Kinetic study on cephamycin C degradation.

Cephamycin C (CepC) is a ß-lactam antibiotic that belongs to the cephalosporin class of drugs. This compound stands out from other cephalosporins for its greater resistance to ß-lactamases, which are enzymes produced by pathogenic microorganisms that present a major mechanism of bacterial resistance to ß-lactam antibiotics. Cephamycin C is produced by the bacterium Streptomyces clavuligerus. Knowledge about the stability of the compound under different values of pH is important for the development of the process of production, extraction, and purification aimed at obtaining higher yields. Therefore, the stability of cephamycin C under different pH levels (2.2, 6.0, 7.0, 7.6, and 8.7) at 20 °C was evaluated in this study. Ultrafiltered broth from batch fermentations of S. clavuligerus was used in the trials. The results indicated that cephamycin C is a more stable compound than other ß-lactam compounds such as penicillin and clavulanic acid. A higher degradation rate was observed at very acidic or basic pH levels, while this rate was lower at quasi-neutral pH levels. After 100 h of trial, the initial CepC showed 46 % degradation at pH 2.2, 71 % degradation at pH 8.7, and varied from 15 to 20 % at quasi-neutral pH levels.

Preliminary studies for cephamycin C purification technique.

A study was made for purification of cephamycin C from fermentation of Streptomyces clavuligerus. Initially, the culture broth was clarified by microfiltration and ultrafiltration, after which the resulting permeates were subjected to nonspecific adsorption and ion-exchange chromatography on resin columns. The antibiotic activity was measured by the biological method at each stage by assaying its activity against the Escherichia coli ESS, super sensitive to ß-lactam antibiotic. The purification processes were assessed in relation to the variables affecting each step. The purification efficiency by nonspecific adsorption was monitored by UV spectrophotometry, while the ion-exchange adsorption fractions were assessed by NMR spectroscopy. Some of the fractions obtained during purification were also analyzed by mass spectrometry (LC/MS and LC/MS/MS) to identify the cephamycin C molecule. These preliminary results proved the process feasibility.

Preliminary investigation of the structure of antibiotics produced by highly active mutants of Streptomyces griseus NRRL 3851 and Streptomyces lactamdurans NRRL 3802.

Streptomyces griseus NRRL 3851 and Streptomyces lactamdurans NRRL 3802 are well known as producers of cephamycins A, B and C, respectively. Antibiotics produced by their highly active mutants: S. griseus G-12 (termed X-12-1 and X-12-2) and S. lactamdurans L-2 (termed X-2) have been isolated and found to belong also to the cephamycin family. Their IR spectra revealed beta-lactam absorption at 1750 cm-1 and their 1H NMR spectra demonstrated the presence of protons attached to 7-methoxycephem skeleton and, in addition, signals attributable to one vinyl proton and four aromatic protons. The chemical shift of the aromatic protons indicated meta substitution in the benzene ring of the antibiotic X-12-1, and para substitution in the benzene ring of the antibiotics X-12-2 and X-2. The product of acid hydrolysis of X-2 was shown to be identical with p-hydroxy-alpha-methoxycinnamic acid.

Discovery, isolation and structure of novel cephamycins of Streptomyces chartreusis.

By the use of HPLC technique after treatment with beta-lactamases, two novel cephamycins, SF-1623 and SF-1623B, were discovered and isolated from the fermentation broth of Streptomyces chartreusis SF-1623. The structures of SF-1623 and SF-1623B were determined to contain 3-sulfothiomethyl and 3-hydroxymethyl groups respectively, by chemical and enzymatic transformation reactions. Studies on the fermentation condition and process for the large scale preparation of antibiotic SF-1623 are also described.

[Preparation of highly purified cephamycin C].

Preparation of highly purified cephamycin C (CM-C) is described in this report. The purification of CM-C was carried out by Sephadex LH-20 chromatography of the N-BOC-CM-C developed with MeOH followed by removal of the protecting group. Partially purified CM-C was further refined by Sephadex LH-20 chromatography developed with MeOH and Diaion HP-20 SS chromatography developed with H2O. CM-C thus obtained showed the UV absorption at 265 nm [E1% 1cm 184.4 (H2O)] which is the strongest absorption ever appeared in the literatures.

Biosynthesis of a 7-alpha-methoxycephalosporin. Incorporation of molecular oxygen.

A 7-alpha-methoxycephalosporin containing a carbamoyloxymethyl substituent at C-3 (cephamycin C) has been isolated from the extracellular fluid of an aqueous suspension of Streptomyces clavuligerus shaken in the presence of 18O2. The cephalosporin has been converted into its N-acetyl dimethyl ester and the distribution of 18O in the latter determined by chemical-ionization mass spectrometry. The results indicate that the oxygen atom of the methoxy group, as well as that linked to the exocyclic methylene group at C-3, is derived from molecular O2.

[Isolation of cephamycins from actinomycete cultures]. / O vydelenii tsefamitsinov iz kul'tur aktinomitsetov

A method for isolation of cephamycins from culture fluids of actinomycetes was developed. It included the stage of effective purification of sulfocation exchange resin SDV-3 (H+) with water desorption. Further purificiation of the antibiotics was achieved with sorption on anion exchange resin and fractional precipitation. The method provided 95-96 per cent purity level of the preparations.

C-2801X, a new cephamycin-type antibiotic II. Isolation and characterization.

Two new species of Streptomyces, S. heteromorphus and heteromorphus and S. panayensis, were found to produce a new atibiotic named C-2801X together with cephamycins A and B. The antibiotics were separated from each other by column chromatography on Amberlite XAD-2 and isolated in pure form as mono-sodium salts. C-2801X mono-sodium salt has a molecular formula C25H28N3O12SNa, and exhibits antibacterial activity against Gram-positive and Gram-negative bacteria including those insensitive to cephamycins A and B. From its physicochemical and biological properties, C2801X was considered to be a new cephamycin-type antibiotic.