Bicyclic piperazinylbenzenesulphonamides are potent and selective 5-HT6 receptor antagonists

Mass spectrometry study of N-alkylbenzenesulfonamides with potential antagonist activity to potassium channels

Herein, we report the synthesis and mass spectrometry studies of several N-alkylbenzenesulfonamides structurally related to sulfanilic acid. The compounds were synthesized using a modified Schotten-Baumann reaction coupled with Meisenheimer arylation. Sequential mass spectrometry by negative mode electrospray ionization (ESI(-)-MS/MS) showed the formation of sulfoxylate anion (m/z 65) observed in the mass spectrum of p-chloro-N-alkylbenzenesulfonamides. Investigation of the unexpected loss of two water molecules, as observed by electron ionization mass spectrometry (EI-MS) analysis of p-(N-alkyl)lactam sulfonamides, led to the proposal of corresponding fragmentation pathways. These compounds showed loss of neutral iminosulfane dioxide molecule (M-79) with formation of ions observed at m/z 344 and 377. These ions were formed by rearrangement on ESI(+)-MS/MS analysis. Some of the molecules showed antagonistic activity against Kv3.1 voltage-gated potassium channels.

N-Arylsulfonyl-2-vinyltryptamines as new 5-HT6serotonin receptor Ligands

Several new 2-vinyl-Nb,Nb-dimethyltryptamines were prepared using Fischer indole synthesis followed by simple functional group transformations and evaluated on 5-HT4, 5-HT5, 5-HT6 and 5-HT7 serotonin receptors. It was found that 2-vinyl substitution conferred a potent and selective 5-HT6 binding activity to these molecules which could be enhanced by Na-arylsulfonyl substituents.

Discovery of 5-HT6 receptor ligands based on virtual HTS

Based on a pharmacophore alignment on a 5-HT(6) ligand applying 4SCan technology, a new lead series was identified and further structurally investigated. K(i)s down to 8 nM were achieved.

A Three-Dimensional Pharmacophore Model for 5-Hydroxytryptamine6 (5-HT6) Receptor Antagonists

Forty-five structurally diverse 5-hydroxytryptamine(6) receptor (5-HT(6)R) antagonists were selected to develop a 3D pharmacophore model with the Catalyst software. The structural features for antagonism at this receptor are a positive ionizable atom interacting with Asp(3.32), a hydrogen bond acceptor group interacting with Ser(5.43) and Asn(6.55), a hydrophobic site interacting with residues in a hydrophobic pocket between transmembranes 3, 4, and 5, and an aromatic-ring hydrophobic site interacting with Phe(6.52).

Hologram quantitative structure activity relationship studies on 5-HT6 antagonists

Predictive hologram quantitative structure activity relationship (HQSAR) models were developed for a series of arylsulfonamide compounds acting as specific 5-HT6 antagonists. A training set containing 48 compounds served to establish the model. The best HQSAR model was generated using atoms, bond, and connectivity as fragment distinction and 4-7 as fragment size showing cross-validated r2(q2) value of 0.702 and conventional r2 value of 0.971. The predictive ability of the model was validated by an external test set of 20 compounds giving satisfactory predictive r2 value of 0.678. The efficiency of HQSAR approach was further evidenced by the generation of predictive models for a training set containing 30 highly diverse, both specific and nonspecific 5-HT6 antagonists. The best HQSAR model for this training set was generated using atoms, bond, and connectivity as fragment distinction and 4-7 as fragment size showing cross-validated r2(q2) value of 0.693 and conventional r2 value of 0.923. This model was also validated by using an external test set of 10 compounds giving satisfactory predictive r2 value of 0.692. The contribution maps obtained from these models were used to explain the individual atomic contributions to the overall activity.

Influence of the 5-HT6 receptor on acetylcholine release in the cortex: pharmacological characterization of 4-(2-bromo-6-pyrrolidin-1-ylpyridine-4-sulfonyl)phenylamine, a potent and selective 5-HT6 receptor antagonist

A small series of aryl pyridyl sulfones has been prepared and investigated for its 5-HT(6) receptor binding properties. Thereof, pyrrolidinyl derivative 11 proved to be a very potent (pK(i) 9) and selective 5-HT(6) receptor antagonist. By means of in vivo microdialysis in the frontal cortex and a passive avoidance paradigm, where 11 reversed a scopolamine induced retention deficit, a functional correlation between 5-HT(6) receptors and cholinergic neurotransmission could be shown, supporting the therapeutic potential of 5-HT(6) receptors in the treatment of cognitive deficits.