Synthesis of novel 2-amino-4-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-4H-pyran-3-carbonitrile derivatives as antimicrobial and antioxidant agents

As a part of systematic investigation of synthesis and biological activities of indole analogues linked to various heterocyclic systems, we have synthesized new compounds viz., 2-amino-4-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-4H-pyran-3-carbonitriles (2a–i), 4,5-diamino-6-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-8-aryl-2-oxo-2,6-dihydrodipyrano [2,3-b:3,2-e]pyridine-3-carbonitriles (3a–i), 4-amino-5-(5′-substituted 2′-phenyl-1H-indol-3-yl)-7-aryl-1H-pyrano[2,3-d]pyrimidin-2(5H)-ones (4a–i), 4-amino-5-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-7-aryl-1H-pyrano[2,3-d]pyrimidin-2(5H)-thiones (5a–i), 4-(5′-subtituted 2′-phenyl-1H-indol-3′-yl)-6-aryl-1,4-dihydropyrano[2,3-c]pyrazol-3-amines (6a–i) and 5-(5′-substituted 2′-phenyl-1H-indol-3′-yl)-7-aryl-3H-pyrano[2,3-d]pyrimidin-4(5H)-ones (7a–i). Antibacterial activity results revealed that, compound 6a showed promising activity versus Escherichia coli, Staphylococcus aureus and Klebsiella pneumoniae. Compound 6d exhibited good activity against S. aureus, K. pneumoniae and Pseudomonas aeruginosa. Antifungal activity results indicated that, compound 4d exhibited maximum zone of inhibition against Aspergillus oryzae and Aspergillus flavus. In case of antioxidant activity, compound 4a showed promising radical scavenging activity, ferric ions (Fe³⁺) reducing antioxidant power (FRAP) and metal chelating activity.     

Discovery of (S)-6-methoxy-chroman-3-carboxylic acid (4-pyridin-4-yl-phenyl)-amide as potent and isoform selective ROCK2 inhibitors

ROCK1 and ROCK2 are highly homologous isoforms. Accumulated studies indicate that they have distinct different functions, and the development of isoform selective ROCK inhibitors will pave new roads for the treatment of various diseases. In this work, a series of amide-chroman derivatives were synthesized and biologically evaluated in order to develop potent and isoform selective ROCK2 inhibitors. Remarkably, (S)-6-methoxy-chroman-3-carboxylic acid (4-pyridin-4-yl-phenyl)-amide ((S)-7c) possessed ROCK2 inhibitory activity with an IC₅₀ value of 3?nM and 22.7-fold isoform selectivity (vs. ROCK1). Molecular docking indicated that hydrophobic interactions were the key element for the high potency and isoform selectivity of (S)-7c. The binding free energies predicted by MM/GBSA were in good agreement with the experimental bioactivities, and the analysis of individual energy terms suggested that residue Lys105 in ROCK1 or Lys121 in ROCK2 was the key residue for the isoform selectivity of (S)-7c.     

Synthesis of novel 7-substituted pyrido[2′,3′:4,5]furo[3,2-d]pyrimidin-4-amines and their N-aryl analogues and evaluation of their inhibitory activity against Ser/Thr kinases

The efficient synthesis of 7-substituted pyrido[2′,3′:4,5]furo[3,2-d]pyrimidin-4-amines and their N-aryl analogues is described. 3,5-Dibromopyridine was converted into 3-amino-6-bromofuro[3,2-b]pyridine-2-carbonitrile intermediate which was formylated with DMFDMA. Functionalization at position 7 of the tricyclic scaffold was accomplished, before or after cyclisation step, by palladium-catalyzed Suzuki–Miyaura cross-coupling while the pyrimidin-4-amines and N-aryl counterparts were synthesized by microwave-assisted formamide degradation and Dimroth rearrangement, respectively. The final products were evaluated for their potent inhibition of a series of five Ser/Thr kinases (CDK5/p25, CK1δ/ε, CLK1, DYRK1A, GSK3α/β). Compound 35 showed the best inhibitory activity with an IC₅₀ value of 49 nM and proved to be specific to CLK1 among the panel of tested kinases.     

Synthesis and evaluation of the NSCLC anti-cancer activity and physical properties of 4-aryl-N-phenylpyrimidin-2-amines

Reported herein are efforts to profile 4-aryl-N-phenylpyrimidin-2-amines in terms of their anti-cancer activity towards non small-cell lung carcinoma (NSCLC) cells. We have synthesized new 4-aryl-N-phenylpyrimidin-2-amines and assessed them in terms of their cytotoxicity (A549, NCI-H187, MCF7, Vero & KB) and physicochemical properties (logD_7.4 and solubility). 13f and 13c demonstrated potent anti-cancer activity in A549 cells (0.2 µM), compared to 0.4 μM for the NSCLC drug Doxorubicin. 13f also displayed low experimental logD_7.4 (2.9) and the best solubility (～40 μM). Compounds 13b and 13d showed the best balance of A549 anti-cancer activity and selectivity. 13g showed good activity and selectivity comparable with the anti-cancer drug Doxorubicin.     

Two distinct classes of novel pyrazolinecarboxamides as potent cannabinoid CB1 receptor agonists

The synthesis and SAR of 3-alkyl-4-aryl-4,5-dihydropyrazole-1-carboxamides 1–23 and 1-alkyl-5-aryl-4,5-dihydropyrazole-3-carboxamides 24–27 as two novel cannabinoid CB₁ receptor agonist classes were described. The target compounds elicited high affinities to the CB₁ as well as the CB₂ receptor and were found to act as CB₁ receptor agonists. The key compound 19 elicited potent CB₁ agonistic and CB₂ inverse agonistic properties in vitro and showed in vivo activity in a rodent model for multiple sclerosis after oral administration.     

Synthesis of 2-(thienyl-2-yl or -3-yl)-4-furyl-6-aryl pyridine derivatives and evaluation of their topoisomerase I and II inhibitory activity,cytotoxicity, and structure–activity relationship

A series of 2-(thienyl-2-yl or -3-yl)-4-furyl-6-aryl pyridine derivatives were designed, synthesized, and evaluated for their topoisomerase I and II inhibition and cytotoxic activity against several human cancer cell lines. Compounds 10–19 showed moderate topoisomerase I and II inhibitory activity and 20–29 showed significant topoisomerase II inhibitory activity. Structure–activity relationship study revealed that 4-(5-chlorofuran-2-yl)-2-(thiophen-3-yl) moiety has an important role in displaying topoisomerase II inhibition.     

Novel aryl carboximidamide and 3-aryl-1,2,4-oxadiazole analogues of naproxen as dual selective COX-2/15-LOX inhibitors: Design,synthesis and docking studies

A series of novel naproxen analogues containing 3-aryl-1,2,4-oxadiazoles moiety (4b-g) and their reaction intermediates aryl carboximidamides moiety (3b-g) was synthesized and evaluated in vitro as dual COXs/15-LOX inhibitors. Compounds 3b-g exhibited superior inhibitory activity than celecoxib as COX-2 inhibitors. Compounds 3b-d and 3g were the most potent COX-2 inhibitors with IC₅₀ range of 6.4 – 8.13 nM and higher selectivity indexes (3b, SI = 26.19; 3c, SI = 13.73; 3d, SI = 29.27; 3g, SI = 18.00) comparing to celecoxib (IC₅₀ = 42.60 nM, SI = 8.05). Regarding 15-LOX inhibitory activity, compounds belonging to aryl carboximidamide backbone 3b-e and 3g were the most potent with IC₅₀ range of 1.77–4.91 nM comparing to meclofenamate sodium (IC₅₀ = 5.64 µM). Data revealed that The levels of NO released by aryl carboximidamides 3b-g were more higher than 3-aryl-1,2,4-oxadiazole derivatives 4b-g, which correlated well with their COX-2 inhibitory activities.     

1,2,4-Triazole-based benzothiazole/benzoxazole derivatives: Design,synthesis, p38α MAP kinase inhibition,anti-inflammatory activity and molecular docking studies

Novel N-(benzothiazol/oxazol-2-yl)-2-[(5-(phenoxymethyl)-4-aryl-4H-1,2,4-triazol-3-yl)thio] acetamide derivatives (5a-n) were synthesized and investigated for in vitro anti-inflammatory activity and p38α MAP kinase inhibition. Compounds showing good in vitro activities (5a, 5b, 5d, 5e, 5i, 5k and 5l) were studied for their in vivo anti-inflammatory activity using carrageenan induced rat paw edema model. Compound 5b emerged as the most active compound with an edema inhibition of 84.43%. It also showed improved GI safety profile with lower ulcer severity index and lipid peroxidation potential. Also, p38α MAP kinase assay of 5b showed superior inhibitory potency (IC₅₀:0.031 ± 0.14 µM) than the standard SB 203580 (IC₅₀:0.043 ± 0.14 µM). To predict their binding mode compounds were also docked against p38α MAP kinase enzyme. Compound 5b and SB 203580 showed hinge region interaction with MET 109.     

Synthesis of novel pyrazolic analogues of chalcones and their 3-aryl-4-(3-aryl-4,5-dihydro-1H-pyrazol-5-yl)-1-phenyl-1H-pyrazole derivatives as potential antitumor agents

Novel (E)-1-aryl-3-(3-aryl-1-phenyl-1H-pyrazol-4-yl)prop-2-en-1-ones 5/6 (pyrazolic chalcones) were synthesized from a Claisen–Schmidt reaction of 3-aryl-1-phenylpyrazol-4-carboxaldehydes 4 with several acetophenone derivatives 1. Subsequently, the microwave-assisted cyclocondensation reaction of chalcones 5/6 with hydrazine afforded the new racemic 3-aryl-4-(3-aryl-4,5-dihydro-1H-pyrazol-5-yl)-1-phenyl-1H-pyrazoles 7 or their N-acetyl derivatives 8 and 9 when reactions where carried out in DMF or acetic acid, respectively. Several of these compounds were screened by the US National Cancer Institute (NCI) for their ability to inhibit 60 different human tumor cell lines, where 5c and 9g showed remarkable activity mainly against leukemia (K-562 and SR), renal cancer (UO-31) and non-small cell lung cancer (HOP-92) cell lines, with the most important GI₅₀ values ranging from 0.04 to 11.4 μM, from the in vitro assays.     

Fluorinated 2-Arylcyclopropan-1-amines – A new class of sigma receptor ligands

Stereoisomeric 2-aryl-2-fluoro-cyclopropan-1-amines have been discovered as a new class of σ receptor ligands showing different selectivity for the two subtypes of the receptor. Generally, compounds substituted in 4-position are much more active than corresponding 3-substituted isomers. trans-2-Fluoro-2-(4-methoxyphenyl)cyclopropan-1-amine (19a) was the most potent (K_i = 4.8 nM) σ₁ receptor ligand, while cis-2-fluoro-2-(4-trifluoromethylphenyl)cyclopropan-1-amine (20b) was the most potent (K_i = 95 nM) σ₂ receptor ligand.     

Novel 3-substituted-1-aryl-5-phenyl-6-anilinopyrazolo[3,4-d]pyrimidin-4-ones: Docking,synthesis and pharmacological evaluation as a potential anti-inflammatory agents

Novel 3-substituted-1-aryl-5-phenyl-6-anilino-pyrazolo[3,4-d]pyrimidin-4-ones of pharmacological significance were synthesized by the reaction of ethyl-(5-amino-3-methylthio-1-aryl-5-phenyl-2H-pyrazole)-4-carboxylates 3a–c with S-methyl diphenyl thiourea independently to produce 1-aryl-3-thiomethyl-5-phenyl-pyrazolo[3,4-d]pyrimidines 4a–c in DMF with catalytic amount of K₂CO₃, which on further treatment with different aromatic amines independently under same reaction conditions generated for compounds 5a–l. The compounds were screened for the anti-inflammatory activity and evaluated for ulcerogenic potential. The compounds 5i exhibited superior anti-inflammatory activity in comparison with diclofenac sodium and comparable activity with celecoxib at a dose of 25 mg/kg. The other compounds 4c, 5c, 5f and 5l were found as active with inhibition of edema in the range of 35–39 after 3 h of administration of test compounds. The ulcerogenic potential of active compounds was observed to be quite lesser as compared to standard. COX-2 docking score of the active compound 5i was found to be better than standard celecoxib.     

Kamolonol suppresses angiotensin II-induced stress fiber formation and cellular hypertrophy through inhibition of Rho-associated kinase 2 activity

Kamolonol (7-[[(1R,2R,4R,4aS,5R,8aS)-4-hydroxy-1,2,4a,5-tetramethyl-6-oxo-3,4,5,7,8,8a-hexahydro-2H-naphthalen-1-yl]methoxy]chromen-2-one) is a sesquiterpene coumarin and an active component of gum extracts from Ferulaassafoetida. The aim of this study was to investigate the anti-fibrotic and anti-cellular hypertrophic effects of kamolonol, and further to explore its possible mechanism. Kamolonol (3–30 μM) significantly inhibited stress fiber formation induced by angiotensin II (Ang II) in rat heart-derived H9c2 cells. Furthermore, kamolonol (3–30 μM) showed a potent inhibitory effect on Ang II-induced cellular hypertrophy in H9c2 cells. Next, a Rho-associated kinase (ROCK) activity was measured because actin stress fiber formation and/or cellular hypertrophy are usually induced by the activation of ROCK. Rho-associated kinase 2 (ROCK2) studies using a time-resolved fluorescence resonance energy transfer (TR-FRET) showed that kamolonol possesses a potent ROCK2 inhibitory activity with IC₅₀ values of 2.27 μM, and has an ATP-competitive inhibitory mode. In validation study, pretreatment of kamolonol (3–30 μM) for 2 h decreased the Ang II-induced phosphorylation of myosin phosphatase 1 (MYPT1) and myosin light chain 2 (MLC2). Taken together, these results indicate that kamolonol suppresses Ang II-induced stress fiber formation and cellular hypertrophy, and propose that one mechanism underlying these anti-fibrotic and anti-cellular hypertrophic effects involves inhibition of the ROCK-MLC pathway.     

New azafluorenones with cytotoxic and carbonic anhydrase inhibitory properties: 2-Aryl-4-(4-hydroxyphenyl)-5H-indeno[1,2-b]pyridin-5-ones

New azafluorenones, 2-aryl-4-(4-hydroxyphenyl)-5H-indeno[1,2-b]pyridin-5-ones, were prepared to evaluate their cytotoxic/anticancer properties, also their inhibitory effects on hCA I and II isoenzymes. Aryl part was changed as [phenyl (H1), 4-methylphenyl (H2), 4-methoxyphenyl (H3), 4-fluorophenyl (H4), 4-bromophenyl (H5), 4-chlorophenyl (H6), 3-hydroxyphenyl (H7), and 4-hydroxyphenyl (H8)]. The structure of the synthesized compounds was characterized by ¹H NMR, ¹³C NMR and HRMS spectra.Cytotoxicity results of the series pointed out that the compounds H6 (PSE: 28.0) and H5 (PSE: 27.3), with the highest potency selectivity expression (PSE) value, can be considered as leader compounds of the study in designing novel anticancer agents. Additionally, all azafluorenones synthesized showed a good inhibition profile towards hCA I and II isoenzymes in the range of 54.14–73.72 nM and 67.28–76.15 nM, respectively.The compounds H5 and H6 can be considered for further designs with their cytotoxic and CA inhibitory profiles.     

Identification of 5H-chromeno[3,4-c]pyridine and 6H-isochromeno[3,4-c]pyridine derivatives as potent and selective dual ROCK inhibitors

A novel series of 5H-chromeno[3,4-c]pyridine, 6H-isochromeno[3,4-c]pyridine and 6H-isochromeno[4,3-d]pyrimidine derivatives as dual ROCK1 and ROCK2 inhibitors is described. Optimization led to compounds with sub-nanomolar inhibitory affinity for both kinases and excellent kinome selectivity. Compound 19 exhibited ROCK1 and ROCK2 IC₅₀ of 0.67 nM and 0.18 nM respectively.     

Differential interactions of 5-(4-piperidyl)-3-isoxazolol analogues with insect γ-aminobutyric acid receptors leading to functional selectivity

γ-Aminobutyric acid (GABA) receptors (GABARs) mediate fast inhibitory synaptic transmission and are also targets for drugs and insecticides. To better understand the molecular interactions of ligands with the orthosteric sites of GABARs, we examined 4-aryl/arylalkyl-5-(4-piperidyl)-3-isoxazolol, 4-aryl-5-(4-piperidyl)-3-isothiazolol, and 5-aryl-4-(4-piperidyl)-1-hydroxypyrazole for their antagonism with regard to three insect GABARs. The 3-isoxazolol was preferable to the 3-isothiazolol and 1-hydroxypyrazole in antagonism to common cutworm and housefly GABARs. Of the tested analogues, 4-(3-biphenylyl)-5-(4-piperidyl)-3-isoxazolol (2a) displayed the greatest antagonism for common cutworm and housefly GABARs, with IC₅₀ values of 3.4 and 10.2 μM, respectively. In contrast to the antagonism of the two GABARs, 2a showed partial agonism for the case of small brown planthopper GABARs, with an EC₅₀ value of 31.3 μM. Homology models and docking simulations revealed that a cation-π interaction between an analogue and an Arg residue in loop C or E of the orthosteric site is a key component of antagonism. This specific phenomenon was lacking in the interactions between 2a and the orthosteric site of small brown planthopper GABARs. These findings provide important insights into designing and developing novel drugs and insecticides.     

2-Thienyl-4-furyl-6-aryl pyridine derivatives: Synthesis,topoisomerase I and II inhibitory activity,cytotoxicity, and structure–activity relationship study

Designed and synthesized 60 2-thienyl-4-furyl-6-aryl pyridine derivatives were evaluated for their topoisomerase I and II inhibitory activities at 20 μM and 100 μM and cytotoxicity against several human cancer cell lines. Compounds 8, 9, 11–29 showed significant topoisomerase II inhibitory activity and compounds 10 and 11 showed significant topoisomerase I inhibitory activity. Most of the compounds (7–21) possessing 2-(5-chlorothiophen-2-yl)-4-(furan-3-yl) moiety showed higher or similar cytotoxicity against HCT15 cell line as compared to standards. Most of the selected compounds displayed moderate cytotoxicity against MCF-7, HeLa, DU145, and K562 cell lines. Structure–activity relationship study revealed that 2-(5-chlorothiophen-2-yl)-4-(furan-3-yl) moiety has an important role in displaying biological activities.     

Synthesis and cytotoxic activity of gamma-aryl substituted alpha-alkylidene-gamma-lactones and alpha-alkylidene-gamma-lactams

A series of 5-aryl-3-alkylidenedihydrofuran-2(3H)-ones 6a–g″ and 11a,b as well as 5-aryl-3-methylidenepyrrolidin-2-ones 10a–c and 12 were synthesized starting from 4-aryl-2-diethoxyphosphoryl-4-oxobutanoates 3a–g. Reaction sequence includes reduction or reductive amination of the carbonyl group, lactonization or lactamization step and finally the Horner–Wadsworth–Emmons olefination of aldehydes using thus obtained 5-aryl-3-diethoxyphosphoryl-3,4-dihydrofuran-2(5H)-ones 5a–g″ or 5-aryl-3-diethoxyphosphorylpyrrolidin-2-ones 9a–c. Furanones 6 and 11, as well as pyrrolidinones 10 and 12, were evaluated in vitro against mouse leukemia cell line L-1210 and two human leukemia cell lines HL-60 and NALM-6. Several of the obtained furanones proved to be very potent against all three cell lines with IC₅₀ values lower than 6 μM. Structure–activity relationships of these compounds, as well as 5-alkyl or 5-arylmethyl-3-methylidenedihydrofuran-2(3H)-ones 13a–e, previously obtained in our laboratory, are discussed.     

Design,synthesis, anticancer evaluation and docking studies of new pyrimidine derivatives as potent thymidylate synthase inhibitors

Cancer is a perplexing and challenging problem for researchers. In this study, a series of 6-aryl-5-cyano-pyrimidine derivatives were designed, synthesized and evaluated for their anticancer activity against HePG-2, MCF-7 and HCT-116 cell lines. Compounds 2, 3d, 4a-c, 5, 8 and 12 displayed high anticancer activity, comparable to that of 5-fluorouracil. Additionally, those compounds with effective anticancer activity were further assessed for their ability to inhibit thymidylate synthase (TS) enzyme. All the tested compounds demonstrated a marked TS inhibitory activity (33.66–74.98%), with IC₅₀ ranging from 3.89 to 15.74 nM. Moreover, apoptosis studies were conducted on the most potent compound 8, to evaluate its proapoptotic potential. Interestingly, compound 8 induced the level of active caspase 3, and elevated the Bax/Bcl2 ratio 44 folds in comparison to the control. Finally, a molecular docking study was conducted to detect the probable interaction between the active compounds and the thymidylate synthase active site.     

3-[2-(Aminomethyl)-5-[(pyridin-4-yl)carbamoyl]phenyl] benzoates as soft ROCK inhibitors

Clinical development of ROCK inhibitors has so far been limited by systemic or local ROCK-associated side effects. A soft drug approach, which involves predictable metabolic inactivation of an active compound to a nontoxic metabolite, could represent an attractive way to obtain ROCK inhibitors with improved tolerability. We herein report the design and synthesis of a new series of soft ROCK inhibitors structurally related to the ROCK inhibitor Y-27632. These inhibitors contain carboxylic ester moieties which allow inactivation by esterases. While the parent esters display strong activity in enzymatic (ROCK2) and cellular (MLC phosphorylation) assays, their corresponding carboxylic acid metabolites have negligible functional activity. Compound 32 combined strong efficacy (ROCK2 IC₅₀ = 2.5 nM) with rapid inactivation in plasma (t_1/2 <5′). Compound 32 also demonstrated in vivo efficacy when evaluated as an IOP-lowering agent in ocular normotensive New-Zealand White rabbits, without ocular side effects.