Disclosed are A3 adenosine receptor antagonists and/or partial agonists and A1 adenosine receptor agonists and/or partial agonists of formula (I): wherein R1 to R5 are as described herein, as well as pharmaceutical compositions thereof and methods of use thereof. The A3 AR antagonists or partial agonists find use in treating a number of diseases such as cancer, glaucoma, and inflammatory diseases, as well as in preventing cardiac ischemia. Also disclosed are radiolabeled compounds of formula (I) and the use thereof in diagnostic imaging of tissues and organs. The A1 AR agonists and partial agonists find use in treating diseases such as seizures, convulsion, stroke, diabetes, pain, arrhythmias, depression, and anxiety and in cardioprotection or neuroprotection.