N-[2-[(substituted chroman-8-yl)oxy]ethyl]-4-(4-methoxyphenyl)butylamines: synthesis and wide range of antagonism at the human 5-HT1A receptor

Studies toward the discovery of the next generation of antidepressants. 3. Dual 5-HT1A and serotonin transporter affinity within a class of N-aryloxyethylindolylalkylamines

N-aryloxylethylindolealkylamines (5) having dual 5-HT transporter and 5-HT(1A) affinity are described. These compounds represent truncated analogues of our previously reported piperidinyl derivatives (3). Compounds in this investigation were found to have more similar affinities and functional activities for the 5-HT(1A) receptor and 5-HT transporter. Though 5-HT(1A) antagonism is not consistently observed throughout series 5, several molecular features were found to be essential to obtain high and balanced activities. The proper placement of a heteroatom in the aryl ring and the length of the linkage used to tether the indole moiety had significant influence on 5-HT(1A) and 5-HT transporter affinities. Introduction of a halogen into the aryl ring usually lowered intrinsic activity and in some cases led to full 5-HT(1A) antagonists. Compounds 33 and 34 were observed to be full 5-HT(1A) antagonists with K(i) values of approximately 30 nM for the 5-HT(1A) receptor and K(i) values of 5 and 0.5 nM for the 5-HT transporter, respectively. Unfortunately, similar to our previous series (3), compounds in this report also had high affinity for the alpha(1) receptor.

Studies toward the discovery of the next generation of antidepressants. Part 2: incorporating a 5-HT(1A) antagonist component into a class of serotonin reuptake inhibitors

The design and synthesis of a novel series of indole derivatives (9) having dual 5-HT transporter reuptake and 5-HT(1A) antagonist activity are described.

Parallel synthesis of 3-aryloxy-2-propanolamines and evaluation as dual affinity 5-HT(1A) and 5-HT re-uptake ligands

A solution phase synthesis for the preparation of 3-aryloxy-2-propanolamine libraries has been developed. This resulted in the identification of 5 as a ligand with dual affinity for 5-HT1A and serotonin reuptake receptors which shows excellent pharmacokinetic parameters.

The 5-HT1A receptor and its ligands: structure and function

An overview is presented on progress made in research on 5-HT1A receptors and their ligands since their discovery in 1983. Molecular biology has offered new tools, for example cloned 5-HT1A receptors, their mutants and chimeras to study structure and function. Many compounds, belonging to different chemical classes, display high affinity and selectivity for 5-HT1A receptors. The majority of these compounds are agonists or partial agonists, full antagonists are still scarce. Agonists and partial agonists are active in various animal models of anxiety and depression. Partial receptor agonists have been proven to be effective in general anxiety disorder and depression in man. Potential therapeutic applications for 5-HT1A receptor antagonists are evaluated, for example, in cognition disorders.

Functional characteristics of a series of N4-substituted 1-(2,3-dihydro-1,4-benzodioxin-5-yl)piperazines as 5-HT1A receptor ligands. Structure-activity relationships

The agonistic/antagonistic profile of a series of 10 N4-substituted 1-(2,3-dihydro-1,4-benzodioxin-5-yl)piperazines is evaluated in the in vitro adenylyl cyclase assay. The profile is severely affected by the characteristics of the N4-substituents ranging from full agonism (benzamidoethyl derivative 1), mixed agonism/antagonism (phthalimidobutyl derivative 7) to predominantly antagonism (saccharinbutyl derivate 9). A novel full antagonist 10, as potent as WAY 100635, is obtained by substitution of Cl at C-7 of the benzodioxinyl moiety in 9.

Synthesis and pharmacological characterization of novel 6-fluorochroman derivatives as potential 5-HT1A receptor antagonists

A series of novel 6-fluorochroman derivatives was prepared and evaluated as antagonists for the 5-HT1A receptor. N-2-[[(6-Fluorochroman-8-yl)oxy]ethyl]-4-(4-methoxyphenyl)butylami ne (3; J. Med. Chem. 1997, 40, 1252-1257) was chosen as a lead, and structural modifications were done on the aliphatic portion of the chroman ring, the tether linking the middle amine and the terminal aromatic ring, the aromatic ring, and lastly the amine. Radioligand binding assays proved that the majority of the novel compounds behaved as good to excellent ligands at the 5-HT1A receptor, some of which were selective with respect to alpha1-adrenergic and D2-dopaminergic receptors. The antagonist activity of the compounds was assessed in the forskolin-stimulated adenylate cyclase assays in CHO cells expressing the human 5-HT1A receptors. Among the modifications attempted, introduction of an oxo or an optically active hydroxy moiety at the chroman C-4 position was effective in ameliorating the receptor selectivity. Six analogues were selected through the in vitro screens and further evaluated for their in vivo activities. A 4-oxochroman derivative (31n), having a terminal 1, 3-benzodioxole ring, demonstrated antagonist activities toward 8-OH-DPAT-induced behavioral and electrophysiological responses in rats.