Automated open-access liquid chromatography high resolution mass spectrometry to support drug discovery projects

The need of a continuous productivity increases in medicinal chemistry laboratories of the pharmaceutical industry motivated the development, over the years, of new software solutions to enable Open-Access in many analytical techniques such as NMR or LC, among others, to characterize and assess the purity of new molecules. These approaches have been widely spread in LC with low resolution MS systems, but similar automated platforms have been rather less explored with high resolution MS. In this work, an improved Automated Open-Access methodology on an UHPLC with DAD coupled to ESI and quadrupole time-of-flight MS system is described. Detailed reports from standard UHPLC-MS runs containing chromatograms and different spectra (MS with different fragmentation) are automatically sent to the chemists. High resolution MS data is typically achieved within ± 1 mDa mass accuracy regardless of sample concentration. Upon training, chemists log-in samples into the system by selecting appropriate methods, being able to interpret the results by themselves in 95% of the cases. The instrument is working unattended, except for a limited number of samples (5%) which require more complex experiments. To the best of our knowledge, this is the first time a completely automated Open-Access LC-HRMS approach has been implemented for medicinal chemists of a pharmaceutical industry.

Discovery of 8-Trifluoromethyl-3-cyclopropylmethyl-7-[(4-(2,4-difluorophenyl)-1-piperazinyl)methyl]-1,2,4-triazolo[4,3-a]pyridine (JNJ-46356479), a Selective and Orally Bioavailable mGlu2 Receptor Positive Allosteric Modulator (PAM)

Positive allosteric modulators of the metabotropic glutamate 2 receptor have generated great interest in the past decade. There is mounting evidence of their potential as therapeutic agents in the treatment of multiple central nervous system disorders. We have previously reported substantial efforts leading to potent and selective mGlu2 PAMs. However, finding compounds with the optimal combination of in vitro potency and good druglike properties has remained elusive, in part because of the hydrophobic nature of the allosteric binding site. Herein, we report on the lead optimization process to overcome the poor solubility inherent to the advanced lead 6. Initial prototypes already showed significant improvements in solubility while retaining good functional activity but displayed new liabilities associated with metabolism and hERG inhibition. Subsequent subtle modifications efficiently addressed those issues leading to the identification of compound 27 (JNJ-46356479). This new lead represents a more balanced profile that offers a significant improvement on the druglike attributes compared to previously reported leads.

Dihydrothiazolopyridone derivatives as a novel family of positive allosteric modulators of the metabotropic glutamate 5 (mGlu5) receptor

Starting from a singleton chromanone high throughput screening (HTS) hit, we describe a focused medicinal chemistry optimization effort leading to the identification of a novel series of phenoxymethyl-dihydrothiazolopyridone derivatives as selective positive allosteric modulators (PAMs) of the metabotropic glutamate 5 (mGlu5) receptor. These dihydrothiazolopyridones potentiate receptor responses in recombinant systems. In vitro and in vivo drug metabolism and pharmacokinetic (DMPK) evaluation allowed us to select compound 16a for its assessment in a preclinical animal screen of possible antipsychotic activity. 16a was able to reverse amphetamine-induced hyperlocomotion in rats in a dose-dependent manner without showing any significant motor impairment or overt neurological side effects at comparable doses. Evolution of our medicinal chemistry program, structure activity, and properties relationships (SAR and SPR) analysis as well as a detailed profile for optimized mGlu5 receptor PAM 16a are described.

Discovery of 3-cyclopropylmethyl-7-(4-phenylpiperidin-1-yl)-8-trifluoromethyl[1,2,4]triazolo[4,3-a]pyridine (JNJ-42153605): a positive allosteric modulator of the metabotropic glutamate 2 receptor

Advanced leads from a series of 1,2,4-triazolo[4,3-a]pyridines with mGlu2 receptor PAM activity are reported. By modification of the analogous imidazo[1,2-a]pyridine series, the newly reported leads have improved potency, in vitro ADMET, and hERG as well as good in vivo PK profile. The optimization of the series focused on improving metabolic stability while controlling lipophilicity by introducing small modifications to the scaffold substituents. Analysis of this series combined with our previously reported mGlu2 receptor PAMs showed how lipophilic ligand efficiency was improved during the course of the program. Among the best compounds, example 20 (JNJ-42153605) showed a central in vivo efficacy by inhibition of REM sleep state at a dose of 3 mg/kg po in the rat sleep-wake EEG paradigm, a phenomenon shown earlier to be mGlu2 mediated. In mice, compound 20 reversed PCP-induced hyperlocomotion with an ED₅₀ of 5.4 mg/kg sc, indicative of antipsychotic activity.

Synthesis, evaluation, and radiolabeling of new potent positive allosteric modulators of the metabotropic glutamate receptor 2 as potential tracers for positron emission tomography imaging

The synthesis and in vitro and in vivo evaluation of a new series of 7-(phenylpiperidinyl)-1,2,4-triazolo[4,3-a]pyridines, which were conveniently radiolabeled with carbon-11, as potential positron emission tomography (PET) radiotracers for in vivo imaging of the allosteric binding site of the metabotropic glutamate (mGlu) receptor subtype 2 are described. The synthesized compounds proved to be potent and selective positive allosteric modulators (PAMs) of the mGlu receptor 2 (mGluR2) in a [³⁵S]GTPγS binding assay and were able to displace an mGluR2 PAM radioligand, which we had previously developed, with IC₅₀ values in the low nanomolar range. The most promising candidates were radiolabeled and subjected to biodistribution studies and radiometabolite analysis in rats. Preliminary small-animal PET (μPET) studies in rats indicated that [¹¹C]20f binds specifically and reversibly to an mGluR2 allosteric site, strongly suggesting that it is a promising candidate for PET imaging of mGluR2 in the brain.

Tricyclic isoxazolines: identification of R226161 as a potential new antidepressant that combines potent serotonin reuptake inhibition and alpha2-adrenoceptor antagonism

In previous articles we have described the discovery of a new series of tricyclic isoxazolines combining central serotonin (5-HT) reuptake inhibition with alpha(2)-adrenoceptor antagonistic activity. We report now on the synthesis, the in vitro binding potency and the primary in vivo activity of six enantiomers within this series, one of which was selected for further pharmacological evaluation and assigned as R226161. Some additional in vivo studies in rats are described with this compound, which proved to be centrally and orally active as a combined 5-HT reuptake inhibitor and alpha(2)-adrenoceptor antagonist.

Synthesis of 7-amino-3a,4-dihydro-3H-[1]benzopyrano[4,3-c]isoxazole derivatives displaying combined alpha2-adrenoceptor antagonistic and 5-HT reuptake inhibiting activities

Following a program searching for dual 5-HT reuptake inhibitors and alpha(2)-adrenoceptor antagonists started at Johnson & Johnson Pharmaceutical Research & Development, we now report on the synthesis of a series of 7-amino-3a,4-dihydro-3H-[1]benzopyrano[4,3-c]isoxazole derivatives, some of which proved to be the most potent alpha(2)-adrenoceptor blockers within this chemical class of tricyclic isoxazolines, while keeping potent 5-HT reuptake inhibiting activity.

4-Phenyl-4-[1H-imidazol-2-yl]-piperidine derivatives, a novel class of selective δ-opioid agonists

A novel series of 4-phenyl-4-[1H-imidazol-2-yl]-piperidine derivatives has been prepared and their synthesis described herein. In vitro affinities for delta-, mu-, and kappa-opioid receptors, as well as the functional activity in the [(35)S]GTPgammaS assay are reported. The most potent and selective delta-opioid agonist 18a exhibited a K(i) of 18 nM, and was >258-fold and 28-fold selective over mu- and kappa-receptors, respectively; the compound is a full agonist with an EC(50) value of 14 nM.

Discovery of new tetracyclic tetrahydrofuran derivatives as potential broad-spectrum psychotropic agents

A series of novel tetracyclic tetrahydrofuran derivatives was prepared and evaluated for its potential psychotropic properties. In vitro affinities for multiple dopaminergic, serotonergic, alpha-adrenergic, and histamine receptors and for the norepinephrine transporter as well as the ED(50) values obtained in some in vivo assays for antipsychotic, anxiolytic, and antidepressant potential are reported. Compounds (-)-1, (-)-8d, and (+)-8d have been identified as potential broad-spectrum psychotropic agents.

Discovery of a new series of centrally active tricyclic isoxazoles combining serotonin (5-HT) reuptake inhibition with alpha2-adrenoceptor blocking activity

The synthesis and pharmacology of a new series of 3-piperazinylmethyl-3a,4-dihydro-3H-[1]benzopyrano[4,3-c]isoxazoles that combine central serotonin (5-HT) reuptake inhibition with alpha(2)-adrenoceptor blocking activity is described as potential antidepressants. Four compounds were selected for further evaluation, and the combination of both activities was found to be stereoselective, residing mainly in one enantiomer. Reversal of the loss of righting induced by the alpha(2)-agonist medetomidine in rats confirmed the alpha(2)-adrenoceptor blocking activity in vivo and also demonstrated CNS penetration. Antagonism of p-chloroamphetamine (pCA)-induced excitation as well as blockade of the neuronal 5-HT depletion induced by p-CA administration in rats confirmed their ability to block the central 5-HTT, even after oral administration. Replacement of the oxygen atom at the 5-position of the tricyclic scaffold by a nitrogen or a carbon atom, as well as O-substitution at position 7, led also to active compounds, both in vitro and in vivo.

Synthesis and structure–activity relationship of 2-(aminoalkyl)-3,3a,8,12b-tetrahydro-2H-dibenzocyclohepta[1,2-b]furan derivatives: a novel series of 5-HT2A/2C receptor antagonists

Following the program started at Johnson & Johnson Pharmaceutical Research & Development searching for 5-HT(2A/2C) antagonists we now report on the synthesis of a series of substituted 2-(aminomethyl)-3,3a,8,12b-tetrahydro-2H-dibenzocyclohepta[1,2-b]furan derivatives. The 5-HT2A, 5-HT2C and H1 receptor affinities of the described compounds are reported. The mCCP antagonistic activity of a set of selected molecules is also reported.

Synthesis of 3a,4-dihydro-3H-[1]benzopyrano[4,3-c]isoxazoles, displaying combined 5-HT uptake inhibiting and α2-adrenoceptor antagonistic activities. Part 2: Further exploration on the cinnamyl moiety

In our previous paper we have described the synthesis of a series of 3-piperazinylmethyl-3a,4-dihydro-3H-[1]benzopyrano[4,3-c]isoxazoles, as novel dual 5-HT reuptake inhibitors and alpha2-adrenoceptor antagonists. That investigation led to the identification of the cinnamyl fragment as the most suitable moiety for combined activity. This paper outlines a further optimisation programme, focused on the exploration of the aromatic ring present on the cinnamyl moiety of compounds 1, 2 and 3.

Synthesis of 2-N,N-Dimethylaminomethyl-2,3,3a,12b-tetrahydrodibenzo-[b,f]furo[2,3-d]oxepin Derivatives as Potential Anxiolytic Agents

New synthesis approaches that have led to a series of novel tetrahydrodibenzo[b,f]furo[2,3-d]oxepin derivatives are described. According to preliminary data these novel tetracycles can be useful intermediates for the preparation of potential new therapeutic agents.

2-(Dimethylaminomethyl)-tetrahydroisoxazolopyridobenzazepine derivatives. Synthesis of a new 5-HT(2C) antagonist with potential anxiolytic properties

Following the program started at Johnson & Johnson Pharmaceutical Research & Development searching for 5-HT(2A/2C) antagonists, we now report on the synthesis of 2-(dimethylaminomethyl)-2,3,3a,8-tetrahydroisoxazolo[3,2-a]pyrido[3,4-c]-[2]benzazepine and 2-(dimethylaminomethyl)-2,3,3a,8-tetrahydroisoxazolo[3,2-a]pyrido[3,2-c]-[2]benzazepine. A new method for the synthesis of pyridobenzazepines is described as well. The affinities for several receptors as well as the mCPP antagonistic activity of the compounds synthesised are described.

Synthesis and biological evaluation of imidazol-2-one and 2-cyanoiminoimidazole derivatives: novel series of PDE4 inhibitors

This communication describes the synthesis and in vitro PDE4 inhibitory activity of a novel series of imidazol-2-one and 2-cyanoiminoimidazole derivatives. The compounds described were also tested in in vivo models to evaluate their anti-inflammatory activity after topical administration as well as their gastro-intestinal side effects. Several compounds proved to be potent PDE4 inhibitors and some 2-cyanoiminoimidazoles showed less pronounced gastro-intestinal side effects than reference compounds but maintained anti-inflammatory activity after topical administration.

Synthesis and structure-activity relationship of 2-(aminoalkyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives: a novel series of 5-HT(2A/2C) receptor antagonists. Part 1

The synthesis of a series of novel 2-(aminoalkyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives as well as their 5-HT(2A/2C) and H(1) receptor binding affinities are described. The in vivo activity as potential anxiolytics of the synthesised compounds was measured in a mCPP challenge test. One of the compounds, 2a, proved to be a potent 5-HT(2A/2C) receptor antagonist showing as well oral activity and therefore could be considered as a potential anxiolytic/antidepressant agent.

Synthesis and structure-activity relationship of 2-(aminoalkyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives: a novel series of 5-HT(2A/2C) receptor antagonists. Part 2

Following the programme started at Janssen Research Foundation searching for 5-HT(2A/2C) antagonists, we now report on the synthesis of a series of substituted 2-(Dimethylaminomethyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives. The 5-HT(2A), 5-HT(2C) and H(1) receptor affinities as well as the mCPP antagonistic activity of the compounds synthesised is described.

NMR investigations of protein-carbohydrate interactions: insights into the topology of the bound conformation of a lactose isomer and beta-galactosyl xyloses to mistletoe lectin and galectin-1

A hallmark of oligosaccharides is their often limited spatial flexibility, allowing them to access a distinct set of conformers in solution. Viewing each individual or even the complete ensemble of conformations as potential binding partner(s) for lectins in protein-carbohydrate interactions, it is pertinent to address the question on the characteristics of bound state conformation(s) in solution. Also, it is possible that entering the lectin's binding site distorts the low-energy topology of a glycosidic linkage. As a step to delineate the strategy of ligand selection for galactosides, a common physiological docking point, we have performed a NMR study on two non-homologous lectins showing identical monosaccharide specificity. Thus, the conformation of lactose analogues bound to bovine heart galectin-1 and to mistletoe lectin in solution has been determined by transferred nuclear Overhauser effect measurements. It is demonstrated that the lectins select the syn conformation of lactose and various structural analogues (Galbeta(1-->4)Xyl, Galbeta(1-->3)Xyl, Galbeta(1-->2)Xyl, and Galbeta(1-->3)Glc) from the ensemble of presented conformations. No evidence for conformational distortion was obtained. Docking of the analogues to the modeled binding sites furnishes explanations, in structural terms, for exclusive recognition of the syn conformer despite the non-homologous design of the binding sites.