1. Synthesis and alpha-adrenergic and I-1-imidazoline activity of 3-phenylpiperidines dimethyl-substituted on the phenyl ring
- Author
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Bruno Macchia, F. Romagnoli, Enrica Martinotti, Vincenzo Calderone, Antonio Lucacchini, Adriano Martinelli, David B. Bylund, Armando Rossello, Elisabetta Orlandini, Marco Macchia, and Gino Giannaccini
- Subjects
Pharmacology ,Agonist ,Stereochemistry ,medicine.drug_class ,Chemistry ,Organic Chemistry ,Adrenergic ,Imidazoline receptor ,General Medicine ,Ring (chemistry) ,Chemical synthesis ,In vitro ,Drug Discovery ,medicine ,Selectivity ,Receptor - Abstract
In a previous study we found that certain 3-phenylpiperidines (PPEs, 5) display a good activity at α2-adrenergic receptors (α2-AR ), whereas they are completely inactive at α1-AR. The PPEs 5 are conformationally restricted analogs of the corresponding adrenergic drug with a phenylethylamine structure (PAEs, 4) in which the benzylic hydroxyl group characteristic of the adrenergic catecholamines is not present. The most interesting of the PPEs proved to be the 3-(3,4-dimethylphenyl) substituted compound (5a) which had been found to be essentially inactive at β1- and β2-AR. The methyl groups present on the aromatic ring of 5a are found, albeit in a different position, on the phenyl of α2-adrenergic agonists with arylimidazolidine and arylimidazole structures. As such PPE 5a provided a unique template for the design of α2-AR ligands. On the basis of these premises, we synthesized all the possible dimethylphenyl-substituted isomers of PPE 5a. Their activity on α1- and α2-AR and on I1-imidazoline receptors (IR) was evaluated in vitro both by radioligand binding assays and by functional tests on isolated preparation. Two selected PPEs, 5a and 5f, were also tested for their affinity on α2-AR subtypes. Conformational studies were carried out by means of theoretical calculations, in order to rationalise the results of pharmacological tests at the molecular level.
- Published
- 1998