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Enhancement by 2'-deoxycoformycin of the 5'-phosphorylation and anti- human immunodeficiency virus activity of 2',3'-dideoxyadenosine and 2'- beta-fluoro-2',3'-dideoxyadenosine

GS Ahluwalia, DA Cooney, T Shirasaka, H Mitsuya, JS Driscoll and DG Johns

Laboratory of Medicinal Chemistry, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892.

The anti-human immunodeficiency virus agents 2',3'-dideoxyadenosine (ddAdo) and 2'-beta-fluoro-2',3'-dideoxyadenosine (2'-beta-F-ddAdo) are rapidly converted, both in vitro and in vivo, to the corresponding inosine analogs by the widely distributed enzyme adenosine deaminase (EC 3.5.4.4). We have determined the effects of the potent adenosine deaminase inhibitor 2'-deoxycoformycin (2'-dCF) on ddAdo and 2'-beta-F- ddAdo metabolism in MOLT-4 cells and on ddAdo antiviral activity in the ATH8 test system. At levels as low as 5 nM in the incubation medium, 2'- dCF effectively blocks the extracellular deamination of both agents, thus permitting their rapid cellular uptake as the unchanged parent compounds, rather than as the less lipid-soluble 2',3'-dideoxyinosine or 2'-beta-fluoro-2',3'-dideoxyinosine. The result is a significant increase in intracellular levels of the pharmacologically active forms 2',3'-dideoxyadenosine-5'-triphosphate and 2'-beta-fluoro-2',3'- dideoxyadenosine-5'-triphosphate. The effect becomes maximal over the range of 50-250 nM 2'-dCF and declines to control levels when extracellular 2'-dCF levels exceed 1 microM. This decrease in ddAdo and 2'-beta-F-ddAdo phosphorylation with higher levels of the inhibitor appears to result from intracellular penetration of 2'-dCF and consequent inhibition of intracellular deamination, a critical step in the activation of both agents through the 5'-nucleotidase pathway. In anti-human immunodeficiency virus assays, a 2.2-fold increase in ddAdo antiviral potency was seen at 2'-dCF levels of 20 and 50 nM.

Volume 46, Issue 5, pp. 1002-1008, 11/01/1994
Copyright © 1994 by American Society for Pharmacology and Experimental Therapeutics






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Copyright © 1994 by the American Society for Pharmacology and Experimental Therapeutics