Pyridazinone hybrids: Design,synthesis and evaluation as potential anticonvulsant agents

A series of new hybrid benzothiazole containing pyridazinones derivatives were designed and synthesized fulfilling all the pharmacophoric requirements essential for the anticonvulsant activity. In-silico and in vitro studies revealed that some of these hybrid derivatives demonstrated admirable GABA AT inhibitory activity. An attempt has also been made to validate the results of in vitro GABA AT inhibition of the most potent compound SPS-5F (IC₅₀ 9.10 μM) through in vivo anticonvulsant screening. Compound SPS-5F administration significantly increases the whole brain GABA level, might be through the inhibition of GABA AT enzyme.     

Design,synthesis and biological evaluation of novel thiosemicarbazide analogues as potent anticonvulsant agents

Novel thiosemicarbazide derivatives were synthesised and evaluated for their anticonvulsant activity and neurotoxicity. Anticonvulsant activity was done for grand mal and petit mal types of epilepsies by maximal electroshock (MES) and pentylenetetrazol (PTZ) induced convulsions methods respectively. Rotarod test was done to determine neurotoxicity. Amongst synthesised compounds, N-(4-bromophenyl)2-[(2-phenylhydrazinyl) carbonothioyl] hydrazinecarbothioamide (5e) is a broad-spectrum anticonvulsant agent since it was active in both (MES) and (PTZ) induced seizure models with no neurotoxicity and N,N-(bis(chlorophenyl)hydrazine-1,2-dicarbothoamide (5g) acts as a selective agent for grand mal epilepsy.     

Design, synthesis, and anticonvulsant activity of N-phenylamino derivatives of 3,3-dialkyl-pyrrolidine-2,5-diones and hexahydro-isoindole-1,3-diones

In the present study on the development of new anticonvulsants, the library of differently substituted N-phenylamino pyrrolidine-2,5-dione and hexahydro-isoindole-1,3-dione derivatives was synthesized. The anticonvulsant activity of all the compounds was evaluated using the maximal electroshock (MES) and pentylenetetrazole (scPTZ) screens, which are the most widely employed seizure models for early identification of candidate anticonvulsants. Their neurotoxicity was determined applying the rotorod test. The pharmacological results revealed that the majority of compounds were effective in electrical (MES) and/or pentylenetetrazole induced seizure (scPTZ) models. The quantitative in vivo anticonvulsant evaluation of N-phenylamino-3,3-dimethyl-pyrrolidine-2,5-dione (15), conducted at the time of peak pharmacodynamic activity (TPE), showed the MES ED₅₀ value of 69.89 mg/kg in rats. The median toxic dose (TD₅₀) was 500 mg/kg, providing compound 15 with a protective index (TD₅₀/ED₅₀) of 7.15 in the MES test.     

Design,synthesis and biological evaluation of 3,5-diaryl isoxazole derivatives as potential anticancer agents

The present study was carried out in the attempt to synthesize a new class of potential anticancer agents comprising eleven compounds (24–34) sharing the 3,5-diarylisoxazole as a core. The chemical structure of the new synthesized compounds was established by IR, ¹H NMR, ¹³C NMR and elemental analysis. Their biological potential towards prostate cancer was evaluated by using cancer PC3 cells and non-tumorigenic PNT1a cells. Interestingly, compound 26 distinguished from others with a quite high selectivity value that is comparable to 5-FU. The binding mode of 26 towards Ribosomal protein S6 kinase beta-1 (S6K1) was investigated at a molecular level of detail by employing docking simulations based on GLIDE standard precision as well as MM-GBSA calculations.     

Design,synthesis and anticonvulsant properties of new N-Mannich bases derived from 3-phenylpyrrolidine-2,5-diones

The synthesis and anticonvulsant properties of new N-Mannich bases of 3-phenyl- (9a–d), 3-(2-chlorophenyl)- (10a–d), 3-(3-chlorophenyl)- (11a–d) and 3-(4-chlorophenyl)-pyrrolidine-2,5-diones (12a–d) were described. The key synthetic strategies involve the formation of 3-substituted pyrrolidine-2,5-diones (5–8), and then aminoalkylation reaction (Mannich-type) with formaldehyde and corresponding secondary amines, which let to obtain the final compounds 9a–d, 10a–d, 11a–d and 12a–d in good yields. Initial anticonvulsant screening was performed in mice (ip) using the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizures tests. The most effective compounds in mice were tested after oral administration in rats. The acute neurological toxicity was determined applying the minimal motor impairment rotarod test. The in vivo results revealed that numerous compounds were effective especially in the MES test (model of human tonic-clonic seizures). The most active in the MES seizures in rats was 1-[(4-benzyl-1-piperidyl)methyl]-3-(2-chlorophenyl)pyrrolidine-2,5-dione (10c) which showed ED₅₀ value of 37.64 mg/kg. It should be stressed that this molecule along with 9a, 9d and 10d showed protection in the psychomotor seizure test (6-Hz), which is known as an animal model of therapy-resistant epilepsy. Furthermore compounds 9a, 9d and 10d were also tested in the pilocarpine-induced status prevention (PISP) test to assess their potential effectiveness in status epilepticus. For the most promising molecule 9d an influence on human CYP3A4 isoform of P-450 cytochrome was studied in vitro.     

Design,synthesis, in vivo and in silico evaluation of phenacyl triazole hydrazones as new anticonvulsant agents

A series of phenacyl triazole hydrazones 3 have been designed based on the hybridization of (arylalkly)triazole and aroyl hydrazone scaffolds as new anticonvulsant agents. The target compounds 3 were easily synthesized from appropriate phenacyl triazoles and aryl acid hydrazides and characterized by IR, NMR and Mass spectroscopy. The in vivo anticonvulsant evaluation of synthesized compounds by using MES and PTZ tests revealed that they are more effective in MES model respect to PTZ test. All compounds showed 33–100% protection against MES-induced seizures at the dose of 100 mg/kg. However, the isonicotinic acid hydrazide derivative 3h showed the best profile of activity in both models. Molecular docking studies of compound 3h with different targets (NMDA, AMPA, GABA_A and sodium channel), postulated that the compound acts mainly via GABA_A receptors. In silico molecular properties predictions indicated that all compounds have favourable oral bioavailability and BBB permeability.     

Unexpected formation of 3-chloro-1-hydroxy-2,6-diarylpiperidin-4-ones: synthesis, antibacterial and antifungal activities

New 3-chloro-1-hydroxy-2,6-diarylpiperidin-4-ones 18-22 were synthesized, characterized by melting point, elemental analysis, MS, FT-IR, one-dimensional NMR ((1)H & (13)C) spectroscopic data and evaluated for their in vitro antibacterial and antifungal activities. All the newly synthesized compounds exerted a wide range of antibacterial activities against the entire tested gram-positive and gram-negative bacterial strains except Escherichia coli. Compounds 21 and 22 exerted strong antifungal activities against Aspergillus flavus, mucor and Microsporum gypsuem. In addition, compound 20 was more potent against Rhizopus.     

Design,synthesis, in vivo,and in silico evaluation of new coumarin-1,2,4-oxadiazole hybrids as anticonvulsant agents

A novel series of coumarin-1,2,4-oxadiazole hybrids were designed, synthesized, and evaluated as anticonvulsant agents. The title compounds were easily synthesized from reaction of appropriate coumarins and 3-aryl-5-(chloromethyl)-1,2,4-oxadiazole derivatives. In vivo anticonvulsant activity of the synthesized compounds were determined using pentylenetetrazole (PTZ)- and maximal electroshock (MES)-induced seizures confirming that they were more effective against MES test than PTZ test. It should be noted that compounds 3b, 3c, and 3e showed the best activity in MES model which possessed drug-like properties with no neurotoxicity. Anticonvulsant activity of the most potent compound 3b was remarkably reduced after treatment with flumazenil which confirmed the participation of a benzodiazepine mechanism in the anticonvulsant activity. Also, docking study of compound 3b in the BZD-binding site of GABA_A receptor confirmed possible binding of 3b to the BZD receptors.     

Design, synthesis and bioevaluation of novel maleamic amino acid ester conjugates of 3,5-bisarylmethylene-4-piperidones as cytostatic agents

A novel series of maleamic amino acid ester conjugates of 3,5-bisarylmethylene-4-piperidones were prepared to investigate the efficacy of micronutrient conjugation in enhancing cytotoxic potency by improving selectivity and delivery. These compounds, prepared as anticancer agents, were expected to demonstrate enhanced selectivity towards malignant cells through the inhibition of topoisomerase IIα via protein thiolation. The cytostatic effects of these compounds were evaluated against three cell lines, namely murine L1210 leukemia cells, human Molt 4/C8 and CEM T-lymphocyte cells. All compounds were found to have greater potency than the reference drug melphalan. Several compounds were found to potently inhibit topoisomerase IIα and displayed cytostatic activity in the nanomolar range.     

Design,synthesis and biological evaluation of 3,5-disubstituted 2-amino thiophene derivatives as a novel class of antitumor agents

In search of new compounds with strong antiproliferative activity and simple molecular structure, we designed a novel series of agents based on the 2-amino-3-alkoxycarbonyl/cyano-5-arylethylthiophene scaffold. The presence of the ethyl spacer between the 2′,5′-dimethoxyphenyl and the 5-position of the thiophene ring, as well as the number and location of methoxy substitutents on the phenyl ring, played a profound role in affecting the antiproliferative activity. Among the synthesized compounds, we identified the 2-amino-3-cyano-[2-(2,5-dimethoxyphenyl)ethyl] thiophene 2c as the most promising derivative against a wide panel of cancer cell lines (IC₅₀ = 17–130 nM). The antiproliferative activity of this compound appears to correlate well with its ability to inhibit tubulin assembly and the binding of colchicine to tubulin. Moreover 2c, as determined by flow cytometry, strongly induced arrest in the G2/M phase of the cell cycle, and annexin-V and propidium iodide staining indicate that cell death proceeds through an apoptotic mechanism that follows the intrinsic mitochondrial pathway.     

Design and synthesis of vidarabine prodrugs as antiviral agents

5′-O-d- and l-amino acid derivatives and 5′-O-(d- and l-amino acid methyl ester phosphoramidate) derivatives of vidarabine (ara-A) were synthesized as vidarabine prodrugs. Some compounds were equi- or more potent in vitro than vidarabine against two pox viruses and their uptake by cultured cells was improved compared to the parent drug.     

3,5-Diaryl-1H-pyrazole as a molecular scaffold for the synthesis of apoptosis-inducing agents

The scaffold of 3,5-diaryl-1H-pyrazole was selected as a molecular template to synthesize novel growth-inhibitory agents in the present study. Our findings suggested that analogs bearing electron-withdrawing groups on one ring while electron-donating groups on another reveal significant activities. In particular, 26 bearing a 1,1′-biphenyl moiety displayed the most potent activity against OVCA, SW620, H460 and AGS cells with GI₅₀ values of 0.67, 0.89, 0.73 and 0.79 μM, respectively. The mechanistic study revealed that 26-mediated apoptosis-inducing effect on OVCA cells was, in part, attributed to the inhibition of protein kinase B/Akt activity, accompanied by the mitochondrial apoptotic pathway through the activation of caspase-9, caspase-3, as well as the cleavage of protein poly(ADP-ribose) polymerase (PARP) and DNA fragmentation. Further structure–activity relationship study employed by Comparative Molecular Field Analysis (CoMFA) was carried out with q² and R² values of 0.671 and 0.846, respectively.     

QSAR analysis of pyrazolidine-3,5-diones derivatives as Dyrk1A inhibitors

Individuals with Down syndrome (DS) suffer from mental retardation. Overexpression and the resulting increased specific activity of Dyrk1A kinase located on chromosome 21 cause a learning and memory deficit in Dyrk1A transgenic mice. To search for therapeutic agents with Dyrk1A inhibition activity, previously we obtained HCD160 as a new hit compound for Dyrk1A inhibition. In the present study, we synthesized 34 HCD160 derivatives to investigate the quantitative structure–activity relationship (QSAR). This analysis could provide important information for novel drug discovery for treatment of DS related learning and memory deficits.     

Antitumor agents 273. Design and synthesis of N-alkyl-thiocolchicinoids as potential antitumor agents

As a part of our continuing study of colchicinoids as therapeutically useful antitumor drugs, thiocolchicine derivatives, including their phosphate and other water soluble salts, were synthesized and evaluated for inhibition of tubulin polymerization and for in vitro cytotoxicity. Three compounds, 7, 10, and 11, showed potent inhibition of tubulin assembly (IC₅₀ = 0.88–1.1 μM). In addition, compound 7, a water soluble succinic acid salt of N-deacetylthiocolchicine (4), showed potent cytotoxicity against a panel of tumor cell lines, suggesting it might be a potential lead to be developed as a therapeutic antitumor agent. Compound 8, a water soluble succinic acid salt of N,N-dimethyl-N-deacetylthiocolchicine (5), showed selective activities against HCT-8 and SK-BR-3 cells. N,N-Diethyl-N-deacetylthiocolchicine (6) seemed not to be a substrate for the P-gp efflux pump, based on the similar ED₅₀ values obtained against P-gp over-expressing KBvin (0.0146 μg/mL) cells and the parent KB (0.0200 μg/mL) cell line.     

Design and synthesis of Pfmrk inhibitors as potential antimalarial agents

The synthesis and inhibitory activities of 10 potential inhibitors of Pfmrk, a Plasmodium falciparum cyclin-dependent protein kinase, are described. The most potent inhibitor is a 3-phenyl-quinolinone compound with an IC(50) value of 18 microM. It is the first compound reported to inhibit Pfmrk at the micro molar range.     

Design and synthesis of novel senkyunolide analogues as neuroprotective agents

A class of senkyunolide analogues bearing benzofuranone fragment were designed, synthesized and evaluated for their neuroprotective effect in models of oxygen glucose deprivation (OGD) and oxidative stress. All tested compounds showed neuroprotection profile based on the cell viability assay. In particular, derivatives 1f–1i possessing furoxan-based nitric oxide releasing functionality exhibited significant biological activities in OGD models. More importantly, compound 1g containing short linker with furoxan displayed the most potent neuroprotection at the concentration of 100?μM (cell survival up to 145.2%). Besides, 1g also showed the middle level neuroprotective effect in model of oxidative stress.     

Design and synthesis of 1,2,3-triazolo-phenanthrene hybrids as cytotoxic agents

A series of new 1,2,3-triazolo-phenanthrene hybrids has been synthesized by employing Cu(I)-catalyzed azide-alkyne cycloaddition (CuAAC) reaction. These compounds were evaluated for their in vitro cytotoxic potential against various human cancer cell lines viz. lung (A549), prostate (PC-3 and DU145), gastric (HGC-27), cervical (HeLa), triple negative breast (MDA-MB-231, MDA-MB-453) and breast (BT-549, 4T1) cells. Among the tested compounds, 7d displayed highest cytotoxicity against DU145 cells with IC₅₀ value of 1.5 ± 0.09 µM. Further, the cell cycle analysis shown that it blocks G0/G1 phase of the cell cycle in a dose dependent manner. In order to determine the effect of compound on cell viability, phase contrast microscopy, AO/EB, DAPI, DCFDA and JC-1 staining studies were performed. These studies clearly indicated that the compound 7d inhibited the cell proliferation of DU145 cells. Relative viscosity measurements and molecular docking studies indicated that these compounds bind to DNA by intercalation.     

Design and synthesis of diarylamines and diarylethers as cytotoxic antitumor agents

Based on a shared structural core of diarylamine in several known anticancer drugs as well as a new cytotoxic hit 6-chloro-2-(4-cyanophenyl)amino-3-nitropyridine (7), 30 diarylamines and diarylethers were designed, synthesized, and evaluated for cytotoxic activity against A549, KB, KB-vin, and DU145 human tumor cell lines (HTCL). Four new leads 11e, 12, 13a, and 13b were discovered with GI(50) values ranging from 0.33 to 3.45μM. Preliminary SAR results revealed that a diarylamine or diarylether could serve as an active structural core, meta-chloro and ortho-nitro groups on the A-ring (either pyridine or phenyl ring) were necessary and crucial for cytotoxic activity, and the para-substituents on the other phenyl ring (B-ring) were related to inhibitory selectivity for different tumor cells. In an investigation of potential biological targets of the new leads, high thoughput kinase screening discovered that new leads 11e, 12 and 13b especially inhibit Mer tyrosine kinase, a proto-oncogene associated with munerous tumor types, with IC(50) values of 2.2-3.0μM. Therefore, these findings provide a good starting point to optimize a new class of compounds as potential anticancer agents, particularly targeting Mer tyrosine kinase.     

Baylis-Hillman reaction assisted parallel synthesis of 3,5-disubstituted isoxazoles and their in vivo bioevaluation as antithrombotic agents

The solution-phase parallel synthesis involving reactions of Baylis-Hillman products of 3-substituted-5-isoxazolecarbaldehydes with nucleophiles and their in vivo antithrombotic evaluations are described along with the results of in vitro platelet aggregation inhibition assay of a few compounds. Results of the detailed evaluation of one of the compounds as an inhibitor of platelet aggregation are also presented.     

Synthesis and structure-activity relationships of 2-alkylidenethiazolidine-4,5-diones as antibiotic agents

2-Alkylidenethiazolidine-4,5-diones were prepared by novel one-pot cyclizations of arylacetonitriles with isothiocyanates and ethyl 2-chloro-2-oxoacetate. The products show antibiotic activity against the Gram-positive bacteria Bacillus subtilis and Staphylococcus aureus.