Mechanism of action of 1-beta-D-2,6-diaminopurine dioxolane, a prodrug of the human immunodeficiency virus type 1 inhibitor 1-beta-D-dioxolane guanosine.
(-)-beta-D-2,6-Diaminopurine dioxolane (DAPD), is a nucleoside reverse transcriptase (RT) inhibitor with activity against human immunodeficiency virus type 1 (HIV-1). DAPD, which was designed as a water-soluble prodrug, is deaminated by adenosine deaminase to give (-)-beta-D-dioxolane guanine (DXG). By using calf adenosine deaminase a K(m) value of 15 +/- 0.7 microM was determined for DAPD, which was similar to the K(m) value for adenosine. However, the k(cat) for DAPD was 540-fold slower than the k(cat) for adenosine. In CEM cells and peripheral blood mononuclear cells exposed to DAPD or DXG, only the 5'-triphosphate of DXG (DXG-TP) was detected. DXG-TP is a potent alternative substrate inhibitor of HIV-1 RT. Rapid transient kinetic studies show the efficiency of incorporation for DXG-TP to be lower than that measured for the natural substrate, 2'-deoxyguanosine 5'-triphosphate. DXG-TP is a weak inhibitor of human DNA polymerases alpha and beta. Against the large subunit of human DNA polymerase gamma a K(i) value of 4.3 +/- 0.4 microM was determined for DXG-TP. DXG showed little or no cytotoxicity and no mitochondrial toxicity at the concentrations tested.
Furman
P A
PA
Triangle Pharmaceuticals, Durham, North Carolina 27707, USA. furmanpa@tripharm.com
Jeffrey
J
J
Kiefer
L L
LL
Feng
J Y
JY
Anderson
K S
KS
Borroto-Esoda
K
K
Hill
E
E
Copeland
W C
WC
Chu
C K
CK
Sommadossi
J P
JP
Liberman
I
I
Schinazi
R F
RF
Painter
G R
GR
D058892:Adenosine Deaminase Inhibitors; D019380:Anti-HIV Agents / Q000494:pharmacology*; D001854:Bone Marrow Cells / Q000187:drug effects / Q000382:microbiology; D002478:Cells, Cultured; D004279:DNA, Viral / Q000096:biosynthesis; D004148:Dioxolanes / Q000494:pharmacology*; D004352:Drug Resistance, Microbial; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006151:Guanosine / Q000031:analogs & derivatives* / Q000494:pharmacology; D015497:HIV-1 / Q000187:drug effects* / Q000201:enzymology / Q000648:ultrastructure; D006801:Humans; D019344:Lactic Acid / Q000378:metabolism; D008854:Microscopy, Electron; D008928:Mitochondria / Q000187:drug effects; D019384:Nucleic Acid Synthesis Inhibitors; D011355:Prodrugs / Q000494:pharmacology*; D011684:Purine Nucleosides / Q000494:pharmacology*; D018894:Reverse Transcriptase Inhibitors / Q000494:pharmacology*
D058892:Adenosine Deaminase Inhibitors; D019380:Anti-HIV Agents; D004279:DNA, Viral; D004148:Dioxolanes; D004791:Enzyme Inhibitors; D019384:Nucleic Acid Synthesis Inhibitors; D011355:Prodrugs; D011684:Purine Nucleosides; D018894:Reverse Transcriptase Inhibitors; C098394:dioxolane guanosine; D006151:Guanosine; D019344:Lactic Acid; C098393:amdoxovir