5, 6, 7 AND 8-AMINO-2-(N,N-DI-N-PROPYLAMINO)-1,2,3,4-TETRAHYDRONAPHTHALENES - CENTRALLY ACTING DA AND 5-HT(1A) AGONISTS

5-, 6-, 7- and 8-Amino-2-(NN-di-n-propylamino)-1,2,3,4-tetrahydronaphthalene were synthesized and compared with the corresponding phenolic compounds in vivo and in vitro for their effects on central serotonergic (5-HT1A) and dopaminergic (D2) systems. The 5- and 8-amino isomers surprisingly showed a 100-fold lower affinity for D2 and 5-HT1A receptors, respectively, than their corresponding phenols. This was also reflected in vivo. The 6-amino- and hydroxy-isomers were equipotent, while the 7-amino compound showed in vivo effects both on dopaminergic and serotonergic systems, the latter not being noticed in vitro. Intermediates 8-bromo-2-(N,N-di-n-propylamino)-1,2,3,4-tetrahydronaphthalene and 2-(N,N-di-n-propylamino)-1,2,3,4-tetrahydronaphthalene-8-carboxylic acid methyl ester were also tested and found to be quite potent 5-HT1A agonists

6,7,8,9-TETRAHYDRO-N,N-DI-N-PROPYL-3H-BENZINDOL-8-AMINES - DERIVATIVES AS POTENT AND ORALLY-ACTIVE SEROTONIN 5-HT1A RECEPTOR AGONISTS

Derivatives and isosteric derivatives of the potent 5-HT1A agonist 8-(di-n-propylamino)-6,7,8,9-tetrahydro-3H-benz[e]indole- 1-carbaldehyde (5) were prepared and evaluated in vivo and in vitro for serotonergic and dopaminergic activity. The 1-cyano analog 8 was found to be almost equipotent to 5 and the previously described 2-cyano derivative 6, while a I-chloro and 1-(1,1,1-trifluoroethyl) substituent (9 and 10, respectively) formed less potent derivatives. The isosteric 6,7,8,9-tetrahydro-1H-benz[g]indoles 4 and 12-15 showed surprisingly low affinity or activity at both serotonergic and dopaminergic systems. The interpretations of these results by means of drug-receptor interactions at the 5-HT1A subtype are discussed. Compounds 6 and 8 were found to have high oral bioavailability in the rat (63% and 54%, respectively)

6,7,8,9-TETRAHYDRO-N,N-DI-N-PROPYL-3H-BENZINDOL-8-AMINES - DERIVATIVES AS POTENT AND ORALLY-ACTIVE SEROTONIN 5-HT1A RECEPTOR AGONISTS

Derivatives and isosteric derivatives of the potent 5-HT1A agonist 8-(di-n-propylamino)-6,7,8,9-tetrahydro-3H-benz[e]indole- 1-carbaldehyde (5) were prepared and evaluated in vivo and in vitro for serotonergic and dopaminergic activity. The 1-cyano analog 8 was found to be almost equipotent to 5 and the previously described 2-cyano derivative 6, while a I-chloro and 1-(1,1,1-trifluoroethyl) substituent (9 and 10, respectively) formed less potent derivatives. The isosteric 6,7,8,9-tetrahydro-1H-benz[g]indoles 4 and 12-15 showed surprisingly low affinity or activity at both serotonergic and dopaminergic systems. The interpretations of these results by means of drug-receptor interactions at the 5-HT1A subtype are discussed. Compounds 6 and 8 were found to have high oral bioavailability in the rat (63% and 54%, respectively)

Different in vitro and in vivo profiles of substituted 3-aminopropylphosphinate and 3-aminopropyl(methyl)phosphinate GABAB receptor agonists as inhibitors of transient lower oesophageal sphincter relaxation

BACKGROUND AND PURPOSE Gastro-oesophageal reflux is predominantly caused by transient lower oesophageal sphincter relaxation (TLOSR) and GABAB receptor stimulation inhibits TLOSR. Lesogaberan produces fewer CNS side effects than baclofen, which has been attributed to its affinity for the GABA transporter (GAT), the action of which limits stimulation of central GABAB receptors. To understand the structure–activity relationship for analogues of lesogaberan (3-aminopropylphosphinic acids), and corresponding 3-aminopropyl(methyl)phosphinic acids, we have compared representatives of these classes in different in vitro and in vivo models. EXPERIMENTAL APPROACH The compounds were characterized in terms of GABAB agonism in vitro. Binding to GATs and cellular uptake was done using rat brain membranes and slices respectively. TLOSR was measured in dogs, and CNS side effects were evaluated as hypothermia in mice and rats. KEY RESULTS 3-Aminopropylphosphinic acids inhibited TLOSR with a superior therapeutic index compared to 3-aminopropyl(methyl)phosphinic acids. This difference was most likely due to differential GAT-mediated uptake into brain cells of the former but not latter. In agreement, 3-aminopropyl(methyl)phosphinic acids were much more potent in producing hypothermia in rats even when administered i.c.v. CONCLUSIONS AND IMPLICATIONS An enhanced therapeutic window for 3-aminopropylphosphinic acids compared with 3-aminopropyl(methyl)phosphinic acids with respect to inhibition of TLOSR was observed and is probably mechanistically linked to neural cell uptake of the former but not latter group of compounds. These findings offer a platform for discovery of new GABAB receptor agonists for the treatment of reflux disease and other conditions where selective peripheral GABAB receptor agonism may afford therapeutic effects.A Lehmann, M Antonsson, A Aurell-Holmberg, LA Blackshaw, L Brändén, T Elebring, J Jensen, L Kärrberg, JP Mattsson, K Nilsson, SS Oja, P Saransaari, S von Ung

(R)-(3-Amino-2-fluoropropyl) Phosphinic Acid (AZD3355), a Novel GABA(B) Receptor Agonist, Inhibits Transient Lower Esophageal Sphincter Relaxation through a Peripheral Mode of Action

Gastroesophageal reflux disease (GERD) affects >10% of the Western population. Conventionally, GERD is treated by reducing gastric acid secretion, which is effective in most patients but inadequate in a significant minority. We describe a new therapeutic approach for GERD, based on inhibition of transient lower esophageal sphincter relaxation (TLESR) with a proposed peripherally acting GABA(B) receptor agonist, (R)-(3-amino-2-fluoropropyl)phosphinic acid (AZD3355). AZD3355 potently stimulated recombinant human GABA(B) receptors and inhibited TLESR in dogs, with a biphasic dose-response curve. In mice, AZD3355 produced considerably less central side effects than the prototypical GABA(B) receptor agonist baclofen but evoked hypothermia at very high doses (blocked by a GABA(B) receptor antagonist and absent in GABA(B)-/- mice). AZD3355 and baclofen differed markedly in their distribution in rat brain; AZD3355, but not baclofen, was concentrated in circumventricular organs as a result of active uptake (shown by avid intracellular sequestration) and related to binding of AZD3355 to native GABA transporters in rat cerebrocortical membranes. AZD3355 was also shown to be transported by all four recombinant human GABA transporters. AR-H061719 [(R/S)-(3-amino-2-fluoropropyl)phosphinic acid], (the racemate of AZD3355) inhibited the response of ferret mechanoreceptors to gastric distension, further supporting its peripheral site of action on TLESR. In summary, AZD3355 probably inhibits TLESR through stimulation of peripheral GABA(B) receptors and may offer a potential new approach to treatment of GERD.Anders Lehmann, Madeleine Antonsson, Ann Aurell Holmberg, L. Ashley Blackshaw, Lena Brändén, Hans Bräuner-Osborne, Bolette Christiansen, John Dent, Thomas Elebring, Britt-Marie Jacobson, Jörgen Jensen, Jan P. Mattsson, Karolina Nilsson, Simo S. Oja, Amanda J. Page, Pirjo Saransaari and Sverker von Ung