Newer GABA derivatives for the treatment of epilepsy including febrile seizures: a bioisosteric approach.

The present study aims at design and synthesis of newer gamma-aminobutyric acid (GABA) derivatives with the combination of thiosemicarbazone and GABA pharmacophores in order to develop newer anticonvulsants. The reported compounds were designed as bioisosteric analogues of GABA semicarbazones. The structures of the synthesized compounds were confirmed by the use of their spectral data besides elemental analysis. Initial anticonvulsant screening was performed using intraperitoneal (i.p.) maximal electroshock-induced seizure (MES), subcutaneous pentylenetetrazole (scPTZ), subcutaneous strychnine (scSTY), and subcutaneous picrotoxin (scPIC)-induced seizure threshold tests. A model involving 22-day old rat pups was also employed to further screen the effects of the test compounds against hyperthermia-induced febrile seizures. Only compounds 1 and 11 were found to be active in the MES test. Most of the compounds were found to be effective in the scPIC and febrile seizure models and very few compounds showed protection in scPTZ and scSTY models. This is the first report on these new GABA derivatives effective in the treatment of febrile seizures.

Newer N-phthaloyl GABA derivatives with antiallodynic and antihyperalgesic activities in both sciatic nerve and spinal nerve ligation models of neuropathic pain.

BACKGROUND: There is considerable research evidence supporting a palliative role for gamma-aminobutyric acid (GABA)-ergic neurotransmission and voltage-gated sodium channel blockade in neuropathic pain conditions. Hence, the present study was undertaken to assess the peripheral analgesic, antiallodynic and antihyperalgesic activities of the synthesized structural analogues of GABA. METHODS: The screening study included acute tissue injury, chronic constriction injury (CCI), and spinal nerve ligation (SNL) models of neuropathic pain. RESULTS: All of the tested compounds sup-pressed the acetic acid-induced writhing response significantly in comparison to the control. In particular, compound JVP-8 was observed to be the most active compound with percent inhibition greater than that of the standard drug aspirin (97.8% inhibition of writhing response as against 97.0% shown by aspirin). In neuropathic pain studies, compound JVP-5 (100 mg/kg i.p.) emerged as the most active compound affording maximum protection against dynamic allodynia and mechanical hyperalgesia in the CCI model, and against spontaneous pain and mechanical hyperalgesia in SNL rats. CONCLUSION: In this study, we have demonstrated that combining phthalimide pharmacophore with GABA has evolved compounds effective for the treatment of neuropathic pain.

Synthesis and anticonvulsant activity of 4-(2-(2,6-dimethylphenylamino)-2-oxoethylamino)-N-(substituted)butanamides: a pharmacophoric hybrid approach.

A series of pharmacophoric hybrids of ameltolide-gamma-aminobutyric acid (GABA)-amides was designed, synthesized, and evaluated for their anticonvulsant and neurotoxic properties. Initial anticonvulsant screening was performed using intraperitoneal (ip) maximal electroshock-induced seizure (MES), subcutaneous pentylenetetrazole (scPTZ), and subcutaneous picrotoxin (scPIC)-induced seizure threshold tests. All the compounds had improved lipophilicity and the pharmacological activity profile confirmed their blood-brain barrier penetration. The titled compounds showed promising activity in scPIC screen indicating the involvement of GABA-mediation. Compound 4-(2-(2,6-dimethylaminophenylamino)-2-oxoethylamino)-N-(2,6-dimethylphenyl) butanamide (7) emerged as the most potent derivative effective in all the three animal models of seizure with no neurotoxicity at the anticonvulsant dose.

Discovery of 4-aminobutyric acid derivatives possessing anticonvulsant and antinociceptive activities: a hybrid pharmacophore approach.

Antiepileptic drugs are often utilized in the treatment of neuropathic pain. The present study aims at the design and synthesis of newer gamma-aminobutyric acid (GABA) derivatives with the combination of aryl semicarbazone and the GABA pharmacophores in order to develop a multifunctional drug useful in the treatment of neurological disorders like epilepsy and neuropathic pain. Various GABA semicarbazones were synthesized and screened for anticonvulsant, peripheral analgesic, antiallodynic, and antihyperalgesic activities. The structures of the synthesized compounds were confirmed by the use of their spectral data in addition to elemental analysis. The synthesized derivatives of the inhibitory neurotransmitter GABA produced anticonvulsant and antinociceptive actions in the acetic acid induced writhing test and peripheral nerve injury (chronic constriction injury and L5 spinal nerve ligation) models of neuropathic pain. The underlying mechanisms are expected to be enhancement of peripheral GABAergic neurotransmission owing to their activity in the scPIC screen and due to various reports on the involvement of GABAergic pathway in peripheral models of neuropathic pain.

Design and synthesis of anticonvulsants from a combined phthalimide-GABA-anilide and hydrazone pharmacophore.

Two series of pharmacophoric hybrids of phthalimide-GABA-anilides/hydrazones were designed and synthesized and evaluated for their anticonvulsant and neurotoxic properties. The structures of the synthesized compounds were confirmed by the use of their spectral data besides elemental analysis. Initial anticonvulsant screening was performed using intraperitoneal (i.p.) maximal electroshock-induced seizure (MES), subcutaneous pentylenetetrazole (scPTZ), subcutaneous strychnine (scSTY), and intraperitoneal picrotoxin (ipPIC)-induced seizure threshold tests. All of the compounds were ineffective in the MES test. Most of the compounds were found to be effective in the scSTY and ipPIC models and very few compounds showed protection in the scPTZ model.

An update on GABA analogs for CNS drug discovery.

GABA (gamma-aminobutyric acid) is one of the major inhibitory transmitters in the central nervous system of mammals. GABA is not transported efficiently into the brain from the bloodstream (i.e. GABA does not effectively cross the blood-brain barrier). Consequently, brain cells provide virtually all of the GABA found in the brain i.e. GABA is biosynthesized by decarboxylation of glutamic acid with pyridoxal phosphate. The implication of low GABA levels in a number of common CNS disease states and/or common medical disorders has stimulated intensive interest in preparing GABA analogs, which have superior pharmaceutical properties in comparison to GABA. Accordingly, a number of GABA analogs, with considerable pharmaceutical activity have been synthesized in the art. This review includes some of the important recent patents on novel GABA analogs and some pharmaceutical compositions there of.

Synthesis of N4-(2,4-dimethylphenyl) semicarbazones as 4-aminobutyrate aminotransferase inhibitors.

Several 2,4-dimethylphenyl substituted semicarbazones were synthesized in three steps involving aryl urea and aryl semicarbazide formation. The structures were confirmed by spectral and elemental analyses. All the compounds were evaluated for anticonvulsant activity by using a series of test models, including maximal electroshock seizure, subcutaneous pentylenetetrazole and subcutaneous strychnine seizure threshold tests. The compounds were also evaluated for behavioural impairement and depression activity. In the neurochemical investigation, potent compounds were evaluated for their effects on rat brain gamma-aminobutyric acid (GABA) levels and in vitro gamma-aminobutyrate transaminase (Pseudomonas fluorescens) activity. Preliminary studies suggest that these compounds exhibit anticonvulsant activity via a GABA-mediated mechanism.