Synthesis and CLOGP correlation of imidooxy anticonvulsants

Development of novel indole-linked pyrazoles as anticonvulsant agents: A molecular hybridization approach

A series of 3-{2-[1-acetyl-5-(substitutedphenyl)-4,5-dihydropyrazol-3-yl]hydrazinylidene}-1,3-dihydro-2H-indol-2-ones 24-43 was synthesized using an appropriate synthetic route and evaluated experimentally by the maximal electroshock test. These compounds were evaluated for antidepressant and antianxiety activities. The most active compound, 3-{2-[1-acetyl-5-(4-chlorophenyl)-4,5-dihydropyrazol-3-yl]hydrazinylidene}-1,3-dihydro-2H-indol-2-one 25, exhibited an ED₅₀ of 13.19 mmol/kg, a TD₅₀ of 43.49 mmol/kg, and a high protective index of 3.29, compared with the standard drug diazepam. To get insights into the intermolecular interactions, molecular docking studies were performed at the active site of the GABA_A receptor and the MAO-A enzyme. Molecular docking studies are also in agreement with the pharmacological evaluation with potent compounds, exhibiting docking scores of -1.5180 and 0.7458 for the GABA_A receptor and MAO-A, respectively. The 3D-QSAR analysis was carried out by Vlife MDS engine 4.3.1, and a statistically reliable model with good predictive power (r²  = 0.7523, q²  = 0.3773) was achieved. The 3D-QSAR plots gave insights into the structure-activity relationship of these compounds, which may aid in the design of potent benzopyrrole derivatives as anticonvulsant agents. So, our research can make a great impact on those medicinal chemists who work on the development of anticonvulsant agents.

Synthesis, Characterization and Anticonvulsant Activity of Novel Fused 1,2,4-Triazolo-1,3,4-Thiadiazoles

A novel category of 1,2,4-triazolo-1,3,4-thiadiazoles were ready by the utilization of 3-amino-4-hydroxybenzoate as the beginning material. Spectral information results were used for the establishing of prepared compounds. Compounds were screened anticonvulsant activity for obtaining better results by MES test and scPTZ methods. The rotarod method was used for neurotoxicity analysis. Majority of the compounds displayed distinguished anticonvulsant impact practically identical to standard drugs (phenytoin and carbamazepine) with slight neurotoxicity.

5,6-Dihydropyrimidine-1(2H)-carbothioamides: Synthesis, in vitro GABA-AT screening, anticonvulsant activity and molecular modelling study

Even after considerable advances in the field of epilepsy treatment, convulsions are inefficiently controlled by standard drug therapy. Herein, a series of pyrimidine-carbothioamide derivatives 4(a-t) was designed as anticonvulsant agents by doing some important structural modifications in well-known anticonvulsant drugs. Two classical animal models were used for the in vivo anticonvulsant screening, maximum electroshock seizure (MES) and subcutaneous pentylenetetrazole (scPTZ) models; followed by motor impairment study by rotarod method. The most active compound 4g effectively suppressed seizure effect in both the animal models with median doses of 15.6 mg/kg (MES ED₅₀), 278.4 mg/kg (scPTZ ED₅₀) and 534.4 mg/kg (TD₅₀) with no sign of neurotoxicity. Furthermore, in vitro GABA-AT enzyme activity assay of 4g showed inhibitory potency (IC₅₀) of 12.23 μM. The docking study also favored the animal studies.

Synthesis, Biological Activity, and Docking Study of Novel Isatin Coupled Thiazolidin-4-one Derivatives as Anticonvulsants

A series of 2-(substituted-phenyl)-3-(2-oxoindolin-3-ylidene)amino)-thiazolidin-4-one derivatives were designed and synthesized under microwave irradiation, using an eco-friendly, efficient, microwave-assisted synthetic protocol that involves cyclocondensation of 3-substituted benzylidine-hydrazono-indolin-2-one 3a-j with thioglycolic acid in dimethyl formamide (DMF) as solvent and anhydrous zinc chloride as a catalyst, keeping in view the structural requirement of the pharmacophore. The intermediate compounds 3a-j were obtained by condensation of the hydrazone of indoline-2,3-dione with aromatic aldehydes. The synthesized derivatives were evaluated for CNS depressant activity and anticonvulsant activity in mice using the maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (sc-PTZ) induced seizure tests. All the derivatives showed good CNS depressant activity and showed protection in the MES test, indicative of their ability to inhibit the seizure spread. A histopathological study was performed to evaluate liver toxicity caused by the synthesized compounds. The compounds were nontoxic. A computational study was performed, in which log P values were calculated experimentally. Virtual screening was performed by molecular docking of the designed compounds into the ATP binding sites of the NMDA and AMPA receptors, to predict if these compounds have analogous binding modes.

Microwave assisted synthesis and docking study of N-(2-oxo-2-(4-oxo-2-substituted thiazolidin-3ylamino)ethyl)benzamide derivatives as anticonvulsant agents

Herewith, we report the design and synthesis of a series of N-(2-oxo-2((4-oxo-2-substituted thiazolidin-3yl)amino)ethyl) benzamide derivatives 7(a-j) under microwave irradiation, based on four component pharmacophoric model to get structural prerequisite indispensable for anticonvulsant activity. The synthesized derivatives were investigated in maximal electroshock seizure (MES), subcutaneous pentylenetetrazole (sc-PTZ) induced seizure and neurotoxicity screening. All the test compounds were administered at a dose of 30, 100 and 300 mg/kg body weight at the time interval of 0.5 h and 4 h. The compounds were also evaluated for behavioral activity and toxicity study. The compound 7 h was found to be most active in MES model. The anticonvulsant screening data shows that 65% of the compounds were found active against MES model when compared to 35% sc-PTZ model. The computational parameter such as docking study, logP determination and ADME prediction were performed to exploit the results.

Synthesis, anticonvulsant properties, and SAR analysis of differently substituted pyrrolidine-2,5-diones and piperidine-2,6-diones

Twenty-two differently substituted 1H-isoindole-1,3(2H)-diones (30-39), 8-azaspiro[4.5]decane-7,9-diones (40-45), and 3-azaspiro[5.5]undecane-2,4-diones (46-51) were synthesized and tested for anticonvulsant activity. These molecules were designed as analogs of previously obtained azaspirosuccinimides (1-24). Initial anticonvulsant screening was performed in mice using the maximal electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure tests. The acute neurological toxicity was determined applying the minimal motor impairment rotorod test. The preliminary pharmacological results showed that 15 new compounds were effective in at least one animal model of epilepsy, from which nine molecules showed protection against both MES and scPTZ seizures. The structure-activity relationship analysis revealed that anticonvulsant activity was connected closely with the structure of the imide fragment; the most favorable one was the hexahydro-1H-isoindole-1,3(2H)-dione core. 2-(2-Chlorophenyl)hexahydro-1H-isoindole-1,3(2H)-dione (31) showed activity in the 6-Hz psychomotor seizure model, which identifies substances effective in partial and therapy-resistant epilepsy. 3-[(4-Chlorophenyl)amino]-3-azaspiro[5.5]undecane-2,4-dione (47) was active in the in vitro hippocampal slice culture neuroprotection assay.

Synthesis and antimicrobial activity of novel quinazolinone–thiazolidine–quinoline compounds

A series of 2-(2-chloroquinolin-3-yl)-5-((aryl)benzylidene)-3-(4-oxo-2-phenylquinazolin-3(4H)-yl)thiazolidin-4-ones (V)_1–12 have been synthesized. In order to establish optimization of different parameters of chemical transformation, that is the reaction pathway for each step and reaction conditions in the each step, in the present paper, different solvents and catalysts were used. The structures of the synthesized compounds were assigned on the basis of elemental analysis, IR, ¹H NMR and ¹³C NMR spectral data. All the newly synthesized compounds were screened against various strains of bacteria and fungi.

Synthesis and anticonvulsant properties of 1-(amino-N-arylmethanethio)-3-(1-substituted benzyl-2, 3-dioxoindolin-5-yl) urea derivatives

Various 1-(amino-N-arylmethanethio)-3-(1-substituted benzyl-2, 3-dioxoindolin-5-yl) urea (5a-p) were designed keeping in view the structural requirements suggested in the pharmacophore model for anticonvulsant activity. Their in vivo anticonvulsant screenings were performed by two most adopted seizure models, maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (scPTZ). Compound 5f was found active in MES screening while compounds 5h, 5i, 5k and 5l showed significant anticonvulsant activity in both the screenings and were devoid of any neurotoxicity. Compound 5h and 5i showed marked protection at 300 mg/kg against MES and scPTZ screening. Compound 5i also showed protection against MES screening at the dose of 100 mg/kg. In 6 Hz screening these two compounds showed significant protection and emerged as lead compounds for future investigations.

Synthesis of benzothiazole semicarbazones as novel anticonvulsants—The role of hydrophobic domain

A series of 1,3-benzothiazol-2-yl semicarbazones (1-15) were prepared in satisfactory yield and evaluated for their anticonvulsant, neurotoxicity and other toxicity studies. All the synthesized compounds were in good agreement with elemental and spectral data. Majority of the compounds were active in MES screen. Selected compounds were checked for their lipophilic character.

Synthesis, physicochemical and anticonvulsant properties of new N-phenylamino derivatives of 2-azaspiro[4.4]nonane- and [4.5]decane-1,3-diones: part V

The synthesis, physicochemical and pharmacological properties of new N-phenylamino derivatives of 2-azaspiro[4.4]nonane-1,3-dione (8-10), 2-azaspiro[4.5]decane-1,3-dione (11-18) and 3-cyclohexyl-pyrrolidine-2,5-dione (19, 20) derivatives were described. The anticonvulsant properties of those compounds were examined by a maximal electroshock (MES) and a pentylenetetrazole (scPTZ) tests, and their neurotoxicity was determined using a rota-rod test. The most active was N-[(2,4-dichlorophenyl)-amino]-2-azaspiro[4.4]nonane-1,3-dione (9), which exhibited anti-seizure properties in the MES model at a dose of 100mg/kg in mice and at a dose of 30mg/kg in rats. To explain the possible mechanism of action, for chosen active derivatives N-[(2,4-dichlorophenyl)-amino]-2-azaspiro[4.4]nonane-1,3-dione (9), N-[(4-bromophenyl)-amino]-2-azaspiro[4.4]nonane-1,3-dione (10), N-[(2,4-dichlorophenyl)-amino]-2-azaspiro[4.5]decane-1,3-dione (12) and N-[(4-bromophenyl)-amino]-2-azaspiro[4.5]decane-1,3-dione (13) their influence on GABA(A) receptors were tested in vitro. Moreover, for all compounds obtained the lipophilic properties were determined by use of RP-HPLC method.

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

The synthesis, physicochemical and pharmacological properties of new N-[(4-arylpiperazin-1-yl)-alkyl]-2-azaspiro[4.4]nonane- (8a-c, 10a-d) and [4.5]decane-1,3-dione (9a-c, 11a-d) derivatives were described. The antiepileptic effects of those compounds were examined by a maximal electroshock (MES) and a pentylenetetrazole (sc. PTZ) tests, and their neurotoxicity was determined using a rota-rod test. Compounds 8c, 9c, 10c, d, 11c, d with a CF(3) group at the 3-position of the 4-arylpiperazine fragment exhibited anti-seizure properties in the MES model; in contrast, their 2-CH(3) and 2-OCH(3) analogues were inactive in both the tests used. Moreover, since the investigated compounds belong to the class of long-chain arylpiperazines, their serotonin 5-HT(1A) and 5-HT(2A) receptor affinity was determined. The relationship between the length of alkylene spacer and 5-HT(1A)/5-HT(2A) receptor activity was observed. Compounds with an ethylene and a propylene bridge (10a-d and 11a-d) were 3-80-fold more potent (K(i) ranged from 3.1 to 94 nM for 5-HT(1A) and 32-465 nM for 5-HT(2A)) than their methylene analogues (8a-c and 9a-c; K(i) ranged from 81 to 370 nM for 5-HT(1A) and 126-1370 nM for 5-HT(2A)). The highest 5-HT(1A) receptor affinity was displayed by 2-OCH(3) and 3-CF(3) phenyl derivatives (10b, 11b: K(i)=6.8 and 5.7 nM, respectively, and 10c, 11c: K(i)=6.0 and 3.1 nM, respectively), while in the case of 5-HT(2A) receptor the highest affinity was observed for the 3-CF(3) phenyl derivatives 10c, d, 11c, d (K(i) ranged from 32 to 86 nM).

Enaminones 9. Further studies on the anticonvulsant activity and potential type IV phosphodiesterase inhibitory activity of substituted vinylic benzamides

Structure-activity relationship studies were employed to synthesize a series of 3- and 3,4-substituted benzamides from 3-amino-2-cyclohexenones. An improved method for the synthesis of benzamides from 3-amino-2-cyclohexenones is presented which provided significantly higher yields (71-79%) for the reported compounds. NMR and X-ray structural analyses were undertaken to note the possible intra- and intermolecular interactions of the synthesized analogs. Molecular modeling studies were used to determine the minimized configuration and were compared to their X-ray structures for correlation. These new entities were evaluated as potential anticonvulsants and type IV phosphodiesterase inhibitors (PDE4).

Synthesis, physicochemical and anticonvulsant properties of N-benzyl and N-aminophenyl derivatives of 2-azaspiro[4.4]nonane and [4.5]decane-1,3-dione. Part I

To continue our systematic SAR studies, two series of N-benzyl- (X=CH2) and N-aminophenyl- (X=NH) derivatives of 2-azaspiro[4.4]nonane (1a-1j) and 2-azaspiro[4.5]decane-1,3-dione (2a-2j) were synthesized, and evaluated in maximum electroshock seizure (MES), subcutaneous pentylenetetrazole (sc.MET) and rotorod (TOX) tests for their anticonvulsant activity. Among those derivatives, the most potent N-aminophenyl-2-azaspiro[4.4]nonane-1,3-dione 1j had ED50=76.27 mg kg-1. X-ray structures for two pairs of derivatives with a different linker were solved. Then 3-D data for the active 1j versus less active 2j, both having an imine linker (X=NH), and the respective parent of compounds with a methylene linker (X=CH2) (1a and 2a) were discussed.

Anticonvulsant activity of phenylmethylenehydantoins: a structure-activity relationship study

Phenylmethylenehydantoins (PMHs) and their des-phenyl analogues were synthesized and evaluated for anticonvulsant activity using the maximal electroshock seizure (MES) assay. The phenyl rings of PMHs were substituted with a wide spectrum of groups, and the selection of substituents was guided by Craig's plot. Phenylmethylenehydantoins substituted with alkyl (2, 3, 5, 6, 12, 14), halogeno (35, 38, 41), trifluoromethyl (11), and alkoxyl (23) groups at the phenyl ring were found to exhibit good anticonvulsant activity with ED(MES(2.5)) ranging from 28 to 90 mg/kg. Substitution of polar groups such as -NO(2), -CN, and -OH was found to be less active or inactive on PMHs. Replacement of the phenyl ring with heteroaromatic rings reduced or caused the loss of anticonvulsant activity. The study identified two PMHs, 14 (ED(MES(2.5)) = 28 +/- 2 mg/kg) and 12 (ED(MES(2.5)) = 39 +/- 4 mg/kg), to be the most active candidates of the series, which are comparable to phenytoin (55, ED(MES(2.5)) = 30 +/- 2 mg/kg) in their protection against seizure. Multivariate analysis performed on the whole series of 54 PMHs further supported the finding that the alkylated phenylmethylenehydantoins are the best acting compounds. The SAR model derived on the basis of 12 of the most active phenylmethylenehydantoins demonstrated good predicting ability (root-mean-square error of prediction (RMSEP) = 0.134; RMSEE = 0.057) and identified LUMO energy and the log P as critical parameters for their anticonvulsant activity.

Nuclear magnetic resonance studies of anticonvulsant enaminones

1H nuclear magnetic resonance (NMR) spectra of enaminones were determined and compared to the anticonvulsant activity of the compounds. Although the precise employment of the NMR data to predict anticonvulsant activity of the enaminones could not be established, general inferences were made. The NMR data confirmed that the enaminones existed predominantly in the amino tautomer, and no evidence was found for the imino tautomer. The ketamine form of the enaminones was supported by the observed spin-spin splittings of the NH with the alpha-protons on certain enaminones. The NH of secondary enaminones was very important in conferring anticonvulsant activity to the enaminones. The peak for the NH proton which could be seen between delta (ppm) 4.50 and 9.70 was present in all of the active enaminones. The tertiary enaminones, which were devoid of the NH proton, were uniformly inactive. It appeared that a combination of steric and electronic effects, lipophilicity, and hydrogen bonding were necessary for the anticonvulsant activity of the enaminones. The cyclic enaminones existed in the trans-S-trans fixed conformation, and the NMR data supported our hypothesis that enantioselectivity is retained in synthesizing enaminones from cyclic, diasteriomeric 1,3-diketones. In addition, the AB system and many unique features were observed in some enaminones. The para, meta, and ortho substituted patterns were observed for monosubstituted phenyl protons, and the NMR patterns for di- and trisubstituted phenyl groups were elucidated.