title: 2-substituted thioadenine nucleoside and nucleotide analogues: synthesis and receptor subtype binding affinities (1).
abstract: The design, synthesis, and receptor subtype binding affinities of several 2-substituted thioadenosine nucleoside and nucleotide analogues are described. Alkylation of 2-thioadenosine (1) with iodopentenylboronic acid followed by iododeboronation gave 2-((E)-1-iodo-1-penten-5-yl) thioadenosine (9). Compound 1 on treatment with 4-nitrobenzyl bromide and propargyl bromide furnished compounds 3 and 5, respectively. The 5'-monophosphate analogues of compounds 3, 5, 7, and 9 were prepared similarly using 2-thioadenosine 5'-monophosphate (2). Treatment of 1 with bromoethylamine hydrobromide provided 2-[(aminoethyl)thio]adenosine (11) which on coupling with N-succinimidyl 3-(4-hydroxyphenyl)propionate gave 2-[[[3-(4-hydroxyphenyl)propionamido]ethyl]thio]adenosine (12). Iodination of 12 gave 2-[[[3-(4-hydroxy-3-iodophenyl)propionamido]ethyl]thio]adenosine (13). Compounds 3-13 were evaluated for their affinities toward A1 and A2 adenosine receptors in rat brain cortex and striatum, respectively using [3H]DPCPX and [3H]CGS21680 as ligands. The nucleotide analogues 4, 6, 8, and 10 inhibited binding of [3H]DPCPX by 10-20% and of [3H]CGS21680 by 40-50% at a concentration of 100 microM suggesting weak affinity toward adenosine receptors. The nucleoside analogues 3, 5, 7, 9, 12, and 13 inhibited the A2 receptor binding of [3H]CGS21680 with Ki values of 1.2-3.67 microM, while A1 receptor binding of [3H]DPCPX was inhibited with Ki values 10-17 microM. The A1/A2 ratios suggest 4-8-fold A2 receptor selectivity.
authors.affiliation: Health Sciences Research Division, Oak Ridge National Laboratory, Tennessee 37831-6229.
authors.forename: A
authors.initials: A
authors.lastname: Hasan
authors.forename: T
authors.initials: T
authors.lastname: Hussain
authors.forename: S J
authors.initials: SJ
authors.lastname: Mustafa
authors.forename: P C
authors.initials: PC
authors.lastname: Srivastava
mesh_terms: D000227:Adenine Nucleotides / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D000241:Adenosine / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D000818:Animals; D000959:Antihypertensive Agents / Q000493:pharmacokinetics; D001667:Binding, Competitive / Q000187:drug effects; D002540:Cerebral Cortex / Q000187:drug effects / Q000378:metabolism; D066298:In Vitro Techniques; D008297:Male; D017072:Neostriatum / Q000187:drug effects / Q000378:metabolism; D009705:Nucleosides / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D010627:Phenethylamines / Q000493:pharmacokinetics; D058915:Purinergic P1 Receptor Antagonists; D011869:Radioligand Assay; D051381:Rats; D017208:Rats, Wistar; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D013438:Sulfhydryl Compounds / Q000138:chemical synthesis* / Q000493:pharmacokinetics; D014970:Xanthines / Q000493:pharmacokinetics
chemical_list: D000227:Adenine Nucleotides; D000959:Antihypertensive Agents; D009705:Nucleosides; D010627:Phenethylamines; D058915:Purinergic P1 Receptor Antagonists; D018047:Receptors, Purinergic P1; D013438:Sulfhydryl Compounds; D014970:Xanthines; C061282:2-(4-(2-carboxyethyl)phenethylamino)-5'-N-ethylcarboxamidoadenosine; C051360:1,3-dipropyl-8-cyclopentylxanthine; D000241:Adenosine