Asparenomycins (ASM) A, B and C, new members of the carbapenem family of antibiotics, are broad spectrum antibiotics with activity against Gram-positive and Gram-negative bacteria. ASM A was bactericidal to both aerobic and anaerobic bacteria, although morphological alterations of ASM A exposed cells differed significantly between Escherichia coli and Bacteroides fragilis; with the former ovoidal forms were produced while with the latter elongated forms were seen. Synergistic activities were observed with a combination of ASM A and ampicillin (ABPC) against various ABPC-resistant bacteria presumably as a result of the inhibition by ASM A of beta-lactamases. ASM A showed relatively weak therapeutic activity against E. coli infected mice, because of instability in body fluids, a common property of the carbapenem family of antibiotics.

Animals↗

PubMed1981

1-Oxacephalosporins: enhancement of beta-lactam reactivity and antibacterial activity.

The effect of replacement of sulfur in the cephem nucleus by oxygen upon the beta-lactamase stability, infrared carbonyl frequency of the beta-lactam ring, and antibacterial activity was investigated. The replacement reduced the stability of beta-lactam compounds to beta-lactamases, increased the IR frequencies, and enhanced the intrinsic antibacterial activity against bacterial strains without beta-lactamase. The instability of 1-oxacephalosporins to beta-lactamases, in other words, high reactivity to the enzymes, seemed to be due to the enhanced chemical reactivity of their beta-lactam rings which was indicated by their higher IR beta-lactam carbonyl frequencies. Based on a view that acylation of the enzyme by beta-lactam compounds occurred in both cases of beta-lactamase hydrolysis and target enzyme inhibition, the suggestion was made that one of the factors which conferred the higher intrinsic antibacterial activity on 1-oxacephalosporins was their high reactivity to the target enzyme(s), as was the case with beta-lactamases.

Anti-Bacterial Agents↗

PubMed1975

Antibiotic A-130, isolation and characterization.

An antibiotic, A-130, was isolated from a strain identified as Streptomyces hygroscopicus, strain A-130. The antibiotic belongs to the nigericin group and like dianemycin, has an alpha, beta-unsaturated ketone chromophore in its molecule. A-130 is active against gram-positive organisms.

Anti-Bacterial Agents↗

PubMed1968