Synthesis, antimicrobial and antioxidant activity of some oxindoles

The present work describes the synthesis and spectral analysis of some new 3(Z)-{4-[4-(arylsulfonyl)piperazin-1-ylbenzylidene)-1,3-dihydro-2H-indol-2-one (5a-j). Ten of the synthesized compounds were screened in vitro against six species of microorganisms, Staphylococcus aureus, Streptococcus pyogenes, Escherichia coli, Pseudomonas aeruginosa, Asperigellus niger and Asperigellus clavatus. Most of the compounds exhibited significant antimicrobial activity. All of these compounds were also screened in vitro for the antioxidant activity using DPPH assay. Most of them have shown very significant antioxidant activity.     

Dihydropyridazinone cardiotonics: the discovery and inotropic activity of 1,3-dihydro-3,3-dimethyl-5-(1,4,5,6-tetrahydro-6-oxo-3-pyridazinyl)-2H -indol-2- one

We discovered that 6 (N-[4-(1,4,5,6-tetrahydro-6-oxo-3-pyridazinyl)phenyl]acetamide) is a potent positive inotrope in dogs, and we have prepared several lactam analogues of this agent. These included 16 (1,3-dihydro-5-(1,4,5,6-tetrahydro-6-oxo-3-pyridazinyl)-2H-indol-2-one), 32 (the analogous quinolin-2-one), and 37 (the analogous benzazepin-2-one). The inotropic ED50's of these compounds were 24, 3.3, and 5.2 micrograms/kg, respectively, after iv administration to pentobarbital-anesthetized dogs. Compound 20 (LY195115, 1,3-dihydro-3,3-dimethyl-5-(1,4,5,6-tetrahydro-6-oxo-3-pyridazinyl)-2H-i ndol-2- one), the geminal dimethyl analogue of 16, was 3.5-fold more potent than 16 when administered iv (ED50 = 6.8 micrograms/kg). However, the most profound effect of the geminal alkyl substitution was on oral activity. The approximate ED50's of 20 and 16 after oral administration to conscious dogs were 25 and 400 micrograms/kg, respectively. The increase in contractility produced by 25 micrograms/kg of 20 was maximally sustained in excess of 8 h. Thus, 20 is one of the most potent and long-acting oral inotropes described to date.     

1,4-Benzoxazin-3(4H)-one derivatives and related compounds as 5-HT1A and 5-HT2A receptor ligands; the effect of the terminal amide fragment on the 5-HT1A/5-HT2A affinity and functional activity

A number of new 1-phenyl- (a), 1-(3-chlorophenyl)- (b) and 1-(2-methoxyphenyl)- (c) piperazine derivatives containing 1,4-benzoxazin-3(4H)-one (2-4), 2,4-benzoxazin-3-(4H)-one (5), 1,2-benzoxazolin-3-one (6) and 1,3-benzoxazolin-2,4-dione (7) were synthesized. Radioligand binding measurements showed that the majority of compounds had a distinct affinity for 5-HT1A (3a, 6a, 2-5b, 6c; Ki = 7.5-81 nM) and/or 5-HT2A (2b, 5-7a,b; Ki = 18-69 nM) receptors. Structure-Activity Relationship (SAR) studies revealed structural features which seem to favour the binding to either or both of these two receptor subtypes. For evaluation of the functional in vivo profile of the most potent 5-HT1A (5b, 6b) and/or 5-HT2A (5-7b) ligands, the following tests were used: the 8-OH-DPAT-induced lower lip retraction (LLR) and behavioral syndrome in rats--for 5-HT1A receptor antagonistic activity, and the (+/-)DOI-induced head twitches in mice and the (+/-)DOI-induced discriminative stimulus properties in rats--for 5-HT2A receptor antagonistic properties. The obtained results show that compounds 5b and 6c behave like potent 5-HT1A antagonists, whereas 5b, 6b and 7b demonstrate 5-HT2A receptor antagonistic properties. None of the in vivo tested compounds, given alone, mimicked 8-OH-DPAT activity in those tests. It seems that derivative 5b, which has an equipotent 5-HT1A and 5-HT2A affinity and antagonistic properties at both these receptors, is a promising potential psychotropic substance.     

Effect of structural modification of the hydantoin ring on anticonvulsant activity

Selectively substituted hydantoins 1 (15 examples), 4-hydroxy-2-imidazolidinones 2 (13 examples), 2-imidazolones 3 (10 examples), 2-imidazolidinones 4 (four examples), vicinal diamines 5 (two examples), and simple amino acid derivatives 6 (four examples) have been prepared and evaluated in the maximal electroshock seizure (MES), subcutaneous pentylenetetrazole seizure threshold (sc Met), and rotorod (Tox) tests. The medium effective doses (ED50) and the medium toxic dose (TD50) for the most active compounds are reported. In general, the most pronounced activity was observed for hydantoins 1 and protected amino acids 6. Within each series of compounds, enhanced anticonvulsant activity was often noted for compounds containing an aromatic group one carbon removed from a nitrogen atom. Among the most active compounds observed were the amino acid derivative N-acetyl-D,L-alanine benzylamide (6d) and the two 2-imidazolones 4-methyl-1-(phenylmethyl)-1,3-dihydro-2H-imidazol-2-one (3e) and 1-phenyl-1,3-dihydro-2H-imidazol-2-one (3g). Compound 6d proved to be slightly more potent in the MES test than phenacemide.     

The role of the 5-HT1D receptor as a presynaptic autoreceptor in the guinea pig

The present study investigated the role of the 5-hydroxytryptamine (5-HT, serotonin)1D receptor as a presynaptic autoreceptor in the guinea pig. In keeping with the literature, the 5-HT1B selective antagonist, 1'-methyl-5-[[2'-methyl-4'-(5-methyl-1,2,4-oxadiazol-3-yl)biphenyl-4-yl]carbonyl]-2,3,6,7-tetrahydrospiro [furo[2,3-f]indole-3,4'-piperidine]oxalate (SB224289) potentiated [3H]5-HT outflow from pre-labelled slices of guinea pig cerebral cortex confirming its role as a presynaptic autoreceptor in this species. In addition, the 5-HT1D receptor-preferring antagonists, 1-[2-[4-(6-fluoro-1H-indol-3-yl)-3,6-dihydro-2H-pyridin-1-yl]-ethyl]-3-pyridin-4-yl-methyl-tetrahydro-pyrimidin-2-one (LY367642), (R)-1-[2-(4-(6-fluoro-1H-indol-3-yl-)-3,6-dihydro-1(2H)-pyridinyl)ethyl]-3,4-dihydro-1H-2-benzopyran-6-carboxamide (LY456219), (S)-1-[2-(4-(6-fluoro-1H-indol-3-yl-)-3,6-dihydro-1(2H)-pyridinyl)ethyl]-3,4-dihydro-1H-2-benzopyran-6-carboxamide (LY456220) and 1-[2-[4-(4-fluoro-benzoyl)-piperidin-1-yl]-ethyl]-3,3-dimethyl-1,2-dihydro-indol-2-one (LY310762), potentiated [3H]5-HT outflow from this preparation with potencies (EC50 values=31-140 nM) in the same range as their affinities for the guinea pig 5-HT1D receptor (Ki values=100-333 nM). The selective 5-HT1D receptor agonist, R-2-(4-fluoro-phenyl)-2-[1-[3-(5-[1,2,4]triazol-4-yl-1H-indol-3-yl)-propyl]-piperidin-4-ylamino]-ethanol dioxylate (L-772,405), inhibited [3H]5-HT outflow. In microdialysis studies, administration of either SB224289 or LY310762 at 10 mg/kg by the intraperitoneal (i.p.) route, potentiated the increase in extracellular 5-HT concentration produced by a maximally effective dose of the selective serotonin re-uptake inhibitor, fluoxetine (at 20 mg/kg i.p.). In addition, the 5-HT1D receptor-preferring antagonist and 5-HT transporter inhibitor, LY367642 (at 10 mg/kg i.p.), elevated extracellular 5-HT concentrations to a greater extent than a maximally effective dose of fluoxetine. It is concluded that the 5-HT1D receptor, like the 5-HT1B receptor, may be a presynaptic autoreceptor in the guinea pig.     

Synthesis, characterization, and biological evaluation of certain 1,3-thiazolone derivatives bearing pyrazoline moiety as potential anti-breast cancer agents

A series of 5-arylidene-2-(3,5-diaryl-4,5-dihydro-1H-pyrazol-1-yl)-1,3-thiazol-4(5H)-ones were synthesized and screened for their in vitro antitumor activity against human breast adenocarcinoma cell line (MCF-7). Five of the test compounds exhibited good antitumor activity superior to the reference drug, doxorubicin, with IC₅₀ range 1.4–2.3 μM. Among the test compounds, 2-[3,5-bis(4-chlorophenyl)-4,5-dihydro-1H-pyrazol-1-yl]-5-(2-methoxybenzylidene)-1,3-thiazol-4(5H)-one (3i) was found to show the most potent anticancer activity.     

Selective, centrally acting serotonin 5-HT2 antagonists. 2. Substituted 3-(4-fluorophenyl)-1H-indoles.

A series of 3-(4-fluorophenyl)-1H-indoles substituted in the 1-position with 4-piperidinyl, 1,2,3,6-tetrahydro-4-pyridinyl, and 4-piperazinyl was synthesized. By variation of the substituents in the benzene part of the indole nucleus in 1-[2-[4-[3-4-fluorophenyl)-1H-indol-1-yl]-1-piperidinyl]-ethyl]-2- imidazolidinones, the highest 5-HT2 receptor affinity and selectivity with respect to dopamine D2 receptors and alpha 1 adrenoceptors were obtained by 5-methyl substitution. Different substituents were introduced in the 1-position of the piperidine ring in the 5-methyl-substituted derivative. Thus replacement of the 2-(2-imidazolidinon-1-yl)ethyl side chain with a 2-(1,3-dimethyl-1-ureido)ethyl or methyl substituent resulted in unchanged affinity and selectivity for 5-HT2 receptors. Replacement with a 2-[3-(2-propyl)-2-imidazolidinon-1-yl]ethyl side chain reduced binding to alpha 1 adrenoceptors with a factor of four, while affinities for 5-HT2 and D2 receptors were retained, compared to the 3-unsubstituted imidazolidinone. Indoles substituted in the 1-position with 4-piperazinyl had generally weaker affinity for both 5-HT2 and D2 receptors compared to corresponding 4-piperidinyl- and 1,2,3,6-tetrahydro-4-pyridinyl-substituted indoles. Introduction of a methyl group in the 2-position of the 5-methyl-substituted indole resulted in further increase of selectivity for the 5-HT2 receptor. Compounds with potent receptor binding also potently inhibited the quipazine-induced head twitch syndrome in rats. The compounds were equally active after oral and subcutaneous administration and showed a long duration of action (> 24 h). In general, the derivatives were found to be considerably more potent at 24 h than at 2 h after the administration. The compounds within this series were prepared as analogues of the previously described 1-(4-fluorophenyl)-3-(4-piperidyl)-1H-indoles by interchange of the C-3 carbon atom and the nitrogen atom in the indole nucleus. The pharmacological results indicate that this isosteric replacement results in higher selectivity for 5-HT2 receptors compared to the former series. The 1-[2-[4-[2,5-dimethyl-3-(4-fluorophenyl)-1H-indol-1-yl]-1- piperidinyl]ethyl]-2-imidazolidinone has high affinity for 5-HT2 receptors (IC50 = 3.4 nM) and extremely low affinity for both dopamine D2 receptors (IC50 = 6900 nM) and alpha 1 adrenoceptors (IC50 = 2300 nM).     

Isolation and characterization of some potential impurities in ropinirole hydrochloride

Three impurities in ropinirole hydrochloride drug substance at levels approximately 0.06-0.15% were detected by reverse-phase high performance liquid chromatography (HPLC). These impurities were isolated from the drug substance. These impurities were analyzed using reverse-phase HPLC. Based on the spectral data (IR, NMR and MS), structures of these impurities were characterized as 4-[2-(propylamino) ethyl]-1,3-dihydro-2H-indol-2-one hydrochloride (impurity-A), 5-[2-(diropylamino) ethyl]-1,4-dihydro-3H-benzoxazin-3-one hydrochloride (impurity-B) and 4-[2-(diropylamino) ethyl]-1H-indol-2,3-dione hydrochloride (impurity-C). Synthesis of these impurities is discussed.     

A novel stereo-selective sulfonylurea, 1-[1-(4-aminobenzoyl)-2,3-dihydro-1H-indol-6-sulfonyl]-4-phenyl-imidazolidin-2-one,has antitumor efficacy in in vitro and in vivo tumor models

The antitumor activities of novel 1-[1-(4-aminobenzoyl)-2,3-dihydro-1H-indol-6-sulfonyl]-4-phenyl-imidazolidin-2-ones were studied to determine the potential of these compounds as antitumor candidates. The agents studied were: DW2143 (1-[1-(4-aminobenzoyl)-2,3-dihydro-1H-indol-6-sulfonyl]-4-phenyl-imidazolidin-2-one), a racemic mixture, and DW2282 [(4S)-1-[1-(4-aminobenzoyl)-2,3-dihydro-1H-indol-6-sulfonyl]-4-phenyl-imidazolidin-2-one], an S-isomer. DW2143 and DW2282 suppressed the in vitro growth of tumor cells at lower concentrations than doxorubicin, but tumor specificity was not observed between the compounds. These compounds when administered orally were not active in syngeneic models of murine Colon 26 adenocarcinoma and L1210 leukemia. However, DW2143 suppressed the growth of SW620 (human colon cancer) and NCI-H23 (human lung cancer) cells in nude mice, inhibiting tumor growth by 87 and 67%, respectively. DW2282 was a more potent inhibitor of SW620 tumor cell growth in nude mice and was also lower in toxicity than DW2143. Moreover, DW2282 did not produce a series of toxic symptoms caused by the aniline metabolites of sulfonylureas, including hypoglycemia. These results suggest that DW2282, an S-isomer, could be a novel antitumor candidate with higher specificity and lower toxicity than other orally active sulfonylureas.     

Dihydropyridazinone cardiotonics: synthesis and inotropic activity of 5'-(1,4,5,6-tetrahydro-6-oxo-3-pyridazinyl)spiro[cycloalkane- 1,3'-[3H]indol]-2'(1'H)-ones

In the 1,3-dihydro-5-(1,4,5,6-tetrahydro-6-oxo-3-pyridazinyl)-2H-indol-2-one series of cardiotonics, we found that a spirocycloalkyl ring may be annealed to the 3-position of the indolone moiety while retaining inotropic activity. An inverse relationship was found between spirocyloalkyl ring size and inotropic potency. ED50 values of the spirocyclopropane 10, spirocyclobutane 12, and spirocyclopentane 13 were 2.7, 35, and 133 micrograms/kg, respectively, following iv administration to pentobarbital-anesthetized dogs. The most potent compound prepared was 11 (5'-(1,4,5,6-tetrahydro-4-methyl-6-oxo-3-pyridazinyl)spiro[cyclopropane- 1,3'-[3H]indol]-2'(1'H)-one), the 4-methyl analogue of 10. This compound had an iv ED50 of 1.5 microgram/kg. Oral activity was evaluated by administering 50 micrograms/kg of 10 to conscious, chronically instrumented dogs. A 39% increase in LV dP/dt60 was observed, and an inotropic effect was demonstrable in excess of 7 h. Thus, the spirocyclic dihydropyridazinone inotropes are potent, long-acting, orally effective cardiotonics. Compound 11 was a potent inhibitor (IC50 = 13 nM) of cAMP phosphodiesterase derived from canine cardiac sarcoplasmic reticulum (SR-PDE). Importantly, -log IC50 values for inhibition of SR-PDE for this entire series of compounds were highly correlated (r = 0.949, p less than 0.02) with their inotropic -log ED50 values, supporting the hypothesis that inhibition of this enzyme contributes to the mechanism of action of the spirocyclic dihydropyridazinones.     

Autoxidation of tetrazepam in tablets: prediction of degradation impurities from the oxidative behavior in solution.

The major route of degradation of tetrazepam (1) is oxidation to 7-chloro-5-(3-keto-cyclohexen-1-yl)-1,3-dihydro-1-methyl-2H-1, 4-benzodiazepin-2-one (3) via the stable 7-chloro-5-(3-hydroperoxy-cyclohexen-1-yl)-1,3-dihydro-1-methyl-2H -1, 4 benzodiazepin-2-one (2). Minor degradation products are 7-chloro-5-(1,2-epoxycyclohexan-1-yl)-1,3-dihydro-1-methyl-2H-1, 4-benzodiazepin-2-one (5) and 7-chloro-1,3-dihydro-1-methyl-2H-1, 4-benzodiazepin-2,5-dione (4), resulting from cleavage of the C-C bond between the cyclohexene ring and the benzodiazepine ring. After 48 h, AIBN (2,2'-azobis[2-methyl-propanenitrile]) in acetonitrile at 40 degrees C produced qualitatively the same impurities as those observed in the stability study of tablets of 1. Other stress tests (thermal stress at 80 degrees C, heavy metal oxidation, hydrogen peroxide, acid-catalyzed oxidation) caused qualitatively different profiles of degradation.     

1-[3-(Diarylamino)propyl]piperidines and related compounds, potential antipsychotic agents with low cataleptogenic profiles

On the basis of a structural model of the postsynaptic dopaminergic antagonist pharmacophore, a series of 1-[3-(diarylamino)propyl]piperidines and related compounds was synthesized and evaluated for potential antipsychotic activity. For a rapid measure of activity, the target compounds were initially screened in vitro for inhibition of [3H]haloperidol binding and in vivo in a test of locomotor activity. Behavioral efficacy of compounds identified from the initial screens was more accurately measured in rats by using a suppression of high base-line medial forebrain bundle self-stimulation test model. The propensity of these compounds for causing extrapyramidal side effects was evaluated by using a rat catalepsy method. On the basis of these test models, we have shown that the methine carbon of the 1-(4,4-diarylbutyl)piperidines can be advantageously replaced with a nitrogen atom. The 1-[3-(diarylamino)propyl]piperidines were less cataleptic than the corresponding 1-(4,4-diarylbutyl)piperidines. The compounds with the widest separation between efficacious dose and cataleptic dose are 8-[3-[bis(4-fluorophenyl)amino]propyl]-1-phenyl-1,3,8-triazaspiro [4. 5]decan-4-one (6), 1-[1-[3-[bis(4-fluorophenyl)amino]propyl]-4-piperidinyl]-1,3-dihydro- 2H-benzimidazol-2-one (11), 1-[1-[3-[bis(4-fluorophenyl)amino]propyl]-1,2,3,6-tetrahydro-4- pyridinyl]-1,3-dihydro-2H-benzimidazol-2-one (22), and 1-[3-[bis(4-fluorophenyl)amino]propyl]-4-(2-methoxyphenyl)piperazine (26).     

Oxindole-based inhibitors of cyclin-dependent kinase 2 (CDK2): design, synthesis, enzymatic activities, and X-ray crystallographic analysis.

Two closely related classes of oxindole-based compounds, 1H-indole-2,3-dione 3-phenylhydrazones and 3-(anilinomethylene)-1,3-dihydro-2H-indol-2-ones, were shown to potently inhibit cyclin-dependent kinase 2 (CDK2). The initial lead compound was prepared as a homologue of the 3-benzylidene-1,3-dihydro-2H-indol-2-one class of kinase inhibitor. Crystallographic analysis of the lead compound bound to CDK2 provided the basis for analogue design. A semiautomated method of ligand docking was used to select compounds for synthesis, and a number of compounds with low nanomolar inhibitory activity versus CDK2 were identified. Enzyme binding determinants for several analogues were evaluated by X-ray crystallography. Compounds in this series inhibited CDK2 with a potency approximately 10-fold greater than that for CDK1. Members of this class of inhibitor cause an arrest of the cell cycle and have shown potential utility in the prevention of chemotherapy-induced alopecia.     

Synthesis and 5-HT1A/5-HT2A receptor activity of N-(4-arylpiperazin-1-yl)alkyl derivatives of 2-azaspiro([4.4]nonane and [4.5]decane-1,3-dione

Two series of N-[(4-arylpiperazin-1-yl)-alkyl]-2-azaspiro[4.4]nonane (5-10) and [4.5]decane-1,3-dione (11-16) derivatives were synthesized and their serotonin 5-HT1A and 5-HT2A receptor affinities were determined. Compounds with the methylene spacer (5-7 and 11-13) exhibited low 5-HT1A/5-HT2A receptor affinity, in contrast to their ethylene analogues regarded as potent 5-HT1A ligands, especially those containing a cyclohexane moiety (14-16; Ki = 5.1, 2.7 and 4.3 nM, respectively) in the 3-position of the pyrrolidine-2,5-dione ring. Moreover, derivatives with 3-chloro substituent (10 and 14) showed distinct affinity for 5-HT2A receptors. The functional activity of compounds 10, 14, 15 and 16 was tested in vivo in the commonly used animal models. In those experiments, the tested compounds showed features of agonists of pre- and postsynaptic (14), agonists of presynaptic and antagonists of postsynaptic (10, 15), or agonists of postsynaptic (16) 5-HT1A receptors. Additionally, 10 and 16 exhibited properties of potential 5-HT2A receptor antagonists. The above results suggested a crucial role of the spacer between the amide fragment and 4-arylpiperazine moiety, as well as of the size of the cycloalkyl ring at the 3-position of pyrrolidine-2,5-dione ring in functional 5-HT1A/5-HT2A properties.     

A new series of benzodiazepines. 1-Hydroxyalkyl derivatives of 1,3-dihydro-2H-1,4-benzodiazepin-2-ones.

A series of new 1-hydroxyalkyl derivatives of 1,3-dihydro-2H-1,4-benzodiazepin-2-ones bearing a 3-hydroxyl or a 4-N-oxide function together with some related compounds have been synthesized. Compound (22) [1-(2-hydroxyethyl)-3-hydroxy-7-chloro-1,3-dihydro-5-(o-fluorophenyl)-2H-1,4-benzodiazepin-2-one] has been selected for further studies both in animals and in humans as an antianxiety-sedative agent.     

Synthesis and cytotoxic evaluation of some new[1,3]dioxolo[4,5-g]chromen-8-one derivatives

Background

Homoisoflavonoids are naturally occurring compounds belong to flavonoid classes possessing various biological properties such as cytotoxicity. In this work, an efficient strategy for the synthesis of novel homoisoflavonoids, [1,3]dioxolo[4,5-g]chromen-8-ones, was developed and all compounds were evaluated for their cytotoxic activities on three breast cancer cell lines.

Methods

Our synthetic route started from benzo[d][1,3]dioxol-5-ol which was reacted with 3-bromopropanoic acid followed by the reaction of oxalyl chloride to afford 6,7-dihydro-8H-[1,3]dioxolo[4,5-g]chromen-8-one. The aldol condensation of the later compound with aromatic aldehydes led to the formation of the title compounds. Five novel derivatives 4a-e were tested for their cytotoxic activity against three human breast cancer cell lines including MCF-7, T47D, and MDA-MB-231 using the MTT assay.

Results

Among the synthesized compounds, 7-benzylidene-6,7-dihydro-8H-[1,3]dioxolo[4,5-g]chromen-8-one (4a) exhibited the highest activity against three cell lines. Also the analysis of acridine orange/ethidium bromide staining results revealed that 7-benzylidene-6,7-dihydro-8H-[1,3]dioxolo[4,5-g]chromen-8-one (4a) and 7-(2-methoxybenzylidene)-6,7-dihydro-8H-[1,3]dioxolo[4,5-g]chromen-8-one (4b) induced apoptosis in T47D cell line.

Conclusion

Finally, the effect of methoxy group on the cytotoxicity of compounds 4b-4d was investigated in and it was revealed that it did not improve the activity of [1,3]dioxolo[4,5-g]chromen-8-ones against MCF-7, T47D, and MDA-MB-231.     

Benzimidazole derivatives. 2. Synthesis and structure-activity relationships of new azabicyclic benzimidazole-4-carboxylic acid derivatives with affinity for serotoninergic 5-HT(3) receptors

A new series of azabicyclic benzimidazole-4-carboxamides 2-21 and -carboxylates 22-30 were synthesized and evaluated for binding affinity at serotoninergic 5-HT(3) and 5-HT(4) receptors in the CNS. Most of the synthesized compounds exhibited high or very high affinity for the 5-HT(3) binding site and low to no significant affinity for the 5-HT(4) receptor. SAR observations indicated that a halogen atom at the 6-position and a nitro group at the 7-position of the benzimidazole ring is the best substitution pattern for 5-HT(3) affinity and 5-HT(3)/5-HT(4) selectivity, as well as no substitution in this ring. (S)-(-)-N-(Quinuclidin-3-yl)benzimidazole-4-carboxamides 2, 8, and 14 bound at central 5-HT(3) sites with high affinity (K(i) = 2.6, 0. 13, and 1.7 nM, respectively) and excellent selectivity over serotonin 5-HT(4) and 5-HT(1A) receptors (K(i) > 1000-10000 nM). Furthermore, these new 5-HT(3) receptor ligands were pharmacologically characterized as potent and selective 5-HT(3) antagonists in the isolated guinea pig ileum (pA(2) = 9.6, 9.9, and 9.1, respectively).     

Synthesis, anticonvulsant properties and 5-HT1A/5-HT2A receptor affinity of new N-[(4-arylpiperazin-1-yl)-propyl]-2-aza-spiro[4.4]nonane and [4.5]decane-1,3-dione derivatives

A series of twenty new N-[(4-arylpiperazin-1-yl)-propyl]-2-aza-spiro[4.4]nonane- and [4.5]decane-1,3-dione derivatives were synthesized and their anticonvulsant activity was evaluated in maximal electroshock (MES) and sc pentertazole (sc PTZ) tests. Their neurotoxicity was examined as well. Although no antiseizure properties of the investigated compounds were found in the MES model, eight of them were active in the sc PTZ test and three, namely 2-{3-[4-(2-fluorophenyl)-piperazin-1yl]-propyl}-2-aza-spiro[4.4]nonane-1,3-dione (7), 2-{3-[4-(2-fluorophenyl)-piperazin-1-yl]-propyl}-7-methyl-2-aza-spiro[4.5]-decane-1,3- dione (22) and 2-{3-[4-(3-chlorophenyl)-piperazin-1-yl]-propyl}-7-methyl-2-aza-spiro[4.5]-decane-1,3-dione (23) were classified to the Anticonvulsant Screening Program (ASP) 1 class. In addition, since the investigated compounds belong to a class of long-chain arylpiperazines, their serotonin 5-HT1A and 5-HT2A receptor affinity was determined. All the 2-OCH3 and 3-Cl derivatives were the most potent 5-HT1A receptor ligands (Ki = 24-143 and 70-107 nM, respectively), whereas the highest 5-HT2A affinity was observed for the unsubstituted and 3-Cl derivatives (Ki = 8-66 nM). No correlation between anticonvulsant and serotonergic activity was observed.     

Synthesis and characterization of the first fluorescent antagonists for human 5-HT4 receptors

Fluorescent antagonists for human 5-HT(4) receptors were synthesized based on ML10302 1, a potent 5-HT(4) receptor agonist and on piperazine analogue 2. These molecules were derived with three fluorescent moieties, dansyl, naphthalimide, and NBD (7-nitrobenz-2-oxa-1,3-diazol-4-yl), through alkyl chains. The synthesized molecules were evaluated in binding assays on the recently cloned human 5-HT(4(e)) receptor isoform stably expressed in C6 glial cells with [(3)H]GR113808 as the radioligand. The affinity values depended upon the basal structure together with the alkyl chain length. The derivatives based on ML10302 were more potent ligands than the derivatives based on piperazine analogue. For ML10302-based ligands, dansyl and NBD derivatives attached through a chain length of one carbon atom 17a and 32, respectively, led to affinities close to the affinity of ML10302. The most potent compounds 17a, 28, and 32 produced an inhibition of the 5-HT stimulated cyclic AMP synthesis in the same cellular system with nanomolar K(b) values. Fluorescent properties of 17a, 28, and 32 were more particularly studied. Interactions of the fluorescent ligand 28 with the h5-HT(4(e)) receptor were indicated using h5-HT(4(e)) receptor transfected C6 glial cell membranes and entire cells. Ligand 28 was also used in fluorescence microscopy experiments in order to label h5-HT(4(e)) receptor transfected C6 glial cells, and subcellular localization of these receptors was more precisely determined using confocal microscopy.     

Facile diversity-oriented synthesis and antitubercular evaluation of novel aryl and heteroaryl tethered pyridines and dihydro-6H-quinolin-5-ones derived via variants of the Bohlmann-Rahtz Reaction

The diversity oriented synthesis of substituted pyridines and dihydro-6H-quinolin-5-ones tethered with aryls and heteroaryls was achieved in very good yields through CeCl(3)·7H(2)O-NaI catalyst via variants of the Bohlmann-Rahtz reaction. β-Enaminones derived from various aryl and heteroaryl methyl ketones were regioselectively reacted with ethyl acetoacetate or 5,5-dimethylcyclohexane-1,3-dione or 4,4-dimethylcyclohexane-1,3-dione and ammonium acetate refluxing in 2-propanol. Applicability of nontoxic cerium catalyst, high reactivity with wide range of aryl and heteroaryl β-enaminones leading to diverse analogues, operational simplicity, and shorter reaction time at comparatively low temperatures are prominent features of the developed protocol. These synthesized substituted pyridines and dihydro-6H-quinolin-5-one analogues have been evaluated for their in vitro antimycobacterial activity against Mycobacterium tuberculosis H37Rv (MTB) by agar dilution method. Among the 48 compounds screened, six compounds 2-(5-chlorothiophen-2-yl)-7,7-dimethyl-7,8-dihydro-6H-quinolin-5-one 4{13,2}, 2-(5-bromothiophen-2-yl)-7,7-dimethyl-7,8-dihydro-6H-quinolin-5-one 4{14,2}, 2-(5-chloro thiophen-2-yl)-6,6-dimethyl-7,8-dihydroquinolin-5(6H)-one 4{13,3}, and 2-(5-bromothiophen-2-yl)-6,6-dimethyl-7,8-dihydroquinolin-5(6H)-one 4{14,3}, 7,7-dimethyl-2-(naphthalen-2-yl)-7,8-dihydroquinoline-5(6H)-one 4{6,2}, 6,6-dimethyl-2-(naphthalen-2-yl)-7,8-di hydroquinolin-5(6H)-one 4{6,3} resulted as the most promising antitubercular agents.