Structural studies of natural products by new nmr techniques. The structure of a new polyether antibiotic,portmicin

The structure of a new polyether antibiotic portmicin has been determined as shown in Fig. 1 by using new NMR tecnniques, HMBC and HOHAHA.     

Synthesis and characterisation of a new polycyclic phenazine from 1,4-naphthoquinone

Bioactive naphthoquinone-derived heterocyclic compounds have been prepared. Herein, we describe the semisynthesis of a new phenazine, through modified Hooker’s reaction, using lapachol as a precursor. This compound was characterised by 2D NMR spectroscopy methods and X-ray analysis.     

Synthetic studies of the antitumor antibiotic streptonigrin. I. Synthesis of the A-B ring portion of streptonigrin

Bromination of 6-methoxy-5,8-quinolinedione gave the 7-bromo derivative in quantitative yield. Treatment of the bromo compound with sodium azide followed by hydrogenation yielded 7-amino-6-methoxy-5,8-quinolinedione, the A-B ring portion of the antitumor antibiotic strep tonigrin. The corresponding 2-methyl homolog was prepared in a similar manner from 6-methoxy-2-methyl-8-nitroquinoline, which in turn, was obtained by a Skraup synthesis from 2-nitro-anisidine and crotonaldehyde.     

A new route for the synthesis of phenazine di-N-oxides

Summary Several phenazine 5,10-dioxides (7a–d) were prepared by the reaction of 2-methyl-3-acetylquinoxaline 1,4-dioxide (2) with different aromatic aldehydes or by direct cyclization of the quinoxaline cinnamoyl derivatives3 in basic medium. In addition, the phenazine derivatives8 and9–12 were synthesized by a one-pot reaction of substitutedo-nitroanilines with different hydroxy compounds in the presence of sodium hypochlorite solution.

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Ein neuer Syntheseweg für Phenazin-di-N-oxide

Zusammenfassung Mehrere Phenazin-5,10-dioxide (7a–d) wurden durch Reaktion von 2-Methyl-3-acetylchinoxalin-1,4-dioxid (2) mit verschiedenen aromatischen Aldehyden oder durch direkte Cyclisierung der Chinoxalinderivate3 in basischem Milieuhergestellt. Zusätzlich wurden die Phenazinderivate8 und9–12 in einer Eintopfreaktion von substituierteno-Nitroanilinen mit verschiedenen Hydroxyverbindungen in Gegenwart von Natriumhypochloritlösung synthetisiert.

     

Mimocin,a new isoquinolinequinone antibiotic

A new isoquinolinequinone antibiotic, mimocin(2), has been isolated from the strain of Streptomyces lavendulae. The structure of mimocin has been deduced from mass and PMR spectral data and confirmed by its synthesis.     

Uncialamycin, a new enediyne antibiotic

[structure: see text] Laboratory cultures of an undescribed streptomycete obtained from the surface of a British Columbia lichen produce uncialamycin (1), a new enediyne antibiotic. The structure of uncialamycin (1) has been elucidated by analysis of spectroscopic data. Uncialamycin (1) exhibits potent in vitro antibacterial activity against gram-positive and gram-negative human pathogens, including Burkholderia cepacia, a major cause of morbidity and mortality in patients with cystic fibrosis.     

Chemistry of a new antibiotic: lactivicin

A novel antibiotic, lactivicin (LTV), was isolated from the culture filtrates of two bacterial strains by various types of chromatography. LTV exists in aqueous solution as an equilibrium mixture of two epimers in a ratio of about 1:1. The chemical structure of LTV (C₁₀H₁₂N₂O₇) was determined to be 2-(4S-acetylamino-3-oxo-2-isoxazolidinyl)-5-oxo-tetrahydrofuran-2-carboxylic acid. The absolute configuration at the C-6 position was elucidated from the CD spectral data and X-ray crystallographic analysis of 4-amino-lactivinic acid obtained by the iminoether method. This compound is useful as a starting material for chemical modification. LTV showed antibacterial activity against Gram-positive and negative bacteria, susceptibility to β-lactamases, and affinity for penicillin-binding proteins. We therefore concluded that LTV is a novel skeleton antibiotic having β-lactam-like activities.     

Fusarielin E, a new antifungal antibiotic from Fusarium sp.

A new antifungal antibiotic,fusarielin E,was isolated from the marine-derived fungus Fusarium sp.Its structure was established on the basis of various NMR spectroscopic analyses and HR-FAB-MS.Fusarielin E displayed significant biological activity against Pyricularia oryzae.     

Microbial products. II. Granaticinic acid,a new antibiotic from a thermophilic streptomycete

Streptomyces sp. XT-11989 produces a mixture of two antibiotics with litmus-like indicator properties. One of them was shown to be identical with granaticin, the other was identified as [1S,3S,4S,7R,9R,10S,13R]-4,7,9,10-tetrahydro-5,12-dioxo-4, 6,10,11,13-pentahydroxy-1,9-dimethyl-(1H,3H)-7,10-ethanonaphtho[2,3-c: 6,7-c]dipyran-3-acetic acid and termed granaticinic acid. Microbial production and nuclear magnetic resonance data of these antibiotics are discussed and the antibacterial properties of the antibiotics are compared.

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Mikrobielle produkte. II. Granaticinsäure, ein neues Antibiotikum von einem thermophilen Streptomyceten

Zusammenfassung Der Streptomycetenstamm XT-11989 produziert eine Mischung von zwei Antibiotika mit Lakmus-ähnlichen Indikatoreigenschaften. Eines dieser Antibiotika erwies sich als Granaticin, das andere wurde als [1S,3S,4S,7R,9R,10S,13R]-4,7,9,10-tetrahydro-5,12-dioxo-4,6,10,11,13-pentahydroxy-1,9-dimethyl-(1H,3H)-7,10-ethanonaphto[2,3-c: 6,7-c]dipyran-3-essigsäure identifiziert und Granaticinsäure benannt. Mikrobiologische Produktion und Kernresonanzdaten dieser antibiotika werden besprochen und ihre antibakteriellen Eigenschaften verglichen.

     

The structure of a new antibiotic,chromoxymycin

Based on ¹H- and ¹³C-NMR spectral data, the planar structure of chromoxymycin, a new antitumor antibiotic, has been determined as shown in Fig. 1.     

Isolation and characteristics of a new antibiotic variamycin

Summary A new antibiotic, variamycin, belonging to the aureolic acid group and distinguished from the latter by the presence in the molecule of a residue of the deoxy sugar variose has been isolated.For a preliminary communication, see [1].All-Union Scientific-Research Institute of Antibiotics. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 646–649, September–October, 1971.     

Structure of monazomycin,a new ionophohous antibiotic

The structure of monazomycin was determined by degradative study in combination with biosynthetic means using ¹³C-NMR.