An antibiotic named S-520 was isolated from a strain S-520 which was identified as Streptomyces diastaticus. The antibiotic is primarily active against gram-positive bacteria. The antibiotic is suggested to be a complex which consists of several peptides closely related to each other. It has λMeOhmax : 227 mμ, 283.5 mμ, 290 mμ and 299.5 mμ and [α]D +13.2°C (in methanol). Analytical data corresponds to C40H59-60O10N8-9Cl. Glycine, valine, isoleucine, ornithine, lysine and some unknown amino acids are produced on hydrolysis.
For further resolution of the peptide antibiotic complex S-520, a dinitrophenyl derivative and an acetyl derivative were prepared. Two forms (I and II) were isolated on thin-layer chromatograghy of the derivatives, but they were found to be interconvertible, and were suggested to be δ-lactone and acid forms respectively. Studies on the acid hydrolysate of the antibiotic complex indicated the presence of glycine (1 mole), D-valine (ca. 0.74 moles), D-isoleucine (ca. 0.18 moles), ornithine (ca. 0.75 moles), lysine (ca. 0.27 moles) and four previously unknown amino acids (named a-I, n-I, n-II, n-III). The construction of the antibiotic complex was discussed.
Rabelomycin, a new benz [a] anthraquinone antibiotic, has been isolated from fermentation broths of Streptomyces olivaceus ATCC 21, 549. It is active against gram-positive microorganisms. Rabelomycin loses water easily when treated with acid. Structures I and III have been proposed for rabelomycin and its dehydration product, respectively.
A new crystalline antimicrobial compound, geldanamycin, has been discovered in the culture nitrates of Streptomyces hygroscopicus var. geldanus var. nova. Geldanamycin is moderately active in vitro against protozoa, bacteria and fungi. It is also active against L-1210 and KB cells growing in culture and against the parasite Syphacia ohlevata, in vivo. The fermentation, assay, chromatography and isolation as well as its biological and chemical properties were investigated. On the basis of its physical and chemical properties, geldanamycin is a complex molecule consisting of an unsaturated moiety attached to a quinone.
Two neutral macrolide antibiotics, kujimycin A (desacetyl lankamycin) and kujimycin B (lankamycin) inhibited the growth of certain macrolide resistant strains of staphylococci. The antimicrobial activities of kujimycins A and B against the strains of clinically isolated staphylococci which were resistant to other antibiotics were examined. Kujimycins A and B inhibited the growth of strains resistant to penicillin (PC), tetracycline (TC), streptomycin (SM), kanamycin (KM) and chloramphenicol (CP) as well as strains of an unknown type of staphylococcus resistant to erythromycin (EM) and oleandomycin (OM) constitutively. Kujimycins A and B did not inhibit the growth of group A strains (EM, OM, leucomycin (LM), spiramycin (SPM) resistant or EM, OM, LM, SPM, lincomycin (LCM) resistant), group B strains (EM, OM-resistant) and group C strains (EM, OM, LM, SPM, LCM-resistant) carrying induced resistance. Kujimycins A and B were found to be capable of inducing macrolide resistance as do EM and OM in inducible resistant strains. Staphylococcus aureus TPR-4B, a laboratory-developed strain, was constitutively resistant to LM and SPM at the concentration of 100 mcg/ml or more but it was sensitive to kujimycins A and B at the concentration of 12.5 mcg/ml. The minimal inhibitory concentrations of kujimycins A and B against Staphylococcus aureus FDA209P did not change at the range of pH 5.8-8.2.