Exploring new labelling strategies for boronated compounds: towards fast development and efficient assessment of BNCT drug candidates

208 p.

Cytotoxicity of liver targeted drug-loaded alginate nanoparticles

In this study, novel liver targeted doxorubicin (DOX) loaded alginate (ALG) nanoparticles were prepared by CaCl2 crosslinking method. Glycyrrhetinic acid (GA, a liver targeted molecule) modified alginate (GA-ALG) was synthesized in a heterogeneous system, and the structure of GA-ALG and the substitution degree of GA were analyzed by H-1 NMR, FT-IR and elemental analysis. The drug release profile under the simulated physiological condition and cytotoxicity experiments of drug-loaded GA-ALG nanoparticles were carried out in vitro. Transmission electron micrographs (TEM) and dynamic light scattering (DLS) analysis showed that drug-loaded GA-ALG nanoparticles have spherical shape structure with the mean hydrodynamic diameter around 214 +/- 11 nm.

Glycyrrhetinic acid-modified nanoparticles for drug delivery: Preparation and characterization

In this work, glycyrrhetinic acid-modified chitosan (mGA-suc-CTS) used as liver targeted carrier for drug delivery, was prepared via hemisuccinate as a bridged group. The structure of the product was confirmed by IR and NMR methods and the degree of substitution (DS) of glycyrrhetinic acid groups was estimated via elemental analysis. Nanoparticles were formed by ionic gelation methold. The drug-loading and release behavior of the nanoparticles were investigated using BSA as the model drug. The results indicated that the carrier with a highest DS of 5.19% could be got and the DS was controlled by changing reaction temperature or feed ratio. BSA could be entrapped into the nanoparticles with the drug-loading ratio of 26.3% and the encapsulation efficiency of 81.5%. A sustained release over an 11-day period was observed in pH 7.4 in vitro.

Comparative effects of GLP-1 and GIP on cAMP production, insulin secretion, and in vivo antidiabetic actions following substitution of Ala8/Ala2 with 2-aminobutyric acid

The two major incretin hormones, glucagon-like peptide-1 (GLP-1), and glucose-dependent insulinotropic polypeptide (GIP), are currently being considered as prospective drug candidates for treatment of type 2 diabetes. Interest in these gut hormones was initially spurred by their potent insulinotropic activities, but a number of other antihyperglycaemic actions are now established. One of the foremost barriers in progressing GLP-1 and GIP to the clinic concerns their rapid degradation and inactivation by the ubiquitous enzyme, dipeptidyl peptidase IV (DPP IV). Here, we compare the DPP IV resistance and biological properties of Abu(8)/ Abu(2) (2-aminobutyric acid) substituted analogues of GLP-1 and GIP engineered to impart DPP IV resistance. Whereas (Abu(8))GLP-1 was completely stable to human plasma (half-life > 12h), GLP-1, GIP, and (Abu(2))GIP were rapidly degraded (half-lives: 6.2, 6.0, and 7.1 h, respectively). Native GIP, GLP-1, and particularly (Abu(8))GLP-1 elicited significant adenylate cyclase and insulinotropic activity, while (Abu(2))GIP was less effective. Similarly, in obese diabetic (ob/ob) mice, GIP, GLP-1, and (Abu(8))GLP-1 displayed substantial glucose-lowering and insulin -releasing activities, whereas (Abu(2))GIP was only weakly active. These studies illustrate divergent effects of penultimate amino acid Ala(8)/Ala(2) substitution with Abu on the biological properties of GLP-1 and GIP, suggesting that (Abu(8))GLP-1 represents a potential candidate for future therapeutic development. (C) 2004 Elsevier Inc. All rights reserved.

Determination of absolute configuration of conformationally flexible cis-dihydrodiol metabolites: Effect of diene substitution pattern on the circular dichroism spectra and optical rotations

Absolute configurations of a number of cis-dihydrodiols (cis-1,2-dihydroxy-3,5-cyclohexadienes), synthetically useful products of TDO-catalyzed dihydroxylations of 1,2- and 1,3-disubstituted benzene derivatives, have been determined by a comparison of calculated and experimental CD spectra and optical rotations and by methods involving X-ray crystallography, H-1 NMR spectra of diastereoisomeric derivatives, and by stereochemical correlations. The computations disclosed a significant effect of the substituents on conformational equilibria of cis-dihydrodiols and chiroptical properties of individual conformers. The assigned absolute configurations of cis-dihydrodiols have allowed the validity of a simple predictive model for TDO-catalyzed arene dihydroxylations to be extended.

Conspicuous by their abstinence: the limited engagement of heroin users in English and Welsh Drug Recovery Wings

Background In recent years, an abstinence-focused, ‘recovery’ agenda has emerged in UK drug policy, largely in response to the perception that many opioid users had been ‘parked indefinitely’ on Opioid Substitution Therapy (OST). The introduction of ten pilot ‘Drug Recovery Wings’ (DRWs) in 2011 represents the application of this recovery agenda to prisons. This paper describes the DRWs’ operational models, the place of opiate dependent prisoners within them, and the challenges of delivering ‘recovery’ in prison. Methods In 2013, the implementation and operational models of all ten pilot DRWs were rapidly assessed. Up to three days were spent in each DRW, undertaking semi-structured interviews with a sample of 94 DRW staff and 102 DRW residents. Interviews were fully transcribed, and coded using grounded theory. Findings from the nine adult prisons are presented here. Results Four types of DRW were identified, distinguished by their size and selection criteria. Strikingly, no mid- or large-sized units regularly supported OST recipients through detoxification. Type A were large units whose residents were mostly on OST with long criminal records and few social or personal resources. Detoxification was rare, and medication reduction slow. Type B's mid-sized DRW was developed as a psychosocial support service for OST clients seeking detoxification. However, staff struggled to find such prisoners, and detoxification again proved rare. Type C DRWs focused on abstinence from all drugs, including OST. Though OST clients were not intentionally excluded, very few applied to these wings. Only Type D DRWs, offering intensive treatment on very small wings, regularly recruited OST recipients into abstinence-focused interventions. Conclusion Prison units wishing to support OST recipients in making greater progress towards abstinence may need to be small, intensive and take a stepped approach based on preparatory motivational work and extensive preparation for release. However, concerns about post-release deaths will remain.

Medicinal chemistry approaches to malaria drug discovery

Tese de doutoramento, Farmácia (Química Farmacêutica e Terapêutica), Universidade de Lisboa, Faculdade de Farmácia, 2016

Substitution of (R,S)-methadone by (R)-methadone: Impact on QTc interval.

Methadone is administered as a chiral mixture of (R,S)-methadone. The opioid effect is mainly mediated by (R)-methadone, whereas (S)-methadone blocks the human ether-à-go-go-related gene (hERG) voltage-gated potassium channel more potently, which can cause drug-induced long QT syndrome, leading to potentially lethal ventricular tachyarrhythmias. To investigate whether substitution of (R,S)-methadone by (R)-methadone could reduce the corrected QT (QTc) interval, (R,S)-methadone was replaced by (R)-methadone (half-dose) in 39 opioid-dependent patients receiving maintenance treatment for 14 days. (R)-methadone was then replaced by the initial dose of (R,S)-methadone for 14 days (n = 29). Trough (R)-methadone and (S)-methadone plasma levels and electrocardiogram measurements were taken. The Fridericia-corrected QT (QTcF) interval decreased when (R,S)-methadone was replaced by a half-dose of (R)-methadone; the median (interquartile range [IQR]) values were 423 (398-440) milliseconds (ms) and 412 (395-431) ms (P = .06) at days 0 and 14, respectively. Using a univariate mixed-effect linear model, the QTcF value decreased by a mean of -3.9 ms (95% confidence interval [CI], -7.7 to -0.2) per week (P = .04). The QTcF value increased when (R)-methadone was replaced by the initial dose of (R,S)-methadone for 14 days; median (IQR) values were 424 (398-436) ms and 424 (412-443) ms (P = .01) at days 14 and 28, respectively. The univariate model showed that the QTcF value increased by a mean of 4.7 ms (95% CI, 1.3-8.1) per week (P = .006). Substitution of (R,S)-methadone by (R)-methadone reduces the QTc interval value. A safer cardiac profile of (R)-methadone is in agreement with previous in vitro and pharmacogenetic studies. If the present results are confirmed by larger studies, (R)-methadone should be prescribed instead of (R,S)-methadone to reduce the risk of cardiac toxic effects and sudden death.

Influence of noninjecting and injecting drug use on mortality, retention in the cohort, and antiretroviral therapy, in participants in the Swiss HIV Cohort Study.

OBJECTIVES: We studied the influence of noninjecting and injecting drug use on mortality, dropout rate, and the course of antiretroviral therapy (ART), in the Swiss HIV Cohort Study (SHCS). METHODS: Cohort participants, registered prior to April 2007 and with at least one drug use questionnaire completed until May 2013, were categorized according to their self-reported drug use behaviour. The probabilities of death and dropout were separately analysed using multivariable competing risks proportional hazards regression models with mutual correction for the other endpoint. Furthermore, we describe the influence of drug use on the course of ART. RESULTS: A total of 6529 participants (including 31% women) were followed during 31 215 person-years; 5.1% participants died; 10.5% were lost to follow-up. Among persons with homosexual or heterosexual HIV transmission, noninjecting drug use was associated with higher all-cause mortality [subhazard rate (SHR) 1.73; 95% confidence interval (CI) 1.07-2.83], compared with no drug use. Also, mortality was increased among former injecting drug users (IDUs) who reported noninjecting drug use (SHR 2.34; 95% CI 1.49-3.69). Noninjecting drug use was associated with higher dropout rates. The mean proportion of time with suppressed viral replication was 82.2% in all participants, irrespective of ART status, and 91.2% in those on ART. Drug use lowered adherence, and increased rates of ART change and ART interruptions. Virological failure on ART was more frequent in participants who reported concomitant drug injections while on opiate substitution, and in current IDUs, but not among noninjecting drug users. CONCLUSIONS: Noninjecting drug use and injecting drug use are modifiable risks for death, and they lower retention in a cohort and complicate ART.

The Na+/H+ exchanger Nhx1 of Saccharomyces cerevisiae is essential to limit drug toxicity

Nhx1 est un antiport vacuolaire de Na+/H+ chez la levure Saccharomyces cerevisiae. Nhx1 joue un rôle important dans le maintien de l’homéostasie ionique du cytoplasme de la cellule. En effet, la mutation du gène NHX1 chez la levure nhx1Δ entraîne une perte de l’homéostasie cellulaire quand les cellules sont cultivées dans un milieu de faible osmolarité. Ce travail rapporte pour la première fois, et contrairement à la cellule parentale, que la mutation du gène NHX1 a pour effet une sensibilité du mutant nhx1Δ à une variété des drogues et des agents cationiques et anioniques lorsque les cellules sont cultivées dans un milieu riche. En outre, dans ces conditions de culture, aucune sensibilité n’a été observée chez le mutant nhx1Δ quand les cellules sont traitées avec différentes concentrations de sel. Nous avons aussi démontré que la sensibilité du mutant nhx1Δ aux différents agents ainsi que la sécrétion de l’enzyme carboxypeptidase Y observé chez ce mutant n’ont pas été restauré lorsque les cellules sont cultivées dans des milieux avec différents pH ou avec différentes concentrations de sel. Enfin, une analyse génétique a révélé que le mutant nhx1Δ montre un phénotype distinct d’autres mutants qui ont un défaut dans le trafic entre le compartiment pré-vacuolaire et l’appareil de Golgi quand ces cellules sont traitées avec différents agents. Cette analyse prouve que la sensibilité de nhx1Δ aux différents agents n’est pas liée au trafic entre le compartiment pré-vacuolaire et l’appareil de Golgi.

La méthadone permet-elle de sortir du monde de la drogue? : points de vue de personnes inscrites aux programmes de substitution

Deux paradigmes se côtoient dans le traitement de la dépendance au Québec. Tout d’abord, il y a le paradigme de l’abstinence avec un modèle d’intervention souvent basé sur les Alcooliques Anonymes. Avec ce modèle, l’alcoolisme (ou la toxicomanie) est défini comme une maladie. En ce qui a trait à la réduction des méfaits, cette dernière vise la réduction des effets néfastes de l’usage de drogues plutôt que l’élimination de leur usage (Brisson, 1997). Nous nous sommes intéressés à une intervention inscrite dans ce paradigme soit le programme de substitution à la méthadone. Cette étude avait comme but de connaître les perceptions de personnes inscrites à ce programme, comprendre comment est vécu le rétablissement à travers la participation au programme et connaître les perceptions de ces personnes en ce qui a trait aux conséquences de la dépendance. Un cadre théorique s’inscrivant dans la perspective de l’interactionnisme symbolique a été choisi. Plus précisément, les processus de transformations normatives de Maria Caiata Zufferey, la théorie de l’étiquetage d’Howard Becker et le concept de stigmate d’Erving Goffman ont été retenus. Ensuite, dix entrevues semi-dirigées auprès d’hommes et de femmes majeures inscrites à un programme de substitution à la méthadone ont été réalisées. En ce qui a trait au chapitre portant sur les résultats, il a mis en lumière différents rapports à la méthadone vécus par les participants. Pour ce faire, trois figures construites à l’aide de l’analyse typologique ont été développées. Il ressort que pour certaines personnes, la méthadone fut décrite comme un substitut nécessaire, pour d’autres, elle correspondait à une aide dont ils veulent se débarrasser et pour une minorité, elle suscitait de l’ambivalence. En définitive, bien que la substitution demeure le traitement de choix pour la dépendance aux opioïdes, il est difficile de parler de sortie du monde de la drogue à l’aide de la méthadone puisque ce traitement apparaît comme étant presque aussi stigmatisé que la dépendance à l’héroïne (Lauzon, 2011). À première vue, la méthadone permet de prendre une distance avec le monde de la drogue (l’argent facile, les vols, la prostitution) et permet de se reconstruire une existence sur la base de repères stables, mais à bien considérer les choses, elle confine les personnes interrogées dans une situation d’ambivalence puisqu’elle les rattache à une identité de toxicomane. Mots-clés : dépendance, programme de substitution à la méthadone, perception, participant, réduction des méfaits, stigmatisation.

Carbon-carbon bond formation : from transition metal catalysis to base-promoted homolytic aromatic substitution

Cette thèse de doctorat porte sur la catalyse à partir de métaux de transition et sur la substitution homolytique aromatique favorisée par une base visant à former de nouvelles liaisons C–C, et à ainsi concevoir de nouvelles structures chimiques. Au cours des vingt dernières années, des nombreux efforts ont été réalisés afin de développer des méthodologies pour la fonctionnalisation de liens C–H, qui soient efficaces et sélectives, et ce à faible coût et en produisant le minimum de déchets. Le chapitre d'introduction donnera un aperçu de la fonctionnalisation directe de liens C–H sur des centres sp2 et sp3. Il sera également discuté dans cette partie de certains aspects de la chimie radicalaire reliés a ce sujet. Les travaux sur la fonctionnalisation d’imidazo[1,5-a]pyridines catalysée par des compleces de ruthénium seront présentés dans le chapitre 2. Malgré l'intérêt des imidazo[1,5-a]azines en chimie médicinale, ces composés n’ont reçu que peu d'attention dans le domaine de la fonctionnalisation de liens C–H. L'étendue de la réaction et l'influence des effets stériques et électroniques seront détaillés. Les cyclopropanes représentent les 10ème cycles carbonés les plus rencontrés dans les petites molécules d’intérêt pharmacologique. Ce sont aussi des intermédiaires de synthèse de choix pour la création de complexité chimique. Malgré de grands progrès dans le domaine de la fonctionnalisation de liens C(sp3)–H, l'étude des cyclopropanes comme substrats dans les transformations directes est relativement nouvelle. Le chapitre trois présentera l'arylation intramoléculaire directe de cyclopropanes. Cette réaction est réalisée en présence de palladium, en quantité catalytique, en combinaison avec des sels d’argent. Des études mécanistiques ont réfuté la formation d'un énolate de palladium et suggéreraient plutôt une étape de métallation - déprotonation concertée. En outre, les cycles de type benzoazepinone à sept chaînons ont été synthétisés par l'intermédiaire d'une séquence d'activation de cyclopropane/ouverture/cyclisation. Une arylation directe intermoléculaire des cyclopropanes a été réalisée en présence d'un auxiliaire de type picolinamide (Chapitre 4). Les deux derniers chapitres de ce mémoire de thèse décriront nos études sur la substitution homolytique aromatique favorisée par une base. Le mécanisme de la réaction de cyclisation intramoléculaire d'halogénures d'aryle, réalisée en présence de tert-butylate de potassium, a été élucidé et se produit via une voie radicalaire (Chapitre 5). La transformation, exempte de métaux de transition, ne nécessite que la présence d’une base et de pyridine comme solvant. Cette réaction radicalaire a été étendue à la cyclisation d'iodures d'alkyle non activés en présence d'un catalyseur à base de nickel et de bis(trimethylsilyl)amidure de sodium comme base (Chapitre 6). Des études de RMN DOSY ont démontré une association entre le catalyseur, la base et le matériel de départ.

Drug bioactivation, covalent binding to target proteins and toxicity relevance

A number of therapeutic drugs with different structures and mechanisms of action have been reported to undergo metabolic activation by Phase I or Phase II drug-metabolizing enzymes. The bioactivation gives rise to reactive metabolites/intermediates, which readily confer covalent binding to various target proteins by nucleophilic substitution and/or Schiff's base mechanism. These drugs include analgesics (e.g., acetaminophen), antibacterial agents (e.g., sulfonamides and macrolide antibiotics), anticancer drugs (e.g., irinotecan), antiepileptic drugs (e.g., carbamazepine), anti-HIV agents (e.g., ritonavir), antipsychotics (e.g., clozapine), cardiovascular drugs (e.g., procainamide and hydralazine), immunosupressants (e.g., cyclosporine A), inhalational anesthetics (e.g., halothane), nonsteroidal anti-inflammatory drugs (NSAIDSs) (e.g., diclofenac), and steroids and their receptor modulators (e.g., estrogens and tamoxifen). Some herbal and dietary constituents are also bioactivated to reactive metabolites capable of binding covalently and inactivating cytochrome P450s (CYPs). A number of important target proteins of drugs have been identified by mass spectrometric techniques and proteomic approaches. The covalent binding and formation of drug-protein adducts are generally considered to be related to drug toxicity, and selective protein covalent binding by drug metabolites may lead to selective organ toxicity. However, the mechanisms involved in the protein adduct-induced toxicity are largely undefined, although it has been suggested that drug-protein adducts may cause toxicity either through impairing physiological functions of the modified proteins or through immune-mediated mechanisms. In addition, mechanism-based inhibition of CYPs may result in toxic drug-drug interactions. The clinical consequences of drug bioactivation and covalent binding to proteins are unpredictable, depending on many factors that are associated with the administered drugs and patients. Further studies using proteomic and genomic approaches with high throughput capacity are needed to identify the protein targetsof reactive drug metabolites, and to elucidate the structure-activity relationships of drug's covalent binding to proteins and their clinical outcomes.

Alcohol Price Considerations on alcohol and Illicit Drug Use in University Students

Background
This study investigates alcohol price and proposed substance use amongst Australian tertiary students.

Methods
Participants were recruited in 2009 via facebook, and were asked to complete a 34-item internetbased survey. 512 people took part, 485 fit the inclusion criteria.

Results
The sample consisted predominately of young (mean age 20.3 years), female (66%) university students. Higher alcohol prices resulted in increased consideration of illicit substances as an alternative indicating a substitution effect, although the majority (60%) of respondents would never consider using ecstasy.

Conclusion
Results indicate substantial room to increase the price of alcohol to achieve alcohol consumption reduction without likely substitution behavior.