5--amino-2--5--dideoxythymidine and Leukemia-L1210

Several thymidine derivatives with hydrophobic 5'-substituents, linked by chemically stable amide and ether links, were synthesized as potential thymidine kinase inhibitors. None of these was active nor were several derivatives of thymidine 5'-acetate, which were previously reported to be inhibitors. It was shown that the apparent inhibition by the latter compounds was due to their facile hydrolysis in aqueous solution with release of thymidine. These results must cast doubt on any conclusions drawn from biological studies with 5'-esters of thymidine.

Topics: Animals; Chromatography, High Pressure Liquid; Leukemia L1210; Mice; Thymidine; Thymidine Kinase; Thymidine Monophosphate

3'-Amino-3'-deoxythymidine decreased the incorporation of [2-14C]thymidine into DNA of L1210 cells in vitro, and produced an accumulation of [2-14C]thymidine di- and triphosphate. The extent of these effects varied with the amount of recovery time after removal of 3'-amino-3'-deoxythymidine prior to addition of labeled thymidine. The distribution of radioactivity in the acid-soluble fraction derived from [3H]3'-amino-3'-deoxythymidine was as follows: 50% as 3'-amino-3'-deoxythymidine, 20% as the monophosphate, 10% as the diphosphate, and 20% as the triphosphate derivatives. No incorporation of [3H]3'-amino-3'-deoxythymidine into L1210 DNA could be detected. 3'-Amino-3'-deoxythymidine-5'-triphosphate is a competitive inhibitor against dTTP with a Ki of 3.3 microM, whereas the Km for dTTP was 8 microM using activated calf thymus DNA as the template and DNA polymerase-alpha. These data indicate that a major site of inhibition by 3'-amino-3'-deoxythymidine is inhibition of the DNA polymerase reaction.

Topics: Animals; Antimetabolites, Antineoplastic; Dideoxynucleosides; DNA Polymerase II; DNA Replication; Kinetics; Leukemia L1210; Mice; Thymidine

3',5'-Diamino-3',5'-dideoxythymidine (7) was synthesized via a nine-step synthesis from thymidine in good overall yield. 3'-Amino-3'-deoxythymidine (8) and 5'-amino-5'-deoxythymidine (12) were prepared with a minor modification of the procedure reported by Horwitz and co-workers. Although the 5'-amino analogue 12 had potent antiviral activity relative to the 3'-amino analogue 8, the latter is a potent inhibitor of the replication of both murine sarcoma 180 cells (ED50 = 5 micrometer) and of murine L1210 cells (ED50 = 1 micrometer) in vitro. Most unexpectedly, however, was the finding of complete lack of either antiviral or antineoplastic activity by the 3',5'-diamino analogue 7 which appears to have acquired the undesirable qualities of both the 3'-amino and 5'-amino analogues of thymidine.

Topics: Animals; Antineoplastic Agents; Antiviral Agents; Cell Division; Cells, Cultured; Leukemia L1210; Sarcoma 180; Thymidine; Virus Replication