Isolation, structure determination and biological activity of A-16686 factors A' 1, A' 2 and A' 3 glycolipodepsipeptide antibiotics.

When Actinoplanes strain ATCC 33076, the producer of A-16686 A1, A2 and A3 complex, is fermented in a suitable medium three additional factors, designated A' 1, A' 2 and A' 3 are produced. These were isolated and characterized, and were shown to differ from the parent components of the original complex by lacking one mannose unit. Bioconversion of A factors into A' factors was achieved by incubation with the mycelium of Actinoplanes ATCC 33076.

Synthesis and biological activity of some amide derivatives of the lantibiotic actagardine.

A series of basic carboxamides of actagardine (1), a lantibiotic possessing good antistreptococcal activity, were synthetized. Some physico-chemical characteristics, in particular charge and lipophilicity, that influence water solubility were determined. The in vitro and in vivo activity was evaluated.

Sequence determination of actagardine, a novel lantibiotic, by homonuclear 2D NMR spectroscopy.

By combination of several 1H NMR techniques, the sequence of actagardine has been elucidated. It has been shown that it is a tetracyclic 19-residue peptide antibiotic. It differs from the previously described lanthionine-containing peptide antibiotics belonging to the lantibiotic class.

N15-alkyl and N15,N15-dialkyl derivatives of teicoplanin antibiotics.

The synthesis and the biological properties of a series of N15-alkyl and N15,N15-dialkyl derivatives of teicoplanin A2, its pseudoaglycones and aglycone are described. The alkylation of the terminal amino group did not affect the ability of these teicoplanin derivatives to bind with Ac2-L-Lys-D-Ala-D-Ala, a synthetic model of the antibiotic's target peptide in bacterial cell walls, but influenced their in vitro and in vivo antimicrobial activities to a different extent, depending on the structure and length of the alkyl chains and the type and number of sugars present.

Synthesis and biological activity of some derivatives of rifamycin P.

A series of derivatives of rifamycin P, an antibiotic produced by fermentation of a mutant strain of Nocardia mediterranea or by chemical modification of rifamycin S, have been prepared. The structures of these compounds were determined by 1H NMR, IR, UV, and LC/MS. Their in vitro and in vivo antibacterial activities in comparison with rifampicin and two other rifamycins under investigation were evaluated.

Ramoplanin: a review of its discovery and its chemistry.

Ramoplanin is a novel antibacterial agent with characteristics that make it suitable for development as a topical treatment for acne, infected wounds, and for treatment of antibiotic-associated diarrhoea. In this paper, the authors will review the discovery process and the descriptive chemistry of this novel molecular entity.

Dechloro teicoplanin antibiotics.

Mono- and didechlorinated derivatives of the antibiotic teicoplanin, its pseudoaglycones and aglycone, and of one amide and ester of deglucoteicoplanin were prepared under selective reductive conditions. The selectivity and rate of dehalogenation were studied and compared to those of vancomycin and deglucovancomycin. The influence of the chlorine substituents on the mechanism of action and antibacterial activity of teicoplanin antibiotics was also investigated.

Laser-induced vaporization mass spectrometry of rifamycins.

The mass spectra of many rifamycins cannot be obtained by electron ionization (EI) owing to their thermal decomposition. When a laser beam is used to vaporize the sample through an optic fibre inserted in a hollow probe which reaches the sample cup, decomposition is minimized and the EI spectra show abundant molecular ions and fragments of structurally high diagnostic value. These ionic species are easily observed owing to the lack of chemical noise often present in soft ionization methods, such as direct liquid chemical ionization and fast atom bombardment.

Ramoplanin (A-16686), a new glycolipodepsipeptide antibiotic. IV. Complete sequence determination by homonuclear 2D NMR spectroscopy.

Homonuclear 2D NMR spectroscopy double quantum filter correlation spectroscopy (DQF-COSY), relayed-COSY, nuclear Overhauser enhancement spectroscopy (NOESY), and DQF-relayed-NOESY) allowed the complete determination of the core depsipeptide of antibiotic ramoplanin (A-16686). In particular, the DQF-relayed-NOESY experiments were essential in assigning the single signals close to the diagonal.

Ramoplanin (A-16686), a new glycolipodepsipeptide antibiotic. III. Structure elucidation.

By combination of chemical, 1H and 13C NMR, and mass spectrometric studies, the structures of the three components of the antibiotic ramoplanin (A-16686), produced by Actinoplanes sp. ATCC 33076, have been elucidated. All the components have structures formed by a common depsipeptide skeleton carrying a dimannosyl group and are differentiated by the presence of various acylamide moieties, derived from C8, C9 and C10 fatty acids.

Structure and biological activity of lipiarmycin B.

Actinoplanes deccanensis ATCC 21983, the producer of antibiotics lipiarmycin A3 and A4, furnished also a related antibiotic designated lipiarmycin B, active against Gram-positive bacteria, including anaerobes, and against Neisseria. The structures of the two major components, B3 and B4, were elucidated from their physico-chemical properties, 1H and 13C NMR spectra and fast atom bombardment mass spectra data in comparison with lipiarmycins A3 and A4.

Synthesis and biological activity of some esters of the N-acetylglucosaminyl aglycone and of the aglycone of teicoplanin.

A series of ester derivatives of teicoplanin-N-acetylglucosaminyl aglycone (T-A3-2) and deglucoteicoplanin was prepared starting from teicoplanin and from the corresponding deglycosylation compounds. The modification of the ionic and lipophilic character of the parent antibiotic strongly influences the spectrum of antibacterial activity in vitro.

Teicoplanin: chemical, physico-chemical and biological aspects.

The structure determination and the physico-chemical properties of teicoplanin, a new glycopeptide antibiotic of the vancomycin-ristocetin family are presented. Some biological studies and the mechanism of action at the molecular level are discussed. Analytical test methods, such as HPLC assay, bioassay and enzymatic assay are described.

Teicoplanin, antibiotics from Actinoplanes teichomyceticus nov. sp. VIII. Opening of the polypeptide chain of teicoplanin aglycone under hydrolytic conditions.

Hydrolysis of teicoplanin (a complex of five closely related factors plus one, more polar component) under selected conditions (acids in a biphasic hydroalcoholic medium) gives the single aglycone with good yields. When the reaction is carried out in homogeneous hydroalcoholic phase the removal of the sugars yields two new compounds. On the basis of fast atom bombardment mass spectra (FAB-MS), acid-base titration, IR, UV and 1H NMR analyses it has been demonstrated that these compounds are two diastereoisomers; they differ from the teicoplanin aglycone in having additional carboxyl and amino groups derived from the hydrolysis of an amide bond.

Teicoplanin, antibiotics from Actinoplanes teichomyceticus nov. sp. VII. Preparation and NMR characteristics of the aglycone of teicoplanin.

Several hydrolytic reactions that transform teicoplanin or its pseudo-aglycones into the aglycone with good yields are described. The most interesting approach is hydrolytic removal of the sugars in benzyl alcohol with the formation of the aglycone benzyl ester which is then submitted to hydrogenolysis. A detailed description of the 1H and 13C NMR spectra of the teicoplanin aglycone hydrochloride is presented.

Synthesis and antibacterial activity of some derivatives of the antibiotic thermorubin.

A series of derivatives has been prepared from the antibiotic thermorubin, some of which show a substantial modification of the original structure. The antibacterial activities are reported.

Physico-chemical and biological properties of actagardine and some acid hydrolysis products.

Actagardine (originally designated as metabolite B or gardimycin) is a polypeptide antibiotic produced by fermentation of Actinoplanes strains ATCC 31048 and 31049. During the course of repeated fermentations two new compounds, coded D and E, were isolated. Some physico-chemical and biological characteristics of actagardine and of both compounds are presented.

7-(D,L-alpha-fluoro-2-thienylacetamido)cephalosporanic acid (L 14655), a new semisynthetic cephalosporin. Synthesis and preliminary biological evaluation.

We describe the synthesis and some preliminary antimicrobial and enzymatic properties of 7-(D,L-alpha-fluoro-2-thienylacetamido)cephalosporanic acid (L 14655), a fluorinated derivative of cephalothin. L 14655 had antimicrobial activity similar to that of cephalothin. Cell-free studies demonstrated that L 14655 was very stable to hydrolysis by type Ia beta-lactamase (325 times more than cephalothin) but not to TEM enzyme.

Synthesis and in vitro biological evaluation of N-[(5-amino-1-beta-D-ribofuranosyl-1H-imidazol-4-yl)carbonyl]-3- (hydroxynitrosamino)-L-alanine (L-alanosine AICO ribonucleoside).

L-Alanosine [3-(hydroxynitrosoamino)-L-alanine] is an antitumor antibiotic that at the present is undergoing phase II clinical trials. Its mode of action as well as its metabolism has been extensively studied, and the metabolite N-[(5-amino-1-beta-D-ribofuranosyl-1H-imidazol-4-yl)carbonyl]-3- (hydroxynitrosoamino)-L-alanine ribonucleotide (L-alanosine AICOR) proved to be an extremely potent inhibitor of de novo purine biosynthesis and is thus primarily responsible for the antitumor activity of the drug. The synthesis of the corresponding ribonucleoside, i.

In vitro activity of A-16686, a potential antiplaque agent.

A-16686, a new glycoproteide antibiotic from Actinoplanes sp., was evaluated as a potential antiplaque agent in comparison with chlorhexidine, benzalkonium chloride, and cetylpyridinium chloride. A-16686 had good activity against gram-positive organisms associated with dental plaque (various streptococci, Streptococcus mutans in particular, lactobacilli, Actinomyces viscosus, and Actinomyces naeslundii); most of the strains tested were clinical isolates.

Teicoplanin, antibiotics from Actinoplanes teichomyceticus nov. sp. VI. Chemical degradation: physico-chemical and biological properties of acid hydrolysis products.

Teicoplanin is an antibiotic complex consisting of five closely related factors, T-A2-1, 2, 3, 4 and 5 and a more polar factor, T-A3-1. By controlled acid hydrolysis the complex is transformed into pseudoaglycones and finally into a single aglycone with consecutive removal of three sugar units. Quantitative determination of sugars obtained by degradative reactions and NMR/LC-MS studies on suitable derivatives confirmed that all the components carry one N-acyl-D-glucosamine and that at least two of them are characterized by N-decanoyl and N-undecanoyl chains on the D-glucosamine unit.

Inhibitory activity and resistance to hydrolysis by beta-lactamases of some (D,L)-7-(alpha-fluoroacylamino)cephalosporins.

The synthesis of a series of (D,L)-7-(alpha-fluoroacylamino)-cephalosporanic acids are described. In vitro antimicrobial activity was determined in comparison with the corresponding non-fluorinated compounds. None of them were found to be better than clinically used cephalosporins.

A-16686, a new antibiotic from Actinoplanes. I. Fermentation, isolation and preliminary physico-chemical characteristics.

Actinoplanes sp. ATCC 33076 is a new strain that was found to produce an antibiotic, designated A-16686, which is a complex of three closely-related polypeptides containing chlorinated phenyl moieties and D-mannose. Both the complex and the single fractions possess a good activity against Gram-positive bacteria.

Structural studies on lipiarmycin. I. Characterization by 1H and 13C NMR spectroscopy and isolation of methyl 2-O-methyl-4-O-homodichloroorsellinate-beta-rhamnoside.

1H and 13C NMR spectral studies of lipiarmycin in CDCl3 and in pyridine-d5 provided evidence for the six partial structures I approximately VI and the two sugar units 1 and 2. Acid methanolysis led to the isolation of methyl 2-O-methyl-4-O-homodichloroorsellinate-beta-rhamnoside, whose structure was determined by spectroscopic methods.