Hiroshi Yonehara

Studies on the ionophorous antibiotics. I. The crystal and molecular structure of salinomycin p-iodophenacyl ester

The crystal structure and absolute configuration of the p-iodophenacyl ester of salinomycin, Cs0H75012I, an antibiotic produced by Streptomyces albus, has been determined by three-dimensional X-ray analysis. The crystals are orthorhombic, space group P212t21 with four molecules in the unit cell of dimensions a= 20.981 (2), b= 22-761 (2), c= 10.493 (1)/~. The structure was solved by the heavy-atom method and refined by the block-diagonal least-squares method with anisotropic thermal factors for the non-hydrogen atoms. The final R is 0.066 for 3288 observed reflexions collected by diffractometry. The absolute configuration was determined by the use of the anomalous dispersion effect of the iodine atom for Cu K0c radiation. This work reveals that salinomycin is a new member of the polyether antibiotics containing a unique tricyclic spiroketal ring system and an unsaturated six-membered ring in the molecule.

The structure of adenomycin (C19-97 substance)

Abstract The structure of adenomycin, a new antibiotic active against Mycobacterium , has been established as a nucleoside consisting of adenine, D-ribose, (−)- chiro -inositol, L-gulosamine, L-serine and sulfate.

Synthesis of detoxininolactone derivatives and the revised absolute stereochemistry of detoxinine

Abstract A stereospecific synthesis of acetyl- L -valyl-detoxininolactone has been performed and the absolute stereochemistry of detoxinine has been revised to (2 S , 3 R , 1′ S )-2-(2′-carboxy-1′-hydroxyethyl)-3-hydroxypyrrolidine.

Biological Transformation of Blasticidin S by Aspergillus fumigatus sp.: Part I. Isolation, Characterization and Structures of Transformed Products and their Biological Properties

A strain of Aspergillus fumigatus isolated from soil, transformed blasticidin S into four substances designated U1, U2, U3 and U4 respectively. U1 is less toxic and retains biological activities. Structural elucidation of these compounds comes to the conclusion that they differ from blasticidin S in pyrimidine base, e.g., uracil instead of cytosine nucleus. The structures of U2, U3 and U4 are elucidated.

The structures of minor congeners of detoxin complex, the selective antagonist of blasticidin S1

The structures of the minor congeners of detoxin complex, viz., detoxins E1, C1, C2, C3, B1, B3 and A1 have been established on the basis of spectral and degradative evidence.

Chemical Studies on Blasticidin S

Acid hydrolysis of cytosinine gave each one mole of cytosine, levulinic acid, ammonia and carbon dioxide. Reduction of cytosinine with PtO2 afforded a mixture of dihydrocytosinine, 3-amino-tetrahydropyran-2-carboxylic acid and cytosine. Ozonolysis of N,N’-diacetylcytosinine methyl ester, followed by oxidation with hydrogen peroxide and acid hydrolysis gave erythro-d-β-hydroxyaspartic acid. These data permitted the assignment of structure (I) for cytosinine. Acid hydrolysis of uracinine gave uracil instead of cytosine, therefore, the structure (II) could be assigned to uracinine. Some stereochemical features and mechanism of levulinic acid formation were discussed.

Studies on the New Seventeen Member Lactonic Antibiotics, Bundlins: Part I. The Structures of Bundlin A and B

Structural elucidation of the antibiotics bundlin A and B have been accomplished by chemical and spectral results together with three dimensional X-ray structure analysis. The structures of bundlins were consisted of seventeen membered carbon skeleton fused with a six membered lactone system and a pyruvamide side chain.

Studies on the Biosynthesis of Blasticidin S: Part I. Precursors of Blasticidin S BiosynthesisPart II. Leucylblasticidin S, a Metabolic Intermediate of Blasticidin S Biosynthesis

Biosynthesis of blasticidin S by the producing organism Streptomyces griseochromogenes has been investigated with the use of 14C-labeled compounds. Studies on the incorporation of the labeled compounds demonstrated that blasticidin S was biosynthesized from d-glucose, cytosine, l-arginine and l-methionine as precursors.During efforts in looking for a metabolic intermediates on the biosynthetic pathway of blasticidin S, it was found that a compound closely related in nature to the parent antibiotic accumulated under a restricted conditions. After the isolation of this compound the structure was elucidated as leucylblasticidin S on the basis of its spectral and degradative evidences. The biosynthetic role of leucylblasticidin S was confirmed as a direct metabolic intermediate with the use of washed cells of Streptomyces griseochromogenes.