Design,Synthesis, and Anticonvulsant Activity Evaluation of 4‐(3‐Alkoxy‐phenyl)‐2,4‐dihydro‐[1,2,4]triazol‐3‐ones

A series of 4‐(3‐alkoxy‐phenyl)‐2,4‐dihydro‐[1,2,4]triazol‐3‐ones were synthesized using the appropriate synthetic route and evaluated experimentally in the maximal electroshock test; their neurotoxicities were evaluated by the rotarod neurotoxicity test. The structures of these compounds were confirmed by IR, MS, ¹H‐NMR, and elementary analysis. All target compounds exhibited anticonvulsant activity to varying degrees in the maximal electroshock test. 4‐(3‐Benzyloxy‐phenyl)‐2,4‐dihydro‐[1,2,4]triazol‐3‐one ( 4i ) was the most promising compound with an ED₅₀ value of 30.5 mg/kg and a protective index (PI) of 18.63, showing a higher safety than the standard carbamazepine (PI = 6.45). In addition, the potency of compound 4i against seizures induced by pentylenetetrazole and 3‐mercaptopropionic acid suggested its broad‐spectrum activity, and the mechanisms of action including inhibition of voltage‐gated ion channels and modulation of GABAergic activity might be involved in its anticonvulsant activity.     

Synthesis and Anticonvulsant Activity of New N‐(Alkyl/Sub‐stituted aryl)‐N′‐[4‐(5‐cyclohexylamino)‐1,3,4‐thiadiazole‐2‐yl)phenyl]thioureas

A series of novel thiourea derivatives carrying the 5‐cylohexylamino‐1,3,4‐thiadiazole moiety was synthesized and their anticonvulsant activity was evaluated. Structures of the synthesized compounds have been confirmed by IR, ¹H‐NMR, and elemental analysis. All of the compounds were administered at a dose of 50 mg/kg. Some of the active compounds have different effects in pentylenetetrazole (PTZ) and maximal electroshock (MES) tests, indicating the therapeutical potential in petit mal seizures, but not in grand mal seizures. Compounds 10 , 11 , 13 , and 14 carrying 2‐methylphenyl, 4‐chlorophenyl, allyl, and 4‐methylphenyl on the thiourea pharmacophore, increased the survival rate in the PTZ model. The ED₅₀ values of the active compounds 10 , 11 , 13 , and 14 were found 68.42, 43.75, 18.75 and 25 mg/kg, respectively.     

Synthesis and Anticonvulsant Activity Evaluation of 5‐Phenyl‐[1,2,4]triazolo[4,3‐c]quinazolin‐3‐amines

In the present study we describe the syntheses and anticonvulsant activity evaluation of 5‐phenyl‐[1,2,4]triazolo[4,3‐c]quinazolin‐3‐amine derivatives. Their anticonvulsant activity and neurotoxicity were evaluated by the maximal electroshock seizure test (MES) and the rotarod test, respectively. The majority of the compounds prepared were effective in the MES screens at a dose level of 100 mg/kg. Of these compounds, the most promising was compound 8h , which showed an ED₅₀ value of 27.4 mg/kg and a protective index (PI) value of 5.8. These values were superior to those provided by valproate (ED₅₀ and PI values of 272 and 1.6, respectively) in the MES test in mice. As well as its anti‐MES efficacy, the potencies of compound 8h against seizures induced by pentylenetetrazole and thiosemicarbazide were also established, with the results suggesting that the GABAergic system‐mediated mechanisms might be involved in its anticonvulsant activity.     

Synthesis and Anticonvulsant Activity of 5‐Phenyl‐[1,2,4]‐triazolo[4,3‐a]quinolines

A series of novel 5‐phenyl‐[1,2,4]‐triazolo[4,3‐a]quinoline derivatives was synthesized by the cyclization of 2‐chloro‐4‐phenyl‐1,2‐dihydronaphthalene with formohydrazide. The starting material 2‐chloro‐4‐phenyl‐1,2‐dihydronaphthalene was synthesized from ethyl‐3‐oxo‐3‐phenylpropanoate and substituted aniline. Their anticonvulsant activities were evaluated by the maximal electroshock (MES) test and their neurotoxicity was evaluated by the rotarod neurotoxicity test (Tox). The maximal electroshock test showed that 7‐hexyloxy‐5‐phenyl‐[1,2,4]‐triazolo[4,3‐a]quinoline 4f was found to be the most potent compound with an ED₅₀ value of 6.5 mg/kg and a protective index (PI = ED₅₀ / TD₅₀) value of 35.1, which was much higher than the PI of the reference drug phenytoin.     

Synthesis and anticonvulsant evaluation of 3-substituted-4-(4-hexyloxyphenyl)-4H-1,2,4-triazoles

A series of 3-substituted-4-(4-hexyloxyphenyl)-4H-1,2,4-triazole derivatives (3a-s) were synthesized as open-chain analogues of 7-hexyloxyl-4,5-dihydro-[1,2,4]triazolo[4,3-a]quinolines (1c) using 4-hexyloxyaniline, acyl hydrazines, and dimethoxy-N,N-dimethylmethanamine as the starting material. Their anticonvulsant activities were evaluated by the maximal electroshock test (MES test) and their neurotoxicity was evaluated by the rotarod neurotoxicity test (Tox). MES test showed that all open-chain compounds exhibited strong anticonvulsant activity and lower neurotoxicity, and that some possessed obviously stronger activity than compound 1c. Compound 3d, 3-propyl-4-(4-hexyloxyphenyl)-4H-1,2,4-triazole was found to be the most potent with an ED₅₀ value of 5.7 mg/kg and protective index (PI = TD₅₀/ED₅₀) value of 11.5, which was much greater than that of the prototype drug phenytoin (PI = 6.9).     

Synthesis and Anticonvulsant Activity of N‐(2‐Hydroxy‐ethyl)amide Derivatives

A series novel of N‐(2‐hydroxyethyl)amide derivatives was synthesized and screened for their anticonvulsant activities by the maximal electroshock (MES) test, and their neurotoxicity was evaluated by the rotarod test (Tox). The maximal electroshock test showed that N‐(2‐hydroxyethyl)decanamide 1g , N‐(2‐hydroxyethyl)palmitamide 1l , and N‐(2‐hydroxyeth‐yl)stearamide 1n were found to show a better anticonvulsant activity and also had lower toxicity than the marked anti‐epileptic drug valproate. In the anti‐MES potency test, these compounds exhibited median effective doses (ED₅₀) of 22.0, 23.3, 20.5 mg/kg, respectively, and median toxicity doses (TD₅₀) of 599.8, >1000, >1000 mg/kg, respectively, resulting in a protective index (PI) of 27.5, >42.9, >48.8, respectively. This is a much better protective index than that of the marked anti‐epileptic drug valproate (PI = 1.6). To further investigate the effects of the anticonvulsant activity in several different models, compounds 1g , 1l , and 1n were tested having evoked convulsions with chemical substances, including pentylenetetrazloe, isoniazide, 3‐mercaptopropionic acid, bicuculline, thiosemicarbazide, and strychnine.     

Synthesis of some 3-(arylalkylthio)-4-alkyl/aryl-5-(4-aminophenyl)-4H-1,2,4-triazole derivatives and their anticonvulsant activity

A series of novel 3-[[(substituted phenyl)methyl]thio]-4-alkyl/aryl-5-(4-aminophenyl)-4H-1,2,4-triazoles 11-20 and several related Schiff's bases, 3-[[(substituted phenyl)-methyl]thio]-4-alkyl/aryl-5-[[[(substituted phenyl/5-nitro-2-furyl)methylene]amino]-phenyl]-4H-1,2,4-triazoles 21-31 were synthesized for evaluation of their biological properties. Structures of the synthesized compounds were confirmed by the use of their spectral data besides elemental analysis. All compounds were evaluated for their anticonvulsant activity by maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) and neurotoxicity (NT) screens. A number of triazole derivatives, exhibited protection after intraperitoneal administration at the dose of 100 and 300 mg/kg in one or both models employed. Compounds 12, 13 and 14 were subjected to oral MES screening in rats at 30 mg/kg and were observed to protect 50% of the animals employed in the experiment. Antimicrobial and antituberculosis activity of these compounds 11-31 were also screened. Some of the tested compounds showed marginal activity against M. tuberculosis H37 Rv.     

Synthesis of 8-alkoxy-4,5-dihydro-[1,2,4]triazole[4,3-a]quinoline-1-ones and evaluation of their anticonvulsant properties

A series of 8-alkoxy-4,5-dihydro-[1,2,4]triazole[4,3-a]quinoline-1-one derivatives were synthesized using 7-hydroxy-3,4-dihydro-2(1H)-quinolone as the starting material. Their anticonvulsant activities were evaluated by the maximal electroshock test (MES) and the subcutaneous pentylenetetrazole test (sc-PTZ), and their neurotoxicities were measured by the rotarod neurotoxicity test (Tox). The tests demonstrated that 8-hexyloxy-4,5-dihydro-[1.2.4]triazole[4.3-a]quinoline-1-one (4e) and 8-heptyloxy-4,5-dihydro-[1,2,4] triazole[4,3-a]quinoline-1-one (4f) were the most potent anticonvulsants, with 4e having ED50 values of 17.17 mg/kg and 24.55 mg/kg and protective index (PI = TD50/ED50) values of 41.9 and 29.3 in the MES and sc-PTZ tests, respectively, and 4f having ED50 values of 19.7 mg/kg and 21.2 mg/kg and PI values of 36.5 and 33.9 in the MES and sc-PTZ tests, respectively. The PI values of 4e and 4f were many fold better than that of the marketed drugs phenytoin, carbamazepine, phenobarbital and valproate, which have PI values in the range of 1.6-8.1 in the MES test and < 0.22-5.2 in the sc-PTZ test. Structure-activity relationships were also discussed.     

Synthesis and Antitubercular Screening of [(2‐Chloroquinolin‐3‐yl)methyl] Thiocarbamide Derivatives

A series of 1‐(substituted‐phenyl)‐1‐[(2‐chloroquinolin‐3‐yl)methyl]thiocarbamide and 1‐(substituted‐phenyl)‐1‐[(2‐chloroquinolin‐3‐yl)methyl]methylthiocarbamide derivatives was synthesized as antitubercular agent. The structure of quinolinyl amines and their thiocarbamide derivatives were established on the basis of IR, ¹H and ¹³C‐NMR and mass spectral data. All the compounds were tested in vitro for antimycobacterial activity against Mycobacterium tuberculosis (ATCC‐25177) in Lowenstein‐Jensen medium by well diffusion method and MIC by twofold serial dilution method. Results of the antitubercular screening revealed that compounds showed moderate to good antitubercular activity. Compound having two halogens in the phenyl rings viz. 3g , 3h , 4g, and 4h exhibited MIC of 50 μg/mL. The computational parameters relevant to absorption and permeation of target compounds were also calculated and found to be well correlated with antitubercular activity.     

Synthesis and Pharmacological Investigation of 2‐(4‐Dimethylaminophenyl)‐3,5‐disubstituted thiazolidin‐4‐ones as Anticonvulsants

A new series of 2‐(4‐dimethylaminophenyl)‐3‐substituted thiazolidin‐4‐one‐5‐yl‐acetyl acetamides/benzamides were synthesized by the nucleophilic substitution of 3‐substituted‐2‐(4‐dimethylaminophenyl)‐thiazolidin‐4‐one‐5‐yl‐acetylchloride with acetamide and benzamide. The starting material 3‐substituted‐2‐(4‐dimethylaminophenyl)‐thiazolidin‐4‐one‐5‐yl‐acetylchloride was synthesized from 3‐substituted‐2‐(4‐dimethylaminophenyl)‐thiazolidin‐4‐one‐5‐yl‐acetic acid, which in turn was prepared by one‐pot reaction of amino component, p‐dimethylamino benzaldehyde and mercapto succinic acid. The title compounds were investigated for their anticonvulsant activities; among the test compounds, compound 2‐(4‐dimethylaminophenyl)‐3‐phenylamino‐thiazolidine‐4‐one‐5‐yl‐acetylbenzamide ( 14 ) emerged as the most active compound of the series and as moderately more potent than the reference standard diazepam.     

Synthesis,In Vitro Cytotoxicity and Radiosensitizing Activity of Novel 3‐[(2,4‐Dinitrophenylamino)Alkyl] Derivatives of 5‐Fluorouracil

Previously, it was reported that 3[3‐(2,4‐dinitrophenylamino)‐propyl]‐5‐fluorouracil 8c unlike its components 5‐fluorouracil (5‐FU) 6 and 2,4‐dinitroaniline 2 in HT‐29 cells under aerobic conditions had no cytotoxicity but showed radiosensitizing activity. In this study several analogues of 8c differing in the number of linking methylene groups were prepared and tested for in vitro cytotoxicity and radiosensitizing activity under both aerobic and hypoxic conditions. Tethered compound 8a was prepared in one pot by the reaction of 5‐FU 6 with paraformaldehyde and 2,4‐dinitroaniline 2 in the presence of the concentrated hydrochloric acid, and compounds 8b–f were prepared by the reaction of N‐(bromoalkyl) ‐ 2,4‐dinitrobenzeneamines 5b–f with 1‐(t‐butoxycarbonyl)‐5‐fluorouracil 7 followed by hydrolysis of the protecting group. The cytotoxicity of the tested compounds were measured by 3‐(4,5‐Dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide (MTT), and propidium iodide (PI)‐digitonin assays and values of sensitization enhancement ratio (SER) as a measure of the radiosensitizing activity were measured from radiation survival curves in the absence and presence of each sensitizer for 37% survival respectively. Results showed that tethered compounds 8a–f induced time‐ and concentration‐dependent cytotoxicity under hypoxia but had no significant effect under aerobic conditions. These compounds also showed selective and concentration‐dependent radiocytotoxicity under hypoxic conditions.