Topoisomerase IV; DNA gyrase

Clinafloxacin shows efficacy against S. pneumonia in parC-gyrA mutants, with a minimum inhibitory concentration (MIC) of 1 μg/ml[2].
Clinafloxacin hydrochloride possesses antibacterial properties against S. aureus mutant strains with altered targets. It has MIC values of 0.016 µg/ml, 0.063 µg/ml, and 0.915 µg/ml against wild type S. aureus, gyrA mutant S. aureus, and gyrA mutant S. aureus, respectively[3].

Clinafloxacin pneumococcal meningitis that is resistant to penicillin responds well to clinafloxacin therapy in the rabbit model.
Clinafloxacin produces an initial reduction at 6 hours when used with the CS strain (2349) (Clinafloxacin MIC=0.12 μg/ml) at doses of 10 mg/kg and 20 mg/kg. The final reduction in mean log cfu/ml at 24 hours is 22.30 and 23.83, respectively. Both are bactericidal at this point, but show regrowth at that time. But in this meningitis model in rabbits, even at 20 mg/kg per day, clinafloxacin (MIC=0.5 μg/ml) does not reduce bacterial titers[3]. This is because the CR strain (4371) exhibits this property.

The antibacterial activities and target inhibition of 15 quinolones against grlA and gyrA mutant strains were studied. The strains were obtained from wild-type Staphylococcus aureus MS5935 by selection with norfloxacin and nadifloxacin, respectively. The antibacterial activities of most quinolones against both mutant strains were lower than those against the wild-type strain. The ratios of MICs for the gyrA mutant strain to those for the grlA mutant strain (MIC ratio) varied from 0.125 to 4. The ratios of 50% inhibitory concentrations (IC50s) of quinolones against topoisomerase IV to those against DNA gyrase (IC50 ratios) also varied, from 0.177 to 5.52. A significant correlation between the MIC ratios and the IC50 ratios was observed (r = 0.919; P < 0.001). These results suggest that the antibacterial activities of quinolones against the wild-type strain are involved not only in topoisomerase IV inhibition but also in DNA gyrase inhibition and that the target preference in the wild-type strain can be anticipated by the MIC ratios. Based on the MIC ratios, the quinolones were classified into three categories. Type I quinolones (norfloxacin, enoxacin, fleroxacin, ciprofloxacin, lomefloxacin, trovafloxacin, grepafloxacin, ofloxacin, and levofloxacin) had MIC ratios of <1, type II quinolones (sparfloxacin and nadifloxacin) had MIC ratios of >1, and type III quinolones (gatifloxacin, pazufloxacin, moxifloxacin, and clinafloxacin) had MIC ratios of 1. Type I and type II quinolones seem to prefer topoisomerase IV and DNA gyrase, respectively. Type III quinolones seem to target both enzymes at nearly the same level in bacterial cells (a phenomenon known as the dual-targeting property), and their IC50 ratios were approximately 2[1].

The increasing incidence of ciprofloxacin resistance in Streptococcus pneumoniae may limit the efficacy of the new quinolones in difficult-to-treat infections such as meningitis. The aim of the present study was to determine the efficacy of clinafloxacin alone and in combination with teicoplanin and rifampin in the therapy of ciprofloxacin-susceptible and ciprofloxacin-resistant pneumococcal meningitis in rabbits. When used against a penicillin-resistant ciprofloxacin-susceptible strain (Clinafloxacin MIC 0.12 microg/ml), clinafloxacin at a dose of 20 mg/kg per day b.i.d. decreased bacterial concentration by -5.10 log cfu/ml at 24 hr. Combinations did not improve activity. The same clinafloxacin schedule against a penicillin- and ciprofloxacin-resistant strain (Clinafloxacin MIC 0.5 microg/ml) was totally ineffective. Our data suggest that a moderate decrease in quinolone susceptibility, as indicated by the detection of any degree of ciprofloxacin resistance, may render these antibiotics unsuitable for the management of pneumococcal meningitis[3].

[1]. Target preference of 15 quinolones against Staphylococcus aureus, based on antibacterial activities and target inhibition.Antimicrob Agents Chemother. 2001 Dec;45(12):3544-7.

[2]. DNA Gyrase and Topoisomerase IV Mutations and their effect on Quinolones Resistant Proteus mirabilis among UTIs Patients. Pak J Med Sci. Sep-Oct 2020;36(6):1234-1240.

[3]. Experimental study of clinafloxacin alone and in combination in the treatment of ciprofloxacin-susceptible and -resistant pneumococcal meningitis.Microb Drug Resist. 2003;9 Suppl 1:S53-9.

7-(3-amino-1-pyrrolidinyl)-8-chloro-1-cyclopropyl-6-fluoro-4-oxo-3-quinolinecarboxylic acid belongs to the quinoline class of compounds. Clinfloxacin is an investigational fluoroquinolone antibacterial drug that has been shown to have good antibacterial activity. However, its approval and marketing have been suspended due to serious side effects.

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Objective: This study aimed to highlight the importance of mutations in the Proteus mirabilis genome associated with fluoroquinolone resistance. Methods: This was a cross-sectional study conducted from June 2016 to May 2017 at different teaching hospitals in Khartoum State. A total of 120 Proteus mirabilis isolates from patients with urinary tract infections from different hospitals in Khartoum State were examined. First, the phenotype of resistant strains was detected using a modified Kurby-Bauer method. Then, mutations in the GyrA, GyrB, ParC, and ParE genes in the isolates were detected using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) combined with sequencing. Results: The resistance rate of Proteus mirabilis to ciprofloxacin was 30%. Mutations at serine position 83 of the GyrA gene and serine position 84 of the ParC gene were detected in all samples after digestion with the Hinf1 restriction endonuclease. Sequencing was performed on 12 samples. Two resistant strains and one susceptible strain were randomly selected from each gene. The mutations associated with ciprofloxacin-resistant Proteus mirabilis were as follows: (1/3) serine position 83 of the GyrA gene was mutated to isoleucine (Ser 83→Ile), and (2/3) serine position 81 of the ParC gene was mutated to isoleucine (Ser 81→Ile). In addition, the study also found silencing mutations in the codons for leucine at position 474 (3/3), valine at position 585 (2/3), histidine at position 612 (1/3), and asparagine at position 639 (1/3) of the GyrB gene, as well as in the codons for isoleucine at position 469 (2/3), aspartic acid at position 531 (2/3), and glycine at position 533 (1/3) of the ParE gene. Conclusion: Ciprofloxacin resistance in Proteus mirabilis can be monitored by detecting mutations in DNA gyrase (encoded by gyrA and gyrB) and topoisomerase IV (encoded by parC and parE). [2]

C17H18CL2FN3O3

402.24752

401.07

C, 50.76; H, 4.51; Cl, 17.63; F, 4.72; N, 10.45; O, 11.93

105956-99-8

105956-97-6; 105956-99-8 (HCl)

60062

Solid powder

1.573 g/cm3

592.3ºCat 760 mmHg

162-168°C

312ºC

3.931

3

7

3

26

626

0

C1CC1N2C=C(C(=O)C3=C2C(=C(C(=C3)F)N4CCC(C4)N)Cl)C(=O)O.Cl

BMACYHMTJHBPOX-UHFFFAOYSA-N

InChI=1S/C17H17ClFN3O3.ClH/c18-13-14-10(5-12(19)15(13)21-4-3-8(20)6-21)16(23)11(17(24)25)7-22(14)9-1-2-9;/h5,7-9H,1-4,6,20H2,(H,24,25);1H

7-(3-aminopyrrolidin-1-yl)-8-chloro-1-cyclopropyl-6-fluoro-4-oxoquinoline-3-carboxylic acid;hydrochloride

CI-960; PD-127391; AM-109; CI960; PD127391; AM109; Clinafloxacin hydrochloride; Clinafloxacin HCl; CI-960 HCl; UNII-G17M59V0FY ;CI 960 HCl

2934.99.9001

Powder      -20°C    3 years

                     4°C     2 years

In solvent   -80°C    6 months

                  -20°C    1 month

Room temperature (This product is stable at ambient temperature for a few days during ordinary shipping and time spent in Customs)

5%TFA: ~3.02 mg/mL
DMSO: ~0.03 mg/mL (~0.08 mM)

Note: Listed below are some common formulations that may be used to formulate products with low water solubility (e.g. < 1 mg/mL), you may test these formulations using a minute amount of products to avoid loss of samples.

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Injection Formulation 1: DMSO : Tween 80： Saline = 10 : 5 : 85 (i.e. 100 μL DMSO stock solution → 50 μL Tween 80 → 850 μL Saline)
*Preparation of saline: Dissolve 0.9 g of sodium chloride in 100 mL ddH ₂ O to obtain a clear solution.
Injection Formulation 2: DMSO : PEG300 ：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL DMSO → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)
Injection Formulation 3: DMSO : Corn oil = 10 : 90 (i.e. 100 μL DMSO → 900 μL Corn oil)
Example: Take the Injection Formulation 3 (DMSO : Corn oil = 10 : 90) as an example, if 1 mL of 2.5 mg/mL working solution is to be prepared, you can take 100 μL 25 mg/mL DMSO stock solution and add to 900 μL corn oil, mix well to obtain a clear or suspension solution (2.5 mg/mL, ready for use in animals).

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Injection Formulation 4: DMSO : 20% SBE-β-CD in saline = 10 : 90 [i.e. 100 μL DMSO → 900 μL (20% SBE-β-CD in saline)]
*Preparation of 20% SBE-β-CD in Saline (4°C，1 week): Dissolve 2 g SBE-β-CD in 10 mL saline to obtain a clear solution.
Injection Formulation 5: 2-Hydroxypropyl-β-cyclodextrin : Saline = 50 : 50 (i.e. 500 μL 2-Hydroxypropyl-β-cyclodextrin → 500 μL Saline)
Injection Formulation 6: DMSO : PEG300 : castor oil : Saline = 5 : 10 : 20 : 65 (i.e. 50 μL DMSO → 100 μLPEG300 → 200 μL castor oil → 650 μL Saline)
Injection Formulation 7: Ethanol : Cremophor : Saline = 10： 10 : 80 (i.e. 100 μL Ethanol → 100 μL Cremophor → 800 μL Saline)
Injection Formulation 8: Dissolve in Cremophor/Ethanol (50 : 50), then diluted by Saline
Injection Formulation 9: EtOH : Corn oil = 10 : 90 (i.e. 100 μL EtOH → 900 μL Corn oil)
Injection Formulation 10: EtOH : PEG300：Tween 80 : Saline = 10 : 40 : 5 : 45 (i.e. 100 μL EtOH → 400 μLPEG300 → 50 μL Tween 80 → 450 μL Saline)

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Oral Formulation 1: Suspend in 0.5% CMC Na (carboxymethylcellulose sodium)
Oral Formulation 2: Suspend in 0.5% Carboxymethyl cellulose
Example: Take the Oral Formulation 1 (Suspend in 0.5% CMC Na) as an example, if 100 mL of 2.5 mg/mL working solution is to be prepared, you can first prepare 0.5% CMC Na solution by measuring 0.5 g CMC Na and dissolve it in 100 mL ddH2O to obtain a clear solution; then add 250 mg of the product to 100 mL 0.5% CMC Na solution, to make the suspension solution (2.5 mg/mL, ready for use in animals).

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Oral Formulation 3: Dissolved in PEG400
Oral Formulation 4: Suspend in 0.2% Carboxymethyl cellulose
Oral Formulation 5: Dissolve in 0.25% Tween 80 and 0.5% Carboxymethyl cellulose
Oral Formulation 6: Mixing with food powders

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Note: Please be aware that the above formulations are for reference only. InvivoChem strongly recommends customers to read literature methods/protocols carefully before determining which formulation you should use for in vivo studies, as different compounds have different solubility properties and have to be formulated differently.

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 (Please use freshly prepared in vivo formulations for optimal results.)