In vitro antimicrobial activity of benzoxazinorifamycin, KRM-1648, against Mycobacterium avium complex, determined by the radiometric method

Tomioka, Haruaki; Saito, Hajime; Fukui, Kenji; Sato, K; Hidaka, T

doi:10.1128/aac.37.1.67

Cited by 33 publications

(23 citation statements)

References 13 publications

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“…This mixture was preincubated at 37ЊC for 30 min. After preincubation, the reaction was begun with the addition of 0.5 g of poly(rA), 0.5 mU of oligo(dT) [12][13][14][15][16][17][18] , and 37 KBq of [ 3 H]TTP, and then the mixture was incubated at 37ЊC for 30 min. The reaction was terminated by chilling of the reaction mixture on ice, and a 50-l aliquot of the reaction mixture was applied to Whatman DE-51 filter paper (2 by 2 cm squares).…”

Section: Methodsmentioning

confidence: 99%

“…M. avium, M. fortuitum, and Escherichia coli were derived from our stock cultures. The MICs of test agents for M. avium were determined with the BACTEC 460 TB system as previously described (17).…”

Section: Methodsmentioning

confidence: 99%

“…KRM was much more effective in inhibiting uptake of 14 C-uracil than was RMP (IC 50 of KRM, 0.04 g/ml; IC 50 of RMP, 0.12 g/ml). These findings suggest, first, that the potent antimycobacterial activity of KRM is due to inhibition of bacterial RNA polymerase and, second, that the activity of KRM against target organisms depends on target cell wall permeability.3Ј-Hydroxy-5Ј-(4-isobutyl-1-piperazinyl)benzoxazinorifamycin (KRM-1648 [KRM]), a newly synthesized rifamycin derivative, exerts much more potent in vitro and in vivo activities against slowly growing mycobacteria, including those of the Mycobacterium avium complex and Mycobacterium tuberculosis, than does rifampin (RMP) (2,9,14,17,18,22,23). Furthermore, KRM is known to exhibit potent activity in vitro and in vivo against gram-positive bacteria (3, 23) but is not effective against gram-negative bacteria or rapidly growing mycobacteria such as Mycobacterium fortuitum (3,14,23).…”

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Mechanism of action of antimycobacterial activity of the new benzoxazinorifamycin KRM-1648

Fukui

Saito

Tomioka

et al. 1995

Antimicrob Agents Chemother

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The mechanism of antimicrobial activity of KRM-1648 (KRM), a new rifamycin derivative with potent antimycobacterial activity, was studied. Both KRM and rifampin (RMP) inhibited RNA polymerases from Escherichia coli and Mycobacterium avium at low concentrations: the 50% inhibitory concentrations (IC 50 s) of KRM and RMP for E. coli RNA polymerase were 0.13 and 0.10 g/ml, respectively, while the IC 50 s for M. avium RNA polymerase were 0.20 and 0.07 g/ml. Both KRM and RMP exerted weak inhibitory activity against Mycobacterium fortuitum RNA polymerase, rabbit thymus RNA polymerases, E. coli DNA polymerase I, and two types of reverse transcriptases. Uptake of 14 C-KRM by M. avium reached 18,000 dpm/mg (dry weight) 1.5 h after incubation, while uptake by E. coli cells was slight. KRM was much more effective in inhibiting uptake of 14 C-uracil than was RMP (IC 50 of KRM, 0.04 g/ml; IC 50 of RMP, 0.12 g/ml). These findings suggest, first, that the potent antimycobacterial activity of KRM is due to inhibition of bacterial RNA polymerase and, second, that the activity of KRM against target organisms depends on target cell wall permeability.3Ј-Hydroxy-5Ј-(4-isobutyl-1-piperazinyl)benzoxazinorifamycin (KRM-1648 [KRM]), a newly synthesized rifamycin derivative, exerts much more potent in vitro and in vivo activities against slowly growing mycobacteria, including those of the Mycobacterium avium complex and Mycobacterium tuberculosis, than does rifampin (RMP) (2,9,14,17,18,22,23). Furthermore, KRM is known to exhibit potent activity in vitro and in vivo against gram-positive bacteria (3, 23) but is not effective against gram-negative bacteria or rapidly growing mycobacteria such as Mycobacterium fortuitum (3,14,23). The spectrum of activity of KRM against gram-positive and gram-negative bacteria is nearly the same as that of RMP (3). Since it is well known that the antimicrobial activity of RMP is due to inhibition of microbial DNA-dependent RNA polymerases (4,5,8,16,19,20), we studied the effects of KRM on mycobacterial RNA polymerases and its ability to permeate bacterial cells. MATERIALS AND METHODSOrganisms. M. avium, M. fortuitum, and Escherichia coli were derived from our stock cultures. The MICs of test agents for M. avium were determined with the BACTEC 460 TB system as previously described (17).Special agents. 14 C-KRM (0.51 MBq/mg) and KRM were obtained from KANEKA Corp. (Takasago, Japan). Other radiolabelled compounds were purchased from Daiichi Pure Chemical (Tokyo, Japan). Rifampin was the kind gift of Daiichi Pharmaceutical Co. (Tokyo, Japan). RNA polymerase (from E. coli) and DNA (type I from calf thymus and type VIII from E. coli) were purchased from Sigma (St. Louis, Mo.). DNA polymerase (type I from E. coli) and TTP were purchased from Takara (Kyoto, Japan). Avian myeloblastosis virus (AMV) reverse transcriptase and Moloney murine leukemia virus (MMLV) reverse transcriptase were purchased from Pharmacia Biotech (Tokyo, Japan). All other chemicals were obtained from Wako Pure Chemical Industries (Tokyo, Japa...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Mechanism of action of antimycobacterial activity of the new benzoxazinorifamycin KRM-1648

Fukui

Saito

Tomioka

et al. 1995

Antimicrob Agents Chemother

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“…The in vivo efficacies of the KRM compounds were compared with those of rifampin and rifabutin against septicemia caused by S. aureus infection in mice. The results are summarized in Table 5 (1,3,6,7,9,10).…”

Section: Resultsmentioning

confidence: 94%

“…1) exhibit potent activity against a variety of mycobacteria including Mycobacterium tuberculosis, Mycobacterium avium, and Mycobacterium intracellulare (1,3,6,7,9,10). These compounds have also been shown to be active against Staphylococcus aureus and Bacillus subtilis but have been shown to be inactive against Escherichia coli and Klebsiella pneumoniae (10).…”

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In vitro and in vivo antibacterial activities of KRM-1648 and KRM-1657, new rifamycin derivatives

Fukui

Tsuji

Miyazaki

et al. 1994

Antimicrob Agents Chemother

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The in vitro and in vivo antibacterial activities of the new rifamycin derivatives KRM-1648 and KRM-1657 were compared with those of rifampin. Rifabutin, ciprofloxacin, and clarithromycin were also tested for reference. The respective MICs of KRM-1648 and KRM-1657 for 90% of the strains tested (MIC90s) were 0.016 and 0.0078 ,ug/ml, respectively, for methicillin-susceptible Staphylococcus aureus, 0.016 and 0.0039 ,ug/ml, respectively, for methicillin-resistant S. aureus, and 0.0625 and 0.016 ,ug/ml, respectively, for methicillin-and quinolone-resistant S. aureus. These MIC90s of KRM-1657 were equal to or 2-to 64-fold lower than those of rifampin. KRM-1648 and KRM-1657 with MIC90s of between 0.002 and 0.078 ,ug/ml were 2-to 128-fold more active than rifampin against Staphylococcus epidermidis and Streptococcus species, including Streptococcus pneumoniae and Streptococcus pyogenes. The MIC90s of KRM-1657 for Haemophilus influenzae and Neisseria gonorrhoeae were 0.25 and 0.1 ,ug/ml, respectively; KRM-1657 was almost as active as rifampin and was 8-to 16-fold more active than KRM-1648 against these strains. The frequency of occurrence of spontaneous mutations to resistance to KRM-1648 and KRM-1657 was equal to that to rifampin. Against systemic infection with S. aureus in mice, the efficacies of KRM-1648 and KRM-1657 were comparable to that of rifampin.The recently synthesized rifamycin derivatives 3'-hydroxy-5'-(4-isobutyl-1 -piperazinyl)benzoxazinorifamycin (KRM-1648) and 3'-hydroxy-5'-(4-propyl-1-piperazinyl)benzoxazinorifamycin (KRM-1657) (Fig. 1) exhibit potent activity against a variety of mycobacteria including Mycobacterium tuberculosis, Mycobacterium avium, and Mycobacterium intracellulare (1, 3, 6, 7, 9, 10). These compounds have also been shown to be active against Staphylococcus aureus and Bacillus subtilis but have been shown to be inactive against Escherichia coli and Klebsiella pneumoniae (10). In the study described here, we conducted further testing to determine the in vitro activities of KRM compounds against gram-positive and gram-negative bacteria with the aim of elucidating their antibacterial properties. The frequency of occurrence of spontaneous mutants of S. aureus resistant to these compounds and the therapeutic efficacies of these compounds against S. aureus infections in mice were also determined. KRM-1648, KRM-1657, rifampin, and clarithromycin were dissolved in dimethyl sulfoxide at 3.2 mg/ml. Rifabutin and ciprofloxacin were dissolved in dimethylformamide and 0.1 N NaOH, respectively, at 3.2 mg/ml. Drug solutions were diluted with medium broth for use. All drugs were stored at -20°C. MATERIALS AND METHODSFor in vivo testing, rifampin was dissolved (and the other three rifamycin derivatives were suspended) in 2.5% gum arabic solution containing 0.05% Tween 80 (polysorbate 80) at 1.6 mg/ml and was then diluted with the same vehicle to achieve the appropriate concentrations. The compounds were /\~/ CH3 N NCH2CH

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Prospects for development of new antimycobacterial drugs

Tomioka

2000

Journal of Infection and Chemotherapy

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In vitro antimicrobial activity of benzoxazinorifamycin, KRM-1648, against Mycobacterium avium complex, determined by the radiometric method

Cited by 33 publications

References 13 publications

Mechanism of action of antimycobacterial activity of the new benzoxazinorifamycin KRM-1648

Mechanism of action of antimycobacterial activity of the new benzoxazinorifamycin KRM-1648

In vitro and in vivo antibacterial activities of KRM-1648 and KRM-1657, new rifamycin derivatives

Prospects for development of new antimycobacterial drugs

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