New adenosine kinase inhibitors with oral antiinflammatory activity: synthesis and biological evaluation.
Several 5-iodotubercidin analogues in the pyrazolo[3,4-d]pyrimidine ring system were synthesized as potential inhibitors of adenosine kinase by a direct Lewis acid-catalyzed glycosylation procedure using both the preformed carbohydrate and the heterocyclic base as starting materials. The 5'-hydroxyl, -chloro, -azido, -deoxy, -amino, and -fluoro derivatives were prepared and evaluated in three systems for biological activity relative to adenosine, the true substrate, and 5-iodotubercidin, a known inhibitor. First, each compound was studied kinetically for inhibition of purified human placental adenosine kinase activity. The order of potency was: iodotubercidin > hydroxyl > amino > or = deoxy > fluoro > chloro >> azido. The Ki values for the 5'-hydroxyl and 5'-amino compounds, the two most potent inhibitors, were 80 and 150 nM, respectively. The inhibition appeared to be essentially competitive in nature, although a noncompetitive component of significance for the more potent inhibitors cannot be ruled out. Second, a bioassay was conducted in which the toxicity of 6-methylmercaptopurine riboside toward human CEM lymphoblasts was reversed by varying concentrations of the compounds. The order of effectiveness of the compounds in this system, representing a functional inhibition of adenosine kinase in cultured cells, was about the same as that with the purified enzyme, except that the 5'-chloro and 5'-fluoro compounds were ineffective. Third, the 5'-hydroxyl derivative was evaluated in vivo in a rat pleurisy inflammation model and displayed biological activity at a dose of 30 mg/kg given orally. Finally, the in vitro toxicity of each compound was assessed in CEM lymphoblasts. Results indicated that the two most potent inhibitors in the pyrazolo[3,4-d]pyrimidine ring system, the 5'-hydroxyl (7) and the 5'-amino (20), were 15-fold and 75-fold, respectively, less growth inhibitory than 5-iodotubercidin.
Cottam
H B
HB
Department of Medicine, University of California, San Diego, La Jolla 92093-0663.
Wasson
D B
DB
Shih
H C
HC
Raychaudhuri
A
A
Di Pasquale
G
G
Carson
D A
DA
D000248:Adenosine Kinase / Q000037:antagonists & inhibitors*; D000284:Administration, Oral; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000138:chemical synthesis* / Q000494:pharmacology*; D002351:Carrageenan; D002478:Cells, Cultured; D004353:Drug Evaluation, Preclinical; D006801:Humans; D007700:Kinetics; D008214:Lymphocytes / Q000187:drug effects / Q000201:enzymology; D010998:Pleurisy / Q000139:chemically induced / Q000188:drug therapy; D011720:Pyrazoles / Q000138:chemical synthesis / Q000494:pharmacology; D011725:Pyridines / Q000138:chemical synthesis / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D014372:Tubercidin / Q000031:analogs & derivatives* / Q000494:pharmacology
D000894:Anti-Inflammatory Agents, Non-Steroidal; D011720:Pyrazoles; D011725:Pyridines; C034214:5-iodotubercidin; D002351:Carrageenan; D000248:Adenosine Kinase; D014372:Tubercidin