Spenolimycin, a new spectinomycin-type antibiotic. II. Isolation and structure determination.

A new water-soluble, basic antibiotic has been isolated from the fermentation beers of Streptomyces gilvospiralis sp. nov. The structure of the antibiotic has been deduced from spectral studies and confirmed by chemical degradation to spectinomycin. This structure, 3'-O-methylspectinomycin-3',4'-enol ether has led to the name spenolimycin.

Lysinomicin, a new aminoglycoside antibiotic. II. Structure and stereochemistry.

The structure of lysinomicin, a new aminocyclitol antibiotic, was established as 3-epi-2'-N-(L-beta-lysyl)-4',5'-didehydro-6'-de-C-methylfortimi cin B (1) on the basis of spectral evidence and chemical degradation of the antibiotic. In the course of the degradation of 1, three additional compounds with interesting biological properties were obtained: 3-epi-2'-N-(L-beta-lysyl)-6'-de-C-methylfortimicin B (4), 3-epi-4',5'-didehydro-6'-de-C-methylfortimicin B (6) and 3-epi-6'-de-C-methylfortimicin B (7).

4-N-Aminoacylation of substances derived from lysinomicin.

The preparations of 4-N-glycyllysinomicin and several 4-N-aminoacyl derivatives of compounds prepared from lysinomicin are presented. The new substances have lower antimicrobial activities than the original 4-N-unsubstituted lysinomicin derivatives. This result indicates that the structure-activity relationship observed with fortimicin A and fortimicin B does not apply to the lysinomicin derivatives studied.

Diastereomeric fortimicin 1,2-epoxides. The preparation of the 1-deamino-2-deoxyfortimicins A and B and the 1,2-di-epi-fortimicins A and B.

The preparation of 1,2-anhydro-2',6'-di-N-benzyloxycarbonyl-1-deaminofortimicin B-4,5-carbamate (4) and its conversion to the two diastereomeric 2',6'-di-N-benzyloxycarbonyl-1-deamino-2-deoxy-1,2-epoxyfortimicin B-4,5-carbamates 7 and 13 are described. The olefin 4 was used for preparation of 1-deamino-2-deoxyfortimicin A (6d) while the beta-epoxide 13 was used for the preparation of 1,2-di-epi-fortimicin A (17b) and 2-amino-1-deamino-2-deoxy-1-hydroxyfortimicin A (19c). The in vitro antibacterial activities of 6d, 17b and 19c are reported.

Substances derived from 4-de-N-methylfortimicin B.

The preparation of 4-de-N-methylfortimicin A analogs as well as the preparation of 4-de-N-methyl-4-N-(beta-aminoethyl)-4-N-ethylfortimicin B is reported. It was shown that the 4-N-methyl group in fortimicin analogs is essential for antibacterial activity since neither the 4-de-N-methylfortimicin A nor the 4-de-N-methyl-4-N-(beta-aminoethyl)-4-N-ethylfortimicin B exhibited useful biological activity.

4-N-Aminoacylfortimicins E.

The conversion of fortimicin E, a minor metabolite from the Micromonospora olivoasterospora fermentation which also produces fortimicin A and fortimicin B, to four 4-N-aminoacylfortimicins E was accomplished. The new 4-N-aminoacylfortimicins E showed only weak antimicrobial activity against several Gram-negative and Gram-positive microorganisms.

N-Didemethyl-n-propionyl-6,9;9, 12-erythromycin A-spiroketal, a new metabolite of erythromycin ethyl succinate in man.

A novel, neutral metabolite of erythromycin was isolated from the urine of a patient treated with erythromycin ethyl succinate. After separation and purification on Sephadex LH-20 column chromatography, the structure of the metabolite was deduced from spectral data to be the propionamide of the didemethylated 6,9;9, 12-spiroketal of erythromycin A.

Modification of seldomycin factor 5 at C-3'.

Attempted removal of the 3'-hydroxyl group of seldomycin factor 5 via displacement of a sulfonate ester has led to 3'-epi-seldomycin factor 5. Removal of the hydroxyl group has been effected by the Barton procedure. The antibacterial activity of 3'-epi- and 3'-deoxyseldomycin factor 5 against various aminoglycoside-resistant strains is discussed.

Spectinomycin modification. IV. 7-deoxy-4(R)-dihydrospectinomycin.

7-Deoxy-4(R)-dihydrospectinomycin (7) has been prepared and its structure firmly established by proton magnetic resonance and high resolution mass spectrometry. This spectinomycin analog is devoid of antibiotic activity.

The structures of the m-chloroperbenzoic acid oxidation products of 8,9-anhydroerythromycins A- and B-6,9-hemiacetal and of (8S)-8-hydroxyerythromycin B.

13C-NMR studies have confirmed the structures of (8S)-8-hydroxyerythromycins A- and B-6,9;9,11-acetal proposed by KROWICKI and ZAMOJSKI2,3) for the products of the m-chloroperbenzoic acid oxidation of 8,9-anhydroerythromycins A- and B-6,9-hemiacetal. The preparations of (8S)-8-methylthiomethoxy- and (8S)-8-methoxyerythromycin B-6,9;9,11-acetals are described. The latter are stable in aqueous acetic acid under conditions which convert (8S)-8-hydroxyerythromycin B-6,9;9,11-acetal into (8S)-8-hydroxyerythromycin B.

Fortimicins A and B, new aminoglycoside antibiotics. III. Structural identification.

The structures of fortimicins A and B have been determined by PMR, CMR, mass spectra and CD combined with chemical degradations. Both antibiotics are pseudodisaccharides and incorporate a novel aminocyclitol, fortamine. In contrast to the diaminocyclitol moieties of known aminoglycosides, fortamine is a 1,4-diamine, contains both N- and O-methyl groups and possesses chiro stereochemistry. Both antibiotics are glycosides of 6-epi-purpurosamine B, but fortimicin A differs from fortimicin B by being a glycyl amide.

A new aminoglycoside antibiotic complex--the seldomycins. III. The structures of seldomycin factors 1 and 2+.

The structures of seldomycin factors 1 and 2 have been determined by consideration of chemical degradation and spectral properties. Factor 1, also known as XK-88-1, is shown to be 6-O-(2-amino-2-deoxy-alpha-D-xylopyranosyl) paromamine (1) and factor 2, also known as XK-88-2, is shown to be 4'-deoxy-neamine (2). Mass spectral evidence has been obtained that suggests the most probable structure for seldomycin factor 3, also known as XK-88-3, is 6'-amino-6'-deoxyseldomycin factor 1 (12).

Spectinomycin modification. II. 7-EPI-sectinomycin.

7-Epi-spectinomycin (9) and 7-epi-4(R)-dihydrospectinomycin (10) have been prepared and their structure firmly established by proton magnetic resonance. Both of these spectinomycin analogs are devoid of antibiotic activity.

A new antibiotic XK-62-2. III The structure of XK-62-2, a new gentamicin C complex antibiotic.

The structure of XK-62-2 has been firmly established to be 6'-N-methylgentamicin C1a (3) by application of spectroscopic methods in conjunction with chemical degradation. The data obtained in every case are completely consistent with the proposed structure.