5-(4-Hydroxy-6-methyl-2-oxo-2H-pyran-3-yl)-7-phenyl-2,3,6,7-tetrahydro-1,4-thiazepines as compounds with high affinity at the benzodiazepine binding site on GABA(A) receptors.

A series of thiazepines has been studied as new ligands for the benzodiazepine binding site of the GABAA receptor. Compounds with high affinity and weak selectivity regarding alpha beta3gamma2, alpha2beta3gamma2, alpha3beta3gamma2, and alpha5beta3gamma2 subtypes were found. The pharmacophore is discussed based on experimental and theoretical results. The thiazepine sulfur atom was found to be able to act as hydrogen bond acceptor.

Substituted 2-aminothiopen-derivatives: a potential new class of GluR6-antagonists.

In the course of search for new therapeutic agents against epilepsy new inhibitors for the kainate receptor subtypes GluR5 and GluR6 were synthesized. We were able to synthesize new substituted thieno[2,3-d]pyrimidines 3a,b, 4a,b, 5a,b as well as thiophene-3-carboxamides 2a-d and a multitude of substituted 4-methyl-5-phenylthiophene-3-carboxylic acids. All compounds described herein were tested for their antagonistic effect towards the kainate receptor subtypes GluR5 and GluR6. The highest activity was observed for ethyl 2-amino-4-methyl-5-phenylthiophene-3-carboxylate 1c with an IC50=0.75 microM at the GluR6 receptor.

Synthesis of thieno[2,3-d]oxazines and thieno[2,3-d]thiazines as subtype specific kainate receptor antagonists.

For the development of new antiepileptics the kainate receptors GluR6 and GluR5 are important targets. Based on the anticonvulsant effects of chinazolines and thieno[2,3-d]pyrimidines that are known from the literature, thieno[2,3-d][1.3]oxazines were synthesized and studied for their inhibitory properties at GluR6 and GluR5 receptors. The strongest inhibitor activity was observed with 5-methyl-6-phenyl-thieno[2,3-d][1.3]oxazines with C1 or C3-substituents in position 2 (3b-f). The 2-trihalide-methyl-substituted compounds 3c and 3d were the most active inhibitors at the GluR5-receptor (IC50=23.4 micromol, 16 microl). The 2-isopropyl-substituted compound 3f displayed the strongest activity at the GluR6-receptor (IC(50)=8.7 micromol). A number of thieno[2,3-d][1.3]thiazines and thieno[2,3-d] pyrimidines that were synthesized from the thieno[2,3][1.3]oxazines did not show any activity.

[Thieno[2,3-d]pyrimidines as antagonists of the glutamate receptors]. / Thieno[2,3-d]pyrimidine als glutamatantagonisten.

Although the function of the kainate receptors in the brain is still not clear, they are increasingly defined as targets in the development of new classes of anti-epileptics. The thienopyrimidines described in this report were tested for their antagonistic effect at the kainate receptor subtypes GluR5 and GluR6. The highest effectiveness was obtained by a 4-ethoxy-thieno[2,3-d]pyrimidin with an IC50 = 68 microM at the GluR6 receptor.

Metabolism of retigabine (D-23129), a novel anticonvulsant.

Retigabine (D-23129, N-(2-amino-4-(4-fluorobenzylamino)-phenyl) carbamic acid ethyl ester) is a potent anticonvulsant in a variety of animal models. Rats metabolized [14C]retigabine mainly through glucuronidation and acetylation reactions. Glucuronides were detected in incubates with liver microsomes or slices, in plasma, and in bile and feces but were absent in urine (0-24 h) that contained about 2% of the dose as retigabine and approximately 29% of the dose in > 20 metabolites, which are derived mainly from acetylation reactions. About 67% of the radioactivity was excreted into feces, approximately 10% of the dose as glucuronide. The metabolite pattern in the urine (0-24 h) of dogs was comparatively simple in that retigabine (13%), retigabine-N-glucuronide (5%), and retigabine-N-glucoside (1%) were present. In the same 24-h interval, about 39% of unchanged retigabine was excreted into feces. Plasma profiling and spectroscopic analysis (liquid chromatography with tandem mass spectrometry NMR) of two isolated urinary metabolites obtained after single oral dosing of 600 mg retigabine in healthy volunteers indicated that both acetylation and glucuronidation are major metabolic pathways of retigabine in humans. We found that in vitro assays with liver slices from rat and humans reveal the major circulating metabolites in vivo.