Nucleoside antibiotics: III. Isolation, structural elucidation and biological properties of 3′-acetamido-3′-deoxyadenosine from Helminthosporium sp. 215

Abstract

Two additional nucleosides have been isolated from the culture filtrates of Helminthosporium sp. 215. They are 3′-acetamido-3′-deoxyadenosine and adenosine. The 3′-amino-3′-deoxyadenosine, isolated from the culture filtrates of Helminthosporium, was converted to 3′-acetamido-3′-deoxyadenosine by treatment with acetic anhydride. The chemical, physical properties and stereochemistry of the synthetic and naturally occurring 3′-acetamido-3′-deoxyadenosine were identical. The mass spectra as reported for 3′-acetamido-3′-deoxyadenosine and 3′-amino-3′-deoxyadenosine are very similar. The acetyl substituent on the 3′-amino-3′-deoxyadenosine position results in a somewhat different fragmentation pattern for 3′-acetamido-3′-deoxyadenosine when compared to 3′-deoxyadenosine. The mass spectrum of 3′-acetamido-3′-deoxyadenosine provides additional evidence for the structure of this nucleoside. The biochemical properties of 3′-amino-3′-deoxyadenosine and 3′-acetamido-3′-deoxyadenosine are markedly different. 3′-Acetamido-3′-deoxyadenosine was not inhibitory against Ehrlich-Lettre tumor cells nor bacteria while 3′-amino-3′-deoxyadenosine was toxic to ascitic adenocarcinoma. 3′-Acetamido-3′-deoxyadenosine was not toxic to mice, whereas 3′-amino-3′-deoxyadenosine was toxic to mice.