Fascaplysin-inspired diindolyls as selective inhibitors of CDK4/cyclin D1

We present the design, synthesis and biological activity of a new series of substituted 3-(2-(1H-indol-1-yl)ethyl)-1H-indoles and 1,2-di(1H-indol-1-yl)alkanes as selective inhibitors of CDK4/cyclin D1. The compounds were designed to explore the relationship between the connection mode of the indolyl moieties and their CDK inhibitory activities. We found all the above-mentioned designed compounds to be selective inhibitors of CDK4/cyclin D1 compared to the closely related CDK2/cyclin A, with IC₅₀ for the best compounds 10m and 13a being 39 and 37 μm, respectively.     

Synthesis of substituted 5[H]phenanthridin-6-ones as potent poly(ADP-ribose)polymerase-1 (PARP1) inhibitors

1-, 2-, 3-, 4-, 8-, or 10-Substituted 5(H)phenanthridin-6-ones were synthesized and found to be potent PARP1 inhibitors. Among the 28 compounds prepared, some showed not only low IC₅₀ values (compound 1b, 10 nM) but also desirable water solubility characteristics. These properties, which are superior to the common PARP1 inhibitors such as benzamides and isoquinolin-1-ones, are essential for potential therapeutic usage. The variety of compounds allows SAR analysis of favored substituents and substituted positions on 5(H)phenanthridin-6-one ring.     

Development of a selective and potent radioactive ligand for histamine H3 receptors: A compound potentially useful for receptor occupancy studies

Radioligands are powerful tools for examining the pharmacological profiles of chemical leads and thus facilitate drug discovery. In this study, we identified and characterized 3-([1,1,1-³H]methyl)-2-(4-{[3-(1-pyrrolidinyl)propyl]oxy} phenyl)-4(3H)-quinazolinone ([³H]1) as a potent and selective radioligand for histamine H₃ receptors. Radioligand [³H]1 exhibited appreciable specific signal in brain slices prepared from wild-type mice but not from histamine H₃ receptor-deficient mice, demonstrating the specificity and utility of [³H]1 as a selective histamine H₃ receptor radioligand for ex-vivo receptor occupancy assays.     

Synthesis and evaluation of N-alkyl-S-[3-(piperidin-1-yl)propyl]isothioureas: High affinity and human/rat species-selective histamine H3 receptor antagonists

S-Alkyl-N-alkylisothiourea compounds containing various cyclic amines were synthesized in the search for novel nonimidazole histamine H₃ receptor (H₃R) antagonists. Among them, four N-alkyl S-[3-(piperidin-1-yl)propyl]isothioureas 18, 19, 22, and 23 were found to exhibit potent and selective H₃R antagonistic activities against in vitro human H₃R, but were inactive against in vitro human H₄R. Furthermore, three alkyl homologs 18–20 showed inactivity for histamine release in in vivo rat brain microdialysis, suggesting differences in antagonist affinities between species. In addition, in silico docking studies of N-[4-(4-chlorophenyl)butyl]-S-[3-piperidin-1-yl)propyl]isothiourea 19 and a shorter homolog 17 with human/rat H₃Rs revealed that structural differences between the antagonist-docking cavities of rat and human H₃Rs were likely caused by the Ala122/Val122 mutation.     

Discovery of 3-alkyl-5-aryl-1-pyrimidyl-1H-pyrazole derivatives as a novel selective inhibitor scaffold of JNK3

Abstract

3-alkyl-5-aryl-1-pyrimidyl-1H-pyrazole derivatives were designed and synthesised as selective inhibitors of JNK3, a target for the treatment of neurodegenerative diseases. Following previous studies, we have designed JNK3 inhibitors to reduce the molecular weight and successfully identified a lead compound that exhibits equipotent activity towards JNK3. Kinase profiling results also showed high selectivity for JNK3 among 38 kinases. Among the derivatives, the IC₅₀ value of 8a, (R)-2-(1-(2-((1-(cyclopropanecarbonyl)pyrrolidin-3-yl)amino)pyrimidin-4-yl)-5-(3,4-dichlorophenyl)-1H-pyrazol-3-yl)acetonitrile exhibited 227?nM, showing the highest inhibitory activity against JNK3.     

2-(3′-Hydroxypropylidene)-1α-hydroxy-19-norvitamin D compounds with truncated side chains

Our recent studies with 2-(3′-hydroxypropylidene) analogs of 1α,25-dihydroxy-19-norvitamin D₃ showed that this 2-substituent creates compounds with very potent biological activity. In the continuing search for vitamin D compounds with selective activity profiles, we prepared a series of 1α-hydroxy-19-norvitamin D analogs characterized by the presence of a 3′-hydroxypropylidene substituent at C-2 and a truncated side chain. These vitamin D compounds were efficiently prepared using convergent syntheses. The C,D-fragments, namely the Grundmann ketones 19, 20, 27, 36 and 37 were synthesized from the known 8β-benzoyloxy-22-aldehydes 12 and 29. These hydrindanones were subjected to Lythgoe type Wittig–Horner coupling with phosphine oxide 21, prepared by us previously, and after hydroxyl deprotection the set of 19-norvitamins 7–11 was successfully obtained. According to our expectations, all analogs (with an exception of the 20R-compound 7) have pronounced in vitro activity. When compared to the natural hormone 1α,25-(OH)₂D₃ (1), they show the same or only slightly reduced affinity for the vitamin D receptor while being similarly effective as 1 in differentiation of HL-60 cells into monocytes.     

Development and characterization of endocannabinoid hydrolases FAAH and MAGL inhibitors bearing a benzotriazol-1-yl carboxamide scaffold

A series of (1H-benzo[d][1,2,3]triazol-1-yl)(4-benzylpiperazin-1-yl)methanones and of (1H-benzo[d][1,2,3]triazol-1-yl)(4-phenylpiperazin-1-yl)methanones has been prepared and tested on human fatty acid amide hydrolase (FAAH) and monoacylglycerol lipase (MAGL). In the benzylpiperazinyl series, compound 29 (ML30) exhibited an IC₅₀ value of 0.54 nM on MAGL, combined with a 1000-fold selectivity versus FAAH, while compounds 11 and 16 acted as potent dual FAAH-MAGL inhibitors (IC₅₀ <10 nM). In the phenylpiperazinyl series, compounds 37, 38, 42, and 43 displayed IC₅₀ values against MAGL in the nanomolar range, whilst being between one and two orders of magnitude less potent on the FAAH, while compounds 31 and 32 were potent FAAH inhibitors (IC₅₀ <20 nM) and over 12-fold selective versus MAGL. The key structural determinants driving the structure–activity relationships were explored by the minimization of the inhibitors inside the active site of both enzymes.     

Discovery of novel selective Janus kinase 2 (JAK2) inhibitors bearing a 1H-pyrazolo[3,4-d]pyrimidin-4-amino scaffold

Janus kinases (JAKs) regulate various cancers and immune responses and are targets for the treatment of cancers and immune diseases. A new series of 1H-pyrazolo[3,4-d]pyrimidin-4-amino derivatives were synthesized and optimized by introducing a functional 3,5-disubstituted-1H-pyrazole moiety into the C-3 moiety of pyrazole template, and then were biologically evaluated as potent Janus kinase 2 (JAK2) inhibitors. Among these molecules, inhibitors 11f, 11g, 11h and 11k displayed strong activity and selectivity against the JAK2 kinase, with IC₅₀ values of 7.2?nM, 6.5?nM, 8.0?nM and 9.7?nM, respectively. In particular, the cellular inhibitory assay and western blot analysis further support the JAK2 selectivity of compound 11g also in cells. Furthermore, compound 11g also exhibited potent inhibitory activity in lymphocytes proliferation assay and delayed hypersensitivity assay. Taken together, the novel JAK2 selective inhibitors discovered in this study may be potential lead compounds for new drug discovery via further development of more potent and selective JAK2 inhibitors.     

Investigation of potent inhibitors of cholinesterase based on thiourea and pyrazoline derivatives: Synthesis,inhibition assay and molecular modeling studies

Owing to the desperate need of new drugs development to treat Alzheimer's ailment the synthesis of 1-aroyl-3-(5-(4-chlorophenyl)-1,2,4-triazole-3-thioneaminylthioureas (2–6) starting from (4-amino-5-(4-chlorophenyl)-4H-1,2,4-triazole-3-thiol) (1) and synthesis of 1-(3-(4-aminophenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl)-2-(4-isobutylphenyl)propan-1-one (7–9) starting from 2-(4-isobutylphenyl)propanehydrazide (a) with the cyclization with substituted chalcones (c-e) was carried out. To check the biological potential of the synthesized compounds, all were subjected to acetylcholinesterase (AChE) and butrylcholinesterase (BChE) inhibition assays. The most potent and selective inhibitor for the acetylcholinesterase was compound 7 having an inhibitory concentration of 123 ± 51 nM, whereas, compound 6 was found as selective inhibitor of butyrylcholinesterase (BChE) with an IC₅₀ value of 201 ± 80 nM. However, the compounds 1 and 2 were found as dual inhibitors i.e. active against both acetylcholinesterase as well as butyrylcholinesterase.     

3-(1′,1′-Dimethylbutyl)-1-deoxy-Δ-THC and related compounds: synthesis of selective ligands for the CB2 receptor

The synthesis and pharmacology of 15 1-deoxy-Δ⁸-THC analogues, several of which have high affinity for the CB₂ receptor, are described. The deoxy cannabinoids include 1-deoxy-11-hydroxy-Δ⁸-THC (5), 1-deoxy-Δ⁸-THC (6), 1-deoxy-3-butyl-Δ⁸-THC (7), 1-deoxy-3-hexyl-Δ⁸-THC (8) and a series of 3-(1′,1′-dimethylalkyl)-1-deoxy-Δ⁸-THC analogues (2, n=0–4, 6, 7, where n=the number of carbon atoms in the side chain−2). Three derivatives (17–19) of deoxynabilone (16) were also prepared. The affinities of each compound for the CB₁ and CB₂ receptors were determined employing previously described procedures. Five of the 3-(1′,1′-dimethylalkyl)-1-deoxy-Δ⁸-THC analogues (2, n=1–5) have high affinity (K_i=<20 nM) for the CB₂ receptor. Four of them (2, n=1–4) also have little affinity for the CB₁ receptor (K_i=>295 nM). 3-(1′,1′-Dimethylbutyl)-1-deoxy-Δ⁸-THC (2, n=2) has very high affinity for the CB₂ receptor (K_i=3.4±1.0 nM) and little affinity for the CB₁ receptor (K_i=677±132 nM).

Scheme 3. (a) (C₆H₅)₃PCH₃⁺ Br⁻, n-BuLi/THF, 65°C; (b) LiAlH₄/THF, 25°C; (c) KBH(sec-Bu)₃/THF, −78 to 25°C then H₂O₂/NaOH.     

Synthesis,characterization, and biological assessment of the four stereoisomers of the H3 receptor antagonist 5-fluoro-2-methyl-N-[2-methyl-4-(2-methyl[1,3′]bipyrrolidinyl-1′-yl)phenyl]benzamide

This Letter describes the asymmetric synthesis of the four stereoisomers (8a–8d) of a potent and highly selective histamine H₃ receptor (H₃R) antagonist, 5-fluoro-2-methyl-N-[2-methyl-4-(2-methyl[1,3′]bipyrrolidinyl-1′-yl) phenyl]benzamide (1). The physico-chemical properties, in vitro H₃R affinities and ADME of 8a–8d were determined. Stereoisomer 8c (2S,3′S) displayed superior in vitro H₃R affinity over other three stereoisomers and was selected for further profiling in in vivo PK and drug safety. Compound 8c exhibited excellent PK properties with high exposure, desired brain to plasma ratio and reasonable brain half life. However, all stereoisomers showed similar unwanted hERG affinities.     

Synthesis and anti-hepatitis C virus activity of novel ethyl 1H-indole-3-carboxylates in vitro

A series of ethyl 1H-indole-3-carboxylates 9a_1–6 and 9b_1–2 were prepared and evaluated in Huh-7.5 cells. Most of the compounds exhibited anti-hepatitis C virus (HCV) activities at low concentration. The selectivity indices of inhibition on entry and replication of compounds 9a₂ (>10; >16.7) and 9b₁ (>6.25; >16.7) were higher than those of the other evaluated compounds, including the lead compound Arbidol (ARB, 6; 15). Moreover, the selective index of inhibition on entry of compound 9a₃ (>6.25) was higher than that of ARB (6). Of these three initial hits, compound 9a₂ was the most potent.     

Synthesis,biological evaluation and docking analysis of 3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-ones as potential cyclooxygenase-2 (COX-2) inhibitors

As a part of our continued efforts to discover new COX inhibitors, a series of 3-methyl-1-phenylchromeno[4,3-c]pyrazol-4(1H)-ones were synthesized and evaluated for in vitro COX inhibitory potential. Within this series, seven compounds (3a–d, 3h, 3k and 3q) were identified as potential and selective COX-2 inhibitors (COX-2 IC₅₀’s in 1.79–4.35 μM range; COX-2 selectivity index (SI) = 6.8–16.7 range). Compound 3b emerged as most potent (COX-2 IC₅₀ = 1.79 μM; COX-1 IC₅₀ >30 μM) and selective COX-2 inhibitor (SI >16.7). Further, compound 3b displayed superior anti-inflammatory activity (59.86% inhibition of edema at 5 h) in comparison to celecoxib (51.44% inhibition of edema at 5 h) in carrageenan-induced rat paw edema assay. Structure–activity relationship studies suggested that N-phenyl ring substituted with p-CF₃ substituent (3b, 3k and 3q) leads to more selective inhibition of COX-2. To corroborate obtained experimental biological data, molecular docking study was carried out which revealed that compound 3b showed stronger binding interaction with COX-2 as compared to COX-1.     

Novel imidazobenzazepine derivatives as dual H1/5-HT2A antagonists for the treatment of sleep disorders

A novel imidazobenzazepine template (5a) with potent dual H₁/5-HT_2A antagonist activity was identified. Application of a zwitterionic approach to this poorly selective and poorly developable starting point successfully delivered a class of high quality leads, 3-[4-(3-R¹-2-R-5H-imidazo[1,2-b][2]benzazepin-11-yl)-1-piperazinyl]-2,2-dimethylpropanoic acids (e.g., 9, 19, 20, and 21), characterized by potent and balanced H₁/5-HT_2A receptor antagonist activities and good developability profiles.     

Design and synthesis of 3,5-diaryl-4,5-dihydro-1H-pyrazoles as new tyrosinase inhibitors

In this study, twenty 3,5-diaryl-4,5-dihydro-1H-pyrazole derivatives with hydroxyl(s) (1a–1p, 2a–2d) were synthesized and their inhibitory activity on mushroom tyrosinase was examined. The results showed that among these compounds, 1-(5-(3,4-dihydroxyphenyl)-3-(4-hydroxyphenyl)-4,5-dihydro-1H-pyrazol-1-yl)ethanone 1d was found to be the most potent tyrosinase inhibitor with IC₅₀ value of 0.301 μM. Kinetic study revealed that these compounds were competitive inhibitors of tyrosinase and their structure–activity relationships were investigated in this article.     

Discovery of novel 2,3-dihydro-1H-inden-1-amine derivatives as selective monoamine oxidase B inhibitors

Inhibition of MAO-B has been an effective strategy for the treatment of Parkinson’s disease. To find more potent and selective MAO-B inhibitors with novel chemical scaffold, we designed and synthesized a series of new 2,3-dihydro-1H-inden-1-amine derivatives on basis of our previous study. Furthermore, the corresponding structure-activity relationship (SAR) of these compounds is detailedly discussed. Compounds L4 (IC₅₀?=?0.11?μM), L8 (IC₅₀?=?0.18?μM), L16 (IC₅₀?=?0.27?μM) and L17 (IC₅₀?=?0.48?μM) showed similar MAO-B inhibitory activity as Selegiline. Moreover, L4, L16 and L17 also exhibited comparable selectivity with Selegiline, indicating that L4, L16 and L17 could be promising selective MAO-B inhibitors for further study.     

The discovery and structure–activity relationships of 2-(piperidin-3-yl)-1H-benzimidazoles as selective,CNS penetrating H1-antihistamines for insomnia

A series of 2-(3-aminopiperidine)-benzimidazoles were identified as selective H₁-antihistamines for evaluation as potential sedative hypnotics. Representative compounds showed improved hERG selectivity over a previously identified 2-aminobenzimidazole series. While hERG activity could be modulated via manipulation of the benzimidazole N1 substituent, this approach led to a reduction in CNS exposure for the more selective compounds. One example, 9q, retained a suitable selectivity profile with CNS exposure equivalent to known centrally active H₁-antihistamines.     

Synthesis,cannabinoid receptor affinity,molecular modeling studies and in vivo pharmacological evaluation of new substituted 1-aryl-5-(1H-pyrrol-1-yl)-1H-pyrazole-3-carboxamides. 2. Effect of the 3-carboxamide substituent on the affinity and selectivity profile

New substituted 1-aryl-5-(1H-pyrrol-1-yl)-1H-pyrazole-3-carboxamides were synthesized by replacing the 2,4-dichlorobenzyl and cyclohexyl moieties at the 3-carboxamide nitrogen of the previously reported CB₁ receptor antagonists/inverse agonists 4 and 5. Several ligands showed potent affinity for the hCB₁ receptor, with K_i concentrations comparable to the reference compounds 1, 4 and 5, and exhibited CB₁ selectivity comparable to 1 and 2. Docking experiments and molecular dynamics (MD) simulations explained the potent hCB₁ binding affinity of compounds 31 and 37. According to our previous studies, 31 and 37 formed a H-bond with K3.28(192), which accounted for the high affinity for the receptor inactive state and the inverse agonist activity. The finding of inhibition of food intake following their acute administration to rats, supported the concept that the CB₁ selective compounds 4 and 52 act as antagonists/inverse agonists.     

Novel 1-aminoethyl-3-arylsulfonyl-1H-pyrrolo[2,3-b]pyridines are potent 5-HT6 agonists

A series of 1-aminoethyl-3-arylsulfonyl-1H-pyrrolo[2,3-b]pyridines 10a–z was prepared as novel 5-HT₆ ligands. The best compounds were high affinity, full agonists at 5-HT₆ receptors. Several agonists demonstrated good selectivity over other serotonergic and dopaminergic receptors. Acute administration of selective agonist 10e significantly increased extracellular GABA concentrations in rat frontal cortex. This compound also reduced adjunctive drinking behavior in the rat schedule-induced polydipsia assay, possibly predictive of efficacy in obsessive compulsive disorder and other anxiety related disorders.