title: Synthesis and evaluation of new N6-substituted adenosine-5'-N-methylcarboxamides as A3 adenosine receptor agonists.
abstract: A number of N(6)-substituted adenosine-5'-N-methylcarboxamides were synthesised and their pharmacology, in terms of their receptor affinity, selectivity and cardioprotective effects, were explored. The first series of compounds, 4a-4f and 5a-5f, showed modest receptor affinity for the A(3)AR with K(i) values in the low to mid muM range. However, the incorporation of a 4-(2-aminoethyl)-2,6-di-tert-butylphenol group in the N(6)-position (in compounds 4g and 5g) significantly improved the affinity with K(i) values of 30 and 9 nM, respectively. Improvements in affinity, as well as selectivity were seen when a functionalized linker was introduced. The N(6)-phenyl series, compounds 7a-7d, demonstrated low to mid nanomolar receptor affinities (K(i)=2.3-45.0 nM), with 7b displaying 109-fold selectivity for the A(3)AR (vs A(1)). The N(6)-benzyl series 9a-9c also proved to be potent and selective A(3)AR agonists and the longer chain length linker 13 was tolerated at the A(3)AR without abrogation of affinity or selectivity. Cardioprotection was demonstrated by a simulated ischaemia cell culture assay, whereby 7b, 7c, 9a, 9b and 9c all showed cardioprotective effects at 100 nM comparable or better than the benchmark A(3)AR agonist IB-MECA, but which were indistinguishable by statistical analysis. For example, compound 9c reduced cell death by 68.0+/-3.6%.
authors.affiliation: Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville VIC 3052, Australia.
authors.forename: Shane M
authors.initials: SM
authors.lastname: Devine
authors.forename: Alison
authors.initials: A
authors.lastname: Gregg
authors.forename: Heidi
authors.initials: H
authors.lastname: Figler
authors.forename: Kate
authors.initials: K
authors.lastname: McIntosh
authors.forename: Vijay
authors.initials: V
authors.lastname: Urmaliya
authors.forename: Joel
authors.initials: J
authors.lastname: Linden
authors.forename: Colin W
authors.initials: CW
authors.lastname: Pouton
authors.forename: Paul J
authors.initials: PJ
authors.lastname: White
authors.forename: Steven E
authors.initials: SE
authors.lastname: Bottle
authors.forename: Peter J
authors.initials: PJ
authors.lastname: Scammells
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D058909:Adenosine A3 Receptor Agonists; D000818:Animals; D001665:Binding Sites; D002316:Cardiotonic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D002460:Cell Line; D020650:Combinatorial Chemistry Techniques; D015195:Drug Design; D015394:Molecular Structure; D032383:Myocytes, Cardiac / Q000166:cytology / Q000187:drug effects; D051381:Rats; D013329:Structure-Activity Relationship
chemical_list: D058909:Adenosine A3 Receptor Agonists; D002316:Cardiotonic Agents; C084956:N(6)-(3-iodobenzyl)-5'-N-methylcarboxamidoadenosine; D000241:Adenosine