Tetranactin, m.p. 105-106°C, [α]23.5D 0 (c 1, chloroform), belongs to the macrotetrolide antibiotic class, as exemplified by nonactin. The molecular formula, C44H72O12, was assigned on the basis of elementary analysis and the molecular weight determined by mass spectroscopy. Tetranactin consists of four units of homononactic acid linked to form a cyclic polyester. Crystal data from X-ray photograph indicate that the tetranactin molecule is either a racemicor meso-form.
The effect of neocarzinostatin on in vitro DNA synthesis by DNA polymerase I prepared from Escherichia coli was investigated. DNA synthesis in vitro by Escherichia coli polymerase I was inhibited in the presence of neocarzinostatin. The inhibition increased when the template was preincubated with the antibiotic. Synthesis directed by poly d(A-T) was more sensitive to the antibiotic than synthesis directed by calf thymus DNA. The melting temperature of DNA decreased whenit was incubated with neocarzinostatin in vitro. From these results it was suggested that the effect of neocarzinostatin on DNAsynthesis in vitro could be caused by a direct interaction of the antibiotic with the template.
Eighteen aminoglycosidic antibiotics and their degradation products, containing 2-deoxystreptamine as a commonmoiety, were separated by gas-liquid chromatography. The largest compounds examined included the pentacyclic lividomycins A and B. These compoundswere separable from each other either as pertrimethylsilyl derivatives or N-trifluoroacetyl pertrimethylsilyl derivatives on a single column of OV-1. The relative retention times are discussed in terms of structure.
Indolequinones postulated as essential structure for activity of mitomycin were synthesized and examined for their antibacterial activities. Acyl esters of 3-hydroxymethylindole(4, 7)dione showed strong activity against Grampositive bacteria but those of 2-hydroxymethylindolequinone did not.
A total of 15 strains of Mycoplasma were examined for in vitro sensitivity to 22 commonly used antibiotics and 9 nitrofurans. They were strains of Mycoplasma mycoides var. mycoides, M. mycoides var. capriy, M. hyorhinis, M. suipneumoniae (hyopneumoniae), M. granularum, M. cams, M. pulmonis, M. arthritidis, M. neurolyticum, M. gallisepticum, and M. laidlawii, all of which were isolated from various animals, except for one strain of M. laidlawii which was isolated from sewage. The sensitivity was determined by observing inhibition of growth in the agar and broth dilution systems. Amongall the mycoplasmasexamined, there were no markeddifferences in susceptibility to these drugs, with the exception of erythromycin and oleandomycin. Antitumor antibiotics, i. e., actinomycin D and mitomycin C, were the most active of all the agents. Tylosin, bottromycin, spiramycin and tetracycline followed them in activity. Kasugamycin, polymyxin B and colistin were noninhibitory. M. suipneumoniaea, which is known as the etiological agent of swine enzootic pneumonia (SEP), and other species of respiratory mycoplasmas of swine were compared with regard to minimuminhibitory concentrations (MIC) upon these drugs. The sensitivity of M. suipneumoniae to the drugs used was similar to that of other mycoplasma.Amongthe new nitrofurans tested, drugs with high activity against the mycoplasma were discovered.
A new antibiotic, SF-837, having potential utility as a chemotherapeutic agent was discovered in the culture broth of Streptomyces mycarofaciens SHOMURA and NIIDA nov. sp. Antibiotic SF-837 is a basic macrolide showing a UV maximum at 232 mμ, and is different from the leucomycins, josamycin, the spiramycins and the tertiomycins. It has a molecular formula C41H67NO15 (MW, 813), and liberated 2 moles of propionic acid on hydrolysis.
The structure of a new macrolide antibiotic SF-837 was determined as 1 by physico-chemical methods in conjunction with chemical means. Mass spectra of SF-837 and related compoundsincluding leucomycins were accounted for in terms of structures.
Three newantibiotics were isolated as minor componentsfrom the culture broth of Streptomyces mycarofaciens, and named as SF-837 A2, A3 and A4. They are basic macrolides and have the molecular formulae of C42H69NO15, C41H65NO15 and C42H67NO15, respectively. SF-837 A2 showed a UV maximum at 232mμ, and gave on hydrolysis propionic acid and n-butyric acid, one mole each, suggesting to be a homologue of SF-837. SF-837 A3and A4 exhibited a UVmaximum at 280 mμ, and liberated two moles of propionic acid and a pair of one propionic acid and one n-butyric acid in their respective hydrolyzates. Their antibacterial activities were analogous to that of SF-837.The physico-chemical characterization of three components established their novelties.