University education of medicinal chemists: comparison of eight countries.

Medicinal chemists are mainly taught in faculties or schools of pharmacy and are available for employment. Yet major pharmaceutical research companies seek organic chemists, rather than medicinal chemists, for new drug discovery. This apparent contradiction led the Medicinal Chemistry Section of IUPAC to send a questionnaire regarding postgraduate academic education for medicinal chemists to the faculties or schools of pharmacy in eight countries, namely, France, Germany, Italy, Japan, Spain, Switzerland, UK and USA. The questionnaire aimed to elicit information about postgraduate medicinal chemistry students, their courses and training, and the occupations taken up after graduation. The replies representing 109 medicinal chemistry departments or sections have been analysed and the results are presented to provide a data base on modern medicinal chemistry curricula for comparative purposes. The information should help guide discussion of the optimum paths to be followed by students in preparation for their careers. The evidence suggests that academic training of medicinal chemists equips them to enter a wide range of occupations, many of which are in industry.

From moclobemide to Ro 19-6327 and Ro 41-1049: the development of a new class of reversible, selective MAO-A and MAO-B inhibitors.

This study describes the serendipitous discovery of moclobemide, a short-acting MAO-A inhibitor which is in an advanced stage of clinical development as an antidepressant. The short duration of action of this MAO inhibitor containing a morpholine ring moiety is due to the complete reversibility (probably by metabolism of the inhibitory molecular species) of MAO-A inhibition. Since moclobemide is much more effective in vivo than expected from its in vitro activity, investigations to identify a possible metabolite(s) more active as MAO-A inhibitor than the parent compound were carried out. The study of the MAO inhibitory characteristics of several known and putative moclobemide metabolites did not allow the identification of a potent MAO-A inhibitor but led to the discovery of Ro 16-6491, a potent MAO-B inhibitor of novel chemical structure. Systematic chemical modification of the aromatic ring system of Ro 16-6491 finally provided Ro 19-6327 and Ro 41-1049 which are highly selective and reversible inhibitors of MAO-B and MAO-A, respectively. Tritiated derivatives of Ro 19-6327 and Ro 41-1049 were used in binding studies to elucidate their mechanisms of action and to study their cellular distribution by quantitative enzyme radioautography.

[3H]Ro 19-6327: a reversible ligand and affinity labelling probe for monoamine oxidase-B.

This study demonstrated the existence of specific binding sites for [3H]Ro 19-6327 in human platelet membranes. This compound is a novel, time-dependent inhibitor of monoamine oxidase type B (MAO-B) and is structurally closely related to [3H]Ro 16-6491. The density of the sites labelled with high affinity by [3H]Ro 19-6327 was similar to that observed in previous studies with [3H]Ro 16-6491 as ligand. Binding was reversible at 20 degrees C and showed a relatively slow dissociation (t1/2 = 220 min). The dissociation rate was markedly decreased (t1/2 = greater than 24h) at 0 degrees C. MAO-B, but not MAO-A inhibitors, effectively prevented the binding of [3H]Ro 19-6327. Like [3H]Ro 16-6491, [3H]Ro 19-6327 is recognized as a substrate by MAO-B, being eventually deaminated by the enzyme. Since the deaminated aldehyde derivative of Ro 19-6327 did not inhibit MAO-B, a still unidentified reversible adduct, formed at the MAO-B active site, might explain the high potency and selectivity of [3H]Ro 19-6327. Incubation of the radioligand-enzyme complex from platelet and brain membranes with NaBH3CN and acetic acid (to pH 4.5) caused the irreversible incorporation of the radioactivity into a single polypeptide as shown by SDS-PAGE analysis. This polypeptide had a molecular weight identical to that of the MAO-B subunit, i.e. 58,000. The presence of unlabelled MAO-B inhibitors in the incubation mixture prevented the covalent incorporation of [3H]Ro 19-6327. The irreversible MAO-B inhibitor, [3H] pargyline, labelled a protein with a molecular weight identical to the protein labelled by [3H]Ro 19-6327.(ABSTRACT TRUNCATED AT 250 WORDS)

Design, synthesis, and X-ray data of novel potential antipsychotic agents. Substituted 7-phenylquinolizidines: stereospecific, neuroleptic, and antinociceptive properties.

The semirigid 7-phenylquinolizidine system was selected for the design of new potential antipsychotic agents because it fulfills earlier considerations on the minimal structural and steric requirements necessary to attain a high affinity to the dopamine receptors and, in addition, leaves open many opportunities for variations. Whereas the initial compound 5a, modeled after the structure of butaclamol, was virtually inactive, the introduction of substituents on the phenyl ring and of further optional structural elements improved the dopamine antagonistic properties by supplying additional binding forces. Initially, a compound in the potency range of chlorpromazine was obtained: (9aH)-2-tert-butyl-7-(2,4-dichlorophenyl)octahydro-2H-qui nolizin-2-ol (5e). By the optical resolution of 5c, it was demonstrated that the biological activity resides in the (-) enantiomer. The absolute configuration of (-)-5e was determined by single-crystal X-ray analysis to be 2S,7R,9aR. Further variations of the optional structural elements led to the unexpected finding of compounds with strong antinociceptive properties, e.g., (2R,7S,9aS)-2-butylocta-hydro-7-phenyl-2H-quinolizin-2 -yl acetate [(+)-26]. Interestingly, this compound belongs to the enantiomeric series opposite to that of the neuroleptic-like (-)-5e.