1-Aryl-3,4-dihydro-1H-quinolin-2-one derivatives, novel and selective norepinephrine reuptake inhibitors

A novel series of 1-aryl-3,4-dihydro-1H-quinolin-2-ones have been discovered as potent and selective norepinephrine reuptake inhibitors. Efficient synthetic routes have been developed which allow for the multi-gram preparation of both final targets and advanced intermediates for SAR expansion.     

Synthesis and SAR of highly potent and selective dopamine D(3)-receptor antagonists: Quinolin(di)one and benzazepin(di)one derivatives. herve.geneste@abbott.com

The synthesis and SAR of novel and selective dopamine D(3)-receptor antagonists based on a 3,4-dihydro-1H-quinolin-2-one, a 1,3,4,5-tetrahydro-benzo[b]azepin-2-one, 1H-quinoline-2,4-dione or a 3,4-dihydro-1H-benzo[b]azepine-2,5-dione scaffold are discussed. A706149 (2.15mg/kg, po) antagonizes PD 128907-induced huddling deficits in rat, a social interaction paradigm.     

Synthesis and anticonvulsant activity of 7-alkoxyl-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolines

A series of 7-alkoxyl-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline derivatives was synthesized using 6-hydroxy-3,4-dihydro-1H-quinolin-2-one as a starting material. Their anticonvulsant activities were evaluated by the maximal electroshock test (MES test) and the subcutaneous (s.c.) pentylenetetrazol test (scMet test), and their neurotoxicity was evaluated by the rotarod neurotoxicity test (Tox). MES and scMet tests show that 7-(4-fluorobenzyloxy)-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinoline 4l was found to be the most potent with ED50 value of 11.8 and 6.7 mg kg(-1) and protective index (PI = TD50/ED50) value of 4.6 and 8.1, respectively.     

Inhibition of monoamine oxidase by 3,4-dihydro-2(1H)-quinolinone derivatives

In the present study, a series of 3,4-dihydro-2(1H)-quinolinone derivatives were synthesized and evaluated as inhibitors of recombinant human monoamine oxidase (MAO) A and B. The 3,4-dihydro-2(1H)-quinolinone derivatives are structurally related to a series of coumarin (1-benzopyran-2-one) derivatives which have been reported to act as MAO-B inhibitors. The results document that the quinolinones are highly potent and selective MAO-B inhibitors with most homologues exhibiting IC₅₀ values in the nanomolar range. The most potent MAO-B inhibitor, 7-(3-bromobenzyloxy)-3,4-dihydro-2(1H)-quinolinone, exhibits an IC₅₀ value of 2.9 nM with a 2750-fold selectivity for MAO-B over the MAO-A isoform. An analysis of the structure–activity relationships for MAO-B inhibition shows that substitution on the C7 position of the 3,4-dihydro-2(1H)-quinolinone scaffold leads to significantly more potent inhibition compared to substitution on C6. In this regard, a benzyloxy substituent on C7 is more favourable than phenylethoxy and phenylpropoxy substitution on this position. It may be concluded that C7-substituted 3,4-dihydro-2(1H)-quinolinones are promising leads for the therapy of Parkinson’s disease.     

α-Tetralone derivatives as inhibitors of monoamine oxidase

In the present study, a series of fifteen α-tetralone (3,4-dihydro-2H-naphthalen-1-one) derivatives were synthesised and evaluated as inhibitors of recombinant human monoamine oxidase (MAO) A and B. The α-tetralone derivatives examined are structurally related to a series of chromone (1-benzopyran-4-one) derivatives which has previously been shown to act as MAO-B inhibitors. The results document that the α-tetralones are highly potent MAO-B inhibitors with all compounds exhibiting IC₅₀ values in the nanomolar range (<78 nM). Although most compounds are selective inhibitors of MAO-B, the α-tetralones are also potent MAO-A inhibitors with ten compounds exhibiting IC₅₀ values in the nanomolar range (<792 nM). The most potent MAO-B inhibitor, 6-(3-iodobenzyloxy)-3,4-dihydro-2H-naphthalen-1-one, exhibits an IC₅₀ value of 4.5 nM with a 287-fold selectivity for MAO-B over the MAO-A isoform, while the most potent MAO-A inhibitor, 6-(3-cyanobenzyloxy)-3,4-dihydro-2H-naphthalen-1-one, exhibits an IC₅₀ value of 24 nM with a 3.25-fold selectivity for MAO-A. Analyses of the structure–activity relationships for MAO inhibition show that substitution on the C6 position of the α-tetralone moiety is a requirement for MAO-A and MAO-B inhibition, and that a benzyloxy substituent on this position is more favourable for MAO-A inhibition than phenylethoxy and phenylpropoxy substitution. For MAO-B inhibition, alkyl and halogen substituents on the meta and para positions of the benzyloxy ring enhance inhibitory potency. It may be concluded that α-tetralone derivatives are promising leads for design of therapies for Parkinson’s disease and depression.     

Mechanical activation of spike fosters SARS-CoV-2 viral infection

The outbreak of SARS-CoV-2 (SARS2) has caused a global COVID-19 pandemic. The spike protein of SARS2 (SARS2-S) recognizes host receptors, including ACE2, to initiate viral entry in a complex biomechanical environment. Here, we reveal that tensile force, generated by bending of the host cell membrane, strengthens spike recognition of ACE2 and accelerates the detachment of spike’s S1 subunit from the S2 subunit to rapidly prime the viral fusion machinery. Mechanistically, such mechano-activation is fulfilled by force-induced opening and rotation of spike’s receptor-binding domain to prolong the bond lifetime of spike/ACE2 binding, up to 4 times longer than that of SARS-S binding with ACE2 under 10 pN force application, and subsequently by force-accelerated S1/S2 detachment which is up to ~10³ times faster than that in the no-force condition. Interestingly, the SARS2-S D614G mutant, a more infectious variant, shows 3-time stronger force-dependent ACE2 binding and 35-time faster force-induced S1/S2 detachment. We also reveal that an anti-S1/S2 non-RBD-blocking antibody that was derived from convalescent COVID-19 patients with potent neutralizing capability can reduce S1/S2 detachment by 3 × 10⁶ times under force. Our study sheds light on the mechano-chemistry of spike activation and on developing a non-RBD-blocking but S1/S2-locking therapeutic strategy to prevent SARS2 invasion.Subject terms: Molecular biology, Structural biology     

Synthesis and in vitro antitumor activity of thiophene analogues of 5-chloro-5,8-dideazafolic acid and 2-methyl-2-desamino-5-chloro-5,8-dideazafolic acid

N-[5-[N-(2-Amino-5-chloro-3,4-dihydro-4-oxoquinazolin-6-yl)methylamino]-2-thenoyl]-L-glutamic acid (6) and N-[5-[N-(5-chloro-3,4-dihydro-2-methyl-4-oxoquinazolin-6-yl)methylamino]-2-thenoyl]-L-glutamic acid (7), the first reported thiophene analogues of 5-chloro-5,8-dideazafolic acid, were synthesized and tested as inhibitors of tumor cell growth in culture. 4-Chloro-5-methylisatin (10) was converted stepwise to methyl 2-amino-5-methyl-6-chlorobenzoate (22) and 2-amino-5-chloro-3,4-dihydro-6-methyl-4-oxoquinazoline (19). Pivaloylation of the 2-amino group, followed by NBS bromination, condensation with di-tert-butyl N-(5-amino-2-thenoyl)-L-glutamate (28), and stepwise cleavage of the protecting groups with ammonia and TFA yielded. Treatment of 9 with acetic anhydride afforded 2,6-dimethyl-5-chlorobenz[1,3-d]oxazin-4-one (31), which on reaction with ammonia, NaOH was converted to 2,6-dimethyl-5-chloro-3,4-dihydroquinazolin-4-one (33). Bromination of, followed by condensation with and ester cleavage with TFA, yielded. The IC(50) of and against CCRF-CEM human leukemic lymphoblasts was 1.8+/-0.1 and 2.1+/-0.8 microM, respectively.     

In silico fragment-based discovery of indolin-2-one analogues as potent DNA gyrase inhibitors

We describe here the fragment-based design of potent DNA gyrase inhibitors. Using the tools of virtual screening and NMR spectroscopy we identified the binding of two low-molecular weight fragments (2-aminobenzimidazole and indolin-2-one) to the 24kDa N-terminal fragment of DNA gyrase B. Further in silico optimization of indolin-2-one led to the discovery of potent DNA gyrase inhibitors.     

Estrogenic and anti-estrogenic compounds from the Thai medicinal plant, Smilax corbularia (Smilacaceae)

From the rhizomes of Smilax corbularia Kunth. (Smilacaceae), 11 compounds, (2R,3R)-2″-acetyl astilbin, (2R,3R)-3″-acetyl astilbin, (2R,3R)-4″-acetyl astilbin, (2R,3R)-3″-acetyl engeletin, (2R,3S)-4″-acetyl isoastilbin, 2-(4-hydroxyphenyl)-3,4,9,10-tetrahydro-3,5-dihydroxy-10-(3,4-dihydroxyphenyl)-(2R,3R,10R)-2H,8H-benzo [1,2-b:3,4-b′] dipyran-8-one, 2-(4-hydroxyphenyl)-3,4,9,10-tetrahydro-3,5-dihydroxy-10-(3,4-dihydroxyphenyl)-(2R,3R,10S)-2H, 8H-benzo [1,2-b:3,4-b′] dipyran-8-one, 3,4-dihydro-7-hydroxy-4-(3,4-dihydroxyphenyl)-5-[(1E)-2-(4-hydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, 3,4-dihydro-7-hydroxy-4-(3,4-dihydroxy-phenyl)-5-[(1E)-2-(3,4-dihydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, 3,4-dihydro-7-hydroxy-4-(4-hydroxy-3-methoxyphenyl)-5-[(1E)-2-(4-hydroxyphenyl) ethenyl]-2H-1-benzopyran-2-one, and 5,7,3′,4′-tetrahydroxy-3-phenylcoumarin along with 34 known compounds were isolated and characterized as 19 flavonoids, 14 catechin derivatives, 6 stilbene derivatives, and 6 miscellaneous substances. All isolates had their estrogenic and anti-estrogenic activities determined using the estrogen-responsive human breast cancer cell lines MCF-7 and T47D. The major constituents were recognized as flavanonol rhamnosides by the suppressive effect on estradiol induced cell proliferation at a concentration of 1 μM. Meanwhile, flavanonol rhamnoside acetates demonstrated estrogenic activity in both MCF-7 and T47D cells at a concentration of 100 μM, and they enhanced the effects of co-treated E2 on T47D cell proliferation at concentrations of more than 0.1 μM.     

Synthesis,biological evaluation and molecular modeling of dihydro-pyrazolyl-thiazolinone derivatives as potential COX-2 inhibitors

A series of dihydro-pyrazolyl-thiazolinone derivatives (5a–5t) have been synthesized and their biological activities were also evaluated as potential cyclooxygenase-2 (COX-2) inhibitors. Among these compounds, compound 2-(3-(3,4-dimethylphenyl)-5-phenyl-4,5-dihydro-1H-pyrazol-1-yl)thiazol-4(5H)-one (5a) displayed the most potent COX-2 inhibitory activity with IC₅₀ of 0.5 μM, but weak to COX-1. Docking simulation was performed to position compound 5a into the COX-2 active site to determine the probable binding model. Based on the preliminary results, compound 5a with potent inhibitory activity and low toxicity would be a potential and selective anti-cyclooxygenase-2 agent.     

Discovery and in vitro evaluation of potent TrkA kinase inhibitors: oxindole and aza-oxindoles

The discovery, synthesis, potential binding mode, and in vitro kinase profile of 3-(3-bromo-4-hydroxy-5-(2'-methoxyphenyl)-benzylidene)-5-bromo-1,3-dihydro-pyrrolo[2,3-b]pyridin-2-one, 3-[(1-methyl-1H-indol-3-yl)methylene]-1,3-dihydro-2H-pyrrolo[3,2-b]-pyridin-2-one as potent TrkA inhibitors are discussed.     

A monoclonal antibody against hinge-cleaved IgG restores effector function to proteolytically-inactivated IgGs in vitro and in vivo

We report a chimeric monoclonal antibody (mAb) directed to a neo-epitope that is exposed in the IgG lower hinge following proteolytic cleavage. The mAb, designated 2095–2, displays specificity for IdeS-generated F(ab’)₂ fragments, but not for full-length IgG or for closely-related F(ab’)₂ fragments generated with other proteases. A critical component of the specificity is provided by the C-terminal amino acid of the epitope corresponding to gly-236 in the IgG1 (also IgG4) hinge. By its ability to bind to IdeS-cleaved anti-CD20 mAb, mAb 2095–2 fully restored antibody-dependent cell-mediated cytotoxicity (ADCC) and complement-dependent cytotoxicity (CDC) against WIL2-S cells to the otherwise inactive anti-CD20 IgG1 F(ab’)₂ fragment. Similarly, 2095–2 reinstated ADCC against MDA-MB-231 cells to an anti-CD142 IgG1 F(ab’)₂ fragment. mAb 2095–2 was also capable of eliciting both CDC and ADCC to IgG4 F(ab’)₂ fragments, an IgG subclass that has weaker ADCC and CDC when intact relative to intact IgG1. The in vitro cell-based efficacy of 2095–2 was extended to the in vivo setting using platelets as a cell clearance surrogate. In a canine model, the co-administration of 2095–2 together with IdeS-generated, platelet-targeting anti-CD41/61 F(ab’)₂ fragment not only restored platelet clearance, but did so at a rate and extent of clearance that exceeded that of intact anti-CD41/61 IgG at comparable concentrations. To further explore this unexpected amplification effect, we conducted a rat study in which 2095–2 was administered at a series of doses in combination with a fixed dose of anti-CD41/61 F(ab’)₂ fragments. Again, the combination, at ratios as low as 1:10 (w/w) 2095–2 to F(ab’)₂, proved more effective than the anti-CD41/61 IgG1 alone. These findings suggest a novel mechanism for enhancing antibody-mediated cell-killing effector functions with potential applications in pathologic settings such as tumors and acute infections where protease activity is abundant.     

Orally bioavailable pyridine and pyrimidine-based Factor XIa inhibitors: Discovery of the methyl N-phenyl carbamate P2 prime group

Pyridine-based Factor XIa (FXIa) inhibitor (S)-2 was optimized by modifying the P2 prime, P1, and scaffold regions. This work resulted in the discovery of the methyl N-phenyl carbamate P2 prime group which maintained FXIa activity, reduced the number of H-bond donors, and improved the physicochemical properties compared to the amino indazole P2 prime moiety. Compound (S)-17 was identified as a potent and selective FXIa inhibitor that was orally bioavailable. Replacement of the basic cyclohexyl methyl amine P1 in (S)-17 with the neutral p-chlorophenyltetrazole P1 resulted in the discovery of (S)-24 which showed a significant improvement in oral bioavailability compared to the previously reported imidazole (S)-23. Additional improvements in FXIa binding affinity, while maintaining oral bioavailability, was achieved by replacing the pyridine scaffold with either a regioisomeric pyridine or pyrimidine ring system.     

Orally bioavailable amine-linked macrocyclic inhibitors of factor XIa

The discovery of orally bioavailable FXIa inhibitors has been a challenge. Herein, we describe our efforts to address this challenge by optimization of our imidazole-based macrocyclic series. Our optimization strategy focused on modifications to the P2 prime, macrocyclic amide linker, and the imidazole scaffold. Replacing the amide of the macrocyclic linker with amide isosteres led to the discovery of substituted amine linkers which not only maintained FXIa binding affinity but also improved oral exposure in rats. Combining the optimized macrocyclic amine linker with a pyridine scaffold afforded compounds 23 and 24 that were orally bioavailable, single-digit nanomolar FXIa inhibitors with excellent selectivity against relevant blood coagulation enzymes.     

Enantioseparation of racemic 4-aryl-3,4-dihydro-2(1H)-pyrimidones on chiral stationary phases based on 3,5-dimethylanilides of N-(4-alkylamino-3,5-dinitro)benzoyl L-alpha-amino acids

Three novel chiral packing materials for high-performance liquid chromatography were prepared by covalently binding of (2S)-N-(3,5-dimethylphenyl)-2-[(4-chloro-3,5-dinitrophenyl)carbonylamino]propan-amide (7), (2S)-N-(3,5-dimethylphenyl)-2-[(4-chloro-3,5-dinitrophenyl)carbonylamino]-4-methylpentanamide (8), and (2S)-N-(3,5-dimethylphenyl)-2-[(4-chloro-3,5-dinitrophenyl)carbonyl-amino]-2-phenylacetamide (9) to aminopropyl silica. The resulting chiral stationary phases (CSPs 1-3) proved effective for the resolution of racemic 4-aryl-3,4-dihydro-2(1H)-pyrimidone derivatives (TR 1-14). The mechanism of their enantioselection, supported by the elution order of (S)-TR 13 and (R)-TR 13 and molecular modeling of the complex of the slower running (S)-TR 13 with CSP 1 is discussed.     

Hit-to-lead investigation of a series of novel combined dopamine D2 and muscarinic M1 receptor ligands with putative antipsychotic and pro-cognitive potential

We describe the discovery of a series of compounds based on 1-{3-[4-(2-oxo-2,3-dihydro-benzoimidazol-1-yl)-piperidin-1-yl]-propyl}-3,4-dihydro-1H-quinolin-2-one (3), showing combined D(2) receptor affinity and M(1) receptor agonism. Based on a strategy of controlling logP, we herein describe a hit-to-lead investigation with the aim of retaining the combined D(2)/M(1) profile, while removing the propensity of the compounds to inhibit the hERG channel, as well as at obtaining acceptable pharmacokinetic properties. Although a SAR was evident for all four parameters in question, it was not possible to separate hERG channel inhibition and D(2) receptor affinity by this effort; whilst it was feasible to obtain compounds with M(1) receptor agonism, acceptable clearance, and weak hERG inhibition.     

7-Amino-3,4-dihydro-1H-quinolin-2-one,a compound similar to the substituted coumarins,inhibits α-carbonic anhydrases without hydrolysis of the lactam ring

Abstract

7-Amino-3,4-dihydro-1H-quinolin-2-one, a compound structurally similar to coumarins, recently discovered class of inhibitors of the α-carbonic anhydrases (CAs, EC 4.2.1.1) was investigated for its interaction with all human (h) CA isoforms, hCA I-XIV. The compound was not an inhibitor of the cytosolic, widespread isoform hCA II (K_I?>?10?µM), was a weak inhibitor of hCA I, III, IV, VA, VI and XIII (K_Is in the range of 0.90–9.5?µM) but effectively inhibited the cytosolic isoform hCA VII (K_I of 480?nM) as well as the transmembrane isoforms hCA IX, XII and XIV (K_Is in the range of 16.1–510?nM). Against many CA isoforms this lactam was a better inhibitor compared to the structurally similar 4-methyl-7-aminocoumarin, but unlike this compound, the lactam ring was not hydrolyzed and the inhibition was due to the intact bicyclic amino-quinolinone scaffold. Bicyclic lactams strucurally related to coumarins are thus a new class of CA inhibitors possessing however a distinct inhibition mechanism compared to the coumarins which undergo a hydrolysis of their lactone ring for generating the enzyme inhibitory species.     

Discovery of potent and selective histamine H3 receptor inverse agonists based on the 3,4-dihydro-2H-pyrazino[1,2-a]indol-1-one scaffold

A novel series of potent histamine H₃ receptor inverse agonists based on the 3,4-dihydro-2H-pyrazino[1,2-a]indol-1-one scaffold has been discovered. Several compounds display high selectivity over other histamine receptor subtypes and have favorable physicochemical properties, low potential for CYP450 enzyme inhibition and high metabolic stability in microsomal preparations. (R)-2-Cyclopropylmethyl-8-(1-isopropyl-piperidin-4-yloxy)-3-methyl-3,4-dihydro-2H-pyrazino[1,2-a]indol-1-one (8t) showed good in vivo efficacy after per os application in an acute rat dipsogenia model of water intake.     

Rational design of conformationally restricted quinazolinone inhibitors of poly(ADP-ribose)polymerase

A successful design of conformationally restricted novel quinazolinone derivatives linked via a cyclopentene moiety as potent poly(ADP-ribose)polymerase-1 (PARP-1) inhibitors has been developed. One selected member of the new series, 8-chloro-2-[(3S)-3-(4-phenylpiperidin-1-yl)cyclopent-1-en-1-yl]quinazolin-4(3H)-one (S-16d), was found to be highly potent with IC(50)=8.7 nM and good brain penetration.     

Moieties of Complement iC3b Recognized by the I-domain of Integrin αXβ2

Complement fragment iC3b serves as a major opsonin for facilitating phagocytosis via its interaction with complement receptors CR3 and CR4, also known by their leukocyte integrin family names, αMβ2 and αXβ2, respectively. Although there is general agreement that iC3b binds to the αM and αX I-domains of the respective β2-integrins, much less is known regarding the regions of iC3b contributing to the αX I-domain binding. In this study, using recombinant αX I-domain, as well as recombinant fragments of iC3b as candidate binding partners, we have identified two distinct binding moieties of iC3b for the αX I-domain. They are the C3 convertase-generated N-terminal segment of the C3b α’-chain (α’NT) and the factor I cleavage-generated N-terminal segment in the CUBf region of α-chain. Additionally, we have found that the CUBf segment is a novel binding moiety of iC3b for the αM I-domain. The CUBf segment shows about a 2-fold higher binding activity than the α’NT for αX I-domain. We also have shown the involvement of crucial acidic residues on the iC3b side of the interface and basic residues on the I-domain side.