An antibiotic active specifically against Mycobacterium tuberculosis BCG has been isolated in crystalline form the culture filtrates of a streptomycete* isolated from a soil sample. The antibiotic has a formula of C₁₀H₁₂N₄O₄ and a characteristic absorption at 263 mμ. Acid hydrolysis study followed by the paperchromatography proved the presence of purine and D-ribose. The subsequent comparative studies with the synthetic specimen proved that the antibiotic is 9-β-D-ribofuranosylpurine.

This nucleoside is a synthetic anticancer agent¹⁾ and its occurrence in nature was first found in the mushroom, Agaricus neburaris, in minute quantity and named as nebuline.²⁾ This is the second case found as the natural product and is the first time that this nucleoside is isolated as a metabolic product of streptomycete.