Aristeromycin, a new antibiotic isolated from the culture broth of Streptomyces citricolor, exhibits inhibition of the growth of Pyricularia oryzae and Xanthomonas oryzae. The structure of aristeromycin, apart from stereochemistry, was assumed as (A) on the basis of physicochemical and chemical properties of aristeromycin and its pentaacetate. By X-ray analysis of aristeromycin hydrobromide the assumed structure was ascertained and the absolute configuration was established as (1'R, 2'S, 3'R, 4'R)-9-[β-2'α, 3'α-dihydroxy-4'β-(hydroxymethyl) cyclopentyl] adenine.
