- Alpidem analogues containing a GABA or glycine moiety as new anticonvulsant agents
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Alpidem analogues containing a GABA (1-3) or glycine (4-6) moiety were synthesized and their interaction with the GABA/benzodiazepine receptor complex at central (CBR) and peripheral (PBR) level was evaluated. In particular, their ability to modulate the specific binding of [3H]-GABA to washed membrane preparations from the rat cerebral cortex, as well as their effects on human recombinant GABAA receptors in Xenopus laevis oocytes, were assessed. Results from these in vitro assays showed that the most active compounds were 1 and 4. Intraperitoneal administration of compound 1 at a dose of 150 mg/kg significantly antagonized pentylenetetrazole-induced seizures in rats and the protective effects were evident for 90 min. However, compound 4 failed to interact with strychnine-sensitive Gly-binding sites. Consistent with these binding results, intraperitoneal administration of compound 4 at 150 mg/kg showed no effect against convulsions induced by strychnine, except for a prolonged time of the latency of convulsions. The results obtained suggest that compound 1 possesses interesting anticonvulsant activity and deserves further investigation as a novel lipophilic GABA derivative.
- Trapani, Giuseppe,Latrofa, Andrea,Franco, Massimo,Carrieri, Antonio,Cellamare, Saverio,Serra, Mariangela,Sanna, Enrico,Biggio, Giovanni,Liso, Gaetano
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- Synthesis and binding affinity of 2-phenylimidazo[1,2-α]pyridine derivatives for both central and peripheral benzodiazepine receptors. A new series of high-affinity and selective ligands for the peripheral type
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A number of 6-substituted or 6,8-disubstituted alkyl 2- phenylimidazo[1,2-a]pyridine-3-carboxylates 5a-h,-acetates 5i-s, 6a-g, and - propionates 5t, 6h and of N,N-dialkyl-2-phenylimidazo[1,2-α]pyridlne-3- carboxamides 7a-d, -aceramides 7e-t or -propionamide 7u were prepared following new synthetic methods, and their affinities for both the central (CBR) and the peripheral (PBR) benzodiazepine receptors evaluated. The compounds of the ester series displayed low affinity for both receptor types. Conversely, most of N,N-dialkyl(2-phenylimidazo[1,2-a]pyridin-3-yl)acetamides 7e-t proved to possess high affinity and selectivity for CBR or PBR depending on the nature of substituents at C(6)- and/or C(8) on the heterocyclic ring system. In particular, the 6-substituted compounds 7f-n displayed ratios of IC50 values (IC50(CBR)/IC50(PBR)) ranging from 0.32 (7m) to 232 (7k), while the 6,8-disubstituted compounds 7o-t were more than 1000-fold more selective for PBR versus CBR. Compounds 7f,m were examined in several different benzodiazepine receptor subtypes. Expression of specific GABA(A) receptor subunit assemblies in Xenopus oocytes was utilized to evaluate functionally both the efficacy and potency of the positive modulation of GABA-evoked C1+ currents by 7f and 7m in comparison with Zolpidem. The rank order of potencies of these drugs was 7f (EC50 = 3.2 x 10-8 M) > Zolpidem (EC50 = 3.6 x 10-8 M) > 7m (EC50 = 2.2 x 10-7 M). The actions of these compounds were also tested on α2β2γ2(s) receptors. However, the EC50 of these compounds was increased, compared to α1β2γ2(s) receptors, by 30-, 4-, and 5-fold for 7m, 7f, and Zolpidem, respectively. Finally, these compounds were almost completely devoid of activity at receptors containing the α5 subunit.
- Trapani, Giuseppe,Franco, Massimo,Ricciardi, Laura,Latrofa, Andrea,Genchi, Giuseppe,Sanna, Enrico,Tuveri, Francesca,Cagetti, Elisabetta,Biggio, Giovanni,Liso, Gaetano
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p. 3109 - 3118
(2007/10/03)
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