Topic
Mitomycin B
About: Mitomycin B is a research topic. Over the lifetime, 24 publications have been published within this topic receiving 278 citations.
Papers
TL;DR: In this article, the nature of the reactive oxygen species generated from certain quinone antitumor antibiotics upon reductive activation in aqueous solution was investigated, and a kinetic criterion was employed involving the relative rate of trapping of hydroxyl and formate radicals by the spin-trap 5,5-dimethyl-1-pyrroline-Noxide (DMPO) in conjunction with epr spectroscopy.
Abstract: The nature of the reactive oxygen species generated from certain quinone antitumor antibiotics upon reductive activation in aqueous solution was investigated. A kinetic criterion was employed involving the relative rate of trapping of hydroxyl and formate radicals by the spin-trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) in conjunction with epr spectroscopy. By comparison with a system involving the photolysis of hydrogen peroxide as a standard free hydroxyl system it was concluded that at pH 7 and at 37 °C reductive activation of adriamycin, daunorubicin, mitomycin B, mitomycin C, and streptonigrin gives rise to free hydroxyl radicals in direct contrast with, for example, the photolysis of quinones in solution.
63 citations
TL;DR: The reactions of the antitumor antibiotic mitomycin B with DNA were examined using ethidium fluorescence assays to compare its action with conventional antibiotics and showed positive results.
Abstract: The reactions of the antitumor antibiotic mitomycin B with DNA were examined using ethidium fluorescence assays. The following three aspects of mitomycin B action have been studied to compare its b...
31 citations
TL;DR: This study provides direct evidence for the catalytic role of MmcR in formation of the 7-OMe group that is characteristic of mitomycins A and B and demonstrates the prerequisite of 7-O-methylation for the production of the clinical agent mitomycin C.
Abstract: Mitomycins are bioreductively activated DNA-alkylating agents. One member of this family, mitomycin C, is in clinical use as part of combination therapy for certain solid tumors. The cytotoxicity displayed by mitomycins is dependent on their electrochemical potential which, in turn, is governed in part by the substituents of the quinone moiety. In this paper we describe studies on the biogenesis of the quinone methoxy group present in mitomycins A and B. An engineered Streptomyces lavendulae strain in which the mmcR methyltransferase gene had been deleted failed to produce the three mitomycins (A, B, and C) that are typically isolated from the wild type organism. Analysis of the culture extracts from the mmcR-deletion mutant strain revealed that two new metabolites, 7-demethylmitomycin A and 7-demethylmitomycin B, had accumulated instead. Production of mitomycins A and C or mitomycin B was selectively restored upon supplementing the culture medium of a S. lavendulae strain unable to produce the key precur...
30 citations
TL;DR: This sensitivity of the Euglena chloroplast to small structural differences in the active centers of antibiotics demonstrates the usefulness of this organism in the study of relationships between biological activity and chemical structure of antibiotics.
Abstract: The effects of some mitomycin antibiotics on the chloroplast system of Euglena gracilis were studied. Only those derivatives which contained an alkyl group on the aziridine nitrogen were effective bleaching agents. Thus, only N-methyl-mitomycin, porfiromycin, and mitomycin B caused a highly significant loss of chloroplasts. This sensitivity of the Euglena chloroplast to small structural differences in the active centers of antibiotics demonstrates the usefulness of this organism in the study of relationships between biological activity and chemical structure of antibiotics.
19 citations
TL;DR: Two new types of mitomycin analogs described as Type I and Type II are produced, which are more active in a prophage induction test and against L1210 lymphatic leukemia in mice.
Abstract: When the normal fermentation medium for the production of mitomycin C with Streptomyces caespitosus is supplemented with a number of primary amines, two new types of mitomycin analogs described as Type I and Type II are produced. Type I analogs are related to mitomycin C with the amine substitution at position C7 on the mitosane ring. Type II analogs also contain the same substitutions at C7 but the conformation of the mitosane ring is related to mitomycin B having an OH at positions C9a and a methyl substituted aziridine. The products obtained from the supplementation of the medium with methylamine, ethylamine, propylamine, propargylamine and 2-methylallylamine were isolated and characterized. In all cases the Type I analogs are more active in a prophage induction test and against L1210 lymphatic leukemia in mice. A number of other amines have been tested and shown to yield new products that have not yet been isolated. No secondary amines are incorporated.
15 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2007 | 1 |
| 1991 | 2 |
| 1990 | 1 |
| 1989 | 2 |
| 1986 | 2 |
| 1985 | 2 |