An overview of the role of nucleosides in chemotherapy.

A wide variety of nucleosides have been synthesized which interfere with the functions of natural nucleosides at many different loci. These analogues may act as substrates or inhibitors of nucleoside-metabolizing enzymes or may bind to cell membrane receptors. Because of quantitative and qualitative differences in the enzymes and receptors of various tissues and species, the nucleoside analogues have found important uses as antitumor, antiviral, antiparasitic and immunomodulating agents.