Streptothricin derivatives from Streptomyces sp. I08A 1776

Five new streptothricin derivatives with a carbamoyl group substituted at C-12 (1-5) and three known analogues have been isolated from the culture broth of Streptomyces sp. I08A 1776 by ion exchange and hydrophilic interaction chromatographic techniques. Their structures were determined by spectroscopic and chemical methods. Compound 3 was a streptothricin derivative possessing a cis-streptolidine moiety. Its absolute configuration was defined by comparison of quantum chemical TDDFT calculated and experimental ECD spectra. Compound 5 and streptothricin E (6) displayed antibacterial and antifungal activity with MIC values in the range 1-64 μg/mL.

A-53930A and B, novel N-type Ca2+ channel blockers

A-53930A, B and C, which inhibit N-type Ca2+ channels, were isolated from the culture broth of Streptomyces vinaceusdrappus SANK 62394. A-53930A and B were new compounds which contained a carbamoyl group on the 6-hydroxyl group of the D-gulosamine part of streptothricin. A-53930C was identical to streptothricin B. A-53930A, B and C inhibited [125I]omega-conotoxin MVIIA binding to N-type Ca2+ channels (IC50= 0.17, 0.091 and 0.071 microM), but did not inhibit [3H]PN200-110 binding to L-type Ca2+ channels (IC50 > 50 microM). These compounds also inhibited [3H]norepinephrine release from chick cerebral cortex synaptosomes (IC50=91.0, 20.6 and 39.5 microM), indicating these compounds selectively block N-type Ca2+ channels which are important for neurotransmitter release. It was also revealed that although A-53930C had antimicrobial activity against gram-negative and -positive bacteria and fungi, A-53930A and B showed weak activity only against gram-negative bacteria.

Streptothricin biosynthesis is catalyzed by enzymes related to nonribosomal peptide bond formation

In a search for strains producing biocides with a wide spectrum of activity, a new strain was isolated. This strain was taxonomically characterized as Streptomyces rochei F20, and the chemical structure of the bioactive product extracted from its fermentation broth was determined to be a mixture of streptothricins. From a genomic library of the producer strain prepared in the heterologous host Streptomyces lividans, a 7.2-kb DNA fragment which conferred resistance to the antibiotic was isolated. DNA sequencing of 5.2 kb from the cloned fragment revealed five open reading frames (ORFs) such that ORF1, -2, -3, and -4 were transcribed in the same direction while ORF5 was convergently arranged. The deduced product of ORF1 strongly resembled those of genes involved in peptide formation by a nonribosomal mechanism; the ORF2 product strongly resembled that of mphA and mphB isolated from Escherichia coli, which determines resistance to several macrolides by a macrolide 2'-phosphotransferase activity; the ORF3 product had similarities with several hydrolases; and the ORF5 product strongly resembled streptothricin acetyltransferases from different gram-positive and gram-negative bacteria. ORF5 was shown to be responsible for acetyl coenzyme A-dependent streptothricin acetylation. No similarities in the databases for the ORF4 product were found. Unlike other peptide synthases, that for streptothricin biosynthesis was arranged as a multienzymatic system rather than a multifunctional protein. Insertional inactivation of ORF1 and ORF2 (and to a lesser degree, of ORF3) abolishes antibiotic biosynthesis, suggesting their involvement in the streptothricin biosynthetic pathway.

A streptothricin-like antibiotic mixture, A-269A (and A-269A')

A streptothricin-like antibiotic, A-269A (referred to as A-269A hereafter) was isolated from the culture broth of Streptomyces sp., strain No. A-269. In this paper, the characterization of the producer, and the production, isolation, physico-chemical properties and biological properties of A-269A are reported. The structure of the antibiotic was also examined by 1H NMR, 13C NMR and fast atom bombardment mass spectra studies. From the spectroscopic data, A-269A was assumed to be a mixture of antibiotic LL-BL 136 and an isomeric compound in which the carbamoyl group is substituted on C-12' hydroxyl instead of C-10 hydroxyl.

New streptothricin-group antibiotics, AN-201 I and II. Screening, fermentation, isolation, structure and biological activity

Two streptothricin-group antibiotics, AN-201 I and II, were newly discovered and isolated from the culture broth of Streptomyces nojiriensis C-13. These antibiotics were purified by IRC-50 (H+) and CM-Sephadex C-50 chromatography, and paper electrophoresis. Structural analysis of AN-201 I and II showed that they were N beta-acetylated derivatives of streptothricin E and D, respectively. They had antibacterial activities against several strains of Escherichia coli, Bacillus subtilis, Micrococcus luteus and Staphylococcus aureus, and showed a strong selective cytotoxic effect on 3T3 cells transformed with SV-40 as compared with their normal cells in a test system in vitro as well as in vivo.

Separation and biologic activities of individual components of S15-1, a streptothricin class antibiotic

A method is described for isolation of gram quantities of the components of the streptothricin complex S15-1 utilizing CM Sephadex column chromatography eluted with 10% acetic acid as an eluant followed by gradient elution with 10% acetic acid containing 0.02 N approximately 0.03 N HCI. Streptothricins F and E, as well as an unidentified component C1, have been isolated and their comparative biological activities determined. Streptothricins F and E were comparable in taeniacidal activity in mice infected with Hymenolepis nana ia feeding either one at 0.05% in the diet removed 92 approximately 100% of the adult tapeworms. The unidentified component C1 was inactive at the levels tested. In contrast, component C1 was the most active in antimicrobial activity against Bacillus subtilis and in inhibiting the urease activity of proteus mirabilis. In the former test, the ratios of activity were; 1:7:30 for F:E:C1 and in the latter; 1:2:4 for F:E:C1.

Glycinothricin, a new streptothricin-class antibiotic from Streptomyces griseus

Glycinothricin is a streptothricin-class antibiotic obtained for the first time from the culture broth of a strain of Streptomyces griseus. Glycinothricin, the deformimino derivative of antibiotic LL-AB664, gives N-methylstreptolidine, N-methyl-D-glucosamine and glycine on acid hydrolysis. In comparison with LL-AB664, glycinothricin is less active against gram-positive and gram-negative bacteria and less toxic to mice.