Naturally Occurring Nucleoside and Nucleotide Antibiotics

Abstract

This chapter reviews that three of the naturally occurring nucleoside antibiotics—that is, tubercidin, 5-azacytidine, and ara-A—have been successfully used in humans as antineoplastic and antiviral agents. A fourth antibiotic, pyrazofurin, is undergoing clinical testing as an antineoplastic agent for carcinoma of the breast. In addition to the health-related application of these naturally occurring nucleoside and nucleotide antibiotics, some have found application as antifungal agents. The chapter discusses that once the structures of some of the nucleoside antibiotics establish, it is possible in some cases to predict the cellular reaction which would be affected by them. The pyrimidine nucleoside antibiotics, which resemble the -CCA terminus of tRNA, bind to ribosomal peptidyltransferase and inhibit protein synthesis in prokaryotes and eukaryotes. Two adenosine analogs, agrocin 84 and thuringiensin, have been isolated as nucleotides. Agrocin 84 prevents cell growth, most probably by interacting with receptor sites on bacterial cell surfaces. Thuringiensin, as a nucleotide, is taken up by mammalian cells and acts as an ATP analog. The aim of this chapter is to evaluate the progress that has been made in the nucleoside antibiotics. Two nucleosides, eritadenine and clitidine, although not antibiotics, are also discussed because of their biological properties.