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

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.

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 ED(50) value of 69.89mg/kg in rats. The median toxic dose (TD(50)) was 500mg/kg, providing compound 15 with a protective index (TD(50)/ED(50)) of 7.15 in the MES test.

Synthesis, physicochemical and anticonvulsant properties of new N-4-arylpiperazin-1-yl amides of (2-aza-1,3-dioxospiro[4.4]non-2-yl)- and [4.5]dec-2-yl)-propionic acid

In continuation of the search of new anticonvulsants, a series of N-4-arylpiperazin-1-yl 2-aza-1,3-dioxospiro[4.4]non-2-yl- (5-8) and [4.5]dec-2-yl- (9-15) propionamides, structurally related to the previously described N-4-arylpiperazin-1-yl amides of 2-aza-1,3-dioxospiro[4.5]dec-2-yl-acetic acid, were synthesized. The designed compounds 5-15 were prepared by condensation of the formerly obtained (2-aza-1,3-dioxospiro[4.5]dec-2-yl)- (3) and (2-aza-1,3-dioxo[4.4]non-2-yl)-(4) propionic acids with the appropriately substituted 4-arylpiperazines, in the presence of the N,N-carbonyldiimidazole (CDIM) reagent. All the compounds were tested for their anticonvulsant activity in the maximum electroshock seizure (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure threshold tests. Several compounds 7-10, 13 and 14 revealed protection in the MES screening.

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, Physicochemical and Anticonvulsant Properties of NewN-(Pyridine-2-yl) Derivatives of 2-Azaspiro[4.4]nonane and [4.5]decane-1,3-dione. Part II

A series of N-(pyridine-2-yl) derivatives of 2-azaspiro[4.4]nonane- (1a-e), 2-azaspiro[4.5]decane- (2a-e) and 6-methyl-2-azaspiro[4.5]decane-1,3-dione (3a-e) were synthesized and tested for their anticonvulsant activity in the maximum electroshock (MES) and subcutaneous pentylenetetrazole (scPTZ) seizure threshold tests. To explain the possible mechanism of action, the most active compounds N-(3-methylpyridine-2-yl)-2-azaspiro[4.4]nonane-1,3-dione (1b), N-(3-methylpyridine-2-yl)-2-azaspiro[4.5]decane-1,3-dione (2b), N-(4-methylpyridine-2-yl)-2-azaspiro[4.5]decane-1,3-dione (2c), and N-(3-methylpyridine-2-yl)-6-methyl-2-azaspiro[4.5]decane-1,3-dione (3b) were tested in vitro for their influence on voltage-sensitive calcium channel receptors, however, they revealed low affinities. For all synthesized compounds the lipophilicity was determined by use of RP-TLC method. The correlation between the lipophilicity and anticonvulsant activity was obtained--the higher the lipophilicity the stronger the anticonvulsant efficacy.

Lipophilicity characterization of newN-phenylamino-azaspiranes as potential anticonvulsant agents

The lipophilicity of a library of N-phenylamino-2-azaspiro[4.4]nonane- and [4.5]decane-1,3-dione derivatives has been determined by reversed-phase thin-layer chromatography with n-propanol-Tris buffer (pH 7.4) mixtures as mobile phases. Examination of chromatographic behaviour revealed a linear correlation between R(M) values and the concentration of n-propanol in the mobile phase. The partition coefficients (logP) were also calculated by use of the PrologP module of the Pallas computer program. Comparison of R(M0) values and calculated (logP(PALLAS)) data revealed the correlation expressed by the equation: logP(PALLAS) = 0.9995 R(M0) + 1.3451 (n = 28; r = 0.8971; F = 107.13; p < 0.05). The role of the lipophilicity in the anticonvulsant activity of a set of compounds examined is discussed: the active anticonvulsants were less lipophilic than inactive ones.