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Drug Candidates (drug + candidate)
Kinds of Drug Candidates Selected AbstractsConformational Analysis of R207910, a New Drug Candidate for the Treatment of Tuberculosis, by a Combined NMR and Molecular Modeling ApproachCHEMICAL BIOLOGY & DRUG DESIGN, Issue 2 2006Sandrine Gaurrand R207910 is an enantiomeric compound from a new class of antimycobacterial agents, the diarylquinolines [Science; 307:223 (2005)]. As enantiospecific interaction is required for biologic activity, we have undertaken a combined nuclear magnetic resonance and molecular modeling study to gain new insights into its conformation in solution and its absolute configuration. A conformational analysis using a Monte-Carlo method has been performed on each of the four possible stereomers of this compound leading to the identification of their most stable conformation. Additional ab initio calculation was performed with emphasis on the strength of the observed intramolecular hydrogen bond. Simultaneously, a complete structural identification has been carried out by a set of monodimensional and bidimensional 1H- 13C-NMR experiments. Determination of inter-proton distances has been achieved by a series of 1H- 1H ROESY NMR experiments with different mixing times followed by a volume quantification of the correlations peaks. These experimental data were compared with the theoretical distances obtained from the conformational analysis. The remarkable match shows that R207910 adopts one of the low-energy conformations predicted by molecular modeling and belongs to the (RS, SR) couple of diastereoisomers. A posteriori validation of our approach has been performed by X-ray structure determination that concluded for the RS configuration. [source] Stereoselective Synthesis of (2S,7S)-7-(4-Phenoxymethyl)-2-(1-N-hydroxyureidyl-3-butyn-4-yl)oxepane: A Potential Antiasthmatic Drug Candidate.CHEMINFORM, Issue 30 2005Mukund K. Gurjar No abstract is available for this article. [source] Etiprednol Dicloacetate, a New Soft Glucocorticoid Drug Candidate.CHEMINFORM, Issue 35 2004Development of Chemistry. Abstract For Abstract see ChemInform Abstract in Full Text. [source] Design, Synthesis, and Pharmacological Investigation of Iodined Salicylimines, New Prototypes of Antimicrobial Drug CandidatesARCHIV DER PHARMAZIE, Issue 5 2010Suo-Ping Xu Abstract A series of 3,5-diiodo-salicylalidene Schiff bases (compounds 1,35) has been synthesized and tested for antimicrobial activity. The compounds were assayed for antibacterial activities by the MTT method. Some of the compounds inhibit the growth of a broad range of bacteria including the species of Bacillus subtilis, Staphylococcus aureus, Streptococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, and Enterobacter cloacae. Among them, compounds 2-[(4-chloro-phenylimino)methyl]-4,6-diiodo-phenol 11 and 2,4-diiodo-6-[(2-morpholin-4-yl-ethylimino)methyl]phenol 19 showed the most potent antibacterial activity with MIC of 3.1, 12.9, 3.3, 6.5, 12.9, 3.3 and 3.2, 12.8, 3.2, 12.8, 12.8, 3.2 ,M against B. subtilis, S. aureus, S. faecalis, P. aeruginosa, E. Coli, and E. cloacae, respectively. [source] A Genomic Screening Approach to the Structure-Guided Identification of Drug Candidates from Natural SourcesCHEMBIOCHEM, Issue 7 2007Andreas Hornung Dr. Abstract The potential of actinomycetes to produce natural products has been exploited for decades. Recent genomic sequence analyses have revealed a previously unrecognized biosynthetic potential and diversity. In order to rationally exploit this potential, we have developed a sequence-guided genetic screening strategy. In this "genome mining" approach, genes that encode tailoring enzymes from natural product biosyntheses pathways serve as indicator genes for the identification of strains that have the genetic potential to produce natural products of interest. We chose halogenases, which are known to be involved in the synthesis of halometabolites as representative examples. From PCR screening of 550 randomly selected actinomycetes strains, we identified 103 novel putative halogenase genes. A phylogenetic analysis of the corresponding putative halogenases, and the determination of their sequential context with mass spectrometric analysis of cultures filtrates revealed a distinct correlation between the sequence and secondary metabolite class of the halometabolite. The described screening strategy allows rapid access to novel natural products with predetermined structural properties. [source] Evolutionary combinatorial chemistry, a novel tool for SAR studies on peptide transport across the blood,brain barrier.JOURNAL OF PEPTIDE SCIENCE, Issue 12 2005Part 2. Abstract The use of high-throughput methods in drug discovery allows the generation and testing of a large number of compounds, but at the price of providing redundant information. Evolutionary combinatorial chemistry combines the selection and synthesis of biologically active compounds with artificial intelligence optimization methods, such as genetic algorithms (GA). Drug candidates for the treatment of central nervous system (CNS) disorders must overcome the blood,brain barrier (BBB). This paper reports a new genetic algorithm that searches for the optimal physicochemical properties for peptide transport across the blood,brain barrier. A first generation of peptides has been generated and synthesized. Due to the high content of N -methyl amino acids present in most of these peptides, their syntheses were especially challenging due to over-incorporations, deletions and DKP formations. Distinct fragmentation patterns during peptide cleavage have been identified. The first generation of peptides has been studied by evaluation techniques such as immobilized artificial membrane chromatography (IAMC), a cell-based assay, log Poctanol/water calculations, etc. Finally, a second generation has been proposed. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd. [source] Identification of intracellular targets of small molecular weight chemical compounds using affinity chromatographyBIOTECHNOLOGY JOURNAL, Issue 1 2007Damien Guiffant Abstract Efforts to characterize small molecular weight chemical inhibitors of pharmacological interest tend to identify molecules with high efficiency and selectivity, to meet the two criteria required for the clinical development of a drug: efficacy and harmlessness. Drug candidates are expected to inhibit efficiently the target they have been optimized against (for example, a particular type of protein kinase). These hits are also designed to not interfere (or as little as possible) with the activity of other cellular enzymes/proteins to reduce undesired side effects. Here we discuss the use of immobilized drugs as affinity chromatography matrices to purify and identify their bona fide intracellular targets. This method not only allows the systematic investigation of the selectivity of pharmacological compounds but also the anticipation of their putative adverse effects. [source] Real-time monitoring of intracellular calcium dynamic mobilization of a single cardiomyocyte in a microfluidic chip pertaining to drug discoveryELECTROPHORESIS, Issue 24 2007Xiujun Li Abstract A microfluidic method for real-time quantitative measurement of cellular response pertaining to drug discovery is reported. This method is capable of multiple-step liquid delivery for measuring the drug response of a single cardiomyocyte, due to the improved cell retention by a newly designed chip. The chip, which consists of a cell-retention chamber with a weir structure, was fabricated just by a one-photomask microfabrication procedure followed by on-chip etching. This method differs from the conventional method, which uses two-mask photolithography to fabricate the microchannel (deep etch) and the weir structure (shallow etch). The dimensions of the weir structure have been predicted by a mathematical model, and confirmed by confocal microscopy. Using this microfluidic method, the dynamic [Ca2+]i mobilization in a single cardiomyocyte during its spontaneous contraction was quantified. Furthermore, we measured the cellular response of a cardiomyocyte on (i) a known cardiotonic agent (caffeine), (ii) a cardiotoxic chemotherapeutic drug (daunorubicin), and (iii) an herbal anticancer drug candidate , isoliquiritigenin (IQ) based on the fluorescent calcium measurement. It was found that IQ had produced a less pronounced effect on calcium mobilization of the cardiomyocytes whereas caffeine and daunorubicin had much stronger effects on the cells. These three experiments on cardiomyocytes pertaining to drug discovery were only possible after the improved cell retention provided by the new chip design (MV2) required for multiple-step real-time cellular analysis on a microchip, as compared with our old chip design (MV1). [source] New Insights into the Chemistry of the Antineoplastic Lanthanum Complex Tris(1,10-phenanthroline)tris(thiocyanato-,N)lanthanum(III) (KP772) and Its Interaction with BiomoleculesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 28 2009Florian Biba Abstract The lanthanide complex tris(1,10-phenanthroline)tris(thiocyanato-,N)lanthanum(III) [La(phen)3(NCS)3] (KP772) is a promising anticancer drug candidate, capable of overcoming resistance of tumors to established chemotherapeutics. The compound was characterized by elemental analysis, IR, 1H NMR spectroscopy, TG/DTA measurements, mass spectrometry and X-ray diffraction analysis. The results indicate that KP772 is a neutral, nine-coordinate complex. In addition the behavior in water, important for the application as a chemotherapeutic drug, and the binding to biomolecules was investigated by capillary electrophoresis and ICP-MS.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Enhancement of learning behaviour by a potent nitric oxide-guanylate cyclase activator YC-1EUROPEAN JOURNAL OF NEUROSCIENCE, Issue 6 2005Wei-Lin Chien Abstract Memory is one of the most fundamental mental processes, and various approaches have been used to understand the mechanisms underlying this process. Nitric oxide (NO), cGMP and protein kinase G (PKG) are involved in the modulation of synaptic plasticity in various brain regions. YC-1, which is a benzylindazole derivative, greatly potentiated the response of soluble guanylate cyclase to NO (up to several hundreds fold). We have previously shown that YC-1 markedly enhances long-term potentiation in hippocampal and amygdala slices via NO-cGMP-PKG-dependent pathway. We here further investigated whether YC-1 promotes learning behaviour in Morris water maze and avoidance tests. It was found that YC-1 shortened the escape latency in the task of water maze, increased and decreased the retention scores in passive and active avoidance task, respectively. Administration of YC-1 30 min after foot-shock stimulation did not significantly affect retention scores in response to passive avoidance test. Administration of scopolamine, a muscarinic antagonist, markedly impaired the memory acquisition. Pretreatment of YC-1 inhibited the scopolamine-induced learning deficit. The enhancement of learning behaviour by YC-1 was antagonized by intracerebroventricular injection of NOS inhibitor L-NAME and PKG inhibitors of KT5823 and Rp-8-Br-PET-cGMPS, indicating that NO-cGMP-PKG pathway is also involved in the learning enhancement action of YC-1. YC-1 is thus a good drug candidate for the improvement of learning and memory. [source] Recombinant vascular basement membrane derived multifunctional peptide blocks endothelial cell angiogenesis and neovascularization,JOURNAL OF CELLULAR BIOCHEMISTRY, Issue 2 2010Chengkun Wang Abstract Angiogenesis is an innovative target in the therapy of cancer and other diseases, but the effects of anti-angiogenic drugs have been rather modest in clinical trials. We have developed a small peptide, recombinant vascular basement membrane derived multifunctional peptide (rVBMDMP), which significantly inhibits endothelial cells in vitro. Here we test the mechanisms of rVBMDMP in angiogenesis balance in assays of tubule formation, colony formation, and apoptosis in HUVE-12 endothelial cells. We also analyzed the differential expression of phosphorylation proteins and related genes in a protein phosphorylation chip and extracellular matrix adhesion molecule cDNA microarray, and validated changes with Western blot or real-time quantitative PCR, respectively. rVBMDMP dose-dependently inhibited colony formation, induced apoptosis, and inhibited in vitro tubule formation. rVBMDMP increased the phosphorylation of 88 signal proteins, including caspase-3, death receptor 3, 4, and 5, and integrin ,V, ,1, and ,3, and down-regulated 41 signal proteins, including EGFR, pEGFR, VEGFR-1, and survivin versus control. rVBMDMP upregulated 14 genes, including collagen 4, 7, and 27, and down-regulated 21 genes, including integrin ,V,3, MMP10, and MMP12. Our study suggests that rVBMDMP inhibits angiogenesis and may be a viable drug candidate in anti-angiogenesis and anticancer therapies. J. Cell. Biochem. 111: 453,460, 2010. © 2010 Wiley-Liss, Inc. [source] Avilamycin did not play a role in the discontinuation of evernimicin as a clinical drug candidateJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 8 2005Aimee E. Belanger [source] A role for glutamate in growth and invasion of primary brain tumorsJOURNAL OF NEUROCHEMISTRY, Issue 2 2008Harald Sontheimer Abstract The vast majority of primary brain tumors derive from glial cells and are collectively called gliomas. While, they share some genetic mutations with other cancers, they do present with a unique biology and have developed adaptations to meet specific biological needs. Notably, glioma growth is physically restricted by the skull, and, unless normal brain cells are destroyed, tumors cannot expand. To overcome this challenge, glioma cells release glutamate which causes excitotoxic death to surrounding neurons, thereby vacating room for tumor expansion. The released glutamate also explains peritumoral seizures which are a common symptom early in the disease. Glutamate release occurs via system Xc, a cystine,glutamate exchanger that releases glutamate in exchange for cystine being imported for the synthesis of the cellular antioxidant GSH. It protects tumor cells from endogenously produced reactive oxygen and nitrogen species but also endows tumors with an enhanced resistance to radiation- and chemotherapy. Pre-clinical data demonstrates that pharmacological inhibition of system Xc causes GSH depletion which slows tumor growth and curtails tumor invasion in vivo. An Food and Drug Administration approved drug candidate is currently being introduced into clinical trials for the treatment of malignant glioma. [source] Development of a nanofiltration process to improve the stability of a novel anti-MRSA carbapenem drug candidateJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 4 2002V. Antonucci Abstract The benzenesulfonate salt of an anti-methicillin-resistant Staphylococcus aureus carbapenem antibiotic studied is a crystalline, nonhygroscopic powder which is stable at room temperature, making it an ideal compound for long-term storage. However, the limited aqueous solubility of this salt prohibits parenteral administration. Conversely, the chloride salt of this carbapenem demonstrates opposing characteristics; it is quantitatively soluble in water, however is amorphous and subject to significant hydrolytic degradation in the solid state. Given two such extreme alternatives for pharmaceutical salt selection, a common approach taken is to develop the bioavailable salt and devise manufacturing and storage conditions that minimize degradation. This report describes a different approach to this manufacturing dilemma via the application of a simple and efficient nanofiltration process to convert the benzenesulfonate salt (storage entity) to the chloride salt (formulated drug product). Such an approach combines the positive attributes of these two salt forms into a single scalable process that reduces processing cycle times via elimination of redundant unit operations, increases the flexibility in manufacturing schedule, and improves overall product quality. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91: 923,932, 2002 [source] Prediction of pharmacokinetics prior to in vivo studies.JOURNAL OF PHARMACEUTICAL SCIENCES, Issue 1 2002Abstract In drug discovery and nonclinical development the volume of distribution at steady state (Vss) of each novel drug candidate is commonly determined under in vivo conditions. Therefore, it is of interest to predict Vss without conducting in vivo studies. The traditional description of Vss corresponds to the sum of the products of each tissue:plasma partition coefficient (Pt:p) and the respective tissue volume in addition to the plasma volume. Because data on volumes of tissues and plasma are available in the literature for mammals, the other input parameters needed to estimate Vss are the Pt:p's, which can potentially be predicted with established tissue composition-based equations. In vitro data on drug lipophilicity and plasma protein binding are the input parameters used in these equations. Such a mechanism-based approach would be particularly useful to provide first-cut estimates of Vss prior to any in vivo studies and to explore potential unexpected deviations between sets of predicted and in vivoVss data, when the in vivo data become available during the drug development process. The objective of the present study was to use tissue composition-based equations to predict rat and human Vss prior to in vivo studies for 123 structurally unrelated compounds (acids, bases, and neutrals). The predicted data were compared with in vivo data obtained from the literature or at Roche. Overall, the average ratio of predicted-to-experimental rat and human Vss values was 1.06 (SD,=,0.817, r,=,0.78, n,=,147). In fact, 80% of all predicted values were within a factor of two of the corresponding experimental values. The drugs can therefore be separated into two groups. The first group contains 98 drugs for which the predicted Vss were within a factor of two of those experimentally determined (average ratio of 1.01, SD,=,0.39, r,=,0.93, n,=,118), and the second group includes 25 other drugs for which the predicted and experimental Vss differ by a factor larger than two (average ratio of 1.32, SD,=,1.74, r,=,0.42, n,=,29). Thus, additional relevant distribution processes were neglected in predicting Vss of drugs of the second group. This was true especially in the case of some cationic-amphiphilic bases. The present study is the first attempt to develop and validate a mechanistic distribution model for predicting rat and human Vss of drugs prior to in vivo studies. © 2002 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 91:129,156, 2002 [source] Method for enantiomeric purity of a quinuclidine candidate drug by capillary electrophoresisJOURNAL OF SEPARATION SCIENCE, JSS, Issue 13 2006Tore Ramstad Abstract A chiral procedure based on EKC was developed and validated for determination of the enantiomeric purity of PHA-543613, a drug candidate that was under development for treatment of the cognitive deficits of Alzheimer's disease and schizophrenia. Separation of enantiomers is accomplished via differential, enantiospecific complexation with a single-isomer, precisely sulfated beta-CD and heptakis-6-sulfato-,-CD (HpS-,-CD). Both neutral and sulfated CDs were screened before selecting HpS-,-CD as the chiral selector. The separation is conducted in a 61 cm×50 ,m uncoated fused silica capillary with 25 mM HpS-,-CD in pH 2.50, 25 mM lithium phosphate as the separation buffer with detection at 220 nm. Application of reverse polarity at ,30 kV results in an elution time of about 12 min for PHA-543613 and 13 min for the undesired S -enantiomer. Quantification is versus an authentic reference S -enantiomer as an external standard in combination with an internal standard. The procedure was validated over the range 0.1,2.0% w/w. The detection limit is 0.01,0.02%. The amount of distomer intrinsic to the drug substance is about 0.1% or less. The developed method was used to generate stability data on multiple lots: in one case for up to 3 years. [source] Analytical strategies for identifying drug metabolitesMASS SPECTROMETRY REVIEWS, Issue 3 2007Chandra Prakash Abstract With the dramatic increase in the number of new chemical entities (NCEs) arising from combinatorial chemistry and modern high-throughput bioassays, novel bioanalytical techniques are required for the rapid determination of the metabolic stability and metabolites of these NCEs. Knowledge of the metabolic site(s) of the NCEs in early drug discovery is essential for selecting compounds with favorable pharmacokinetic credentials and aiding medicinal chemists in modifying metabolic "soft spots". In development, elucidation of biotransformation pathways of a drug candidate by identifying its circulatory and excretory metabolites is vitally important to understand its physiological effects. Mass spectrometry (MS) and nuclear magnetic resonance (NMR) have played an invaluable role in the structural characterization and quantification of drug metabolites. Indeed, liquid chromatography (LC) coupled with atmospheric pressure ionization (API) MS has now become the most powerful tool for the rapid detection, structure elucidation, and quantification of drug-derived material within various biological fluids. Often, however, MS alone is insufficient to identify the exact position of oxidation, to differentiate isomers, or to provide the precise structure of unusual and/or unstable metabolites. In addition, an excess of endogenous material in biological samples often suppress the ionization of drug-related material complicating metabolite identification by MS. In these cases, multiple analytical and wet chemistry techniques, such as LC-NMR, enzymatic hydrolysis, chemical derivatization, and hydrogen/deuterium-exchange (H/D-exchange) combined with MS are used to characterize the novel and isomeric metabolites of drug candidates. This review describes sample preparation and introduction strategies to minimize ion suppression by biological matrices for metabolite identification studies, the application of various LC-tandem MS (LC-MS/MS) techniques for the rapid quantification and identification of drug metabolites, and future trends in this field. © 2007 Wiley Periodicals, Inc., Mass Spec Rev [source] New developments in natural products-based anti-AIDS research,MEDICINAL RESEARCH REVIEWS, Issue 1 2007Donglei Yu Abstract This review discusses anti-HIV natural products from several compound classes, including terpenoids, coumarins, alkaloids, polyphenols, tannins, and flavonoids. Natural products can provide novel anti-AIDS chemotherapeutic leads that are structurally unique or have new mechanisms of action. The drug discovery and development process proceeds from bioactivity-directed isolation and identification of a promising lead natural product, followed by rational design-based structural modification and structure,activity relationship analyses to optimize the lead compound as a drug candidate. This process is notably exemplified by the discovery of the modified betulinic acid derivative, DSB [PA-457], which is currently in Phase II clinical trial and is the first-in-class HIV maturation inhibitor (MI). © 2006 Wiley Periodicals, Inc. Med Res Rev, 27, No. 1, 108,132, 2007 [source] Pharmacokinetics and its role in small molecule drug discovery researchMEDICINAL RESEARCH REVIEWS, Issue 5 2001Graham R. Jang Abstract Pharmacokinetics (PK), which describes the disposition of a drug in the body, should be a primary consideration in the selection of a drug candidate, ultimately contributing to its eventual clinical success or failure. Accordingly, a sound understanding of PK concepts and an appreciation of the judicious use of PK and related (e.g., metabolism, transporter) data in drug discovery can be beneficial to those involved in the process. This review defines important PK parameters (e.g., clearance, volume of distribution, half-life), describes methods of PK data analysis (noncompartmental vs. compartmental) and provides an overview of additional concepts such as allometric scaling, PK/pharmacodynamic modeling, and nonlinear PK. Furthermore, the role and strategic use of PK screens in drug discovery are discussed. © 2001 John Wiley & Sons, Inc. Med Res Rev, 21, No. 5, 382,396, 2001 [source] Role of drug metabolism in drug discovery and developmentMEDICINAL RESEARCH REVIEWS, Issue 5 2001Gondi N. Kumar Abstract Metabolism by the host organism is one of the most important determinants of the pharmacokinetic profile of a drug. High metabolic lability usually leads to poor bioavailability and high clearance. Formation of active or toxic metabolites will have an impact on the pharmacological and toxicological outcomes. There is also potential for drug,drug interactions with coadministered drugs due to inhibition and/or induction of drug metabolism pathways. Hence, optimization of the metabolic liability and drug,drug interaction potential of the new chemical entities are some of the most important steps during the drug discovery process. The rate and site(s) of metabolism of new chemical entities by drug metabolizing enzymes are amenable to modulation by appropriate structural changes. Similarly, the potential for drug,drug interactions can also be minimized by appropriate structural modifications to the drug candidate. However, the optimization of the metabolic stability and drug,drug interaction potential during drug discovery stage has been largely by empirical methods and by trial and error. Recently, a lot of effort has been applied to develop predictive methods to aid the optimization process during drug discovery and development. This article reviews the role of drug metabolism in drug discovery and development. © 2001 John Wiley & Sons, Inc. Med Res Rev, 21, No. 5, 397,411, 2001 [source] Utility of porous graphitic carbon stationary phase in quantitative liquid chromatography/tandem mass spectrometry bioanalysis: quantitation of diastereomers in plasmaRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2006Yuan-Qing Xia A major challenge in selecting an appropriate stationary phase for diastereomeric separation is that it is difficult to predict which of the commercially available stationary phases could achieve the required liquid chromatographic (LC) separation. This work describes the selection and evaluation of a porous graphitic carbon (PGC) column coupled with tandem mass spectrometry (MS/MS) for the simultaneous quantitation of an experimental drug candidate (I), its two diastereomeric metabolites (II and III), and its demethylated metabolite (IV) in rat plasma. In addition, we investigated the PGC column for the separation of another drug candidate (VI), its two diastereomeric metabolites (VII and VIII) and its ketone metabolite (IX). The PGC column showed excellent chromatographic resolution for the two diastereomers II and III, as well as for VII and VIII. In contrast, the required resolution for the diastereomers II and III could not be achieved using silica-bonded C18, C30, phenyl, perfluorinated, polar embedded and polar end-capped phases. The PGC column showed ruggedness with excellent reproducibility of retention times, peak symmetry and response over a period of more than 400 injections of a plasma acetonitrile-precipitation extract. Excellent accuracy and precision were achieved, with accuracy of 94,108% and intra- and inter-run precision within 9%. This work indicates that PGC is a valuable addition to the repertoire of LC columns used for quantitative LC/MS/MS bioanalysis, especially where the separation and quantitation of diastereomeric analytes is involved. Copyright © 2006 John Wiley & Sons, Ltd. [source] Separation of a BMS drug candidate and acyl glucuronide from seven glucuronide positional isomers in rat plasma via high-performance liquid chromatography with tandem mass spectrometric detectionRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 11 2006Y.-J. Xue A high-performance liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for the determination of a BMS drug candidate and its acyl glucuronide (1- O - , glucuronide) in rat plasma. A 50-µL aliquot of each plasma sample was fortified with acetonitrile containing the internal standard to precipitate proteins and extract the analytes of interest. After mixing and centrifugation, the supernatant from each sample was transferred to a 96-well plate and injected into an LC/MS/MS system. Chromatographic separation was achieved isocratically on a Phenomenex Luna C18, 3,mm,×,150,mm, 3,µm column. The mobile phase contained 0.075% formic acid in 70:30 (v/v) acetonitrile/water. Under the optimized chromatographic conditions, the BMS drug candidate and its acyl glucuronide were separated from its seven glucuronide positional isomers within 10,min. Resolution of the parent from all glucuronides and acyl glucuronide from its positional isomers was critical to avoid their interference with quantitation of parent or acyl glucuronide. Detection was by positive ion electrospray MS/MS on a Sciex API 4000. The standard curve, which ranged from 5 to 5000,ng/mL, was fitted to a 1/x2 weighted quadratic regression model for both the BMS drug candidate and its acyl glucuronide. Whole blood and plasma stability experiments were conducted to establish the sample collection, storage, and processing conditions. The validation results demonstrated that this method was rugged and repeatable. The same methodology has also been used in mouse and human plasma for the determination of the BMS drug candidate and its acyl glucuronide. Copyright © 2006 John Wiley & Sons, Ltd. [source] First Exposure in Man: Toxicological ConsiderationsBASIC AND CLINICAL PHARMACOLOGY & TOXICOLOGY, Issue 2000Per Spindler Recommendations on the type and extent of preclinical safety studies that should be conducted prior to first dose in man have been developed by the International Conference on Harmonisation, and the European Committee for Proprietary Medicinal Products. These recommendations include studies designed to characterise local tolerance and general toxicity of the drug candidate as well as its genotoxic potential and ability to interfere with reproduction. For trials which can be categorised as low dose PK screening trials and trials with products where rodent and non-rodent (primarily dog) models do not show any biological response (e.g. some biotechnology-derived hormones and cytokines) other testing paradigms should be used. The present recommendations for preclinical testing have had an important impact on the documented impressive safety record of phase I clinical trials. In this spirit we extend our warmest and sincerest thanks to Professor Jens S. Schou for his long and deep engagement in European and International harmonisation of preclinical test recommendations. His efforts have had a substantial impact on the present testing recommendations, which are of obvious benefit to the safety of the patient. [source] Human radiolabeled mass balance studies: objectives, utilities and limitationsBIOPHARMACEUTICS AND DRUG DISPOSITION, Issue 4 2009Natalia Penner Abstract The determination of metabolic pathways of a drug candidate through the identification of circulating and excreted metabolites is vitally important to understanding its physical and biological effects. Knowledge of metabolite profiles of a drug candidate in animals and humans is essential to ensure that animal species used in toxicological evaluations of new drug candidates are appropriate models of humans. The recent FDA final guidance recommends that human oxidative metabolites whose exposure exceeds 10% of the parent AUC at steady-state should be assessed in at least one of the preclinical animal species used in toxicological assessment. Additional toxicological testing on metabolites that have higher exposure in humans than in preclinical species may be required. The metabolite profiles in laboratory animals and humans are generally accomplished by mass balance and excretion studies in which radiolabeled drugs are administered to these species. The biological fluids are collected, analysed for total radioactivity and evaluated for a quantitative profile of metabolites. Thus, these studies not only determine the rates and routes of excretion but also provide very critical information on the metabolic pathways of drugs in preclinical species and humans. In addition, these studies are required by regulatory agencies for the new drug approval process. Despite the usefulness of these radiolabeled mass balance studies, there is little concrete guidance on how to perform or assess these complex studies. This article examines the objectives, utilities and limitations of these studies and how these studies could be used for the determination of the metabolite exposure in animals and humans. Copyright © 2009 John Wiley & Sons, Ltd. [source] Rapid whole monoclonal antibody analysis by mass spectrometry: An Ultra scale-down study of the effect of harvesting by centrifugation on the post-translational modification profile,BIOTECHNOLOGY & BIOENGINEERING, Issue 1 2010C.Q. Reid Abstract With the trend towards the generation and production of increasing numbers of complex biopharmaceutical (protein based) products, there is an increased need and requirement to characterize both the product and production process in terms of robustness and reproducibility. This is of particular importance for products from mammalian cell culture which have large molecular structures and more often than not complex post-translational modifications (PTMs) that can impact the efficacy, stability and ultimately the safety of the final product. It is therefore vital to understand how the operating conditions of a bioprocess affect the distribution and make up of these PTMs to ensure a consistent quality and activity in the final product. Here we have characterized a typical bioprocess and determined (a) how the time of harvest from a mammalian cell culture and, (b) through the use of an ultra scale-down mimic how the nature of the primary recovery stages, affect the distribution and make up of the PTMs observed on a recombinant IgG4 monoclonal antibody. In particular we describe the use of rapid whole antibody analysis by mass spectrometry to analyze simultaneously the changes that occur to the cleavage of heavy chain C-terminal lysine residues and the glycosylation pattern, as well as the presence of HL dimers. The time of harvest was found to have a large impact upon the range of glycosylation patterns observed, but not upon C-terminal lysine cleavage. The culture age had a profound impact on the ratio of different glycan moieties found on antibody molecules. The proportion of short glycans increased (e.g., (G0F)2 20,35%), with an associated decrease in the proportion of long glycans with culture age (e.g., (G2F)2 7,4%, and G1F/G2F from 15.2% to 7.8%). Ultra scale-down mimics showed that subsequent processing of these cultures did not change the post-translational modifications investigated, but did increase the proportion of half antibodies present in the process stream. The combination of ultra scale-down methodology and whole antibody analysis by mass spectrometry has demonstrated that the effects of processing on the detailed molecular structure of a monoclonal antibody can be rapidly determined early in the development process. In this study we have demonstrated this analysis to be applicable to critical process design decisions (e.g., time of harvest) in terms of achieving a desired molecular structure, but this approach could also be applied as a selection criterion as to the suitability of a platform process for the preparation of a new drug candidate. Also the methodology provides means for bioprocess engineers to predict at the discovery phase how a bioprocess will impact upon the quality of the final product. Biotechnol. Bioeng. 2010;107: 85,95. © 2010 Wiley Periodicals, Inc. [source] Enantioselective reduction of pentoxifylline to lisofylline using whole-cell Lactobacillus kefiri biotransformationBIOTECHNOLOGY JOURNAL, Issue 4 2007bieta P, kala; Dr. Abstract Lisofylline (LSF) is a drug candidate that has been under investigation for acute respiratory distress syndrome, acute lung injury, septic shock and mucositis. As LSF is not commercially available in our country, we produced it for pharmacokinetic studies. In the present work whole-cell reduction of pentoxifylline [1-(5-oxohexyl)-3,5-dimethylxanthine] to LSF [1-(5R-hydroxyhexyl)-3,5-dimethylxanthine] using Lactobacillus kefiri DSM 20587 was investigated. Glucose or 2-propanol was used as a co-substrate to regenerate the NADPH cofactor. The reaction conditions were optimized. The influence of different concentrations of co-substrates on the yield and enantioselectivity of the biotransformation of pentoxifylline into LSF were tested. Maximum yield (100%) of biotransformation was reached in the presence of glucose as a co-substrate. At glucose concentrations of 675 and 900 mM the bioreduction of pentoxifylline proceeded highly enantioselectively (enantiomeric excess for the R enantiomer of 98%). [source] Obovatol attenuates microglia-mediated neuroinflammation by modulating redox regulationBRITISH JOURNAL OF PHARMACOLOGY, Issue 8 2010Jiyeon Ock Background and purpose:, Obovatol isolated from the medicinal herb Magnolia obovata exhibits a variety of biological activities. Here, the effect of obovatol and its mechanism of action on microglial activation, neuroinflammation and neurodegeneration were investigated. Experimental approach:, In microglial BV-2 cells stimulated with lipopolysaccharide (LPS), we measured nitric oxide (NO) and cytokine production, and activation of intracellular signalling pathways by reverse transcription-polymerase chain reaction and Western blots. Cell death was assayed in co-cultures of activated microglia (with bacterial LPS) and neurons and in LPS-induced neuroinflammation in mice in vivo. Key results:, Obovatol inhibited microglial NO production with an IC50 value of 10 µM. Obovatol also inhibited microglial expression of proinflammatory cytokines and inducible nitric-oxide synthase, which was accompanied by the inhibition of multiple signalling pathways such as nuclear factor kappa B, signal transducers and activators of transcription 1, and mitogen-activated protein kinases. In addition, obovatol protected cultured neurons from microglial toxicity and inhibited neuroinflammation in mice in vivo. One molecular target of obovatol in microglia was peroxiredoxin 2 (Prx2), identified by affinity chromatography and mass spectrometry. Obovatol enhanced the reactive oxygen species (ROS)-scavenging activity of Prx2 in vitro, thereby suppressing proinflammatory signalling pathways of microglia where ROS plays an important role. Conclusions and implications:, Obovatol is not only a useful chemical tool that can be used to investigate microglial signalling, but also a promising drug candidate against neuroinflammatory diseases. Furthermore, our results indicate that Prx2 is a novel drug target that can be exploited for the therapeutic modulation of neuroinflammatory signalling. [source] F90927: A New Member in the Class of Cardioactive SteroidsCARDIOVASCULAR THERAPEUTICS, Issue 3 2007Markus Keller ABSTRACT F90927 is a newly developed cardioactive drug with a steroid-like structure. It acts directly and agonistically on the cardiac L-type Ca2+ channel by shifting its voltage-dependent activation toward more negative potentials. This leads to an increased influx of Ca2+ and, therefore, to a stronger contraction; however, no arrhythmias occur. Calcium current stimulation can already be observed at nanomolar concentrations, but higher concentrations of F90927 elevate intracellular Ca2+ concentration, causing a reduction of the myocardial compliance and an increased diastolic blood pressure. Vessels also react to F90927 and contract in its presence. Binding of F90927 with the L-type Ca2+ channel presumably occurs in the vicinity of the transmembrane domains III and IV of the ,1 subunit. F90927 exhibits no use dependence and interacts with Ca2+ channel inhibitors of all three known classes of channel modulators (dihydropyridines, phenylalkylamines, and benzothiazepines), suggesting that it is a member of a new class of Ca2+ channel modulators. Due to its adverse effects on blood pressure and vessel contraction, F90927 is not an ideal drug candidate. It has, however, some unique properties, which makes it a promising tool to study the function of the L-type Ca2+ channel. [source] The experimental Alzheimer drug phenserine: preclinical pharmacokinetics and pharmacodynamicsACTA NEUROLOGICA SCANDINAVICA, Issue 2000N. H. Greig Phenserine, a phenylcarbamate of physostigmine, is a new potent and highly selective acetylcholinesterase (AChE) inhibitor, with a >50-fold activity versus butyrylcholinesterase (BChE), in clinical trials for the treatment of Alzheimer's disease (AD). Compared to physostigmine and tacrine, it is less toxic and robustly enhances cognition in animal models. To determine the time-dependent effects of phenserine on cholinergic function, AChE activity, brain and plasma drug levels and brain extracellular acetylcholine (ACh) concentrations were measured in rats before and after phenserine administration. Additionally, its maximum tolerated dose, compared to physostigmine and tacrine, was determined. Following i.v. dosing, brain drug levels were 10-fold higher than those achieved in plasma, peaked within 5 min and rapidly declined with half-lives of 8.5 and 12.6 min, respectively. In contrast, a high (>70%) and long-lasting inhibition of AChE was achieved (half-life >8.25 h). A comparison between the time-dependent plasma AChE inhibition achieved after similar oral and i.v. doses provided an estimate of oral bioavailability of 100%. Striatal, in vivo microdialysis in conscious, freely-moving phenserine-treated rats demonstrated >3-fold rise in brain ACh levels. Phenserine thus is rapidly absorbed and cleared from the body, but produces a long-lasting stimulation of brain cholinergic function at well tolerated doses and hence has superior properties as a drug candidate for AD. It selectively inhibits AChE, minimizing potential BChE side effects. Its long duration of action, coupled with its short pharmacokinetic half-life, reduces dosing frequency, decreases body drug exposure and minimizes the dependence of drug action on the individual variations of drug metabolism commonly found in the elderly. [source] Insight Into the Kinetic of Amyloid , (1,42) Peptide Self-Aggregation: Elucidation of Inhibitors' Mechanism of ActionCHEMBIOCHEM, Issue 17 2007Manuela Bartolini Dr. Abstract The initial transition of amyloid , (1,42) (A,42) soluble monomers/small oligomers from unordered/,-helix to a ,-sheet-rich conformation represents a suitable target to design new potent inhibitors and to obtain effective therapeutics for Alzheimer's disease. Under optimized conditions, this reliable and reproducible CD kinetic study showed a three-step sigmoid profile that was characterized by a lag phase (prevailing unordered/,-helix conformation), an exponential growth phase (increasing ,-sheet secondary structure) and a plateau phase (prevailing ,-sheet secondary structure). This kinetic analysis brought insight into the inhibitors' mechanism of action. In fact, an increase in the duration of the lag phase can be related to the formation of an inhibitor,A, complex, in which the non-amyloidogenic conformation is stabilized. When the exponential rate is affected exclusively, such as in the case of Congo red and tetracycline, then the inhibitor affinity might be higher for the pleated ,-sheet structure. Finally, by adding the inhibitor at the end of the exponential phase, the soluble protofibrils can be disrupted and the A, amyloidogenic structure can revert into monomers/small oligomers. Congo red and tetracycline preferentially bind to amyloid in the ,-sheet conformation because both decreased the slope of the exponential growth, even if to a different extent, whereas no effect was observed for tacrine and galantamine. Some very preliminary indications can be derived about the structural requirements for binding to nonamyloidogenic or ,-sheet amyloid secondary structure for the development of potent antiaggregating agents. On these premises, memoquin, a multifunctional molecule that was designed to become a drug candidate for the treatment of Alzheimer's disease, was investigated under the reported circular dichroism assay and its anti-amyloidogenic mechanism of action was elucidated. [source] | |||||||||||||||||||||||||||||||||||||