Synthesis and Selective Inhibitory Activity of 1-Acetyl-3,5-diphenyl-4,5-dihydro-(1H)-pyrazole Derivatives against Monoamine Oxidase

An efficient metal-free and catalyst-free C-S/C-O bond-formation strategy: synthesis of pyrazole-conjugated thioamides and amides

An operationally simple and metal-free approach is described for the synthesis of pyrazole-tethered thioamide and amide conjugates. The thioamides were generated by employing a three-component reaction of diverse pyrazole C-3/4/5 carbaldehydes, secondary amines, and elemental sulfur in a single synthetic operation. The advantages of this developed protocol refer to the broad substrate scope, metal-free and easy to perform reaction conditions. Moreover, the pyrazole C-3/5-linked amide conjugates were also synthesized via an oxidative amination of pyrazole carbaldehydes and 2-aminopyridines using hydrogen peroxide as an oxidant.

Dihydropyrazole-Carbohydrazide Derivatives with Dual Activity as Antioxidant and Anti-Proliferative Drugs on Breast Cancer Targeting the HDAC6

Breast cancer (BC) is the most frequently diagnosed cancer and is the second-most common cause of death in women worldwide. Because of this, the search for new drugs and targeted therapy to treat BC is an urgent and global need. Histone deacetylase 6 (HDAC6) is a promising anti-BC drug target associated with its development and progression. In the present work, the design and synthesis of a new family of dihydropyrazole-carbohydrazide derivatives (DPCH) derivatives focused on HDAC6 inhibitory activity is presented. Computational chemistry approaches were employed to rationalize the design and evaluate their physicochemical and toxic-biological properties. The new family of nine DPCH was synthesized and characterized. Compounds exhibited optimal physicochemical and toxicobiological properties for potential application as drugs to be used in humans. The in silico studies showed that compounds with –Br, –Cl, and –OH substituents had good affinity with the catalytic domain 2 of HDAC6 like the reference compounds. Nine DPCH derivatives were assayed on MCF-7 and MDA-MB-231 BC cell lines, showing antiproliferative activity with IC₅₀ at μM range. Compound 2b showed, in vitro, an IC₅₀ value of 12 ± 3 µM on human HDAC6. The antioxidant activity of DPCH derivatives showed that all the compounds exhibit antioxidant activity similar to that of ascorbic acid. In conclusion, the DPCH derivatives are promising drugs with therapeutic potential for the epigenetic treatment of BC, with low cytotoxicity towards healthy cells and important antioxidant activity.

Synthesis, Antitumor Activity, Molecular Docking and DFT Study of Novel Pyrimidiopyrazole Derivatives

BACKGROUND

In this investigation, 2-cyano-N-(2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-yl) acetamide (3) reacts with dimethylformamide dimethyl acetal (DMF-DMA) to afford the corresponding (E)- 2-cyano-3-(dimethylamino)-N-(2,4-dioxo-1,2,3,4-tetrahydropyrimidin-5-yl)acrylam-ide (4) utilizing microwave irradiation. The condensation reactions of acrylamide derivative 4 with hydrazine derivatives obtain pyrazole derivatives 6a and 6b; respectively. The synthesized compounds demonstrate in vitro antitumor activity against liver tumor cell line HepG2. Furthermore, additional studies were carried out on the most effective compound 6b to evaluate the potential interaction against 4hdq synthase complex with ΔE= -4.5Kcal/mol and with short distance = 1.727Å and 2.027Å, respectively. The comprehensive theoretical studies of compounds 6a and 6b is based on bond length, bond angles and energy gap HOMO-LUMO. In addition, the vibrational frequencies of optimized compounds 6a and 6b were examined through DFT/B3LYP/6+31G(d) basis set.

METHODS

In this research, synthesis of novel pyrimidiopyrazole derivatives calculated the computational studies to find suitable drug-receptor interactions and biological activity.

RESULTS AND DISCUSSION

The synthesized pyrimidiopyrazole derivative 6b exhibited high antitumor activity IC50 =12.6 μg/ml and interacted it with 4hdq synthase complex with ΔE=-4.5Kcal/mol and with short distance = 1.727Å and 2.027Å. Furthermore, the optimized compounds utilize Gaussian 09W.

CONCLUSION

In the optimized pyrimidiopyrazole derivatives, 6b showed better antitumor activity HeG-2 against 5-flurouracil due to its energy and confirmed more potent of hydrogen bond interaction with protein pocket.

A Comprehensive Review of Monoamine Oxidase-A Inhibitors in their Syntheses and Potencies

BACKGROUND

Monoamine oxidases (MAOs) play a crucial role during the development of various neurodegenerative disorders. There are two MAO isozymes, MAO-A and MAO-B. MAO-A is a flavoenzyme, which binds to the outer mitochondrial membrane and catalyzes the oxidative transformations of neurotransmitters like serotonin, norepinephrine, and dopamine.

MATERIALS AND METHODS

Focus on synthetic studies has culminated in the preparation of many MAOA inhibitors, and advancements in combinatorial and parallel synthesis have accelerated the developments of synthetic schemes. Here, we provided an overview of the synthetic protocols employed to prepare different classes of MAO-A inhibitors. We classified these inhibitors according to their molecular scaffolds and the synthetic methods used.

RESULTS

Various synthetic and natural derivatives from a different class of MAO-A inhibitors were reported.

CONCLUSION

The review provides a valuable tool for the development of a new class of various selective MAO-A inhibitors for the treatment of depression and other anxiety disorders.

Heterocyclic Compounds: Pharmacology of Pyrazole Analogs From Rational Structural Considerations

Low quality of life and life-threatening conditions often demand pharmacological screening of lead compounds. A spectrum of pharmacological activities has been attributed to pyrazole analogs. The substitution, replacement, or removal of functional groups on a pyrazole ring appears consistent with diverse molecular interactions, efficacy, and potency of these analogs. This mini-review explores cytotoxic, cytoprotective, antinociceptive, anti-inflammatory, and antidepressant activities of some pyrazole analogs to advance structure-related pharmacological profiles and rational design of new analogs. Numerous interactions of these derivatives at their targets could impact future research considerations and prospects while offering opportunities for optimizing therapeutic activity with fewer adverse effects.

New 2-Pyrazoline and Hydrazone Derivatives as Potent and Selective Monoamine Oxidase A Inhibitors

Thirty compounds having 1-[2-(5-substituted-2-benzoxazolinone-3-yl) acetyl]-3,5-disubstitutedphenyl-2-pyrazoline structure and nine compounds having N'-(1,3-disubstitutedphenylallylidene)-2-(5-substituted-2-benzoxazolinone-3-yl)acetohydrazide skeleton were synthesized and evaluated as monoamine oxidase (MAO) inhibitors. All of the compounds exhibited selective MAO-A inhibitor activity in the nanomolar or low micromolar range. The results of the molecular docking for hydrazone derivatives supported the in vitro results. Five compounds, 6 (0.008 μM, Selectivity Index (SI): 9.70 × 10^-4), 7 (0.009 μM, SI: 4.55 × 10^-5), 14 (0.001 μM, SI: 8.00 × 10^-4), 21 (0.009 μM, SI: 1.37 × 10^-5), and 42 (0.010 μM, SI: 5.40 × 10^-6), exhibiting the highest inhibition and selectivity toward hMAO-A and nontoxic to hepatocytes were assessed for antidepressant activity as acute and subchronic in mice. All of these five compounds showed significant antidepressant activity with subchronic administration consistent with the increase in the brain serotonin levels and the compounds crossed the blood-brain barrier according to parallel artificial membrane permeation assay. Compounds 14, 21, and 42 exhibited an ex vivo MAO-A profile, which is highly consistent with the in vitro data.

Synthesis and spectroscopic characterizations of hexakis[(1-(4'-oxyphenyl)-3-(substituted-phenyl)prop-2-en-1-one)]cyclotriphosphazenes: their in vitro cytotoxic activity, theoretical analysis and molecular docking studies

The hexachlorocyclotriphosphaze compound (N₃P₃Cl₆, HCCP) was reacted with excess (E)-(1-(4'-oxyphenyl)-3-(substituted-phenyl)prop-2-en-1-ones (2-11) to produce hexakis[(1-(4-oxyphenyl)-3-(substituted-phenyl)prop-2-en-1-one)]cyclotriphosphazenes (CP 2-11). The structures of products (CP 2-11) were confirmed using elemental analysis, FT-IR, MS spectral analysis as well as ³¹P, ¹H and ¹³C-APT NMR techniques and their thermal properties determined by TGA and DSC techniques. The HOMO-LUMO energy gap and chemical reactivity identifiers were calculated and HOMO and LUMO images were viewed. According to the calculations, all the chemical potential values of CP 2-11 are negative and it shown that the molecules are stable. The in vitro cytotoxic of CP 2-11 investigated and their activity potentials were evaluated by molecular docking studies with Autodock Vina softwares. CP 2-11 compounds were found to demonstrate cytotoxic activity against human cancer cell lines (A2780, LNCaP and PC-3). The CP 2-11 compounds reduced the cell viability against all cancer cell lines in the range 36%-90% especially. The results showed that these compounds are powerful candidate molecules for pharmaceutical applications.

The evaluation of 1-tetralone and 4-chromanone derivatives as inhibitors of monoamine oxidase

Abstract

Monoamine oxidase (MAO) is of much clinical relevance, and inhibitors of this enzyme are used in the treatment for neuropsychiatric and neurodegenerative disorders such as depression and Parkinson’s disease. The present study synthesises and evaluates the MAO inhibition properties of a series of 33 1-tetralone and 4-chromanone derivatives in an attempt to discover high-potency compounds and to expand on the structure–activity relationships of MAO inhibition by these classes. Among these series, eight submicromolar MAO-A inhibitors and 28 submicromolar MAO-B inhibitors are reported, with all compounds acting as specific inhibitors of the MAO-B isoform. The most potent inhibitor was a 1-tetralone derivative (1h) with IC₅₀ values of 0.036 and 0.0011 µM for MAO-A and MAO-B, respectively. Interestingly, with the reduction of 1-tetralones to the corresponding alcohols, a decrease in MAO inhibition potency is observed. Among these 1-tetralol derivatives, 1p (IC₅₀ = 0.785 μM) and 1o (IC₅₀ = 0.0075 μM) were identified as particularly potent inhibitors of MAO-A and MAO-B, respectively. Potent compounds such as those reported here may act as leads for the future development of MAO-B specific inhibitors.

Graphic abstract

The present study describes the MAO inhibitory activities of a series of 1-tetralone and 4-chromanone derivatives. Numerous high-potency MAO-B specific inhibitors were identified.

Electronic supplementary material

The online version of this article (10.1007/s11030-020-10143-w) contains supplementary material, which is available to authorised users.

Evaluation of nitrocatechol chalcone and pyrazoline derivatives as inhibitors of catechol-O-methyltransferase and monoamine oxidase

Literature reports that chalcones inhibit the monoamine oxidase (MAO) enzymes, mostly with specificity for the MAO-B isoform, while nitrocatechol compounds are established inhibitors of catechol-O-methyltransferase (COMT). Based on this, nitrocatechol derivatives of chalcone have been proposed to represent dual-target-directed compounds that may inhibit both MAO-B and COMT. Both these enzymes play key roles in the metabolism of dopamine and levodopa, and inhibitors are thus relevant to the treatment of Parkinson's disease. The present study expands on the discovery of dual MAO-B/COMT inhibitors by synthesising additional nitrocatechol derivatives of chalcones which include heterocyclic derivatives, and converting them to the corresponding pyrazoline derivatives. The newly synthesised chalcone and pyrazoline compounds were evaluated as inhibitors of human MAO and rat COMT, and the inhibition potencies were expressed as IC₅₀ values. A pyrazoline derivative, compound 8b, was the most potent COMT inhibitor with an IC₅₀ value of 0.048 μM. This is more potent than the reference COMT inhibitor, entacapone, which has an IC₅₀ value of 0.23 μM. The results indicated that the pyrazoline derivatives (IC₅₀ = 0.048-0.21 µM) are more potent COMT inhibitors than the chalcones (IC₅₀ = 0.14-0.29 µM). Unfortunately, the chalcone and pyrazoline derivatives were weak MAO inhibitors with IC₅₀ values > 41.4 µM. This study concludes that the nitrocatechol derivatives investigated here are promising COMT inhibitors, while not being suitable as MAO inhibitors. Using molecular docking, potential binding modes and interactions of selected inhibitors with COMT are proposed.

Single Heterocyclic Compounds as Monoamine Oxidase Inhibitors: From Past to Present

Inhibitors of monoamine oxidase (MAO) have shown therapeutic values in a variety of neurodegenerative diseases such as depression, Parkinson's disease and Alzheimer's disease. Heterocyclic compounds exhibit a broad spectrum of biological activities and vital leading compounds for the development of chemical drugs. Herein, we focus on the synthesis and screening of novel single heterocyclic derivatives with MAO inhibitory activities during the past decade. This review covers recent pharmacological advancements of single heterocyclic moiety along with structure- activity relationship to provide better correlation among different structures and their receptor interactions.

La(OTf)3-catalysed one-pot synthesis of pyrazole tethered imidazo[1,2-a]azine derivatives and evaluation of their light emitting properties

La(OTf)₃catalysed one-pot facile protocol has been unfolded towards diversity-oriented synthesis of highly fluorescent pyrazole C-3(5) tethered imidazo[1,2-a]azines.

Cytotoxic Effects of Newly Synthesized Heterocyclic Candidates Containing Nicotinonitrile and Pyrazole Moieties on Hepatocellular and Cervical Carcinomas

In this study, a series of newly synthesized substituted pyridine 9, 11-18, naphthpyridine derivative 10 and substituted pyrazolopyridines 19-23 by using cycnopyridone 8 as a starting material. Some of the synthesized candidates are evaluated as anticancer agents against different cancer cell lines. In vitro cytotoxic activities against hepatocellular and cervical carcinoma cell lines were evaluated using standard MTT assay. Different synthesized compounds exhibited potential in vitro cytotoxic activities against both HepG2 and HeLa cell lines. Furthermore, compared to standard positive control drugs, compounds 13 and 19 showed the most potent cytotoxic effect with IC₅₀ values of 8.78 ± 0.7, 5.16 ± 0.4 μg/mL, and 15.32 ± 1.2 and 4.26 ± 0.3 μg/mL for HepG2 and HeLa cells, respectively.

Design, Synthesis, Docking Studies and Monoamine Oxidase Inhibition of a Small Library of 1-acetyl- and 1-thiocarbamoyl-3,5-diphenyl-4,5-dihydro-(1H)-pyrazoles

New N-acetyl/N-thiocarbamoylpyrazoline derivatives were designed and synthesized in high yields to assess their inhibitory activity and selectivity against human monoamine oxidase A and B. The most important chiral compounds were separated into their single enantiomers and tested. The impact of the substituents at N1, C3 and C5 positions as well the influence of the configuration of the C5 on the biological activity were analyzed. Bulky aromatic groups at C5 were not tolerated. p-Prenyloxyaryl moiety at C3 oriented the selectivity toward the B isoform. The results were also corroborated by molecular modelling studies providing new suggestions for the synthesis of privileged structures to serve as lead compounds for the treatment of mood disorders and neurodegenerative diseases.

Absolute configuration and biological profile of pyrazoline enantiomers as MAO inhibitory activity

A new racemic pyrazoline derivative was synthesized and resolved to its enantiomers using analytic and semipreparative high-pressure liquid chromatography. The absolute configuration of both fractions was established using vibrational circular dichroism. The in vitro monoamine oxidase (MAO) inhibitory profiles were evaluated for the racemate and both enantiomers separately for the two isoforms of the enzyme. The racemic compound and both enantiomers were found to inhibit hMAO-A selectively and competitively. In particular, the R enantiomer was detected as an exceptionally potent and a selective MAO-A inhibitor (K_i  = 0.85 × 10^-3  ± 0.05 × 10^-3  μM and SI: 2.35 × 10^-5 ), whereas S was determined as poorer compound than R in terms of K_i and SI (0.184 ± 0.007 and 0.001). The selectivity of the enantiomers was explained by molecular modeling docking studies based on the PDB enzymatic models of MAO isoforms.

Curcumin-based pyrazoline analogues as selective inhibitors of human monoamine oxidase A

A series of 2-methoxy-4-(5-phenyl-4,5-dihydro-1H-pyrazol-3-yl)phenol (pyrazoline) derivatives (2-6) have been synthesized and tested for human monoamine oxidase (hMAO) inhibitory activity. The most active derivative (2) behaved as a competitive hMAO-A inhibitor, with an inhibition constant value of 0.08 μM and a strong hMAO-A selectivity (K_i(hMAO-B)/K_i(hMAO-A) > 1751). In addition, 2 exhibited little to no cytotoxic effects up to a 25 μM concentration and provided the best blood-brain barrier permeability among the derivatives synthesized. Molecular dynamics simulations revealed that a chlorine substituent at the para-position of the phenyl ring in 2 enabled a π-π stacking interaction with Tyr407 and Tyr444 that resulted in the formation of an "aromatic sandwich" structure. Consequently, this tight-binding aromatic cage culminated in a dramatically reduced active site volume that is believed to be the origin of the observed selectivity between the hMAO-A and hMAO-B isozymes. Removal of the chlorine from 2 disrupted the favorable intermolecular interactions and resulted in a selectivity change towards hMAO-B.

Synthesis and biological evaluation of novel pyrazoline-based aromatic sulfamates with potent carbonic anhydrase isoforms II, IV and IX inhibitory efficacy

Herein we report the synthesis of a new series of aromatic sulfamates designed considering the sulfonamide COX-2 selective inhibitors celecoxib and valdecoxib as lead compounds. These latter were shown to possess important human carbonic anhydrase (CA, EC 4.2.1.1) inhibitory properties, with the inhibition of the tumor-associated isoform hCA IX likely being co-responsible of the celecoxib anti-tumor effects. Bioisosteric substitution of the pyrazole or isoxazole rings from these drugs with the pyrazoline one was considered owing to the multiple biological activities ascribed to this latter heterocycle and paired with the replacement of the sulfonamide of celecoxib and valdecoxib with its equally potent bioisoster sulfamate. The synthesized derivatives were screened for the inhibition of four human carbonic anhydrase isoforms, namely hCA I, II, IV, and IX. All screened sulfamates exhibited great potency enhancement in inhibiting isoform II and IV, widely involved in glaucoma (K_Is in the range of 0.4-12.4 nM and 17.7 and 43.3 nM, respectively), compared to the lead compounds, whereas they affected the tumor-associated hCA IX as potently as celecoxib.

N1-benzenesulfonyl-2-pyrazoline hybrids in neurological disorders: Syntheses, biological screening and computational studies

A novel series of 1,3,5-trisubstituted-2-pyrazolines (5a-5t) was prepared via Claisen Schmidt condensation, followed by heterocyclization with hydrazine hydrate, substitution of N1 hydrogen of 2-pyrazoline nucleus with 4-chlorobenzenesulfonylchloride, applying conventional and green chemistry approaches. Among the two, microwave assisted organic synthesis (MAOS) emerged as a better synthetic tool in terms of faster reaction rate and high yield. Various physicochemical and spectral studies were conducted to characterize the synthesized derivatives including- IR, Mass, ¹H-NMR, ¹³C-NMR and elemental analysis. During pharmacological evaluation, compound 5b showed excellent anti-anxiety activity and compound 5k exhibited the best antidepressant effect at the tested doses, 50 and 100 mg/kg b.w., being comparable to diazepam and imipramine, respectively. The docking experiments confirmed the probable mechanism of neuropharmacological action, showing excellent affinity towards MAO-A target protein, which was also evidenced from some of the key interactions with binding site residues Ala68, Tyr69 and Phe352. Furthermore, complimentary in silico pharmacokinetic recital without any potential risk of neurotoxicity (as evaluated by rotarod and actophotometer tests), or carcinogenicity, mutagenicity, reproductive toxicity, acute toxicity and irritancy (as predicted by LAZAR and OSIRIS programs) signified their probable use in depression and anxiety disorders.

Privileged scaffolds as MAO inhibitors: Retrospect and prospects

This review aims to be a comprehensive, authoritative, critical, and readable review of general interest to the medicinal chemistry community because it focuses on the pharmacological, chemical, structural and computational aspects of diverse chemical categories as monoamine oxidase inhibitors (MAOIs). Monoamine oxidases (MAOs), namely MAO-A and MAO-B represent an enormously valuable class of neuronal enzymes embodying neurobiological origin and functions, serving as potential therapeutic target in neuronal pharmacotherapy, and hence we have coined the term "Neurozymes" which is being introduced for the first time ever. Nowadays, therapeutic attention on MAOIs engrosses two imperative categories; MAO-A inhibitors, in certain mental disorders such as depression and anxiety, and MAO-B inhibitors, in neurodegenerative disorders like Alzheimer's disease (AD) and Parkinson's disease (PD). The use of MAOIs declined due to some potential side effects, food and drug interactions, and introduction of other classes of drugs. However, curiosity in MAOIs is reviving and the recent developments of new generation of highly selective and reversible MAOIs, have renewed the therapeutic prospective of these compounds. The initial section of the review emphasizes on the detailed classification, structural and binding characteristics, therapeutic potential, current status and future challenges of the privileged pharmacophores. However, the chemical prospective of privileged scaffolds such as; aliphatic and aromatic amines, amides, hydrazines, azoles, diazoles, tetrazoles, indoles, azines, diazines, xanthenes, tricyclics, benzopyrones, and more interestingly natural products, along with their conclusive SARs have been discussed in the later segment of review. The last segment of the article encompasses some patents granted in the field of MAOIs, in a simplistic way.

2-pyrazoline derivatives in neuropharmacology: Synthesis, ADME prediction, molecular docking and in vivo biological evaluation

A novel series of 1,3,5-trisubstituted-2-pyrazoline derivatives (PFC-1 to PFC-16) were synthesized in a three step reaction using conventional and microwave assisted green chemistry approach. The synthesized derivatives were characterized and their chemical structures were established by various physicochemical methods such as IR, Mass, ¹H-NMR, ¹³C-NMR and elemental analysis. The synthesized compounds were tested for their neuropharmacological potential. The compounds exhibited significant antidepressant and anti-anxiety activities against various behavioral in vivo models. Compounds PFC-3 and PFC-12 were found to be the most active derivatives in the series. The 2-pyrazoline analogs, having 2-hydroxyphenyl and anthracen-9-yl substitution at 3^rd position while 4-benzyloxyphenyl and 4-methylphenyl substitution at 5^th position, were decisive in eliciting good antidepressant and anxiolytic properties, respectively. The docking experiments revealed that the synthesized derivatives were potential inhibitors of MAO-A protein, which plays a central role in managing depression and anxiety disorders. The most potent derivatives were found to be involved in some key interactions with Tyr407, Tyr444, Phe352 and Ala68 amino acid residues at the binding site of MAO-A protein. All the synthesized derivatives successfully passed the pharmacokinetic barriers of absorption, distribution, metabolism and elimination as predicted using in silico techniques without showing any substantial indication of acute and neurotoxicity. This was further confirmed in the laboratory by performing acute toxicity studies as per OECD guidelines.

Current status of pyrazole and its biological activities

Pyrazole are potent medicinal scaffolds and exhibit a full spectrum of biological activities. This review throws light on the detailed synthetic approaches which have been applied for the synthesis of pyrazole. This has been followed by an in depth analysis of the pyrazole with respect to their medical significance. This follow-up may help the medicinal chemists to generate new leads possessing pyrazole nucleus with high efficacy.

Concise Total Synthesis of 1,3-Diphenylpropane Derivatives Griffithanes A, B and F

Concise and efficient total syntheses of diarylpropanes griffithane A, B and F, isolated from Combretum griffithii, have been accomplished from methoxybenzaldehyde. The Claisen–Schmidt condensation between aldehyde and acetophenone was applied to form chalcone as a key step. The structures of chalcones are confirmed by crystal X-ray crystallography.

Organocatalytic [4+1]-annulation approach for the synthesis of densely functionalized pyrazolidine carboxylates

The present protocol provides optically active pyrazolidine carboxylates with derivatizable functional groups in high yields with excellent enantio- and diastereoselectivities.

Design and synthesis of novel 2-pyrazoline-1-ethanone derivatives as selective MAO inhibitors

Thirty seven novel 2-pyrazoline-1-ethanone derivatives were designed, synthesized and evaluated as selective hMAO inhibitors. Among them, compounds 7h (IC50=2.40 μM) and 12c (IC50=2.00 μM) exhibited best inhibitory activity and selectivity against hMAO-A, surpassing that of the positive control Clorgyline (IC50=2.76 μM). Based on selective activity of hMAO-A, SAR analysis showed that the order of N1 substituent contribution was bromo (3)>piperidinyl (4)>morpholinyl (5)>imidazolyl (6), and compounds with electron-withdrawing substituents (-F, -Cl) at C3 or C5 phenyl ring of 2-pyrazoline nucleus dedicated stronger MAO-A inhibitory activity. Molecular docking showed that compounds 7h and 12c were nicely bound to hMAO-A via two hydrogen bonds (SER209, GLU216), one Pi-Pi interaction and three hydrogen bonds (SER209, GLU216, TYR69), one Sigma-Pi interaction, respectively. In addition, the substituent at C3 position of 2-pyrazoline with the N1 acetyl has little effect on MAO-A inhibitory activity. These data support further studies to assess rational design of more efficiently selective hMAO inhibitors in the future.

Synthesis, characterization, and evaluation of a novel inhibitor of WNT/β-catenin signaling pathway

Background

Wnt/β-catenin signaling is a highly conserved pathway in organism evolution and is important in many biological processes. Overactivation of Wnt/β-catenin signaling is closely related to tumor development and progression. To identify potent small molecules that can fight aberrant Wnt/β-catenin-mediated cancer, we synthesized a novel pyrazoline derivative (N-(4-hydroxybenzyl)-1,3,4-triphenyl-4,5-dihydro-1H-pyrazole-5-carboxamide, BHX) to block Wnt signaling, and determined the absolute configuration of its precursor (ethyl 1,3,4-triphenyl-4,5-dihydro-1H-pyrazole-5-carboxylate). We then evaluated the inhibitory effect of BHX in vitro and in vivo.

Results

Cell proliferation was assessed in three human cancer cell lines (A549, HT29, and MGC803) in the presence and absence of BHX using MTS assays. BHX effectively inhibited A549, HT29, and MGC803 cell proliferation with IC₅₀ of 5.43 ± 1.99, 6.95 ± 0.24, and 7.62 ± 1.31 μM, respectively. BHX significantly induced apoptosis and G1 phase arrest in A549 and MGC803 cells. The β-catenin protein level was markedly reduced in A549 and MGC803 cells under BHX treatment. The inhibitory effect of BHX in vivo was investigated using a mouse xenograft model. A549 xenograft growth was suppressed by 50.96% in nude mice treated continuously with 100 mg/kg BHX for 21 d. Weight remained almost unchanged, which indicates the low toxicity of the compound.

Conclusions

Our data suggest that BHX is a new drug candidate for cancer treatment because of its potent effect on the Wnt/β-catenin pathway and low toxicity.

Monoamine oxidase inhibitory activity of 3,5-biaryl-4,5-dihydro-1H-pyrazole-1-carboxylate derivatives

Ethyl and phenyl carbamate derivatives of pyrazoline (3a-3h) were synthesized and tested for their MAO inhibitory activity. All the compounds were found to be selective towards MAO-A. Phenyl carbamates (3e-3h) were better than ethyl carbamates (3a-3d) and displayed the best selectivity index. Compound 3f (KiMAO-A; 4.96 ± 0.21 nM) was found to be equally potent as that of standard drug, Moclobemide (KiMAO-A; 5.01 ± 0.13 nM) but with best selectivity index (8.86 × 10(-5)). Molecular docking studies with R &S conformer of 3f revealed S-enantiomer is better than R-enantiomer as reported earlier by other groups. It is proposed that VdW's radii of the substitution (bulkiness) in ring B determine the potency of phenyl carbamates.