A protozoan Tetrahymena pyriformis W as a test organism can be useful in the preliminary screening for antiprotozoals, especially antitrichomonas agents. By this screening method, ikarugamycin, a new antibiotic with specific antiprotozoal activity was found in the culture of Streptomyces sp. No. 8603 isolated from a soil sample. The morphological characteristics of Streptomyces sp. No. 8603 include formation of gray aerial mycelium, dark brown growth and aerial hyphae forming a long spiral. Strain No. 8603, belonging to a chromogenic type, was identified as a variety of Streptomyces phaeochromogenes and given the name Streptomyces phaeochromogenes var. ikaruganensis SAKAI. Ikarugamycin was isolated as white crystalline needles, decomposing at 252-255°C, and exhibiting optical rotation [α]20D+360° (c 1.10, dimethylformamide). Its molecular formula C29H38O4N2 was given by elementary and mass spectrum analyses. The ultraviolet absorption gave two maximal peaks at 220mμ and 325mμ in methanol. Ikarugamycin showed strong antiprotozoal activities: MIC 0.3-1.25 mcg/ml against Trichomonas vaginalis, MIC 1.0 meg/ml against Tetrahymena pyriformis W and MIC 2-10 meg/ml against Entamoeba histolytica. The median lethal dose of ikarugamycin was 6 mg/kg, determined in mice by intraperitoneal administration. Hexahydro-ikarugamycin was obtained by catalytic hydrogenation of ikarugamycin and its physicochemical and biological properties were investigated. It is similarly active against T. vaginalis as is the antitrichomonas agent, azalomycin F and its acute toxicity (LD50 300 mg/kg, ip, in mice) is less than that of ikarugamycin and azalomycin F.
A polarimetric study was made of the interaction of the tetramminecopper (TACu) reagent and the Cupra B reagent with bluensomycin, desamidinodecarbamoyl (DADC) bluensomycin, and several reference compounds of the streptomycin series. The results obtained with TACu support the choice of 5b as the correct formula for DADC-bluensomycin. It follows that bluensomycin is 9, and bluensidine is 1D-1-O-carbamoyl-3-deoxy-3-guanidino-scyllo-inositol (2). A phosphorylated aminosugar, D-glucosamine 1-phosphate, gives a normal Δ[M] value with TACu.
The affinities of ten streptomycin (SM) derivatives were compared to that of tritium labelled dihydro-streptomycin (T-DHS) towards "run off" 70S ribosomal particles from a sensitive E. coli. The in vitro affinities were correlated with the in vivo activities (killing activities). High affinity and activity could only be demonstrated in derivatives with an intact streptidine (SD) moiety. Furthermore an interaction between the streptose branch and the amino group was necessary to obtain high affinity and activity. The highest in vivo activity was found when the amino group was N-mono-methyl substituted. Our results indicate that SM binds to two sites at the 70S particles, one having the character of a cation-exchanger (RNA), the other being presumably a metal ion (Mg2+). The metal ion probably forms a complex with the glucosamine and the streptose branch moieties.
Further hydrolytic and oxidation studies on the antibiotic vancomycin have resulted in a revision of the structure of one of the aromatic units and the identification of N-methylleucine as a terminal group.
The incorporation of 14C-labeled glucose, shikimate, benzoate, L-phenylalanine, and DL-tryptophan into antimycin A by Streptomyces AY-B-265 was examined. The most efficient incorporation was observed with L-phenylalanine-14C (U) (0.18%) and variously 14C-labeled DL-tryptophan (up to 2.0%). Analysis of degradation products from 14C-labeled antimycin produced from benzene-ring-14C-DL-tryptophan and L-phenylalanine-14C (U) showed a high proportion of the isotope present in the 3-aminosalicylic acid residue. Incorporation of 2-ring-14C-DL-tryptophan followed by degradation of the antimycin demonstrated that carbon-2 of the indole ring was incorporated into the 3-formamido carbonyl of antimycin in high yield. Tryptophan dilution studies suggested a fairly large tryptophan pool in cells transferred to resting medium for incorporation studies.
A new antibiotic, jolipeptin, was isolated from the cells of Bacillus polymyxa var. colistinus KOYAMA, a colistin-producing strain. Jolipeptin is a polypeptide antibiotic containing glycine, alanine, serine, valine, glutamic acid and α, γ-diaminobutyric acid. It contains no fatty acids as does colistin. It inhibits growth of gram-positive and gram-negative bacteria.
Jolipeptin causes a release of 260 mμ, absorbing materials from the jolipeptin-sensitive strains, Escherichia coli B and Bacillus subtilis PCI 219. Moreover, Jolipeptin lyses not only protoplasts of B. subtilis PCI 219 and Micrococcus lysodeikticus, but also spheroplasts of E. coli B and Pseudomonas aeruginosa IFO 3901. In contrast, colistin, produced simultaneously with Jolipeptin, lysed spheroplasts of E. coli B and P. aeruginosa IFO 3901, but not protoplasts of gram-positive bacteria, the latter being colistin-insensitive strains. On the basis of this study, it was concluded that Jolipeptin acts primarily on the cellular membrane.