title: Identification and biochemical studies on novel non-nucleoside inhibitors of the enzyme adenosine kinase.
abstract: The enzyme adenosine kinase (AK) plays a key role in the regulation of intracellular and extracellular concentration of adenosine (Ado), which exhibits potent hormonal activity in cardiovascular, nervous and immune systems. In view of the pharmacological effects of Ado, there is much interest in identifying inhibitors of AK, which can augment its tissue-protective effects. In this study, we have screened 1040 compounds from a chemical library of putative kinase inhibitors for their effect on purified human recombinant AK. These studies have identified 8 novel, non-nucleoside AK inhibitors. Four of these compounds (viz. 2-tert-butyl-4H-benzo[1,2,4]thiadiazine-3-thione (2759-0749); N-(5,6-diphenyl-furo[2,3-d]pyrimidin-4-yl)-propionamide (3998-0118); 3-[5,6-Bis-(4-methoxy-phenyl)-furo[2,3-d]pyrimidin-4-ylamino]-propan-1-ol (4072-2732); and 2-[2-(3,4-dihydroxy-phenyl)-5-phenyl-1H-imidazol-4-yl]-fluoren-9-one (8008-6198)), which inhibited human AK in a concentration-dependent manner in a low micromolar range (IC(50) = 0.38 approximately 1.98 microM) were further studied. Kinetic and structural studies on these compounds provide evidence that inhibition of AK by these compounds was competitive with respect to Ado and non-competitive for ATP. All of these compounds also inhibited uptake of Ado and its metabolism in cultured mammalian cells at comparable concentrations indicating their efficient cellular penetrability. These AK inhibitors, whose chemical structures differ significantly from all previously known inhibitors, provide useful lead compounds for identification of more potent but less toxic AK inhibitors that may prove useful for therapeutic purposes.
authors.affiliation: Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Jae
authors.initials: J
authors.lastname: Park
authors.forename: Gayathri
authors.initials: G
authors.lastname: Vaidyanathan
authors.forename: Bhag
authors.initials: B
authors.lastname: Singh
authors.forename: Radhey S
authors.initials: RS
authors.lastname: Gupta
mesh_terms: D000241:Adenosine / Q000378:metabolism; D000248:Adenosine Kinase / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D007700:Kinetics; D011743:Pyrimidines / Q000737:chemistry / Q000494:pharmacology; D011994:Recombinant Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D013829:Thiadiazines / Q000737:chemistry / Q000494:pharmacology
chemical_list: D004791:Enzyme Inhibitors; D011743:Pyrimidines; D011994:Recombinant Proteins; D013829:Thiadiazines; D000248:Adenosine Kinase; D000241:Adenosine