Field desorption mass spectrometry has been shown to be the method of choice in determining molecular weights of a number of non-volatile or thermally unstable antibiotics.Examples are neomycin, streptolydigin, and novobiocin, which do not give molecularions by electron impact or chemical ionization mass spectrometry. In addition, field desorption mass spectrometry provides good indication of the composition of complexes of antibiotics, as illustrated by streptovaricin, filipin, and dermostatin.
A new iron-containing antibiotic named NRCS-15 was isolated from a Streptomyces strain. The antibiotic inhibits the growth of Gram-positive bacteria. The antibiotic is similar to the sideromycin group of antibiotics in that it contains iron but it differs in some other characters. Antibiotic NRCS-15 liberated 8 amino and 3 organic acids on hydrolysis. The morphological and physiological characteristics of the producing organism as well as the isolation and properties of the antibiotic are described.
A new nucleoside antibiotic, inhibiting the growth of fungi, could be isolated from Streptomyces exfoliatus. The antibiotic was found by a screening method based on the inhibition of zygospore formation of Mucor hiemalis. It is composed of equal amounts of adenine, L-leucine, and an unusual tetrahydroxy-monocarbonic acid, C11H14O9 with properties similar to a carbohydrate.
An evaluation of the 100 MHz NMR spectrum strongly suggests that the structure of cerulenin is (2S) (3R) 2, 3-epoxy-4-oxo-7, 10-dodecadienoyl amide rather than the -6, 10-dodecadienoyl amide analog. This conclusion was experimentally supported by a spin-decoupling study in a benzene-chloroform mixed solvent system.
Eighty to 100% of mice stressed with an intraperitoneal dose of 200-240 mgbromoethylamine hydrobromide (BEA)/kg and infected intraveneously 72 hours laterwith Proteus mirabilis, Pseudomonas, Escherichia coli or Serratia host large numbers of bacteria in their kidneys 3-4 days post-infection. If death (probably due to uremic poisoning) does not intervene, the infection lasts for weeks. The therapeutic effects of carbenicillin and ampicillin were tested in this pyelonephritis model. Carbenicillin was effective against Pseudomonas ; ampicillin had an effect against P. mirabilis, but neither carbenicillin nor ampicillin was effective against Serratia-induced pyelonephritis.
Cefoxitin, a semi-synthetic derivative of cephamycin C, is an analogue of cephalo-thin, and the two compounds were found to have many properties in common. A total of 232 strains of bacteria, representing 13 genera, isolated recently from clinical material, have been tested for sensitivity to both antibiotics. Against Gram-positive organisms, cephalothin was at least 8 times more active than cefoxitin, but against sensitive Gram-negative strains the activities of the two compounds were similar. Cefoxitin was active against a higher proportion of Bacteroides fragilis, Enterobacter spp. and Klebsiella spp. than was cephalothin, and was effective against 11 out of 12 indole-producing Proteus strains tested, all but one of which were resistant to cephalothin. Cefoxitin was remarkably stable in the presence of organisms which produce β-lactamase. Thus, on microbiological grounds, cefoxitin represents a significant advance over presently avail-able conventional cephalosporins.
The production of the antibiotic, indolmycin, was shown to be inhibited by glucose at 0.5%. Concentrations of glucose of 0.005% and 0.01% produced a stimulation of indolmycin production. Of a selection of mono and disaccharides examined, glucose and to a lesser extent mannose, caused inhibition of indolmycin production. Galactose, fructose and sucrose all caused stimulation of indolmycin synthesis.
A group of epipolythiopiperazinedione antibiotics was obtained from the fermentation broth of Penicillium turbatum. The fermentation, isolation, biological properties and structure elucidation of three metabolites of this group are discussed.
Brefeldin A is an antifungal antibiotic and a fatty acid derivative biosynthesized from palmitate (C16). The action mechanism of the antibiotic was studied using Candida albicans IAM 4888, the most sensitive strain tested. The antifungal activity was reversed to some extent by a variety of fatty acids (C10-C14), fatty alcohols (C10-C14) and iso-prenoids such as ergosterol and geraniol. However, amino acids and nucleosides were ineffective in reversing the antifungal activity. The results suggest that the antibiotic growth inhibition is due to the inhibition or disturbance of lipid metabolism.
Bleomycins, a group of glycopeptide antibiotics differ from one another in their terminal amine moieties. 14C-Methyl-labeled 3-aminopropyl-dimethylsulfonium was con-firmed to be incorporated into the amine moiety of bleomycin A2. Addition of amines of bleomycin A2, A2'-a, A2'-b, A2'-c, A5, B2 and B4 to fermentation media increased the rate of production of the bleomycin which contained the added amine. Addition of the amines of bleomycins A2, A2'-b, A2'-C, A5, B2 and B4 suppressed production of the other natural bleomycins almost completely. New bleomycins which contained deiminated products of amines of B2 and B4 were isolated from media to which these amines were added. Amines which were not found in natural bleomycins also suppressed production of natural bleomycins and caused production of new biosynthetic bleomycins which con-tained the added amines. The data of the production of these new bleomycins suggested a relationship of the incorporation rates to the structures of possible metabolites.
In the course of screening for new antibiotics, spectinomycin (abbreviated as SPM)-like activity was discovered. The producing culture, strain No. MK43 was unlike the known SPM-producers, Streptomyces spectabilis1) and S. flavopersicus2). Since SPM has recently become more important for the treatment of disease such as gonorrhea3), identification of the products and the organism was carried out.