Design and Synthesis of Some Novel 4-(4-substituted aryl) Semicarbazones as Anticonvulsant Agents.

In the present study, a series of 4-(4-substituted aryl) semicarbazones were synthesized from substituted anilines and subsequently evaluated for their anticonvulsant activities. The anticonvulsant activities were established by the anticonvulsant drug development (ADD) programme NIH, USA using experimental animal, adult male FCM mice (20-25 g) and adult Sprague-Dawley rats (100-150 g) and screened against electroshock seizure, subcutaneous metrazole and minimal neurotoxicity tests in mice. Compound 7 was found equipotent to carbamazepine in both MES and ScPTZ tests. This study has highlighted the importance of distal alkyl chain which influences the anticonvulsant activity.

Synthesis, anticonvulsant and CNS depressant activity of some new bioactive 1-(4-substituted-phenyl)-3-(4-oxo-2-phenyl/ethyl-4H-quinazolin-3-yl)-urea.

Several new 1-(4-substituted-phenyl)-3-(4-oxo-2-phenyl/ethyl-4H-quinazolin-3-yl)-urea were synthesized and screened for anticonvulsant, CNS depressant and sedative-hypnotic activity in the mice. After i.p. injection to mice at doses of 30, 100, and 300 mg/kg body weight synthesized compounds were examined in the maximal electroshock induced seizures (MES) and subcutaneous pentylenetetrazole (scPTZ) induced seizure models in mice. Spectroscopic data and elemental analysis were consistent with the newly synthesized compounds. The neurotoxicity was assessed using the rotorod method. Compounds E1, E6, E9, E12, P3, P4 and P6 were found to be active in the MES screen whereas E1, P4, P6 and P11 were found to be active in the scPTZ screen. All except E6, E11 and P6 showed more than 50% decrease in locomotor activity at 1h of compound administration via actophotometer screen. CNS depressant activity screened with the help of the forced swim method resulted into some potent compounds. All the compounds were found to exhibit potent CNS depressants activity as indicated by increased immobility time. It can be concluded that newly synthesized compounds possessed promising CNS activities.

Cyclization of the semicarbazone template of aryl semicarbazones: synthesis and anticonvulsant activity of 4,5-diphenyl-2H-1,2,4-triazol-3(4H)-one.

A new series of 4,5-diphenyl-2H-1,2,4-triazol-3(4H)-one were synthesized to study the effect of cyclization of the semicarbazone moiety of aryl semicarbazones on the anticonvulsant activity. 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 in four animal models of seizures, viz. maximal electroshock seizure (MES), subcutaneous pentylenetetrazole (scPTZ), subcutaneous strychnine (scSTY), and subcutaneous picrotoxin (scPIC)-induced seizure threshold tests. The compounds were also evaluated for neurotoxicity. Compounds 4, 9, 14-19 exhibited anticonvulsant activity in all the four animal models of seizure.

CNS depressant and anticonvulsant activities of some novel 3-[5-substituted 1,3,4-thiadiazole-2-yl]-2-styryl quinazoline-4(3H)-ones.

A series of new 3-[5-substituted phenyl-1,3,4-thiadiazole-2-yl]-2-styryl quinazoline-4(3H)-ones were synthesized and evaluated for anticonvulsant, sedative-hypnotic and CNS depression activities. After i.p. injection to mice or rat at doses of 30, 100, and 300 mg/kg body weight 2-styryl quinazolin-4(3H)-ones derivatives were examined in the maximal electroshock (MES) induced seizures and subcutaneous pentylenetetrazole (scPTZ) induced seizure models in mice. Rotorod method was employed to determine the neurotoxicity. Out of 18 compounds only 4a, 4e and 4p showed anticonvulsant activity in one or more test models. All except 4l and 4q exhibited significant sedative-hypnotic activity via actophotometer screen. Forced swim pool method to determine CNS depressant activity resulted in some potent compounds. It can be concluded that synthesized compounds exhibited better sedative-hypnotic and CNS depressant activities than anticonvulsant activity.

Synthesis and CNS depressant activity of some novel 3-[5-substituted 1,3,4-thiadiazole-2-yl]-2-styryl quinazoline-4(3H)-ones.

A series of novel 3-[5-substituted phenyl-1,3,4-thiadiazole-2-yl]-2-styryl quinazoline-4(3H)-ones were synthesized and evaluated for anticonvulsant, sedative-hypnotic and CNS depressant activities. After i.p. injection to mice at doses of 30, 100, and 300mg/kg body weight 2-styrylquinazolin-4(3H)-one derivatives were examined in the maximal electroshock induced seizures (MES) and subcutaneous pentylenetetrazole (scPTZ) induced seizure models in mice. The neurotoxicity was assessed using the rotorod method. Out of eighteen compounds only 4a, 4d, 4e, 4j and 4k showed anticonvulsant activity in one or more test models. All except 4e and 4f exhibited significant sedative-hypnotic activity via actophotometer screen. CNS depressant activity screened with the help of the forced swim pool method resulted into some potent compounds. From the experimental observation it can be concluded that synthesized compounds exhibited relatively better sedative-hypnotic and CNS depressant activities.

Synthesis and anticonvulsant activity of some novel 3-aryl amino/amino-4-aryl-5-imino-Delta2-1,2,4-thiadiazoline.

A series of 3-aryl amino/amino-4-aryl-5-imino-Delta(2)-1,2,4-thiadiazoline have been synthesized using an appropriate synthetic route and characterized by elemental analyses and spectral data. The anticonvulsant activity of all the synthesized compounds was evaluated against maximal electroshock induced seizures (MES) and subcutaneous pentylenetetrazole (ScPTZ) induced seizure models in mice. The neurotoxicity was assessed using the rotorod method. All the test compounds were administered at doses of 30, 100, and 300 mg/kg body weight and the anticonvulsant activity was noted at 0.5 and 4 h time intervals after the drug administration. Some of the compounds were evaluated for the Phenobarbitone induced hypnosis potentiation test. Among the compounds tested, all except 2h showed protection from MES seizures, whereas only 3b was found to be active in the ScPTZ test.

Quantum mechanical modeling of N4-(2, 5-disubstituted phenyl) semicarbazones: synthesis and anticonvulsant activity of N4-(2, 5-dimethylphenyl/ -2-fluoro-5-methyl phenyl) semicarbazones.

Two new series of N4-(2, 5-disubstitutedphenyl) semicarbazones were synthesized and evaluated for the anticonvulsant activity in various animal models of seizures. Quantum mechanical modeling was carried out on these compounds to understand the structural features essential for activity. The higher the difference in HOMO and LUMO energy levels the greater was the activity profile. Substitution with fluoro group on the ortho position of the aryl ring was found to decrease the reactivity and hence the activity profile of aryl semicarbazones, which has been justified with the molecular orbital surface analysis of the synthesized compounds.

Synthesis and structure-activity relationship on anticonvulsant aryl semicarbazones.

Seven series of various substituted aryl semicarbazones were synthesized and evaluated for anticonvulsant activity in the maximal electroshock seizure (MES) and subcutaneous pentylenetetrazole (scPTZ) induced seizure threshold tests. A comprehensive structure-activity relationship was derived comparing the substituents on the aryl ring and in the carbimino terminal. Generally the order of activity was 4-F > 2-Br = 3-Br = 4-Cl > 4-CH(3) > 4-Br > 3-Cl > 3-CH(3) with respect to the primary aryl group. Most of the compounds exhibited activity both in the MES and scPTZ screens. The 4-fluorophenyl substituted semicarbazones (5a-5y) emerged as the most potent compounds exhibiting anticonvulsant activity in mouse intraperitoneal (i.p.) and rat per oral (p.o.) MES, scPTZ and psychomotor seizure (6 Hz) screens.

Synthesis of aryl semicarbazones as potential anticonvulsant agents.

A series of 4-ethoxyphenyl semicarbazones (1-10) have been synthesized using an appropriate synthetic route and characterized by elemental analyses and spectral data. The anticonvulsant activity of all the synthesized compounds was evaluated against maximal electroshock induced seizures (MES) and subcutaneous pentylenetetrazole (scPTZ) induced seizure models in mice. The neurotoxicity was assessed using the rotorod method. All the test compounds were administered at doses of 30, 100, and 300 mg/kg body weight and the anticonvulsant activity was noted at 0.5 and 4 h time intervals after the drug administration. Among the compounds tested, compounds except 3, 4 and 10 showed protection from seizures in both the animal models. Compounds 6 and 8 were found to increase gamma-aminobutyric acid (GABA) levels in the medulla oblongata region of the rat brain.

Anticonvulsant and neurotoxicity evaluation of some 6-substituted benzothiazolyl-2-thiosemicarbazones.

Various 6-substituted benzothiazolyl-2-thiosemicarbazones were synthesized and screened for anticonvulsant activity in maximal electroshock induced seizure (MES) and subcutaneous pentylenetetrazole (scPTZ) induced seizure models in mice. The neurotoxicity was assessed using the rotorod method. The 6-methyl benzothiazolyl-2-thiosemicarbazones showed anticonvulsant activity in both mice i.p. and rat oral MES screen. The 6-nitro benzothiazolyl thiosemicarbazone derivative 1a emerged as the most promising one with anti-MES activity in mice i.p., rat i.p. and rat p.o. evaluations. All the compounds exhibited lesser or no neurotoxicity compared to phenytoin. The isatinimino derivatives had shown better activity when compared to the benzylidene or acetophenone derivatives.

Anticonvulsants containing the N-(3-aryl-2-propenoyl) amido pharmacophore.

A series of 1-(3-aryl-2-propenoyl)-4-oxopiperidines (1) as well as some related semicarbazones (2) and thiosemicarbazones (3) were prepared in order to determine whether the relative locations of aryl rings and amidic groups would lead to novel anticonvulsant agents. Initially the compounds were administered intraperitoneally to mice and examined in the maximal electroshock (MES), subcutaneous pentylenetetrazole (scPTZ) and neurotoxicity (NT) screens. The biodata revealed that anticonvulsant properties were displayed by most of the compounds in series (1), in half of the semicarbazones (2) while protection was absent by members of series (3). Molecular modeling was utilized in order to compare the positions of a phenyl ring in relation to amidic groups in representative compounds in series (1-3) with previously reported anticonvulsant agents. Molecular simplification of 4-oxo-1-(3-phenyl-2-propenoyl)piperidine (la) led to 1-(3-phenyl-2-propenoyl)piperidine (7) and N,N-diethylcinnamamide (8) with retention of anticonvulsant properties. Both (la) and (8) afforded protection in the hippocampal kindling screen in rats. When administered orally to rats, (la) and (8) demonstrated activity in the MES screen and in the case of (8), a huge protection index was observed revealing it to be an important lead compound. The IC50 values of all of the compounds towards murine P388 cells were in excess of 50 microM while several compounds displayed cytotoxicity towards Mycobacterium tuberculosis.

4-sulphamoylphenyl semicarbazones with anticonvulsant activity.

A series of 4-sulphamoylphenyl semicarbazone derivatives were prepared starting from sulphanilamide and screened for anticonvulsant activity. The results indicated that greater protection was obtained in the maximal electroshock screen (MES) and subcutaneous strychnine (scSTY) than the subcutaneous pentylenetetrazole (scPTZ) tests. All the compounds showed low neurotoxicity when compared to the clinically used drugs. Compounds with substituted acetophenone (8-11) showed good activity in the rat oral MES screen. Seven compounds (6, 8-10, 12, 14 and 15) exhibited anticonvulsant activity greater than sodium valproate. Among the new derivatives evaluated, compound 10 emerged as the most active compound as indicated by its protection in the MES and scSTY screens and with low neurotoxicity. Seven compounds possessed sedative-hypnotic activity.

Cytotoxic and topographical properties of 6-arylidene-2-dimethylaminomethylcyclohexanone hydrochlorides and related compounds.

A number of 2-arylidenecyclohexanones (1a-h) were converted into the corresponding Mannich bases (2a-h) and (3a,f). Evaluation against murine L1210 cells as well as human Molt 4/C8 and CEM T-lymphocytes revealed the marked cytotoxicity of the Mannich bases and also the fact that almost invariably these compounds were more potent than the precursor enones (1a-h). Further evaluation of most of the Mannich bases towards a panel of nearly 60 human tumour cell lines confirmed their utility as potent cytotoxins. In this assay, the compounds showed growth-inhibiting properties greater than the anticancer alkylator melphalan. QSAR studies revealed that in some cell lines compounds possessing small electron-attracting aryl substituents showed the greatest potencies. Molecular modeling and X-ray crystallography demonstrated that various interatomic distances and torsion angles correlated with cytotoxicity. A representative compound (2a) demonstrated weak inhibiting properties towards human N-myristoyltransferase and stimulated a tyrosine protein kinase. A single dose of 100 mg/kg of most of the compounds did not prove to be lethal in mice.

Synthesis and anticonvulsant and neurotoxicity evaluation of N4-phthalimido phenyl (thio) semicarbazides.

The phenyl (thio) semicarbazide derivatives of phthalimido pharmacophore were synthesized and evaluated for their anticonvulsant and neurotoxic properties. Initial anticonvulsant screening was performed using intraperitoneal (i.p.), maximal electroshock-induced seizure (MES), subcutaneous pentylenetetrazole (scPTZ) and subcutaneous strychnine (sc STY)-induced seizure threshold tests in mice. Compound 2c afforded protection in all the three screens. Compounds except 1d, 2a and 2d showed no neurotoxicity up to 300 mg/kg. Compounds 1a, 1b, 2c, 2d, 2g and 2i were found to show oral MES activity. The compounds exhibited CNS depression and behavioral despair side effects, lesser than the conventional antiepileptic drugs.

3,5-bis(phenylmethylene)-1-(N-arylmaleamoyl)-4-piperidones: a novel group of cytotoxic agents.

A series of novel 3,5-bis(phenylmethylene)-1-(N-arylmaleamoyl)-4-piperidones 3 have been synthesized which displayed potent cytotoxicity towards human Molt 4/C8 and CEM T-lymphocytes as well as murine P388 and L1210 leukemic cells. In contrast, the related N-arylmaleamic acids 4 possessed little or no cytotoxicity in these four screens. Molecular modeling revealed certain interplanar and bond angles and interatomic distances which were perceived to contribute to the observed bioactivity as well as providing suggestions for future structural modifications of the piperidones 3. Evaluation of representative compounds in series 3 and 4 on the activity of human N-myristoyltransferase revealed that, at the maximum concentration utilized, namely 250 microM, only weak inhibiting properties were displayed by some of the compounds in series 4. Various members of series 3 and 4 were well tolerated in mice.

Cytotoxic 4'-aminochalcones and related compounds.

A series of 4'-aminochalcones 1 and related maleamic acids 2 and Schiff bases 3 were designed and synthesized as candidate cytotoxic agents. The atomic charges on different atoms of representative compounds were calculated. Evaluation of the enones 1-3 against human Molt 4/C8 and CEM T-lymphocytes as well as murine P388 and L1210 leukemic cells revealed that approximately 40% of the IC50 values generated were less than 10 microM. In some cases cytotoxicity was correlated with the Hammett sigma values of the aryl substituents and less frequently with the aryl Hansch pi values. Evidence was obtained that in general these compounds displayed selective toxicity for certain malignant cells and were well tolerated in mice. This study has revealed various directions whereby the project may be amplified in the future with a view to finding compounds with increased cytotoxicity to tumour cells.

Are certain diuretics also anticonvulsants?

A history of diuretic use has been shown to be protective for first unprovoked seizure in adult patients. Recent animal studies suggest that certain diuretics have anticonvulsant activity. We evaluated the potential for the anticonvulsant activity of current diuretic use in a population-based, case-control study in older adults. We also tested chlorthiazide and furosemide for seizure protection in animal models of epilepsy. Concurrent medical prescription of any diuretic was protective for the development of epilepsy [odds ratio (OR) = 0.62, 95% confidence interval (CI) = 0.39-0.99]. A protective effect for current thiazide use was observed (OR = 0.53, CI = 0.31-0.90), and a protective effect for furosemide was suggested (OR = 0.44, CI = 0.1-1.9). In mice, both chlorthiazide and furosemide suppressed the occurrence of maximal electroshock-induced seizures in a dose-dependent manner. Chlorthiazide's toxic dose for 50% of animals tested (TD50) could not be achieved even with dosing as high as 1,500 mg/kg for furosemide; TD50 was 549 mg/kg. Results were similar in rats. Furosemide and chlorthiazide are protective for unprovoked seizures in an epidemiological study and in animal models. Given the potential therapeutic value for seizure control, low toxicity, and low cost, therapeutic efficacy should be explored in clinical studies.

Functionalized amino acid anticonvulsants: synthesis and pharmacological evaluation of conformationally restricted analogues.

Proven conformationally restricted analogues of anticonvulsant functionalized amino acids (FAAs) were prepared using short-range cyclizations and evaluated in pharmacological assays providing new information concerning the structural requirements for FAA function.

Synthesis of some 1-(2-naphthyl)-2-(imidazole-1-yl)ethanone oxime and oxime ether derivatives and their anticonvulsant and antimicrobial activities.

In this study, oxime and oxime ether derivatives of anticonvulsant nafimidone [1-(2-naphthyl)-2-(imidozole-1-yl)ethanone] were prepared as potential anticonvulsant compounds. Nafimidone oxime was synthesized by the reaction of nafimidone and hydroxylamine hydrochloride. O-Alkylation of the oxime by various alkyl halides gave the oxime ether derivatives. Anticonvulsant activity of the compounds was determined by maximal electroshock (MES) and subcutaneous metrazole (scMet) tests in mice and rats according to procedures of the Antiepileptic Drug Development (ADD) program of the National Institutes of Health (NIH). In addition to anticonvulsant evaluation, compounds were also screened for possible antibacterial and antifungal activities because of the structural resemblance to the azole antifungals, especially to oxiconazole. All compounds were evaluated against three human pathogenic fungi and four bacteria using the microdilution method. Most of the compounds exhibited both anticonvulsant and antimicrobial activities; the O-alkyl substituted compounds (2, 3, 4 and 5) were found to be more active than the O-arylalkyl substituted compounds in both screening paradigms.

Amino acid derivatives with anticonvulsant activity.

A series of benzylamides of N-alkylated, N-acylated or free nine cyclic and one linear amino acids as potential anticonvulsants have been synthesized. The structures of the obtained compounds were designed on the basis of the previously determined structure and physicochemical properties/anticvonvulsant activity relationship of the formerly synthesized compounds of this type. The obtained compounds were evaluated in mice after intraperitoneal (i.p.) administration, by maximal electroshock seizure test (MES test), subcutaneous (s.c.) pentylenetetrazol test (s.c. PTZ test) and by the rotarod neurotoxicity test (Tox test). The results were the basis for their classification into one of three classes of the Anticonvulsant Screening Project (ASP) of the Antiepileptic Drug Development Program (ADDP) of the NIH. Three selected compounds were tested quantitatively in rats after oral administration. The MES ED50, s.c. PTZ ED50, Tox TD50 were determined and their protective index (PI) values were calculated. Anticonvulsant activity of the most promising compound (15) was examined in different seizure models. The respective ED50 and PI values of this compound were as follows: against bicuculline, 73 and 1.4; against PTZ, 47 and 2.2; against strychnine, 73 and 1.4; against pilocarpine 156, and 0.7; against kainic acid (2-carboxy-4-isopropenyl-3-pyrrolidineacetic acid), 39 and 2.6; against AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid), 10 and 10.3 and against NMDA (N-methyl-D-Aspartic acid), 114 and 0.9.