Pyridazomycin (1), a new antifungal antibiotic produced by Streptomyces violaceoniger sp. griseofuscus (strain Tii 2557), was detected in a selective screening against Mucor hiemalis (Tii 179/180). The amino acid side chain of 1 can be seen as L-ornithine, whose r-nitrogen atom is part of a pyridazine ring building a quaternary ammonium system. The structure of 1 was established by spectroscopic analysis of the parent compoundand degradation products. The occurrence of a pyridazine ring in microbial secondary metabolites is unique.In the course of our screening for antifungal antibiotics especially active against Mucor hiemalis (Tii 179/180) we isolated pyridazomycin as a strongly basic compound from the culture filtrate of Streptomyces violaceoniger sp. griseofuscus (strain Tii 2557). In this report we describe the fermentation, isolation, physico-chemical characterization, structural elucidation and some biological properties of pyridazomycin2).Fermentation and Isolation The producing organism was a new soil isolate collected near Tula, Mexico, and identified as Streptomyces violaceoniger sp. griseofuscus (strain Tii 2557). Production of pyridazomycin was conducted in 100-ml Erlenmeyer flasks. The cultures were harvested at 72 hours, when pyridazomycin production was maximal. The culture filtrate was adjusted to pH 3.0~3.5 and applied to Dowex 50W-X4.The active fractions were eluted with 4%aqueous ammoniasolution and adsorbed on charcoal. After elution with methanol the crude extract was further purified by chromatography on silica gel (butanol -acetic acid -water, 2 : 1 : 1) and Sephadex G-10 (water) followed by cation exchange on an Amberlite IRC-50 column with 0.5 msodium chloride solution as eluent. Repeated chromatography on Sephadex G-10 yielded pure pyridazomycin.Characterization and Structure ElucidationPyridazomycin is a white, hygroscopic amorphous powder (dec above 119°C), insoluble in t Seerefl.
Manumycin(1), produced by Streptomyces parvulus (strain Tu 64), was isolated from the mycelium by extraction with acetone and could easily be purified chromatographically. Chemical degradation of 1 (C8iH38N2O7) gave 2-acetamino-3-hydroxycyclopent-2-enone (2) by acetolysis, 2,4,6-trimethyl-2,4-decadienoic acid (3) by alkaline hydrolysis, and 2-(2,4,6-trimethyl-2,4-decadienoylamino)-5,6-epoxy-l ,4-benzoquinone (5) by mild chromic acid oxidation. In connection with a detailed spectroscopic analysis, the structure of 1 could be elucidated and the (^-configuration of the double bonds in the triene and diene chain was established.Manumycin exhibits biological activity against Gram-positive bacteria and fungi and furthermore, an inhibition of the developmental processes of someinsects.Streptomyces parvulus (strain Tu 64) produces the pale yellow antibiotic manumycin0in association with more lipophilic red pigments, which were identified as C25-prodigiosms2), and the colorless hydrophilic amino acid antagonist L-2,5-dihydrophenylalanine3). Previous reports1»4) have already described the isolation and structure of manumycin, whose structural elements could not be classified with a known group of antibiotics. In the meantime similar compounds such as asukamycin5'6), U-621627) and U-56,4078) have been discovered, which could be added to the manumycin group. Structural features incline us to consider these antibiotics as broken chain ansamycins9). To verify this hypothesis, biosynthetic studies of manumycin and asukamycin are in progress10*n). In our preliminary report0, chemical degradation reactions have been described to prove the structure of manumycin.Getting more information from subsequent spectra, we are nowable to derive the structure of manumycinby a detailed spectroscopic analysis in connection with only a few chemical derivatization reactions. In this full paper we describe the fermentation of strain Tu 64 as well as a simpler isolation method, more biological data and a detailed chemical and spectroscopic characterization of manumycin. Fermentation and Isolation Streptomyces parvulus (strain Tii 64) is unstable as its phenotype, and a good logarithmic growth phase is not a reliable indication for producing an identical spectrum of secondary metabolites. The production of the red prodigiosins, starting 36~40 hours after inoculation, does however indicate the formation of manumycin,because these compoundsappear simultaneously. The strain Tii 64 was cultivated in 1-liter, 10-liter and 120-liter fermentors, using soybean meal 2% and mannitol 2% as a culture medium.Inoculum was prepared in Erlenmeyer flasks containing the same mediumand shaken for 60 hours at 28°C. Fig. 1 shows a typical time course of the fermentation in a 10-liter fermentor. The production of manumycinstarts after the log-phase, reaching its maximum76 hours
Pyrrolams A to D (1 -4), biosynthetically new pyrrolizidinones produced by Streptomyces olivaceus, have been discovered by chemical screening. Their structures have been determined by spectroscopic methods and by a comparison of (R)-dihydropyrrolam A (5) with a synthetic sample obtained from (S)-proline. The pyrrolams differ from the necine bases found in plant-originating pyrrolizidine alkaloids by their less complicated structures.
The structure of colabomycin A (1) was elucidated by a detailed spectroscopic analysis. Two-dimensional NMR spectroscopy experiments provided assignments of the proton and carbon resonances of the tetraene carboxamidechains occurring in 1. The configurations of eight out of nine double bonds were determined by analysis of their coupling constants. The absolute configurations of C-4 (45), C-5 (5R) and C-6 (65) were established from the CD spectra of the parent compound and of 2-(6-Qxo-2,4-hexadienoylamino>5,6-epoxy-l,4benzoquinone (2), which was obtained from 1 by mild chromic acid oxidation. Colabomycin A (1), produced by Streptomyces griseoflavus, belongs to the manumycin group of antibiotics1}. This paper deals with the determination of the chain lengths of the two polyene carboxamideunits, the configurations of their double bonds, and the absolute configurations of the centers of chirality of 1.
The yellow colabomycins Ato C, three new antibiotics of the manumycin group produced by Streptomyces griseoflavus (strain Tu 2880), were detected by chemical screening. They were isolated from mycelium extracts by columnchromatography on various adsorbents, followed by preparative reversed phase HPLC. The main compound, colabomycin A (1), was characterized and shown to be chiefly biologically active against Gram-positive bacteria and stem cells of murine LI210 leukemia.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.