The discovery of 4-(3-pentylamino)-2,7-dimethyl-8-(2-methyl-4-methoxyphenyl)-pyrazolo-[1 ,5-a]-pyrimidine: a corticotropin-releasing factor (hCRF1) antagonist

Structure activity relationship studies led to the discovery of 4-(3-pentylamino)-2,7-dimethyl-8-(2-methyl-4-methoxyphenyl)-pyrazo lo-[1,5-a]-pyrimidine 11-31 (DMP904), whose pharmacological profile strongly supports the hypothesis that hCRF1 antagonists may be potent anxiolytic drugs. Compound 11-31 (hCRF1 Ki = 1.0+/-0.2 nM (n = 8)) was a potent antagonist of hCRF1-coupled adenylate cyclase activity in HEK293 cells (IC50= 10.0+/-0.01 nM versus 10 nM r/hCRF, n = 8); alpha-helical CRF(9-41) had weaker potency (IC50 = 286+/-63 nM, n = 3). Analogue 11-31 had good oral activity in the rat situational anxiety test; the minimum effective dose for 11-31 was 0.3 mg/kg (po). Maximal efficacy (approximately 57% reduction in latency time in the dark compartment) was observed at this dose. Chlordiazepoxide caused a 72% reduction in latency at 20 mg/kg (po). The literature compound 1 (CP154526-1, 30 mg/kg (po)) was inactive in this test. Compound 11-31 did not inhibit open-field locomotor activity at 10, 30, and 100 mg/kg (po) in rats. In beagle dogs, this compound (5 mg/kg, iv, po) afforded good plasma levels. The key iv pharmacokinetic parameters were t1/2, CL and Vd,ss values equal to 46.4+/-7.6 h. 0.49+/-0.08 L/kg/h and 23.0+/-4.2 L/kg, respectively. After oral dosing, the mean Cmax, Tmax t1/2 and bioavailability values were equal to 1260+/-290 nM, 0.75+/-0.25 h. 45.1+/-10.2 h and 33.1%, respectively. The overall rat behavioral profile of this compound suggests that it may be an anxiolytic drug with a low motor side effect liability.     

Antagonists of the human CCR5 receptor as anti-HIV-1 agents. Part 4: synthesis and structure-activity relationships for 1-[N-(methyl)-N-(phenylsulfonyl)amino]-2-(phenyl)-4-(4-(N-(alkyl)-N-(benzyloxycarbonyl)amino)piperidin-1-yl)butanes

(2S)-2-(3-Chlorophenyl)-1-[N-(methyl)-N-(phenylsulfonyl)amino]-4-[spiro(2,3-dihydrobenzthiophene-3,4'-piperidin-1'-yl)]butane S-oxide (1b) has been identified as a potent CCR5 antagonist having an IC50=10 nM. Herein, structure-activity relationship studies of non-spiro piperidines are described, which led to the discovery of 4-(N-(alkyl)-N-(benzyloxycarbonyl)amino)piperidine derivatives (3-5) as potent CCR5 antagonists.     

Discovery and SAR of novel,potent and selective hexahydrobenzonaphthyridinone inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1)

A novel hexahydrobenzonaphthyridinone PARP-1 pharmacophore is reported, subsequent SAR exploration around this scaffold led to selective PARP-1 inhibitors with low nanomolar enzyme potency, displaying good cellular activity and promising rat PK properties.     

The discovery and synthesis of novel adenosine substituted 2,3-dihydro-1H-isoindol-1-ones: potent inhibitors of poly(ADP-ribose) polymerase-1 (PARP-1)

A series of novel 4-(N-acyl)-2,3-dihydro-1H-isoindol-1-ones have been prepared from methyl-3-nitro-2-methylbenzoate and linked through various spacers to the adenosine derivatives 11 and 12. We found that potent inhibition of poly(ADP-ribose)polymerase-1 (PARP-1) was achieved when isoindolinone was linked to adenosine by a spacer group of a specific length. Introduction of piperazine and succinyl linkers between the isoindolinone and adenosine core structures resulted in highly potent compounds 8a and 10b, which showed IC(50) values of 45 and 100 nM, respectively.     

Design and synthesis of poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors. Part 4: biological evaluation of imidazobenzodiazepines as potent PARP-1 inhibitors for treatment of ischemic injuries

A class of poly(ADP-ribose) polymerase (PARP-1) inhibitors, the imidazobenzodiazepines, are presented in this text. Several derivatives were designed and synthesized with ionizable groups (i.e., tertiary amines) in order to promote the desired pharmaceutical characteristics for administration in ischemic injury. Within this series, several compounds have excellent in vitro potency and our computational models accurately justify the structure-activity relationships (SARs) and highlight essential hydrogen bonding residues and hydrophobic pockets within the catalytic domain of PARP-1. Administration of these compounds (5q, 17a and 17e) in the mouse model of streptozotocin-induced diabetes results in maintainance of glucose levels. Furthermore, one such inhibitor (5g, IC(50)=26 nM) demonstrated significant reduction of infarct volume in the rat model of permanent focal cerebral ischemia.     

Designing,synthesis and bioactivities of 4-[3-(4-hydroxyphenyl)-5-aryl-4,5-dihydro-pyrazol-1-yl]benzenesulfonamides

In this study, 4-[3-(4-hydroxyphenyl)-5-aryl-4,5-dihydro-pyrazol-1-yl]benzenesulfonamide (1–9) types compounds were synthesized and their chemical structures were confirmed by ¹H NMR, ¹³C NMR and HRMS spectra. Cytotoxic and carbonic anhydrase (CA) inhibitory effects of the compounds were investigated. Cytotoxicity experiments pointed out that compound 4, (4-[5-(4-chlorophenyl)-3-(4-hydroxyphenyl)-4,5-dihydro-pyrazol-1-yl]benzenesulfonamide), exerting the highest tumor selectivity (TS) and potency selectivity expression (PSE) values, can be considered as a lead compound of this study in terms of development of novel anticancer agents. All synthesized sulfonamides showed a good inhibition profile on hCA IX and XII in the range of 53.5–923?nM and 6.2–95?nM, respectively. These compounds were 2.5–13.4 times more selective for the inhibition of hCA XII versus hCA IX, except compound 2 which had similar inhibitory action towards both isoenzymes.     

Effects of 10-(2-propynyl)-estr-4-ene-3,17-dione (MDL 18,962)--a mechanism-based irreversible inhibitor of aromatase--in cultured human foreskin fibroblasts

In male subjects, peripheral aromatization of androgens accounts for most of the estrogen production, and skin is an important site of such enzymatic activity. We have studied the effects of a mechanism-based, irreversible aromatase inhibitor, 10-(2-propynyl)-estr-4-ene-3,17-dione (MDL 18,962) on androgen action and metabolism in cultured human foreskin fibroblasts. Cells were incubated simultaneously in the presence of substrate, androstenedione, and inhibitor, MDL 18,962. Aromatase activity was linear with time up to 3 h of incubation at 37 degrees C in the absence and presence of 1.0-10 nM inhibitor. The IC50 for four different cell strains ranged from 4.0 to 8.6 nM MDL 18,962. Kinetic analysis of competitive inhibition by the Eadie-Hofstee method yielded an apparent Ki of 2.75 nM for the inhibitor. Preincubation of cells with MDL 18,962 resulted in irreversible inhibition of aromatase activity which was time- and concentration-dependent. We calculated a Ki of 7.6 nM for MDL 18,962. Preincubation of cells with 25 nM MDL 18,962 suppressed enzyme activity for up to 6 h following removal of the inhibitor, before a return of enzyme activity due to synthesis of new enzyme. MDL 18,962 (0.2-20 microM) did not influence the 5 alpha-reduction of testosterone (200 nM). In addition, binding of dihydrotestosterone (2 nM) to androgen receptors was not affected by MDL 18,962 (25-1000 nM). In summary, MDL 18,962 is a specific, high potency inhibitor of aromatase. By virtue of its high binding affinity to the enzyme active site, it competes very effectively with substrate, resulting in irreversible inactivation of aromatase.     

4-(1,1-Dioxo-1,4-dihydro-1lambda6-benzo[1,4]thiazin-3-yl)-5-hydroxy-2H-pyridazin-3-ones as potent inhibitors of HCV NS5B polymerase

4-(1,1-Dioxo-1,4-dihydro-1lambda(6)-benzo[1,4]thiazin-3-yl)-5-hydroxy-2H-pyridazin-3-one analogs were discovered as a novel class of inhibitors of HCV NS5B polymerase. Structure-based design led to the identification of compound 3a that displayed potent inhibitory activities in biochemical and replicon assays (1b IC(50)<10 nM; 1b EC(50)=1.1 nM) as well as good stability toward human liver microsomes (HLM t(1/2)>60 min).     

Substituted uracil derivatives as potent inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1)

A new class of PARP-1 inhibitors, namely substituted fused uracil derivatives were synthesised. Starting from a derivative with an IC(50)=2microM the chemical optimisation program led to compounds with more than a 100-fold increase in potency (IC(50)<20nM). Additionally, physicochemical and pharmacokinetic properties were evaluated. It could be shown that compounds bearing a piperazine or phenyl substituted betaAla-Gly side chain exhibited the best overall profile.     

4-(1-Phenyl-1H-pyrazol-4-yl)quinolines as novel, selective and brain penetrant metabotropic glutamate receptor 4 positive allosteric modulators

4-(1-Phenyl-1H-pyrazol-4-yl)quinoline (1) was identified by screening the Lundbeck compound collection, and characterized as having mGlu4 receptor positive allosteric modulator properties. Compound 1 is selective over other mGlu receptors and a panel of GPCRs, ion channels and enzymes, but has suboptimal lipophilicity and high plasma and brain non-specific binding. In view of the challenges at the hit-to-lead stage previously reported in the development of mGlu4 receptor positive allosteric modulators (PAMs), a thorough structure-mGlu4 PAM activity relationship study was conducted to interrogate the chemical tractability of this chemotype. The central pyrazole ring tolerates the addition of one or two methyl groups. The C-7 position of the quinoline ring provides a site tolerant to hydrophilic substituents, enabling the design of diverse analogs with good in vitro mGlu4 PAM potency and efficacy, as well as improved microsomal turnover in vitro, compared to 1. In spite of the excellent ligand efficiency of 1 (LE=0.43), optimization of in vitro potency for this series reached a plateau around EC(50)=200 nM.     

Novel retinoic acid 4-hydroxylase (CYP26) inhibitors based on a 3-(1H-imidazol- and triazol-1-yl)-2,2-dimethyl-3-(4-(phenylamino)phenyl)propyl scaffold

Retinoic acid (RA), the biologically active metabolite of vitamin A, is used medicinally for the treatment of hyperproliferative diseases including dermatological conditions and cancer. The antiproliferative effects of RA have been well documented as well as the limitations owing to toxicity and the development of resistance to RA therapy. RA metabolism inhibitors (RAMBAs or CYP26 inhibitors) are attracting increasing interest as an alternative method for enhancing endogenous levels of retinoic acid in the treatment of hyperproliferative disease. Here the synthesis and inhibitory activity of novel 3-(1H-imidazol- and triazol-1-yl)-2,2-dimethyl-3-(4-(phenylamino)phenyl)propyl derivatives in a MCF-7 CYP26A1 microsomal assay are described. The most promising inhibitor methyl 2,2-dimethyl-3-(4-(phenylamino)phenyl)-3-(1H-1,2,4-triazol-1-yl)propanoate (6) exhibited an IC(50) of 13 nM (compared with standards Liarozole IC(50) 540 nM and R116010 IC(50) 10 nM) and was further evaluated for CYP selectivity using a panel of CYP with >100-fold selectivity for CYP26 compared with CYP1A2, 2C9 and 2D6 observed and 15-fold selectivity compared with CYP3A4. The results demonstrate the potential for further development of these potent inhibitors.     

Novel alkoxybenzamide inhibitors of poly(ADP-ribose) polymerase

We have previously described poly(ADP-ribose) polymerase-1 (PARP-1) inhibitors based on a substituted benzyl-phthalazinone scaffold. As an alternative chemical template, a novel series of alkoxybenzamides were developed with restricted conformation through intramolecular hydrogen bond formation; the compounds exhibit low nM enzyme and cellular activity as PARP-1 inhibitors.     

Discovery of potent, selective, and metabolically stable 4-(pyridin-3-yl)cinnolines as novel phosphodiesterase 10A (PDE10A) inhibitors

We report the discovery of 6,7-dimethoxy-4-(pyridin-3-yl)cinnolines as novel inhibitors of phosphodiesterase 10A (PDE10A). Systematic examination and analyses of structure-activity-relationships resulted in single digit nM potency against PDE10A. X-ray co-crystal structure revealed the mode of binding in the enzyme's catalytic domain and the source of selectivity against other PDEs. High in vivo clearance in rats was addressed with the help of metabolite identification (ID) studies. These findings combined resulted in compound 39, a promising potent inhibitor of PDE10A with good in vivo metabolic stability in rats and efficacy in a rodent behavioral model.     

Design and synthesis of 4-(2,3-dihydro-1H-benzo[d]pyrrolo[1,2-a]imidazol-7-yl)-N-(5-(piperazin-1-ylmethyl)pyridine-2-yl)pyrimidin-2-amine as a highly potent and selective cyclin-dependent kinases 4 and 6 inhibitors and the discovery of structure-activity relationships

Cyclin-dependent kinases 4/6 play an important role in regulation of cell cycle, and overexpress in a variety of cancers. Up to now, new CDK inhibitors still need to be developed due to its poor selectivity. Herein we report a novel series of 4-(2,3-dihydro-1H-benzo[d]pyrrolo[1,2-a]imidazole-7-yl)-N-(5-(piperazin-1-ylmethyl)pyridine-2-yl)pyrimidin-2-amine anologues as potent CDK 4/6 inhibitors based on LY2835219 (Abemaciclib). Compound 10d, which exhibits approximate potency on CDK4/6 (IC₅₀?=?7.4/0.9?nM), has both good pharmacokinetic characters and high selectivity on CDK1 compared with LY2835219. Overall, compound 10d could be a promising candidate and a good starting point as anticancer drugs.     

Discovery and SAR of orally efficacious tetrahydropyridopyridazinone PARP inhibitors for the treatment of cancer

PARP-1, the most abundant member of the PARP superfamily of nuclear enzymes, has emerged as a promising molecular target in the past decade particularly for the treatment of cancer. A number of PARP-1 inhibitors, including veliparab discovered at Abbott, have advanced into different stages of clinical trials. Herein we describe the development of a new tetrahydropyridopyridazinone series of PARP-1 inhibitors. Many compounds in this class, such as 20w, displayed excellent potency against the PARP-1 enzyme with a K(i) value of <1nM and an EC(50) value of 1nM in a C41 whole cell assay. The presence of the NH in the tetrahydropyridyl ring of the tetrahydropyridopyridazinone scaffold improved the pharmacokinetic properties over similar carbon based analogs. Compounds 8c and 20u are orally available, and have demonstrated significant efficacy in a B16 murine xenograft model, potentiating the efficacy of temozolomide (TMZ).     

Evaluation of the eutomer of 4-{3-(4-chlorophenyl)-3-hydroxypyrrolidin-1-yl}-1-(4-fluorophenyl)butan-1-one, {(+)-SYA 09}, a pyrrolidine analog of haloperidol

Enantiomeric separation of the racemic 4-{3-(4-chlorophenyl)-3-hydroxypyrrolidin-1-yl}-1-(4-fluorophenyl)butan-1-one, a pyrrolidine analog of haloperidol, {(+/-)-SYA 09}, and subsequent binding studies revealed that most of the binding affinity at dopamine and serotonin receptors resides in the (+)-isomer {(+)-SYA 09} or the eutomer. Further pharmacological evaluation of the eutomer revealed that it has a higher affinity for the dopamine D4 (DAD4) receptor subtype (Ki = 3.6 nM) than for the DAD2 subtype (Ki = 51.1 nM) with a ratio of 14.2 (D2Ki/D4Ki ratio = 14.2). In an animal model of antipsychotic efficacy, the (+)-SYA 09 was efficacious with an ED50 value of 1.6 mg/kg, i.p., and at twice this value, (+)-SYA 09 did not induce significant catalepsy in rats.     

Synthesis and SAR of 5-, 6-, 7- and 8-aza analogues of 3-aryl-4-hydroxyquinolin-2(1H)-one as NMDA/glycine site antagonists

A series of 5-, 6-, 7- and 8-aza analogues of 3-aryl-4-hydroxyquinolin-2(1H)-one was synthesized and assayed as NMDA/glycine receptor antagonists. The in vitro potency of these antagonists was determined by displacement of the glycine site radioligand [(3)H]5,7-dicholorokynurenic acid ([(3)H]DCKA) in rat brain cortical membranes. Selected compounds were also tested for functional antagonism using electrophysiological assays in Xenopus oocytes expressing cloned NMDA receptor (NR) 1A/2C subunits. Among the 5-, 6-, 7-, and 8-aza-3-aryl-4-hydroxyquinoline-2(1H)-ones investigated, 5-aza-7-chloro-4-hydroxy-3-(3-phenoxyphenyl)quinolin-2-(1H)-one (13i) is the most potent antagonist, having an IC(50) value of 110 nM in [(3)H]DCKA binding and a K(b) of 11 nM in the electrophysiology assay. Compound 13i is also an active anticonvulsant when administered systemically in the mouse maximum electroshock-induced seizure test (ED(50)=2.3mg/kg, IP).     

4-(3-Aryloxyaryl)quinoline sulfones are potent liver X receptor agonists

A series of 4-(3-aryloxyaryl)quinolines with sulfone substituents on the terminal aryl ring (7) was prepared as LXR agonists. High affinity LXR ligands with excellent agonist potency and efficacy in functional assays of LXR activity were identified. In general, these sulfone agonists were equal to or superior to previously described alcohol and amide analogs in terms of affinity, functional potency, and microsomal stability. Many of the sulfones had LXRβ binding IC₅₀ values <10 nM while the most potent compounds in an ABCA1 mRNA induction assay in J774 mouse cells had EC₅₀ values <10 nM and were as efficacious as T0901317.     

Beta(3)-adrenoceptor agonists for the treatment of frequent urination and urinary incontinence: 2-[4-(2-[[(1S,2R)-2-hydroxy-2-(4-hydroxyphenyl)-1-methylethyl]amino]ethyl)phenoxy]-2-methylpropionic acid.

In a search for novel analogues of β₃-adrenoceptor (AR) agonists relaxing the bladder for treatment of urinary dysfunction, 2-[4-(2-{[(1S,2R)-2-hydroxy-2-(4-hydroxyphenyl)-1-methylethyl]amino}ethyl)phenoxy]-2-methylpropionic acids (1a–e), into which a fibrate-like structure had been incorporated, were synthesised. Compound 1a was found to be a selective β₃-AR agonist in functional assays using the ferret detrusor (β₃-AR), rat uterus (β₂-AR), and rat atrium (β₁-AR); β₃: EC₅₀=7.8 nM, β₂: IC₅₀=7,300 nM, β₁: EC₂₀=23,000 nM. The introduction of a chlorine atom or methyl substituent at the ortho-position on the phenyl ring of 1a further improved β₃-AR selectivity. In an in vivo study, 1a lowered intrabladder pressure (ED₅₀=31 μg/kg) in rats, without increasing heart rate, in keeping with the in vitro results. Consequently, it is proposed that 1a and its analogues (1b–e), possess β₃-AR agonistic activity in the absence of undesirable β₁- or β₂-AR mediated actions, and may be useful for clinical treatment and pharmacological studies.