inhibitors both containing an unusual azepinone scaffold. Checkpoint kinase 2 (Chk2) is a novel target for anti-cancer drug design. The enzyme mediates cell proliferation in response to DNA damage by inducing cell cycle arrest, which facilitates the DNA repair pathways. Chk2 inhibition has been recognised as a potential target for the chemopotentiation of current anti-cancer treatments. Few Chk2 inhibitors are known, kenpaullone has been identified as a novel and selective ATP competitive Chk2 inhibitor (IC50 = 0.8 uM). Debromohymenialdisine (DBH) also containing an azepinone scaffold has also been reported to inhibit Chk2. Poly(ADP-ribose)polymerase-l (PARP-1) is activated in response to DNA damage, and inhibition can potentiate cancer chemotherapy and radiotherapy. A PARP-1 inhibitor in combination with a cytotoxic agent should enhance drug activity by blocking the repair capabilities of PARP-1 in cancer cells. Although many types of inhibitors have been identified for each of these three enzymes, compounds containing a seven-membered lactam ring have been identified as key inhibitors for CDKs/Chk2/PARP-l. This study is entered upon developing the synthesis for a series of novel inhibitors of these three enzymes containing the essential lactam pharmacophore in their structures. The compounds synthesised in this study were assessed by a number of biological assays showing moderate or good growth or catalytic inhibitory activity against CDKs and PARP-1 respectively, while assays against Chk2 showed no inhibition

Design, synthèse et criblage de chimiothèques peptidomimétiques pour la découverte d'agents antinéoplasiques

Le criblage des interactions protéine-protéine représente une approche thérapeutique prometteuse et novatrice qui est encore sous-exploitées par l’industrie pharmaceutique et la recherche biomédicale. Par contre, la nature étendue de la surface d’interaction complique le développement d’inhibiteurs par les méthodes classiques de criblage avec des chimiothèques de petites molécules. En effet, l’espace chimique couvert par les structures moléculaires retrouvées au sein des chimiothèques disponibles est peu adapté à la réalité des interactions protéine-protéine. Dans le but de développer des structures privilégiées et mieux adaptées, le chimiste médicinal doit comprendre la nature de ces interactions et s’éloigner du dogme traditionnel des molécules dites « drug-like ». Les peptides sont d’excellents candidats pour inhiber et étudier ces interactions, mais leur faible perméabilité membranaire et leur sensibilité aux protéases limitent leur utilisation in vivo. Le peptidomimétisme devient alors un concept plus que pertinent pour combiner la sélectivité et l’efficacité d’interaction des peptides avec la biodisponibilité et la stabilité métabolique des molécules organiques. De nombreuses plateformes peptidomimétiques sont disponibles ou en émergence mais plusieurs défis de taille se présentent à l’horizon. En effet, l’incorporation d’une grande diversité moléculaire et l’adaptation de ces plateformes avec les méthodes de criblage biologique à haut débit ne sont que quelques exemples des défis auxquels les chimistes et biochimistes devront répondre. Cet ouvrage présente des travaux qui ont portés sur le développement et l’exploitation de diversités moléculaires peptidomimétiques de nature diverse, tant macrocyclique qu’hétérocyclique. Dans un premier temps, diverses méthodologies de synthèse novatrices ont été développées pour étendre la diversité moléculaire accessible des peptoïdes et pour permettre le criblage à haut débit de peptoïdes cycliques selon l’approche combinatoire «one-bead-one-compound». Dans un deuxième temps, la méthodologie de synthèse Ugi-deFmoc-SNAr a été développée pour permettre la synthèse rapide et efficace de benzo-1,4-diazépin-3-ones hautement diversifiées. C’est grâce à cette méthodologie qu’une chimiothèque de première génération a pu être produite et criblée sur des lignées cellulaires du cancer de l’ovaire, de la prostate et du pancréas. Un composé a d’ailleurs été identifié pour son activité antiproliférative in vitro et son activité antitumorale in vivo. Ces différents travaux répondent au même but : exploiter des structures privilégiées pour découvrir de nouveaux modulateurs d’interaction protéine-protéine ou simplement des agents bioactifs novateurs avec des propriétés pharmacologiques prometteuses.Targeting protein-protein interactions represents an innovative and under-exploited therapeutic approach by the pharmaceutical industry and biomedical research. Because of their physicochemical nature, protein-protein interactions represent a major challenge for conventional screening methods with small molecule libraries. Indeed, the chemical space covered by the molecular structures found in the available libraries is poorly adapted to the reality of protein-protein interactions. In order to develop privileged and better adapted structures, the medicinal chemist must understand the nature of these interactions and move away from the traditional dogma of the so-called drug-like molecules. Peptides are excellent candidates for studying these interactions, nevertheless their pharmacological properties are generally disappointing in vivo. Peptidomimetism is then a more than relevant concept to combine the selectivity and efficiency of interaction against proteins with the concepts of bioavailability and metabolic stability. Many peptidomimetic platforms are available or emerging, and several major challenges are on the horizon. Indeed, the incorporation of a large molecular diversity and the adaptation of these platforms with the high throughput biological screening methods are only a few examples of the challenges that chemists and biochemists will have to meet. This work deals with the development and exploitation of different peptidomimetic molecular diversities, either macrocyclic or heterocyclic, but which serve the same purpose: to exploit privileged structures to discover new modulators of protein-protein interactions or simply innovative bioactive agents with advantageous pharmacological properties

Influence of a methylated-B-Cyclodextrin on the solubility and photostability of midazolam in aqueous solution

Midazolam, used clinically as an anticonvulsant, anxiolytic, muscle relaxant and sedative is a photolabile imidazo-benzodiazepine which is marketed under the trade names Dormicum® and Hypnovel® as tablets and injectables. Because of an aqueous solubility of < 0.1 mg/ml above pH 4, the preparation of aqueous dosage formulations near physiological pH, requires a solubilizer. The aim of this study was thus to prepare a 10 mg/ml midazolam aqueous solution for topical application using randomly-methylated-pcyclodextrin (RAMEB), considered to be a suitable candidate as a solubilizer because of its absorption enhancing properties, and to investigate its effect on both the solubility and the photostability of midazolam. Solubility studies of midazolam (excess of 15 mg/ml) in the presence of 0, 5,10,20, 30% m/v of RAMEB at pH 5.0 and pH 5.8 (phosphate buffer) were undertaken and the results analyzed using a UV method validated for linearity, accuracy, precision and specificity. A stability-indicating HPLC method was developed and validated (precision and accuracy, linearity, range, limit of quantitation, specificity, robustness and ruggedness) for application to kinetic photostability studies and the identification of photodegradants by LC-MS. Forced degradation studies were carried out at concentrations of 0.5 mg/ml of midazolam instead of the target concentration of 10 mg/ml because of the acceleratory effect of the decreased concentration on the rate of photodegradation. The solutions of midazolam with and without RAMEB were irradiated at 550 W/m² for 12 hrs in order to degrade the drug to ± 10% of the original concentration. The UV method proved to be valid in terms of linearity with a correlation coefficient of 0.9998, precise and accurate, and specific for the determination of midazolam in the presence of RAMEB. The results of the phase solubility studies indicated that desired solubility of 10 mg/ml was achieved with 30% m/v RAMEB at pH 5.0. RAMEB slightly decreased the photostability of midazolam, the rate constants being 0.137 and 0.154 hr⁻¹ in the absence and presence of RAMEB, respectively. LC-MS analysis revealed that one of the major photoproducts in the presence and absence of RAMEB was N-desalkylflurazepam, a starting material in the synthesis of midazolam. RAMEB inhibited formation of some photoproducts and introduced two new photoproducts, a dimer and an addition product. The difference in the nature of these photoproducts formed may be attributed to the ability of RAMEB to provide conformational control and to stabilize free radicals. Although RAMEB improved the solubility of midazolam to the target concentration, photostability is decreased with the presence of different photoproducts. These studies have however provided information on the overall photostability of midazolam, the identity of its photodegradants and the photodegradation pathway in the presence and absence of RAMEB, and may be used for further method development and validation for the analysis of aqueous dosage forms containing RAMEB as a solubilizer.KMBT_363Adobe Acrobat 9.53 Paper Capture Plug-i