Knowledge-based analysis of multi-potent G-protein coupled receptors ligands.

A large number of chemical structures that interact with G-protein coupled receptors (GPCRs) have been disclosed in patents or published papers. Most of these compounds are selective for a given protein target; however, it is well recognized that some GPCR-drugs interact with multiple targets. Using a literature database, we have identified compounds that act on different GPCRs.

Assessing the chemical diversity of an hsp90 database.

The 90-kDa heat shock protein (hsp90) has emerged as a new, promising target for cancer drug discovery. With the simultaneous disruption of a large range of oncogenic pathways, hsp90 inhibition results in either cytostasis or cell death. Diverse inhibitors of this molecular chaperone are currently under intensive study, and several have reached clinical trials.

Drug repositioning using in silico compound profiling.

Background: Drug repositioning is a current strategy to find new uses for existing drugs, patented or not, and for late-stage candidates that failed for lack of efficacy.

Results: In silico profiling of several marketed drugs (methadone, rapamycin, saquinavir and telmisartan) was performed, exploiting a vast amount of published information. Similar compounds were assessed in terms of target-activity profiles for major drug-target families.

Virtual screening for cytochromes p450: successes of machine learning filters.

Cytochromes P450 (CYPs) are crucial targets when predicting the ADME properties (absorption, distribution, metabolism, and excretion) of drugs in development. Particularly, CYPs mediated drug-drug interactions are responsible for major failures in the drug design process. Accurate and robust screening filters are thus needed to predict interactions of potent compounds with CYPs as early as possible in the process.

Assessing the chemical and biological diversity of an ion channels knowledge database.

The aim of the present work is to assess the chemical and biological diversity of ligands reported in scientific articles or patents to be active against ion channels targets. A specific query of the AurSCOPE Ion Channel knowledge database was constructed to retrieve a set of the most active non-peptide ligands tested in binding or electrophysiology experiments against all ion channel families. A biological activity threshold cutoff expressed by K(i), IC(50), or EC(50) was set to 300 nM.

Ligand-based virtual screening to identify new T-type calcium channel blockers.

T-type calcium channels are involved in the generation of rhythmical firing patterns in the mammalian central nervous system and in various pathological alterations of neuronal excitability such as in epilepsy or neuropathic pain. In the search for new T-type calcium channel blockers that would help to treat these disorders, we have followed a bi-dimensional pharmacophore-based virtual screening approach to identify new inhibitors. Nineteen molecules extracted from AurSCOPE Ion Channels knowledgebase were used as query molecules to screen an external database.

Boosted regression trees, multivariate adaptive regression splines and their two-step combinations with multiple linear regression or partial least squares to predict blood-brain barrier passage: a case study.

The use of some unconventional non-linear modeling techniques, i.e. classification and regression trees and multivariate adaptive regression splines-based methods, was explored to model the blood-brain barrier (BBB) passage of drugs and drug-like molecules.

Assessing potency of c-Jun N-terminal kinase 3 (JNK3) inhibitors using 2D molecular descriptors and binary QSAR methodology.

JNK3 signaling pathway is gaining interest due to its involvement in many neurological disorders. The purpose of this study was to explore for the first time the use of a large and diverse dataset in combination with binary QSAR methodology for predicting JNK3 activity class. Data were extracted from Aureus Pharma' AurSCOPE Kinase knowledge database and active or inactive classes were assigned to ligands based on IC50 biological activity.

Development of an ADME and drug-drug interactions knowledge database for the acceleration of drug discovery and development.

It is widely recognised that predicting or determining the absorption, distribution, metabolism and excretion (ADME) properties of a compound as early as possible in the drug discovery process helps to prevent costly late-stage failures. Although in recent years high-throughput in vitro absorption distribution metabolism excretion toxicity (ADMET) screens have been implemented, more efficient in silico filters are still highly needed to predict and model the most relevant metabolic and pharmacokinetic end points, and thereby accelerate drug discovery and development. The usefulness of the data generated and published for the chemist, biologist or project manager who ultimately wants to understand and optimise the ADME properties of lead compounds cannot be argued with.

Recursive partitioning for the prediction of cytochromes P450 2D6 and 1A2 inhibition: importance of the quality of the dataset.

The purpose of this study was to explore the use of detailed biological data in combination with a statistical learning method for predicting the CYP1A2 and CYP2D6 inhibition. Data were extracted from the Aureus-Pharma highly structured databases which contain precise measures and detailed experimental protocol concerning the inhibition of the two cytochromes. The methodology used was Recursive Partitioning, an easy and quick method to implement.

In silico classification of HERG channel blockers: a knowledge-based strategy.

The blockage of the hERG potassium channel by a wide number of diverse compounds has become a major pharmacological safety concern as it can lead to sudden cardiac death. In silico models can be potent tools to screen out potential hERG blockers as early as possible during the drug-discovery process. In this study, predictive models developed using the recursive partitioning method and created using diverse datasets from 203 molecules tested on the hERG channel are described.

Cannabinoid penetration into mouse brain as determined by ex vivo binding.

We have used an ex vivo binding assay in the mouse to evaluate the brain penetration of cannabinoid receptor ligands. After intraperitoneal or oral administration, the pharmacological activity linked to the compound was assessed by using by [3H]WIN 55212-2 binding on cerebellar membranes. The brain penetration was high for compounds like methanandamide or delta9-tetrahydrocannabinol but poor for synthetic agonists such as (cis)-3-(2-hydroxy-4-(1,1-dimethylheptyl)phenyl]-(trans)-4-(3-hydr oxypropyl)cyclohexanol (CP 55940) or, R-(+)-(2,3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]pyrol[1,2,3-d e]-1,4-benzoxazin-6-yl)(1-napthalenyl)methanone monomethane-sulfonate (WIN 55212-2).

Unresponsiveness to cannabinoids and reduced addictive effects of opiates in CB1 receptor knockout mice.

The function of the central cannabinoid receptor (CB1) was investigated by invalidating its gene. Mutant mice did not respond to cannabinoid drugs, demonstrating the exclusive role of the CB1 receptor in mediating analgesia, reinforcement, hypothermia, hypolocomotion, and hypotension. The acute effects of opiates were unaffected, but the reinforcing properties of morphine and the severity of the withdrawal syndrome were strongly reduced.

Complex pharmacology of natural cannabinoids: evidence for partial agonist activity of delta9-tetrahydrocannabinol and antagonist activity of cannabidiol on rat brain cannabinoid receptors.

Delta9-tetrahydrocannabinol (delta9-THC), cannabinol and cannabidiol are three important natural cannabinoids from the Marijuana plant (Cannabis sativa). Using [35S]GTP-gamma-S binding on rat cerebellar homogenate as an index of cannabinoid receptor activation we show that: delta9-THC does not induce the maximal effect obtained by classical cannabinoid receptor agonists such as CP55940. Moreover at high concentration delta9-THC exhibits antagonist properties.

Interaction of brain cannabinoid receptors with guanine nucleotide binding protein: a radioligand binding study.

The binding of a classical cannabinoid agonist, [3H]R-(+)-(2,3-dihydro-5-methyl-3-[(4-morpholinyl)methyl]pyrol[1,2 ,3-de]-1,4-benzoxazin-6-yl)(1-napthalenyl)methanone monomethanesulfonate ([3H] WIN55212-2), and a selective cannabinoid receptor (CB1) antagonist, N-(piperidin-1-yl)-5-(4-chlorophenyl)1-(2,4-dichlorophenyl)-4-meth yl-1H-pyrazole-3-carboxamide hydrochloride ([3H]SR141716A), to rat cannabinoid receptors was evaluated using rat cerebellar membranes. Guanine nucleotides inhibited [3H]WIN55212-2 binding by approximately 50% at 10 microM and enhanced [3H]SR141716A binding very slightly. In the same tissue, the binding of guanosine 5'-O-[gamma-[35S]thio]triphosphate ([35S]GTP-gamma-S) was characterized and the influence of cannabinomimetics evaluated on this binding.

Localization of presenilin-1 mRNA in rat brain.

We examined the regional and cellular distribution of presenilin-1 gene expression in the rat brain by in situ hybridization. Microscopic analysis demonstrated that presenilin-1 mRNA is predominantly expressed in areas such as the occipital cortex, the pyramidal layer of the hippocampus, thalamic nuclei and the cerebellar granular layer. The expression of presenilin-1 is mostly neuronal: only a weak hybridization signal was found in the corpus callosum and in the astrocytoma cell lines U373MG and U138MG.

The naphtosultam derivative RP 62203 (fananserin) has high affinity for the dopamine D4 receptor.

The dopamine D4 receptor is a potential target for novel antipsychotic drugs. Most available compounds with affinity for the dopamine D4 receptor also bind to dopamine D2 receptors. This report describe the affinity of the 5-HT2A receptor antagonist RP 62203 (fananserin) for the human dopamine D4 receptor.

Biochemical and pharmacological characterization of cannabinoid binding sites using [3H]SR141716A.

This study describes the binding characteristics of cannabinoid binding sites expressed in rat cerebellar membranes using the tritiated derivative of SR141716A, the newly described cannabinoid receptor antagonist. A single population of high-affinity binding sites (K(D) = 0.59 +/- 0.

Effects of AMPA receptor modulators on the production of arachidonic acid from striatal neurons.

The abilities of different compounds acting at alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionate (AMPA) receptors to modulate the overflow of [3H]arachidonic acid from rat striatal neurons were examined. The combination of AMPA (0.1 mM) and carbachol (1mM) stimulated [3H]arachidonic acid production, this effect could be dose-dependently enhanced by the newly discovered allosteric modulator of AMPA receptors: cyclothiazide.

Effects of non-NMDA receptor modulators on [3H] dopamine release from rat mesencephalic cells in primary culture.

The effects of AMPA and kainate on [3H]dopamine release from fetal (embryonic day 15) rat mesencephalic neurons in primary culture were enhanced markedly in a dose-dependent fashion by cyclothiazide, a recently described inhibitor of AMPA receptor desensitization. The EC50 value for cyclothiazide was 2.2 +/- 0.

Differential effects of propofol and ketamine on cytosolic calcium concentrations of astrocytes in primary culture.

Propofol has been shown recently to alter cellular communication mediated by gap junctions between astrocytes (a glial cell subpopulation involved in major brain functions). As marked increases in concentrations of cytosolic calcium ([Ca2+]i) produce closure of the gap junction, we have investigated the effects of both propofol and ketamine on resting [Ca2+]i concentrations in mouse cultured astrocytes using microfluorimetry with the indo-1 fluorescent probe. Propofol 10(-5) and 10(-4) mol litre-1 induced a monophasic transitory Ca2+ peak in a large subpopulation of the cells tested.

Differential localization of 3H-[Pro9]SP binding sites in the guinea pig and rat brain.

Due to the existence of differences in the pharmacological properties of tachykinin NK-1 receptors in the rat and the guinea pig, the autoradiographic distribution of NK-1 binding sites was compared in the brain of the two species using the selective NK-1 ligand 3H-[Pro9]SP. If a good similarity in the distribution of NK-1 binding sites could be seen in basal ganglia, a relative absence of correlation was observed between the estimated optical densities in other brain structures of the two species. For instance, the interpeduncular nucleus, the lateral habenular nucleus and the deep layers of the cerebral cortex were labeled in the guinea pig but not in the rat while the reverse was observed for the columns of the vermis lobules 9-10, the dorsal raphe nucleus, the medial habenular nucleus, the superficial cortical layers and the dorsal hippocampus.

A new selective bioassay for tachykinin NK3 receptors based on inositol monophosphate accumulation in the guinea pig ileum.

The selective agonists of tachykinin NK1, NK2 and NK3 receptors, respectively [Pro9]substance P, [Lys5,MeLeu9,Nle10]neurokinin A-(4-10) and senktide, stimulated phosphoinositide breakdown in slices of the guinea pig ileum. This was also the case with septide which has recently been found to act on a new type of tachykinin receptors in this tissue. The NK1, NK2 and septide-evoked responses were completely antagonized in the combined presence of (+/-)-CP-96,345 and MEN 10,376 which are potent and selective antagonists of tachykinin NK1 and NK2 receptors respectively in the guinea pig ileum.

Importance of the leucine side-chain to the spasmogenic activity and binding of substance P analogues.

Previous studies with Substance P (SP) antagonists (GR 71251, [DPro9, Pro10, Trp11]SP and [DPro9, MeLeu10, Trp11]SP) have suggested the existence in the guinea-pig ileum (GPI) of two distinct tachykinin receptors associated with the contractile responses of [Pro9]SP and septide. In addition [Apa9-10]SP, a glycine-substituted analogue of SP with a carba bond between residues 9 and 10, [Gly9-psi(CH2-CH2)-Gly10]SP = [Apa9-10]SP, was shown to belong to the 'septide family' (low affinity for NK-1 specific binding sites and high potency in the GPI). In order to establish the importance of the isopropyl side-chain in position 10, the binding potencies and activities of [Gly9-psi(CH2-CH2)-Gly10]SP, [Ala10]SP, [Gly9-psi(CH2-CH2)-Leu10]SP and [Gly9-psi(CH2-CH2)-DLeu10]SP were compared.