Adenosine receptor agonists: synthesis and biological evaluation of the diastereoisomers of 2-(3-hydroxy-3-phenyl-1-propyn-1-yl)NECA

Bioorg Med Chem. 1997 Dec;5(12):2267-75. doi: 10.1016/s0968-0896(97)00172-7.


Among the recently reported 2-(ar)alkynyl derivatives of 5'-N-ethylcarboxamidoadenosine (NECA), the (R,S)-2-(3-hydroxy-3-phenyl-1-propyn-1-yl)NECA [(R,S)-PHPNECA or SCH 59761] was found to be a very potent agonist at A1 and A2A receptor subtypes, with a Ki of 2.5 nM and 0.9 nM, respectively. Furthermore, this compound showed an inhibitory activity on platelet aggregation 16-fold higher than NECA, being the most potent anti-aggregatory nucleoside reported so far. Since this compound bears a chiral carbon in the side chain, the diastereoisomer separation was undertaken both by chiral HPLC and by a stereospecific synthetic method. Binding assays have shown that the (S)-diastereomer is about fivefold more potent and selective than the (R)-diastereomer as agonist of the A2A receptor subtype [(S)-PHPNECA, KiA2A = 0.5 nM; (R)-PHPNECA, KiA2A = 2.6 nM]. Functional studies indicated that (S)-PHPNECA possesses marked vasodilating activity and produces a relevant decrease in heart rate. Moreover, the (S)-diastereomer proved to be about ten times more potent than the (R)-diastereomer in inducing cardiovascular effects, in in vivo hemodynamic studies. However, the greatest difference between these two enantiomers resulted in the platelet aggregation test: in fact, the (R)-diastereomer displayed an inhibitory activity similar to that of NECA, whereas the (S)-diastereomer was 37-fold more active than NECA as an inhibitor of rabbit platelet aggregation, induced by ADP. These data suggest that (S)-PHPNECA could be a useful tool to investigate the mode of binding of agonists to the platelet adenosine receptor subtype.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine / analogs & derivatives*
  • Adenosine / chemical synthesis
  • Adenosine / pharmacology
  • Animals
  • Blood Pressure / drug effects
  • Chromatography, High Pressure Liquid
  • Heart Rate / drug effects
  • Male
  • Models, Molecular
  • Platelet Aggregation / drug effects
  • Platelet Aggregation Inhibitors / chemical synthesis*
  • Platelet Aggregation Inhibitors / pharmacology
  • Purinergic P1 Receptor Agonists*
  • Rabbits
  • Rats
  • Rats, Inbred SHR
  • Rats, Sprague-Dawley
  • Stereoisomerism


  • 2-(3-hydroxy-3-phenyl-1-propyn-1-yl)-5'-N-ethylcarboxamidoadenosine
  • Platelet Aggregation Inhibitors
  • Purinergic P1 Receptor Agonists
  • Adenosine