Heiichi Sakai

NOCARDICIN A, A NEW MONOCYCLIC β-LACTAM ANTIBIOTIC

Nocardicin A is a new monocyclic beta-lactam antibiotic obtained from the fermentation broth of a strain of actinomycetes. The producing organism, strain WS 1571, was identified as Nocardia uniformis subsp. tsuyamanensis ATCC 21806. The antibiotic, obtained as colorless crystals, exhibits moderate in vitro antibacterial activity against a broad-spectrum of Gram-negative bacteria including Proteus and Pseudomonas. It has low toxicity in laboratory animals.

A New Toxic Substance, Teleocidin, Produced by Streptomyces.: Part I. Production, Isolation and Chemical StudiesPart II. Biological Studies of Teleocidin

In the course of studies on the screening of specific toxic substances produced by Streptomyces against aquatic organisms, it was recognised that a newly isolated Streptmyces, 2A 1563, which was considered to be a variant species of Streptomyces mediocidicus produces a new toxic substance, Teleocidin. Teleocidin was isolated as a white powder resembling crystals with a crystal appearance from the methanol extracts of the cultured mycellium, and showed a specific toxic action toward Japanese killifish and mice, but did not exhibit any inhibition against microorganisms.

Studies on New Antimetabolite N-1409

New antimetabolite N-1409, an antagonist of L-threonine was isolated from the fermentation broth of Streptomyces. Taxonornical study on the producing strain made it a new species and named Streptomyces plumbeus n. sp. Sakai et Park after its leaden color of matured aerial mycelium. N-1409 substance was isolated as colorless needles, mp 218_??_220°C. Its molecular formula C12H21N4O8P•3/2 H2O was determined by elementary analysis and alkali titration. On acid hydrolysis, L-alanine, L-aspartic acid and a new phosphorus containing amino acid were obtained.

TERRECYCLIC ACID A, A NEW ANTIBIOTIC FROM ASPERGILLUS TERREUS

The structure of a new antibiotic, terrecyclic acid A, from a strain of Aspergillus terreus Thom, was established as I on the basis of spectroscopic and chemical evidences, by comparison of spectroscopic data with quadrone, a known antitumor substance, and further by conversion of terrecyclic acid A to quadrone through pyrolysis.

Structure of Plumbemycin A and B, Antagonists of L-Threonine from Streptomyces plumbeus

The structure of plumbemycin A and B, new antimetabolites from Streptomyces plumbeus, which are antagonist of l-threonine, were assigned to be l-alanyl-l-aspartyl-d-2-amino-5-phosphono-3-czs-pentenoic acid and l-alanyl-l-asparaginyl-d-2-amino-5-phosphono-3-m-pentenoic acid, respectively.

Studies on the biosynthesis of terrecyclic acid A II confirmation of the cyclization mechanism and hydrogen shifts using [2-2H3]acetate and [213C2H3]acetate

Abstract Feeding experiments with [2-3H3]acetate and [2-13C2H3]acetate in Aspergillus terreus Thom No. 14 indicated that the hydrogen at C-2 in terrecyclic acid A is incorporated without migration from the precursor acetic acid; the results favour our groups earlier speculation for the cyclization to the tricyclic skeleton in the biosynthetic scheme.

Urocanic Acid, Produced by Sporogenous Bacteria: Part I. Fermentation, Isolation and Chemical Studies

On the screening of microorganisms which accumulate ultra violet light absorbing substances, some sporogenous bacteria were selected as powerful strains for production of a crystalline substance having a maximum absorption at 267.5 mμ (pH 6.0 in water). These strains were microbiologically examined and named B. subtilis var. thermophilus. Submerged fermentation was carried out for 48 hrs at 37°C in glucose bouillon medium and the isolation of substance was performed by absorption to active carbon and elution with ammonia water.On the basis of chemical studies of this crystal, it was identified as urocanic acid.