Parker W B, Shaddix S C, Bowdon B J, Rose L M, Vince R, Shannon W M, Bennett L L
Kettering-Meyer Laboratory, Southern Research Institute, Birmingham, Alabama 35205.
Antimicrob Agents Chemother. 1993 May;37(5):1004-9. doi: 10.1128/AAC.37.5.1004.
Carbovir (CBV) [the (--)-enantiomer of the carbocyclic analog of 2',3'-dideoxy-2',3'-didehydroguanosine] is a potent inhibitor of human immunodeficiency virus type 1 (HIV) replication in vitro. We have characterized the metabolism of CBV and its effect on cellular metabolism in an effort to better understand its mechanism of action. CBV was primarily metabolized to the 5'-triphosphate of CBV (CBV-TP) to concentrations sufficient to inhibit HIV reverse transcriptase. Infection of CEM cells with HIV did not affect the metabolism of CBV. In CEM cells, there was no evidence of the degradation of CBV by purine nucleoside phosphorylase. The half-life of CBV-TP in CEM cells was 2.5 h, similar to that of the 5'-triphosphate of zidovudine (AZT). However, unlike the levels of the 5'-triphosphate of AZT, CBV-TP levels declined without evidence of a plateau. CBV did not affect the metabolism of AZT, and AZT did not affect the metabolism of CBV. A small amount of CBV was incorporated into DNA in intact CEM cells, and this incorporation was increased by incubation with mycophenolic acid, an inhibitor of IMP dehydrogenase. CBV specifically inhibited the incorporation of nucleic acid precursors into DNA but had no effect on the incorporation of radiolabeled precursors into RNA or protein. CBV did not decrease the level of TTP, dGTP, dCTP, or dATP. These results suggested that the cytotoxicity of CBV was due to the inhibition of DNA synthesis. Further studies are necessary to identify the target(s) responsible for growth inhibition.
卡波韦（CBV）[2'，3'-二脱氧-2'，3'-二脱氢鸟苷碳环类似物的（-）-对映体]是1型人类免疫缺陷病毒（HIV）体外复制的有效抑制剂。我们已对CBV的代谢及其对细胞代谢的影响进行了表征，以更好地了解其作用机制。CBV主要代谢为CBV的5'-三磷酸酯（CBV-TP），其浓度足以抑制HIV逆转录酶。用HIV感染CEM细胞不会影响CBV的代谢。在CEM细胞中，没有证据表明嘌呤核苷磷酸化酶会降解CBV。CBV-TP在CEM细胞中的半衰期为2.5小时，与齐多夫定（AZT）的5'-三磷酸酯相似。然而，与AZT的5'-三磷酸酯水平不同，CBV-TP水平下降且没有达到平台期的迹象。CBV不影响AZT的代谢，AZT也不影响CBV的代谢。在完整的CEM细胞中，少量CBV被掺入DNA中，与肌苷单磷酸脱氢酶抑制剂霉酚酸一起孵育可增加这种掺入。CBV特异性抑制核酸前体掺入DNA，但对放射性标记前体掺入RNA或蛋白质没有影响。CBV不会降低TTP、dGTP、dCTP或dATP的水平。这些结果表明，CBV的细胞毒性是由于对DNA合成的抑制。有必要进行进一步研究以确定负责生长抑制的靶点。
