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At least 19 recordsLinked to original sources
PubMed1975

The mutagenic action of nitroimidazoles. II. Effects of 2-nitroimidazoles.

The 2-nitroimidazoles Ro-71051 (N-benzyl-2-nitro-1-imidazole-acetamide) and Ro-5-9963 (3(2-nitro-1-imidazolyl)-1,2-propanediol) increased the mutation rate of a Klebsiella pneumoniae mutant to streptomycin-resistance including streptomycin-dependence in Luria and Delbruck's fluctuation test in concentrations of 0.05-1 mM and 0.02-0.2 mM respectively. The 2-nitroimidazole, azomycin, (Ro-5-9129/001) failed to increase the mutation rate. The results are compared to those obtained with the 5-nitroimidazoles methronidazoles metronidazole, nimorazole and dimetridazole, which caused a degree of increase similar to Ro-7-1051 and Ro-59963.

Acetamides↗
PubMed1979

The mutagenic action of nitroimidazoles. IV. A comparison of the mutagenic action of several nitroimidazoles and some imidazoles.

The mutagenic action of 51 imidazoles was investigated. The fluctuation test of Luria and Delbrück was used, with Klebsiella pneumoniae as test organism. 8 compounds, including 5 with a weak mutagenic action in the fluctuation test, were also investigated by the Ames test in which Salmonella typhimurium TA100 was used. Of the 51 imidazoles examined, 33 were nitroimidazoles. 31 of the latter appeared to be mutagenic, whereas out of the 18 other imidazoles without a nitro group only 2 were mutagenic. Several of the substances tested for mutagenicity showed an antimicrobial activity. No direct relationship between antimicrobial action, growth inhibition and mutagenicity was established. With methyl-nitroimidazoles a relationship was found between the chemical structure and mutagenic action. However, when the nitroimidazoles had a more complex chemical structure, a relationship between this structure and mutagenicity could not be established.

Drug Evaluation, Preclinical↗
PubMed1977

Chemotherapeutically active nitro compounds. 4. 5-Nitroimidazoles (Part I).

More than 135 new 2-methyl-5-nitroimidazoles substituted in 1-position and 1-methyl-5-nitroimidazoles substituted in 2-position were investigated for their activity against various protozoan species, in particular Entamoeba histolytica in the golden hamster, Trichomonas fetus, Trypanosoma brucei and T. cruzi in the NMRI mouse. Among the nitroimidazoles substituted in the 1-position only two preparations exhibited a similar effect as metronidazole preparations exhibited a similar effect as metronidazole against T. fetus. In the class of the nitroimidazoles substituted in the 2-position 16 compounds were as effective as metronidazole, 19 showed an effect superior to metronidazole, 1 was as good as tinidazole and 2 exhibited an activity superior to tinidazole against T. fetus. Only few compounds displayed any amoebicidal activity. Of the mono and bis-hydrazones of 1-methyl-5-nitroimidazole-2-aldehyde substituted in the 2-position 3 compounds had an amoebicidal effect 2 to 8 times stronger than that of metronidazole. Only few representatives of the 1-methyl-5-nitroimidazoles substituted in the 2-position produced a useful trypanocidal effect when given in relatively high doses. The structure-activity relationship of 5-nitroimidazole derivatives has been discussed.

Animals↗
PubMed1976

New data on the mechanism and speed of action of nitroimidazoles on prokaryota and eukaryota with and without mitochondria.

The spectrum of action of nitroimidazoles ranges from anaerobic bacteria to aerobic bacteria which are also capable of growth, although sometimes with difficulty, in anaerobic atmosphere and to protozoa without and with mitochondria; in the latter case the anti-protozoal activity depends on the importance of the extramitochondrial enzymes which respond to nitroimidazoles. The more anaerobic the organisms, the greater their sensitivity. In the most sensitive protozoa, the trichomonads, most of the enzymatic reactions inhibited by these drugs take place in the hydrogenosomes; these are cytoplasmatic organelles surrounded by a membrane whose disintegration, in fact, is the first visible effect of the action of the nitroimidazoles. Various nitroimidazoles act with different speed on these and other protozoa, whose membranes can difinitely possess different degrees of permeability towards substances with different chemico-physical characteristics. In the treatment of trichomoniasis, the specific speed of action of a drug is perhaps as important as its half-life in man.

Amoeba↗
PubMed1978

Assay conditions and the demonstration of nitroimidazole resistance in Tritrichomonas foetus.

Tritrichomonas foetus KV(1), a nitroimidazole-susceptible strain, and KV(1)/M100, its nitroimidazole-resistant daughter strain, differed markedly in their in vivo susceptibility to metronidazole. In vitro susceptibility testing in multiwell plates and tubes with different trichomonad media containing no, or low concentrations of, ascorbate demonstrated that the resistant strain behaves like the susceptible one, if tested under anaerobic conditions (deep cultures in tubes or multiwell plates in anaerobic jars), but shows resistance if tested in the presence of air (multiwell plates exposed to air). In media containing high concentrations of ascorbate, no resistance was observed even in air. The results suggest that the two strains differ in the regulation of internal redox systems and underscore the role testing methods may play in the in vitro detection of nitroimidazole-resistant protozoan parasites.

Culture Media↗
PubMed1977

Nitroimidazoles with antibacterial activity against Neisseria gonorrhoeae.

Nitroimidazoles have been prepared which show interesting activity against the bacterium, Neisseria gonorrhoeae, in addition to the activities usually shown by nitroimidazoles against protozoa and anaerobic bacteria. The compounds were prepared by alkylation of 1-methyl-2-mercaptoimidazole, followed by nitration. Optimum activity occurs with a 5-nitro group and a free carboxyl at the end of the group attached to the sulfur. The linkage between the sulfur atom and the carboxyl group can be alkylene or phenoxyalkylene. These compounds have only weak activity against other aerobic or facultative bacteria.

Anti-Bacterial Agents↗
PubMed1976

Antitrichomonad action, mutagenicity, and reduction of metronidazole and other nitroimidazoles.

Twelve 4- and 5-nitroimidazole derivatives, including metronidazole and two of its metabolites, tinidazole, dimetridazole, and nimorazole, were tested for antitrichomonad action on Tritrichomonas foetus (KV(1)) and Trichomonas vaginalis (ATCC 30001) for mutagenicity on a nitroreductase-positive (TA 100) and a nitroreductase-deficient (TA 100-FR(1)) strain of Salmonella typhimurium, as well as for the reducibility of the nitro group by T. foetus homogenates. Compounds with activity <1% of that of metronidazole are regarded as inactive. All antitrichomonad compounds induce mutations and can be reduced. S. typhimurium TA 100 gave mutations under both aerobiosis and anaerobiosis; TA 100-FR(1), however, gave mutations only under anaerobiosis. Certain compounds that are reducible, and the nonreducible derivatives, were inactive. Metronidazole and its inactive 4-nitro analogue were reduced in a four-electron process in ferredoxin- or methyl viologen-mediated reactions with the same velocity. The results underscore the role of the reduction of the nitro group in the antitrichomonad and in the mutagenic activity of nitroimidazoles.

Aerobiosis↗
PubMed1977

The activity of four antimicrobial agents. Including three nitroimidazole compounds, against Bacteroides sp.

Forty strains of Bacteroides sp. were tested against three nitroimidazole compounds, metronidazole, tinidazole and nimorazole and the aminoglycosidic antibiotic spectinomycin. The effect of altering the inoculum and the presence of serum upon the minimum inhibitory concentration (MIC) was also noted. The three nitroimidazole compounds were all very active (average MIC = circa 0.25 mg/l). Tinidazole was twofold more active. The MIC of spectinomycin was 32 mg/l.

Anti-Bacterial Agents↗
PubMed1978

Chemotherapeutically acitve nitro compounds. 4. 5-Nitroimidazoles (Part III).

More than 100 1-methyl-5-nitroimidazoles substituted in the 2-position via an oxymethyl group were synthesized and their structure-activity relationship toward various protozoa was investigated. Among the derivatives substituted with an aromatic radical there are most of the compounds which are highly effective against trichomonads; 9 preparations are superior to tinidazole and 29 are superior to metronidazole in mice infected with Trichomonas fetus, and 9 compounds exhibit a better effect than metronidazole in golden hamsters intrahepatically infected with Entamoeba histolytica. In the same series one dialkylamino-acetamide derivative shows excellent trypanocidal activity in the NMRI mouse, but this effect is limited to Trypanosoma brucei; 12 preparations developed a trypanocidal effect only after relatively high doses; their range of efficacy included Trypanosoma cruzi, among others, after repeated treatment. Of the carboxyl acid, carbamic acid and sulphonic acid esters synthesized only the already known group of carbamic acid esters possesses a pronounced antiprotozoal effect. Among the preparations substituted with a heterocyclic radical some of the pyridine derivatives proved to have distinct trichomonacidal activity. The influence of the type of substitution and the stability of the C-X bond in 2-substituted 5-nitroimidazoles of all compounds synthesized so far (I--III, 4th report) are discussed in 2 tables.

Animals↗
PubMed1977

1-Methyl-2-nitroimidazol-5-yl derivatives. IVth Communication.

The chemico-physical data and antimicrobial activities are described of a new series of 2-nitroimidazole derivatives prepared by condensing 1-methyl-2-nitroimidazole-5-carboxaldehyde with N-substituted hydroxylamines, N-aminopiperazines and N-aminopiperidines.

Animals↗
PubMed1978

Chemotherapeutically active nitro compounds. 4.5-Nitroimidazoles (Part II).

More than 170 1-methyl-5-nitroimidazoles substituted in the 2-position via an aminomethyl, thiomethyl, sulphinylmethyl or sulphonylmethyl group were synthesized and tested for their effect against various protozoa. In the NMRI mouse which had been i.p. infected with Trichomonas fetus 2 compounds showed an effect superior to that of tinidazole and 31 showed similarly good efficacy as that compound. In comparison with metronidazole 54 preparations proved to be distinctly more active, while 34 others lay in the range of efficacy of the standard compound. A large majority of the most active derivatives is substituted in the 2-position via a C--S bridge with heterocyclics, particularly with a pyridyl radical. An effect against Entamoeba histolytica in the intrahepatically infected golden hamster was observed much less often. Only 14 preparations developed a systemic effect comparable with that of metronidazole. In the NMRI mouse infected i.p. with Trypanosoma brucei or s.c. with T. cruzi parasitemia was clearly influenced by 11 compounds. With a few exceptions a trypanocidal effect against T. brucei occurred only at high doses. Only 3 compounds showed pronounced suppressive activity against blood forms of T. cruzi and only after prolonged treatment. The structure-activity relationship of the new 5-nitroimidazoles is discussed.

Animals↗
PubMed1977

The mutagenic action of nitroimidazoles. II. Tinidazole, ipronidazole, panidazole and ornidazole.

The 5-nitroimidazoles tinidazole (Fasigyn), ipronidazole (Ro-7-1554), panidazole and ornidazole (Tiberal, Ro-7-0207) in concentrations of 0.02--1 mM per liter increased the mutation frequency of Klebsiella pneumoniae. Escherichia coli K12 and Citrobacter freundii to streptomycin resistance, including streptomycin dependence, in Luria and Delbrück's fluctuation test. At low concentration (0.1 mM), the increase of the mutation frequency caused by each compound was nearly the same, i.e. 3--4 times the spontaneous mutation frequency. At higher concentrations, considerable differences between the mutagenic activities of the compounds occurred.

Citrobacter↗
PubMed1979

Effect of lipophilicity of nitroimidazoles on radiosensitization of hypoxic bacterial cells in vitro.

The effect of radiosensitization of hypoxic bacterial cells by 9 nitroimidazoles was measured in the bacterial strains E. coli AB 1157 and S. lactis 712. Seven of these compounds were similar to misonidazole in their redox properties, but differed widely in their lipophilicites. The dependence of sensitization enhancement on reduction potential was similar to that reported in mammalian cells. The efficiency of sensitization was similar for compounds of low lipophilicity, but increased if the octanol: water partition coefficients of the compounds were higher than about 3.5. With one compound, otherwise similar to misonidazole, the increased lipophilicity led to about one order of magnitude lower concentration achieving the same degree of radiosensitization.

Anaerobiosis↗
PubMed1979

Response of the solid Guerin epitheliomas of rats to fractionated irradiation and a new 4-nitroimidazole.

The transplantable Guerin epithelioma in Wistar rats was used to test the in vivo effectiveness of 1-(2-hydroxy-3-methoxypropyl)-2-methyl-4-nitroimidazole (P1) as a tumour-cell radiosensitizer after its oral administration at relatively low doses. The radiosensitizing ability of P1 was compared with that of metronidazole. The results indicate that P1 is less toxic than metronidazole, and greater concentrations of P1 in blood and tumour tissues are obtained for the same administered dose of the compounds. The radiosensitizing ability of P1, determined from tumour-regression rates and local-control percentage at 130 days, was higher than that of metronidazole.

Animals↗
PubMed1979

Changes in nerve conduction velocity in the mouse after acute and chronic administration of nitroimidazoles.

The effect of the nitroimidazoles misonidazole, Ro-05-9963, RGW-608 and metronidazole on nerve conduction velocity (NCV) were measured in the anaesthetized mouse. The compounds were administered by i.p. injection either as a single dose of 1 mg/g (only 0.5 mg/g for RGW-608) or in 36 fractions of 0.15 mg/g over 18 days (only 4 fractions in 2 days for RGW-608). After single doses a reduction in nerve conduction velocity was seen with all the compounds except metronidazole, which had no significant effect. During chronic exposure, a reduction in NCV occurred towards the end of the course of injections. All compounds produced an effect, although RGW-608 was the most neurotoxic, giving the largest reduction in NCV after only 4 injections. After the end of chronic exposure to misonidazole, Ro-05-9963 and metronidazole, recovery to normal took 2-3 weeks.

Animals↗
PubMed1978

Mode of action of the 2-nitroimidazole derivative benznidazole.

Using cultures of Trypanosoma cruzi cells in a liquid medium, the mode of action of the 2-nitroimidazole derivative benznidazole was examined. Benznidazole inhibits protein synthesis and RNA synthesis in T. cruzy. The DNA synthesis is only slightly decreased and no effect on the aerobic respiration of T. cruzi was observed.

Animals↗
PubMed1976

The effect of nitroimidazole and nitroxyl radiosensitizers on the post-irradiation synthesis of DNA.

The modification of DNA damage by three radiosensitizing drugs, present during gamma-irradiation of hypoxic Chinese hamster cells, was investigated. Both 2-methyl-5-nitroimidazole-1-ethanol (metronidazole) and 1-(2-nitro-1-imidazole)-3-methoxy-2-propranol (Ro-07-0582) were found to cause large increases in the yield of DNA single-strand breaks (SSB); triacetoneamine-N-oxyl (TAN) was found to have only a small effect on SSB production. The three drugs tested did not inhibit the rejoining of SSB. A pulse label and chase procedure was used to examine post-irradiation DNA synthesis. TAN present during irradiation under hypoxia was found to cause interruptions in subsequent DNA synthesis. Metronidazole and Ro-07-0582 had no effect on post-irradiation DNA synthesis. In addition, the effects of pre- and post-irradiation exposure to TAN were investigated, since these treatments have shown increased cell-killing in survival studies. TAN pre- and post-treatments were found to have no significant effect on subsequent DNA synthesis.

Cells, Cultured↗
PubMed1977

The effect of the nitroimidazole drug dimetridazole on microaerophilic campylobacters.

Dimetridazole, a nitroimidazole drug reported to act only on obligately anaerobic micro-organisms, is widely used for the prevention and treatment of swine dysentery. Forty-four strains of the microaerophilic bacterium Campylobacter coli isolated from either healthy or diseased pigs, and a strain of Campylobacter fetus, were all sensitive to dimetridazole. The sensitivities (minimal inhibitory concentration less than 10 microng per ml) were similar to those of anaerobic bacteria. Dimetridazole inhibited growth of campylobacters in a shaken culture in air, but did not inhibit uptake of oxygen. Inhibition of growth appeared to result from an inhibition of nucleic-acid synthesis and does not seem to depend upon interference with electron transport in the catabolism of pyruvate.

Animals↗