Clinafloxacin Research Articles

Ciprofloxacin and Clinafloxacin Antibodies for an Immunoassay of Quinolones: Quantitative Structure⁻Activity Analysis of Cross-Reactivities.

A common problem in the immunodetection of structurally close compounds is understanding the regularities of immune recognition, and elucidating the basic structural elements that provide it. Correct identification of these elements would allow for select immunogens to obtain antibodies with either wide specificity to different representatives of a given chemical class (for class-specific immunoassays), or narrow specificity to a unique compound (mono-specific immunoassays). Fluoroquinolones (FQs; antibiotic contaminants of animal-derived foods) are of particular interest for such research. We studied the structural basis of immune recognition of FQs by antibodies against ciprofloxacin (CIP) and clinafloxacin (CLI) as the immunizing hapten. CIP and CLI possess the same cyclopropyl substituents at the N1 position, while their substituents at C7 and C8 are different. Anti-CIP antibodies were specific to 22 of 24 FQs, while anti-CLI antibodies were specific to 11 of 26 FQs. The molecular size was critical for the binding between the FQs and the anti-CIP antibody. The presence of the cyclopropyl ring at the N1 position was important for the recognition between fluoroquinolones and the anti-CLI antibody. The anti-CIP quantitative structure–activity relationship (QSAR) model was well-equipped to predict the test set (pred_R2 = 0.944). The statistical parameters of the anti-CLI model were also high (R2 = 0.885, q2 = 0.864). Thus, the obtained QSAR models yielded sufficient correlation coefficients, internal stability, and predictive ability. This work broadens our knowledge of the molecular mechanisms of FQs’ interaction with antibodies, and it will contribute to the further development of antibiotic immunoassays.

Cytotoxicity and antigenotoxicity evaluation of acetylshikonin and shikonin

Shikonin (SH) is used as a red pigment for food coloring and cosmetics, and has cytotoxic activity towards cancer cells. However, due to strong toxicity SH has limited potential as an anticancer drug. Acetylshikonin (ASH) is one of the SH derivatives with promising anticancer potential. In present study, we attempted to evaluate and compare the cytotoxicity of SH and ASH towards a normal cell line (V79) and in addition to evaluate their antigenotoxic activity. The evaluation was made with the use of the set of cytotoxicity assays with V79 line and the micronucleus test in vitro performed using clinafloxacin (CLFX), ethyl methanesulfonate (EMS) as direct genotoxins and cyclophosphamide (CPA) as indirect genotoxin. For CPA and EMS the simultaneous protocol was used and for CLFX three different variants were performed: pretreatment, simultaneous, and post-treatment. A higher cytotoxic effect was observed for SH. The EC50 values obtained for SH were approximately twofold lower compared to that of ASH. Moreover, ASH exhibited an antigenotoxic potential against CPA-induced genotoxicity, whereas SH has no activity. However, ASH increased the EMS-induced genotoxicity, when SH exhibited no effect. Both compounds decreased the genotoxicity of CLFX in pretreatment and simultaneous protocol. Based on the results of the present study it can be concluded that ASH is less cytotoxic than SH to normal cells and has comparable antigenotoxic potential.

A Specific and High-Throughput Fluorescence Polarization Immunoassay for Surveillance Screening of Clinafloxacin in Milk

In this study, antibody specific to clinafloxacin (CLI) was generated for the first time, and a rapid and specific surveillance screening method, fluorescence polarization immunoassay (FPIA), was developed for the detection of CLI residue in milk. The developed FPIA showed a working range from 0.8 to 787.3 μg/L with the IC50 of 25.6 μg/L. The cross-reactivity to other fluoroquinolone drugs was negligible, which demonstrated high specificity. Good recoveries, ranged from 97.9 to 112.7 %, in spiked milk samples were obtained. The proposed FPIA was also validated by high performance liquid chromatography as a reference method, and the two methods yielded concordant results. The investigation indicated that the proposed FPIA is suitable for surveillance screening purposes to detect CLI residue in milk.

Relationship of cellular topoisomerase IIα inhibition to cytotoxicity and published genotoxicity of fluoroquinolone antibiotics in V79 cells

Fluoroquinolone (FQ) antibiotics are bacteriocidal through inhibition of the bacterial gyrase and at sufficient concentrations in vitro, they can inhibit the homologous eukaryotic topoisomerase (TOPO) II enzyme. FQ exert a variety of genotoxic effects in mammalian systems through mechanisms not yet established, but which are postulated to involve inhibition of TOPO II enzymes. To assess the relationship of inhibition of cell nuclear TOPO II to cytotoxicity and reported genotoxicity, two FQ, clinafloxacin (CLFX) and lomefloxacin (LOFX), having available genotoxicity data showing substantial differences with CLFX being more potent than LOFX, were selected for study. The relative inhibitory activities of these FQ on nuclear TOPO IIα in cultured Chinese hamster lung fibroblasts (V79 cells) over dose ranges and at equimolar concentrations were assessed by measuring nuclear stabilized cleavage complexes of TOPO IIα–DNA. Cytotoxicity was measured by relative cell counts.Both FQ inhibited V79 cell nuclear TOPO IIα. The lowest-observed-adverse-effect levels for TOPO IIα inhibition were 55μM for CLFX, and 516μM for LOFX. The no-observed-adverse-effect-levels were 41μM for CLFX, and 258μM for LOFX. At equimolar concentrations (175μM), CLFX was more potent than LOFX. Likewise, CLFX was more cytotoxic than LOFX.Thus, the two FQ, inhibited TOPO IIα in intact V79 cells, differed in their potencies and exhibited no-observed-adverse-effect levels. These findings are in concordance with published genotoxicity data and observed cytotoxicity.

Facile synthesis and <italic>in vitro/vivo</italic> bioactivities of amido derivatives of clinafloxacin

Nineteen new amido derivatives of clinafloxacin (CF) were prepared in 52.8%～97.5% via the condensation of selected carboxylic acids with clinafloxacin. The chemical structures of these target molecules were confirmed by 1H NMR, 13C NMR and HR MS. Following the preliminary evaluation of antibacterial activity through agar diffusion method, the minimal inhibitory concentrations (MICs) of all the obtained amido derivatives of CF were measured by Micro-dilution method. The toxicity of the active compounds of interest was confirmed by acute toxicity test in mice. The stability of most of target compounds was detected by use of the general agar diffusion procedure on the keeping time of 30–90 days, subsequently. The results showed that TM1-b and TM1-l possessed stronger antibacterial activity, lower toxicity, larger solubility and higher stability than CF, and thus may be exploitable as lead compounds. This finding may provide some helpful guidances for further investigation.

In vivo photochemical micronucleus induction due to certain quinolone antimicrobial agents in the skin of hairless mice

The skin micronucleus test combined with irradiation due to a sunlight simulator having a spectrum almost identical to solar irradiation was used as a novel in vivo testing method for detecting or comparing the photochemical chromosome damage of quinolone antibacterial agents (quinolones). Eight-week-old male SKH1 hairless mice were orally administered once lomefloxacin (LFLX), a strong in vitro photochemical clastogen, at 25 or 50 mg/kg, followed by light irradiation at 7.9–9.4 J/cm 2 of ultraviolet A (UVA). Animals were killed on Days 2, 3, 4, 5 or 8 (the dosing day was designated as Day 1), and the incidence of micronucleus in the epidermis was determined. As results, LFLX at either dose caused significant increases in the micronucleus frequency, which peaked on Day 4. These changes tended to return to the control level on Day 8. Then, the micronucleus induction potential of the quinolone derivatives levofloxacin (LVFX) and clinafloxacin (CLFX) at 10, 20 or 40 mg/kg was assessed on Day 4 under the same experimental conditions as for LFLX. Although LVFX was negative even at 40 mg/kg, CFLX dose-dependently induced significant increases in micronucleus frequency at all doses. The correlation of magnitude among the three quinolones in the skin micronucleus test with light irradiation was similar to that in our previous in vitro photochemical clastogenicity study. No significant increase in micronucleus frequency was observed in any of three quinolones employed without light irradiation. In conclusion, the experimental method presented here would be a useful tool for detecting in vivo photochemical chromosome damage and for research on photochemical carcinogenesis of chemicals.

In vitro photochemical clastogenicity of quinolone antibacterial agents studied by a chromosomal aberration test with light irradiation

The photochemical clastogenic potential of 12 quinolone antibacterial agents with or without light irradiation was assessed by an in vitro chromosomal aberration test using cultured CHL cells. Exposure to all test compounds, except for DK-507k, increased the incidence of cells with structural aberrations excluding gap (TA) following light irradiation. Test compounds used in the present study under light irradiation were divided into three groups based on their ED 50 values, doses inducing chromosomal aberrations in 50% of cells. The first group with ED 50 values below 30 μg/ml includes sparfloxacin (SPFX), clinafloxacin (CLFX), gemifloxacin (GMFX), lomefloxacin (LFLX), sitafloxacin (STFX), grepafloxacin (GPFX) and fleroxacin (FLRX); the second group with ED 50 values of 100 μg/ml, enoxacin (ENX) and levofloxacin (LVFX); the third group with little or no potency, moxifloxacin (MFLX), trovafloxacin (TVFX) and DK-507k. The photochemical clastogenicity of these compounds correlates well with their reported in vivo phototoxic potentials. In the chemical structure and clastogenicity relationships, substitution of a methoxy group at the C-8 position in the quinolone nucleus was confirmed to reduce not only photochemical clastogenicity, but also the clastogenic potential of quinolone antibacterial agents.

In VitroPhotogenotoxic Activity of Clinafloxacin: A Paradigm Predicting Photocarcinogenicity

Fluoroquinolone antiinfective drugs exhibit phototoxic, photogenotoxic, and photocarcinogenic activities in experimental systems which may be interrelated. Clinafloxacin (CLX), a new fluoroquinolone, is a potent antiinfective agent being developed for use in life-threatening infections. While this drug has previously been demonstrated to be phototoxic, this report evaluated the photogenotoxic and photocarcinogenic potential of CLX. When Skh-1 mice were administered CLX in the presence of ultraviolet light (UVA) at the maximum tolerated dose expected for a photocarcinogenicity bioassay, induction of DNA strand breakage was noted in keratinocytes isolated from these animals. When compared with other well-studied fluoroquinolonesin vitro,CLX and Lomefloxacin (LMX) were equally effective in producing chromosome damage and DNA strand breakage in Chinese hamster ovary (CHO) cells exposed to UVA. Treatment of CHO cells with CLX in the presence of UVA also resulted in hydroxyl radical formation. However, coincubation of CHO cells with CLX and various antioxidants markedly reduced hydroxyl radical formation, but inhibited photogenotoxicity only to a limited extent. Thus, while reactive oxygen species contribute to the photogenotoxic activity of CLX, other factors may be involved. Since CLX exhibits both phototoxic and photogenotoxic activity, we predict that CLX would be photocarcinogenicin vivo.The present study suggests that under conditions of human exposure, the potential risk for CLX-induced photocarcinogenicity is small.

Pharmacokinetics of Oral and Intravenous Clinafloxacin

Pharmacokinetics of Oral and Intravenous Clinafloxacin

In vitro and in vivo activities of moxifloxacin and clinafloxacin against Mycobacterium tuberculosis.

On 10% oleic acid-albumin-dextrose-catalase-enriched 7H11 agar medium, the MIC at which 90% of the isolates are inhibited for 20 strains of Mycobacterium tuberculosis was 0.5 microg of sparfloxacin (SPFX) or moxifloxacin (MXFX) per ml and 1.0 microg of clinafloxacin (CNFX) per ml, indicating that the in vitro activities of SPFX and MXFX were virtually identical and were slightly greater than that of CNFX. However, the in vivo activities of these drugs in a murine tuberculosis model differed considerably. Female Swiss mice were infected intravenously with 6.2 x 10(6) CFU of the H37Rv strain and treated for 4 weeks, beginning the next day after infection, with isoniazid (INH) serving as the positive control. By the criteria of 30-day survival rate, spleen weight, gross lung lesion, and mean number of CFU in the spleen, treatment with CNFX at up to 100 mg/kg of body weight six times weekly displayed no measurable effect against M. tuberculosis, whereas both SPFX and MXFX were effective; administration six times weekly of either of the latter two drugs demonstrated dosage-dependent bactericidal effects, as measured by enumeration of CFU in the spleens, and MXFX appeared more bactericidal than the same dosage of SPFX. Of the three fluoroquinolones, only MXFX at 100 mg/kg six times weekly appeared as bactericidal as INH at 25 mg/kg six times weekly. Thus, MXFX may be an important component of the newer combined regimens for treatment of tuberculosis.