Rajendra P. Maskey

1-Hydroxy-1-norresistomycin and Resistoflavin Methyl Ether: New Antibiotics from Marine-derived Streptomycetes † , ††

Cultivation of the marine-derived streptomycete isolate B8005 delivered three known antibiotics, resistomycin (1), resistoflavin (3a) and tetracenomycin (4), and a further member of the rare resistomycin class, the weakly antibiotically active 1-hydroxy-1-norresistomycin (2). From a related marine strain B4842, 1 and resistoflavin methyl ether (3b) have been isolated. The formation of 2 is of interest from a biosynthetic point of view.

Furan Oligomers and β-Carbolines from Terrestrial Streptomycetes

2,5-Bis(hydroxymethyl)furan monoacetate (3) and 2,5-bis(hydroxymethyl)furan diacetate (4) were obtained as new natural products from an ethyl acetate extract of the terrestrial Streptomyces sp. isolate GW11/1695. Another Streptomyces isolate, GW21/1313, delivered a dimer (6) and a trimer (7) of (hydroxymethyl)furfural. The latter strain also produced 4-hydroxy-2-(5-(hydroxymethyl)furan-2-ylmethylene)-5-methylfuran-3-one (5), perlolyrin (8), and two new beta-carboline derivatives, 9 and 10. 2,5-Bis(hydroxymethyl)furan diacetate (4) exhibited weak cytotoxic activity against brine shrimp larvae.

Kettapeptin: Isolation, Structure Elucidation and Activity of a New Hexadepsipeptide Antibiotic from a Terrestrial Streptomyces sp.

The ethyl acetate extract of the Streptomyces sp. isolate GW99/1572 exhibited significant biological activity against Gram-positive bacteria and delivered kettapeptin (1), a new hexadepsipeptide antibiotic of the azinothricin type. The structure was elucidated by various 1D and 2D NMR techniques, mass spectrometry and by comparison of the NMR data with those of closely related antibiotics. The absolute configuration of the compound was derived by crystal structure analysis and by comparison with the optical rotation data of related compounds.

Isolation and structure elucidation of Diazaquinomycin C from a terrestrial streptomyces sp. and confirmation of the akashin structure

In the screening of terrestrial Streptomycetes for bioactive components, a new antibiotic designated as diazaquinomycin C (2b) was isolated. The new antibiotic was found to be a homologue of diazaquinomycin A (2a) by spectroscopic methods and by comparison of the NMR data with those of 2a. The same strain additionally produced the akashins 1a–1c. The configuration of the N–O acetale bond in these rare glycosylated dichloroindigo derivatives was confirmed to be β.

Isolation and structure determination of phenazostatin D, a new phenazine from a marine actinomycete isolate Pseudonocardia sp. B6273

A new phenazine derivative, phenazostatin D (1a), was isolated from an extract of the actinomycete isolate Pseudonocardia sp. B6273 via a TLC-guided chemical screening. The structure of the compound was assigned by spectroscopic methods and found to be the meso-form of phenazostatin B (1b). Phenazostatin D was inactive against the tested bacteria and fungi. The strain also produced the known phenazine antibiotic methyl saphenate (2).

5-(2-Methylphenyl)-4-pentenoic Acid from a Terrestrial Streptomycete

Abstract From a terrestrial Streptomycete, GW 10/2517, the new 5-(2-methylphenyl)-4-pentenoic acid (1a) was isolated. The structure of 1a was proven by a detailed spectroscopic analysis and by synthesis.

Isolation, structure elucidation and activity of anthracycline acetates from a terrestrial Streptomyces sp.

The red coloured ethyl acetate extract of the Streptomyces sp. isolate GW37/3236 delivered the two new antibiotics 13-O-acetyl-bisanhydro-13-dihydrodaunomycinone (3c) and 4,13-O-diacetylbisanhydro- 4-O-demethyl-13-dihydrodaunomycinone (3d) and additionally several known compounds. The quinones 3c and 3d are the first naturally occurring quinone acetates. Their structures were derived by comparison of the NMR data with those of bisanhydro-13-dihydrodaunomycinone (3b) and by interpretation of the 2D NMR data accompanied by the molecular weight and formula. 2-Acetamido-3-hydroxybenzamide (5) was also isolated from the extract and was identified by comparison of the NMR data with those of 2-acetamidobenzamide and by 2D NMR correlations. 6,9,11- Trihydroxy-4-methoxy-5,12-naphthacenedione (4) is isolated for the first time as a natural product.

2-Alkyl-3,4-dihydroxy-5-hydroxymethylpyridine Derivatives: New Natural Vitamin B6 Analogues from a Terrestrial Streptomyces sp.

The ethyl acetate extract of the strain Streptomyces sp. GW23/1540 has yielded four new 2-alkyl-5-(hydroxymethyl)pyridine-3,4-diols, 5-hydroxymethyl-2-isopropyl-pyridine-3,4-diol (1a), 5-hydroxymethyl-2-propyl-pyridine-3,4-diol (1b), 2-sec-butyl-5-hydroxymethyl-pyridine-3,4-diol (1c), and 5-hydroxymethyl-2-isobutyl-pyridine-3,4-diol (1d). Similarly, the strain Streptomyces sp. GW63/1571 afforded 2-sec-butyl-5-hydroxymethyl-pyridine-3,4-diol (1c) and another new natural product, (3aS, 7aR)-3a-hydroxy-3a,4,7,7a-tetrahydro-1-benzofuran-2(3H)-on e (3), together with anthranilic acid, anthranilamide, and phenylacetamide. The new natural products were inactive against three micro algae, the fungus Mucor miehei, the yeast Candida albicans, and the bacteria Staphylococcus aureus, Bacillus subtilis, Escherichia coli, and Streptomyces viridochromogenes.

Juglorescein, Juglocombins and Juglochromans: Structure of Juglomycin Dimers from Streptomycetes

Novel juglomycin derivatives with a C28 skeleton were isolated from the Streptomyces strains 815 and GW4184. Juglorescein (1a) and juglocombin A (2a) and B (3a) are C,C dimers of juglomycin C (10) with a five membered ring between the two monomeric moieties. In the juglochromans A-D (4a, 5a, 6a, 6c), two juglomycin C (10) units are connected by C,C and C,O bonds forming a central isochroman or a chroman system. The structures of the new natural products were elucidated by detailed spectra analyses, by comparison of the NMR data with those of related compounds and by biosynthetic considerations. The new natural products were antimicrobially inactive.

Juglomycins G-J: Isolation from Streptomycetes and Structure Elucidation

From the Streptomyces spp. 815 and GW4184, four new 4-juglon-2-ylbutyric acid derivatives, the juglomycins G - J (3a, 4a, 4c, 5c), have been isolated and characterised. The structures were derived from the 1D and 2D NMR data and mass spectra and confirmed by comparison with structurally related compounds. The absolute configuration was deduced from the CD spectra. The new natural products exhibited weak antibacterial activity similar to juglomycin A (5a).