Shinji Miura

Synthesis of 4′-C-fluoromethylnucleosides as potential antineoplastic agents

Abstract 2-Deoxy- d -erythro-, ribo-, and arabino-pentofuranosylcytosines, which have a fluoromethyl group at the 4′-position, were synthesized. Introduction of fluorine was achieved by DAST treatment of 4-C- hydoxymethyl- d -ribofuranose , the key intermediate of 4′-C-methylnucleosides. Among these nucleosides, the 2′-deoxy derivative exhibited potent antineoplastic activity in vitro.

The Antitumor Mechanism of 1‐(2‐Deoxy‐2‐fluoro‐4‐thio‐β‐D‐arabinofuranosyl)‐cytosine: Effects of Its Triphosphate on Mammalian DNA Polymerases

The mechanism of action of the antitumor nucleoside analog l‐(2‐deoxy‐2‐fluoro‐4‐thio‐β‐D‐arabinofuranosyl)cytosine (4′‐thio‐FAC) was investigated. 4′‐Thio‐FAC inhibited cellular DNA synthesis, but not RNA and protein syntheses. We observed potent inhibitory action of the triphosphate of 4′‐thio‐FAC (4′‐thio‐FACTP) against DNA polymerase α, whereas it showed moderate inhibition of DNA polymerase P and little inhibition of DNA polymerase β. The kinetic analysis showed that the inhibition mode of 4′‐thio‐FACTP towards DNA polymerase a was mixed type, implying a chain‐terminating effect of 4′‐thio‐FACTP. The triphosphate of 2′‐deoxy‐2′,2′‐difluorocytidine (gemcitabine), a known antitumor nucleoside, did not show potent inhibition of these three DNA polymerases. Thus, the effect of the diphosphate of gemcitabine on ribonucleotide reductase was suggested to be more important for the antitumor action of gemcitabine. From these findings, the main target enzymes of 4′‐thio‐FAC and gemcitabine appear to be different. We found a synergistic effect of the two drugs in an in vitro model, which supports the above idea.

Synthesis and Biological Activities of 2′-Modified 4′-Thionucleosides

Abstract We have synthesized 4′-thioDMDC, 4′-thiogemcitabine, and 4′-thioarabinonucleosides, as potential antitumor and antiviral agents, originated from D-glucose. Biological activities of these compounds are also described.