title: Novel 5-HT3 antagonists. Indole oxadiazoles.
abstract: The synthesis and biochemical evaluation of a series of indole oxadiazole 5-HT3 antagonists are described. The key pharmacophoric elements have been defined as a basic nitrogen, a linking group capable of H-bonding interactions, and an aromatic moiety. The steric limitations of the aromatic binding site have been determined by substitution about the indole ring. Variation of the heterocyclic linking group has shown that while two hydrogen-bonding interactions are possible, only one is essential for high affinity. The environment of the basic nitrogen has been investigated and shown to be optimal when constrained within an azabicyclic system. These results have been incorporated into a proposed binding model for the 5-HT3 antagonist binding site, in which the optimum distance between the aromatic binding site and the basic amine is 8.4-8.9 A and the steric limitations are defined by van der Waals difference mapping.
authors.affiliation: Department of Medicinal Chemistry, Merck Sharp and Dohme Research Laboratories, Harlow, Essex, England.
authors.forename: C J
authors.initials: CJ
authors.lastname: Swain
authors.forename: R
authors.initials: R
authors.lastname: Baker
authors.forename: C
authors.initials: C
authors.lastname: Kneen
authors.forename: J
authors.initials: J
authors.lastname: Moseley
authors.forename: J
authors.initials: J
authors.lastname: Saunders
authors.forename: E M
authors.initials: EM
authors.lastname: Seward
authors.forename: G
authors.initials: G
authors.lastname: Stevenson
authors.forename: M
authors.initials: M
authors.lastname: Beer
authors.forename: J
authors.initials: J
authors.lastname: Stanton
authors.forename: K
authors.initials: K
authors.lastname: Watling
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D001921:Brain / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D002540:Cerebral Cortex / Q000378:metabolism; D004563:Electrochemistry; D007202:Indicators and Reagents; D007211:Indoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D008958:Models, Molecular; D008968:Molecular Conformation; D015394:Molecular Structure; D010069:Oxadiazoles / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000378:metabolism; D012702:Serotonin Antagonists / Q000138:chemical synthesis* / Q000737:chemistry / Q000494:pharmacology; D013329:Structure-Activity Relationship; D000077526:Tropisetron
chemical_list: D007202:Indicators and Reagents; D007211:Indoles; D010069:Oxadiazoles; D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D000077526:Tropisetron