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Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Detection of DNA damage photosensitized by fluoroquinolones
  5. Mechanisms of DNA damage photosensitized by fluoroquinolones
  6. Summary and outlook
  7. Acknowledgments
  8. References

This review focuses on DNA damage photosensitized by the fluoroquinolone (FQ) antibacterial drugs. The in vivo evidence for photocarcinogenesis mediated by FQs is presented in the introduction. The different methods employed for detection of DNA-photodamage mediated by FQs are then summarized, including gel electrophoresis (with whole cells, with isolated DNA and with oligonucleotides) and chromatographic analysis (especially HPLC with electrochemical and MS/MS detection). The chemical mechanisms involved in the formation of the reported lesions are discussed on the basis of product studies and transient spectroscopic evidence. In general, the literature coverage is limited to the last decade, although some earlier citations are also included.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Detection of DNA damage photosensitized by fluoroquinolones
  5. Mechanisms of DNA damage photosensitized by fluoroquinolones
  6. Summary and outlook
  7. Acknowledgments
  8. References

Fluoroquinolones (FQs) are well-established antibacterial drugs, whose pharmacological activity is associated with inhibition of the bacterial topoisomerase (DNA gyrase and topoisomerase IV). They contain a fluorine atom attached at position C-6 of the bicyclic skeleton; in some cases a second halogen substituent is present at position C-8. The structures of two series of FQs relevant for the purpose of this review are shown in Charts 1 and 2.

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Figure Chart 1..  Structure of 6,8-dihalogenated fluoroquinolones.

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Figure Chart 2..  Structure of 6-fluoroquinolones.

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A number of reports have shown that FQs may be very efficient photosensitizers and have revealed that DNA is one of the most relevant biological targets for this effect. Indeed, FQs are one of the few families of drugs that have been found to be photocarcinogenic in vivo. Thus, the photocarcinogenic activity of LOM, FLE, OFL and CIP has been tested in mice exposed to UVA after oral administration of the drugs (1,2). Under these conditions, radiation enhances tumor prevalence and drastically shortens the median latent period in comparison with UVA alone. In this context, LOM and FLE are the most potent photochemical carcinogens; thus, all the FQs studied have the capability of enhancing UVA-induced phototumorigenesis as shown by the increased number of benign neoplasms, but only LOM and FLE cause the development of malignant neoplasms like squamous cell carcinomas in the majority of the treated animals (1–3).

The present review focuses on the accumulated evidence found for FQ-mediated DNA photodamage in cells, isolated DNA and oligonucleotides, as well as on the mechanistic studies performed to elucidate the molecular basis of the observed lesions.

Detection of DNA damage photosensitized by fluoroquinolones

  1. Top of page
  2. Abstract
  3. Introduction
  4. Detection of DNA damage photosensitized by fluoroquinolones
  5. Mechanisms of DNA damage photosensitized by fluoroquinolones
  6. Summary and outlook
  7. Acknowledgments
  8. References

Electrophoresis with whole cells

The single cell electrophoresis assay (also known as comet assay) is a rapid, simple, visual and sensitive technique for measuring DNA damage in individual eukaryotic cells. It has been used for in vivo and in vitro studies in the evaluation of the genotoxic potential of ionizing and UV radiations, as well as the phototoxic potential of psoralens, nonsteroidal anti-inflammatory drugs, promazines, FQs, etc.

The cells, embedded in a low-melting agarose-microgel, are submitted to an electrophoretic field. Under these conditions, fragmented DNA migrates away from the DNA nucleus to form the fast moving tail; the overall structure resembles a comet with a circular head corresponding to the undamaged DNA and a tail of damaged DNA. This pattern is determined by the extent of DNA damage and thus, quantitative measurement of DNA strand breaks (SB) can be performed by taking into account the length of the comet tail and the amount of DNA both in the tail and in the nucleus. The comet assay is a versatile technique for detecting damage and, with adjustments of the protocol, it can be used to quantify the presence of a wide variety of DNA lesions. In neutral buffer only double strand breaks (DSB) are detectable, while alkaline electrophoresis conditions also allow detection of single strand breaks (SSB) and alkali labile sites (ALS). In addition, this assay can be combined with the use of specific antibodies or with DNA repair enzymes to evaluate the level of modified purine and pyrimidine bases. During the treatment with DNA repair enzymes, the lesions are converted into DNA SSB, which are subsequently revealed by gel electrophoresis. The substrates of Escherichia coli formamidopyrimidine DNA N-glycosylase (Fpg) are mostly modified purine bases including 8-oxo-7,8-dihydroguanine, 2,4-diamino-6-hydroxy-5-formamidopyrimidine and 4,6-diamino-5-formamidopyrimidine. By contrast, E. coli endonuclease III (Endo III) is more specific for oxidized pyrimidine bases such as thymine and cytosine glycols or 5-hydroxy-5-methylhydantoin. Cyclobutane thymine dimers (T<>T, Chart 3) are revealed by T4 Endonuclease V (Endo V) or Micrococcus luteus Endonuclease. Comet assay can also be used to assess cellular repair ability by investigating the removal of the comet scores when cells are incubated in the dark at 37°C after irradiation and then submitted to the electrophoresis process.

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Figure Chart 3..  Structure of DNA damages photosensitized by FQs.

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The results obtained using this technique (4–15) are summarized in Table 1. The comet assay has been performed with cells extracted from rodents submitted to oral administration of SPA (15), LOM, CLI and CIP (6) followed by UVA irradiation. For all compounds, an increase in the comet tail length has been observed in epidermal cells (6,15). Likewise, photogenotoxicity has also been detected in cells from retina and cornea of rodents treated with LOM, CLI and CIP (6).

Table 1.   DNA damage detected by comet assay.
FQComet assay
SSB, DSB, ALSOxidized pyrimidineT<>TOxidized purine
  1. +/− = uncertain results. Literature references are given between parentheses.

ENO+ (4)− (4) +/− (4)
CIP+ (5–8)   
FLE+ (8)   
LOM+ (4,6–12)+ (4)+ (10,12)+/− (4)
NOR+ (4,8)− (4) +/− (4)
OFL+ (4,7), − (5)− (4) +/− (4)
RUF+ (13,14)   
SPA+ (7,15)   
BAY+ (8,11)   
CLI+ (6)   

The in vitro version of comet assay can be performed with a large number of cell types; thus cultured cells like fibroblasts, keratinocytes, melanocytes, yeast Saccharomyces cerevisiae, or cells extracted from mouse lymphoma or hamster lung have been considered to assess FQ photogenotoxicity. The potential of SPA, LOM, FLE, CIP, BAY, NOR, RUF, ENO, OFL to photoinduce SSB, DSB and ALS has been experimentally demonstrated (4,5,7–14). Comet analysis associated with repair enzymes has revealed formation of Fpg-sensitive sites after irradiation in the presence of ENO, LOM, OFL and NOR; nevertheless, accurate quantitation of oxidized purines is difficult due to a high background level of SB in the absence of irradiation (4). In the case of oxidized pyrimidine bases, a significant amount of Endo III-sensitive sites has been obtained only for LOM (4). Formation of cyclobutane thymine dimers has been evidenced for LOM using enzymatic treatment (Endo V) (12) or immunochemical detection (10).

Concerning the repair ability of cells, a decrease in the comet score reflecting a removal of SB photosensitized by CIP and RUF has been observed upon incubation of irradiated samples in the dark (8,14).

Electrophoresis with isolated DNA

Supercoiled circular DNA is a useful model for the detection of alterations such as SBs or base damage. The principle relies on the fact that SBs induce a change in DNA structure (topology) that is detectable by agarose gel electrophoresis. It is a very sensitive technique, as only one SSB is enough to convert the supercoiled circular form (Form I) into the nicked relaxed form (Form II), while DSB lead to the formation of linear DNA (Form III). These three forms exhibit different electrophoretic mobilities, and thus they are easily separated by agarose gel electrophoresis. In addition to the detection of direct DNA SBs induced by reactive oxygen species (ROS), the technique also allows revealing DNA base damages when combined with specific DNA repair enzymes (Endo V, Endo III, Fpg, etc.).

Numerous FQs have been reported to induce SSB on plasmid DNA (7,11,14,16–32); the results are shown in Table 2. As a general trend, FQs with a fluorine at C-8 (LOM, FLE, ORB, BAY and SPA) show a higher potential as DNA cleaving agents, while methoxy substitution (MOX) tends to reduce this effect. Singlet oxygen has been proposed to be the main species involved in DNA cleavage as suggested by the use of quenchers like NaN3 or DABCO (18,19,22). Studies in the presence of mannitol, ethanol or ascorbic acid have shown the possible role of free radicals although to a lesser extent. In the case of LOM, OFL and BAY, more complete studies have revealed their potential to induce oxidative damages on purine and pyrimidine bases (11,27,29,30). Cyclobutane thymine dimer formation has been evidenced for ENO, PEF and NOR (24,28), whereas OFL and RUF appear to be unable to photosensitize this lesion (Fig. 1) (24,29).

Table 2.   DNA lesions observed onto plasmid DNA.
FQAgarose gel
SSBOxidized pyrimidineT<>TOxidized purine
  1. +/− = uncertain results. Literature references are given between parentheses.

ENO+ (16–23) + (24) 
CIP+ (7,16,17,22,23,25,26)   
FLE+ (16,17,20)   
LOM+ (11,16,17,20,22,23,25–27)+ (27) + (27)
NOR+ (16,17,20,23) + (24,28) 
OFL+ (7,16,17,22,23,29)+ (29,30)− (24,29)+ (29,30)
ORB+ (16,17)   
PEF+ (16,17) + (24) 
RUF+ (14,16,17) − (24) 
SPA+ (7,16,17,19,22,23,31,32)   
CLI+ (16,17)   
MOX+/− (26,30)+/− (30) +/− (30)
TOS+ (23)   
BAY+ (11,26,27)+ (11,27) + (11,27)
GAT− (23)   
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Figure 1.  DNA Form I (supercoiled native form) and Form II obtained from mixtures containing pBR322 and FQs after 15 min of irradiation and subsequent T4 Endo V treatment (adapted from Lhiaubet-Vallet et al. [24]).

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Electrophoresis with oligonucleotides

To gain further insight into the mechanism involved in DNA photosensitization by FQs, sequencing experiments have been performed on 32P-labeled oligonucleotides from human DNA c-Ha-ras-1 proto-oncogene and p53 tumor suppressor gene (33). With this technique, the cleavage pattern revealed after hot piperidine treatment of double strand DNA provides information about the photosensitization process. Detection of alkali-labile sites at 5′-G of a GG step, or selectively at consecutive G sites, is considered as the fingerprint of an electron transfer mechanism, while uniform cleavage at all the guanines reveals singlet oxygen-mediated damages (34). The pattern of DNA photodamage induced by LOM, FLE and CIP has been compared with that obtained in the presence of nalidixic acid, which shows the site-specific damage formation at consecutive guanines characteristic of an electron transfer mechanism. By contrast, the distribution obtained for LOM, FLE and CIP does not show any preference for neighboring guanines. On the basis of the obtained fragment pattern and on the effect of NaN3 addition or the use of deuterium oxide as solvent, it has been proposed that singlet oxygen is the primary reactive species in DNA-photosensitized oxidation by these three FQs (33).

Chromatographic analysis

Analytical detection of photosensitized DNA damages was performed by HPLC coupled with various types of detection (UV, electrochemical, fluorescence, MS/MS) (Table 3).

Table 3.   HPLC-detected lesions on DNA or isolated nucleosides.
 Cellular DNANaked DNAdGuo
8-oxodGuoOxidized pyrimidineT<>T8-oxodGuoOxidized pyrimidineT<>TdSpoxazolone
  1. +/− = uncertain results. Literature references are given between parentheses. *Too low to be measured by HPLC-MS/MS.

RUF+ (13)  + (39,40)  +++ (39,40)+ (39,40)
OFL+/− (4)  + (4,40)− (4)− (4)+++ (4,40)+ (4,40)
CIP+ (38)  + (26)    
MOX− (35)  +/− (26)    
BAY+ (35)  + (26)    
LOM+/− (4) + (36–38)(4)*+ (4)+ (4,26)+ (4)+ (4)+ (4)+++ (4)
ENO+/− (4)(4)*+ (4)+ (4)+ (4)+ (4)+ (4)+++ (4)
NOR  + (4)+ (4)− (4)+ (4)+++ (4)+ (4)

In these assays, formation of the dGuo oxidized form, namely 8-oxodGuo (Chart 3), has been largely investigated. This lesion, which can be generated by both Type I and Type II mechanisms, is used as a biomarker of oxidative damage. Thus, 8-oxodGuo has been detected in cellular DNA after irradiation in the presence of RUF, CIP, BAY and LOM (13,14,35–38). By contrast, only slight induction of OFL, ENO, LOM has been reported by Sauvaigo et al. (4).

Experiments performed on naked DNA have shown that RUF, OFL, CIP, BAY, LOM, ENO and NOR (4,26,39,40) photosensitize formation of this biomarker. For both cellular and naked DNA, the dihalogenated FQs, LOM and BAY have shown the highest oxidative potential; by contrast, the 6-methoxy derivative MOX induces very low levels of 8-oxodGuo (26,35). Thymine damage has also been considered by monitoring formation of oxidized products such as thymidine glycols (ThdGly), 5-formyl-2′-deoxyuridine (ForUrd) and 5-(hydroxymethyl)-2′-deoxyuridine (HMdUrd); the structures are shown in Chart 3. Products of this type have been detected for ENO and LOM (4). It is important to note that the amount of oxidized pyrimidines observed in the case of LOM has been related to its ability to act as a Type I photosensitizer. Finally, NOR, LOM and ENO have been reported to produce cis-syn cyclobutadithymine dimer formation (4).

As stated above, formation of 8-oxodGuo in the double helix can occur through photosensitization mechanisms involving free radicals, electron transfer and/or singlet oxygen. Thus, based only on DNA studies, it is difficult to evaluate the contribution of Type I and Type II pathways. To address this issue, a quantitative determination of the photoproducts formed from the free dGuo nucleoside is necessary. Guanine is the most susceptible DNA component to suffer a Type I photosensitization reaction (it exhibits the lowest oxidation potential among DNA bases) and is the only base that can be oxidized by a Type II process. The oxazolone derivative (2,2-diamino-4-[(2-deoxy-β-d-erythro-pentofuranosyl)amino]-2,5-dihydrooxazol-5-one, Chart 3) arises from transformation of the guanine radical cation initially generated by electron abstraction from dGuo; it is considered as a hallmark of Type I processes. On the other hand, the diastereoisomeric spiroiminodihydantoins (dSp Chart 3) are diagnostic for a singlet oxygen mechanism. Until a few years ago, the structure reported for this lesion was not correct; indeed, it was initially assigned as that of its structural isomers (4R)- and (4S)-4-hydroxy-8-oxo-4,8-dihydro-2′-deoxyguanosine (4-OH-8-oxodGuo). In this review, the results attributed to 4-OH-8-oxodGuo will be reported as corresponding to dSp. The relatively high ratio between the yields of dSp and oxazolone formation found for RUF, OFL and NOR (4,39,40) reveals the ability of these drugs to act as Type II photosensitizers. By contrast, LOM and ENO have been found to induce higher amounts of oxazolone, suggesting a predominance of Type I mechanisms (4).

Mechanisms of DNA damage photosensitized by fluoroquinolones

  1. Top of page
  2. Abstract
  3. Introduction
  4. Detection of DNA damage photosensitized by fluoroquinolones
  5. Mechanisms of DNA damage photosensitized by fluoroquinolones
  6. Summary and outlook
  7. Acknowledgments
  8. References

In the previous sections, it has been shown that UVA-irradiated FQs may induce DNA damage. The mechanism of cellular DNA damage by UVA depends on various factors such as the content and the chemical properties of photosensitizers, their location within cells and oxygen concentration (41). As stated above, the two main targets of DNA are thymine and guanine bases (4). The former has the lowest triplet energy level of the DNA bases, so it will be possible to observe formation of thymine cyclobutane dimers (T<>T) when an energy transfer process between the sensitizer excited state and thymine is favored (24). On the other hand, guanine has the lowest oxidation potential among the four DNA bases; hence, when an oxidative electron transfer process between the photosensitizer excited state and DNA takes place, it will mainly affect the guanine base (41). Formation of radical cationic intermediates in this way, leading to DNA damage, is classified as a Type I mechanism. By contrast, the direct interaction of a base with singlet oxygen belongs to a Type II mechanism. Charts 1 and 2 show the structures of FQs with known DNA photosensitizing properties (41). In fact, almost every FQ studied so far has been found to produce DNA damage in the presence of light (1,8,16,23,25,42). Nevertheless, specific mechanisms have been proposed to justify the results obtained for the different FQ antibiotics. For instance, oxidative DNA damage photosensitized by FQs may involve Type I and/or Type II mechanisms to a different extent. On the other hand, formation of T<>T is a more selective process and not all FQs are able to mediate this reaction (4,24,28).

For a satisfactory understanding of the processes that may cause base modifications upon interaction of DNA with excited FQs, it is necessary to know the photophysical and photochemical properties of the drug chromophore. Thus, FQs have a quinolone main ring with a fluorine atom at C-6 and a dialkylamino substituent at C-7 (see Scheme 1); the main structural differences can be associated with the nature of X at position 8, which can be a carbon atom supporting electron-donating or withdrawing substituents, as well as a nitrogen atom. In this context, when an FQ has a halogen atom attached at C-8 (see Chart 1), photodehalogenation is very efficient through direct halogen-aryl heterolysis. This ensues with the release of halide anions and formation of a reactive aryl cation (Scheme 1) (20,43–46). Photolysis of 6-fluoroderivatives can also produce a defluorination process, but in this case the photodegradation mechanism involves nucleophilic photosubstitution by hydroxide anion (47). Typical examples are ENO, NOR and CIP (48,49). The presence of electron-donating substituents at C-8 increases the photostability of 6-fluoroquinolones; thus photodehalogenation has not been observed for OFL, RUF and MOX (Chart 2) (30,39,40,50).

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Figure Scheme 1..  Photodehalogenation pathways of fluoroquinolones.

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Photosensitized damage to DNA mediated by LOM has been attributed to oxidation of nucleobases (mainly guanine) by a Type I mechanism. Thus, the aryl cation arising from photodefluorination of LOM would be involved in the modification of DNA substructures located in the close vicinity (20). It has also been observed that the contribution of the Type I mechanism in the LOM photosensitization of dGuo is higher than that of Type II. Generation of radical intermediates followed by reaction with oxygen justifies oxazolone production from dGuo nucleoside or formation of 8-oxodGuo in studies performed with whole DNA (Scheme 2) (4,26).

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Figure Scheme 2..  Major mechanisms of UV-induced DNA and dGuo damage in the presence of FQs.

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Nevertheless, it has been observed that formation of SSB in plasmid DNA upon irradiation in the presence of LOM and FLE does not require oxygen (20). Other studies have shown that LOM is able to photosensitize formation of T<>T cyclobutane dimers in cellular and isolated DNA (4,12). These results were attributed to energy transfer from LOM triplet excited state to the thymine bases; however, LOM photodegradation is not affected by the presence of DNA (51), which would be against the energy transfer process. In this context, a series of FQs have been investigated to understand photosensitized formation of thymine dimers with FQs whose triplet energy levels are between 280 and 260 kJ mol−1, clearly lower than that determined for thymine and thymidine 5′-monophosphate (310 kJ mol−1) (24,28). At FQ concentrations and light doses insufficient to produce direct SSB, ENO, PEF and NOR are able to produce T<>T dimers in DNA (revealed by treatment with the selective repair enzyme T4 endonuclease V). By contrast, other FQs as OFL, RUF and the N(4′)-acetyl derivative of NOR (ANOR) are inefficient in this assay. The triplet energy values (ET) of FQs have been found to be the major factor determining this behavior. Thus, the ET values of FQs were estimated by means of laser flash photolysis using different energy acceptors, a methodology that allows energy determination with low error (<1%). In this way, triplet state energies of ENO, PEF, NOR, ANOR, OFL and RUF have been established as 273, 269, 269, 265, 262 and 253 kJ mol−1, respectively. Hence, the ET threshold required for a compound to become a potential photosensitizer via T<>T formation is in the range defined between the triplet energies of NOR and ANOR (namely 265–269 kJ mol−1, see T-T absorptions and triplet levels in Fig. 2) (24,28). These results can explain the important DNA strand-breaking activity exhibited by ENO after revealing with Endo V. However, the involvement of Type I and Type II mechanisms in the photosensitization of DNA by this FQ has also been observed (4).

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Figure 2.  Transient absorption spectra of NOR and ANOR triplet excited state in N2O-purged aqueous solutions (left). Triplet energy of some FQs and the threshold value to mediate the formation of T<>T in DNA (right) (adapted from Lhiaubet-Vallet et al. [24]).

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A limited number of studies have evaluated the contribution of all the possible mechanisms of UV-induced DNA damage photosensitized by FQs. Type I, Type II and triplet energy transfer pathways have been analyzed in parallel (under the same conditions) for LOM, ENO, NOR and OFL using dGuo as well as cellular and isolated DNA, as targets. The most interesting results are shown in Fig. 3. Accordingly, OFL and NOR would act mainly via a Type II mechanism, whereas LOM and ENO would behave rather as Type I photosensitizers. The extent of oxidative damage has been found to be relatively low; by contrast, T<>T dimers represent the major class of damage in isolated and cellular DNA upon UVA irradiation in the presence of ENO, LOM and NOR. As expected, the levels of T<>T dimers and the formation rate of 8-oxodGuo in DNA depend on the employed FQ (4). However, the resulting lesions in isolated and cellular DNA cannot be completely correlated. This has been attributed to the different binding affinity of FQs to isolated DNA, which is higher for ENO than for LOM (51). In agreement with the above results, variations in the photodynamic DNA strand-breaking activity by ENO, CIP and OFL in the presence of various scavengers of ROS such as calatase for H2O2, or NaN3 and DABCO for 1O2, confirm that singlet oxygen plays an important role in this type of damage (22). This has been confirmed by mechanistic studies on the photosensitized oxidation of dGuo and DNA by OFL and RUF, further supporting the relevance of the Type II process (39,40). Formation of 8-oxodGuo by irradiation of OFL and RUF in the presence of DNA is more efficient for the latter FQ, in agreement with the detection of higher amounts of products in the RUF photosensitized oxidation of dGuo. Using oxazolone and dSp as fingerprints of Type I and Type II mechanisms, respectively, relative Type II/Type I ratios of 10 (OFL) and 18 (RUF) have been determined. As a representative example, Scheme 3 shows the most relevant processes occurring after excitation of RUF in aerated solutions, in the presence of DNA, dGuo or Thd. Molecular oxygen and dGuo compete for quenching of RUF triplet; also the fact that the respective rate constants (k5 and k10) differ by 2 orders of magnitude justifies the predominance of Type II process (39). The quenching rate constant of OFL triplet excited state by dGuo and DNA has been found to be 3 × 108 and 1 × 108 m−1 s−1, respectively. The lower contribution of Type II guanine oxidation for OFL can be explained by a decrease in the triplet energy when sulfur instead of oxygen is attached to position C-8 of the FQ ring system. As a consequence, phosphate anions are able to quench the FQ triplet but not the RUF triplet; this reveals that the reaction medium may have a strong influence on the photochemistry of OFL and hence on its photobiological properties (40).

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Figure 3.  FQs photosensitized induction of T<>T and 8-oxodGuo in isolated and cellular DNA (adapted from Sauvaigo et al. [4]).

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Figure Scheme 3..  Processes occurring after excitation of aerated solutions of RUF in the presence of DNA, dGuo or Thd (adapted from Belvedere et al. [39]).

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Summary and outlook

  1. Top of page
  2. Abstract
  3. Introduction
  4. Detection of DNA damage photosensitized by fluoroquinolones
  5. Mechanisms of DNA damage photosensitized by fluoroquinolones
  6. Summary and outlook
  7. Acknowledgments
  8. References

The main transient species generated upon photoexcitation of FQs are the triplet state and (in the case of the dihalogenated derivatives) the aryl cations. Both short-lived intermediates may be involved in DNA damage, either through oxygen-dependent or oxygen-independent processes. Photosensitized DNA oxidation is a rather general observation; it occurs mainly at the guanine base and proceeds by Type I or Type II pathways. Conversely, thymine dimer formation is the result of triplet–triplet energy transfer; it is more selective and requires a relatively high triplet level. Finally, it has been suggested that aryl cations may modify DNA bases via alkylation; however, this possibility still remains to be checked and constitutes an interesting field for further investigations.

Acknowledgments

  1. Top of page
  2. Abstract
  3. Introduction
  4. Detection of DNA damage photosensitized by fluoroquinolones
  5. Mechanisms of DNA damage photosensitized by fluoroquinolones
  6. Summary and outlook
  7. Acknowledgments
  8. References

Acknowledgements— Financial support by the Spanish Government (Red RETICS de Investigación de Reacciones Adversas a Alergenos y Fármacos – RIRAAF and Ramón y Cajal contract to Dr. Virginie Lhiaubet-Vallet) and by the Generalitat Valenciana (Prometeo program) are gratefully acknowledged.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Detection of DNA damage photosensitized by fluoroquinolones
  5. Mechanisms of DNA damage photosensitized by fluoroquinolones
  6. Summary and outlook
  7. Acknowledgments
  8. References
  • 1
    Mäkinen, M., P. D. Forbes and F. Stenbäck (1997) Quinolone antibacterials: A new class of photochemical carcinogens. J. Photochem. Photobiol. B, Biol. 37, 182187.
  • 2
    Klecak, G., F. Urbach and H. Urwyler (1997) Fluoroquinolone antibacterials enhance UVA-induced skin tumors. J. Photochem. Photobiol. B, Biol. 37, 174181.
  • 3
    Johnson, B. E., N. K. Gibbs and J. Ferguson (1997) Quinolone antibiotic with potential to photosensitize skin tumorigenesis. J. Photochem. Photobiol. B, Biol. 37, 171173.
  • 4
    Sauvaigo, S., T. Douki, F. Odin, S. Caillat, J. L. Ravanat and J. Cadet (2001) Analysis of fluoroquinolone-mediated photosensitization of 2′-deoxyguanosine, calf thymus and cellular DNA: Determination of Type-I, Type-II and triplet–triplet energy transfer mechanism contribution. Photochem. Photobiol. 73, 230237.
  • 5
    Sanchez, G., M. E. Hidalgo, J. M. Vivanco and J. Escobar (2005) Induced and photoinduced DNA damage by quinolones: Ciprofloxacin, ofloxacin and nalidixic acid determined by comet assay. Photochem. Photobiol. 81, 819822.
  • 6
    Wirnitzer, U., N. Gross-Tholl, B. Herbold and E. Von Keutz (2006) Photo-chemically induced DNA effects in the comet assay with epidermal cells of SKH-1 mice after a single oral administration of different fluoroquinolones and 8-methoxypsoralen in combination with exposure to UVA. Mutat. Res. 609, 110.
  • 7
    Zhang, T., J. L. Li, J. Xin, X. C. Ma and Z. H. Tu (2004) Compare two methods of measuring DNA damage induced by photogenotoxicity of fluoroquinolones. Acta Pharmacol. Sin. 25, 171175.
  • 8
    Reavy, H. J., N. J. Traynor and N. K. Gibbs (1997) Photogenotoxicity of skin phototumorigenic fluoroquinolone antibiotics detected using the comet assay. Photochem. Photobiol. 66, 368373.
  • 9
    Struwe, M., K. O. Greulich, W. Suter and U. Plappert-Helbig (2007) The photo comet assay—A fast screening assay for the determination of photogenotoxicity in vitro. Mutat. Res. 632, 4457.
  • 10
    Marrot, L., J. P. Belaidi, C. Jones, P. Perez, L. Riou, A. Sarasin and J. R. Meunier (2003) Molecular responses to photogenotoxic stress induced by the antibiotic lomefloxacin in human skin cells: From DNA damage to apoptosis. J. Invest. Dermatol. 121, 596606.
  • 11
    Marrot, L., J. P. Belaidi, C. Chaubo, J. R. Meunier, P. Perez and C. Agapakis-Causse (2001) Fluoroquinolones as chemical tools to define a strategy for photogenotoxicity in vitro assessment. Toxicol. In Vitro 15, 131142.
  • 12
    Traynor, N. J. and N. K. Gibbs (1999) The phototumorigenic fluoroquinolone lomefloxacin photosensitizes pyrimidine dimer formation in human keratinocytes in vitro. Photochem. Photobiol. 70, 957959.
  • 13
    Catalfo, A., M. L. Calandra, M. Renis, M. E. Serrentino and G. De Guidi (2007) Rufloxacin-induced photosensitization in yeast. Photochem. Photobiol. Sci. 6, 181189.
  • 14
    Catalfo, A., C. Scifo, S. Stella, A. Belvedere, M. Renis and G. De Guidi (2005) Rufloxacin induced photosensitization in bio-models of increasing complexity. Photochem. Photobiol. Sci. 4, 304314.
  • 15
    Struwe, M., K. O. Greulich, U. Junker, C. Jean, D. Zimmer, W. Suter and U. Plappert-Helbig (2008) Detection of photogenotoxicity in skin and eye in rat with the photo comet assay. Photochem. Photobiol. Sci. 7, 240249.
  • 16
    Condorelli, G., G. De Guidi, S. Giuffrida, P. Miano, S. Sortino and A. Velardita (1996) Membrane and DNA damage photosensitized by fluoroquinolone antimicrobials agents: A comparative screening. Med. Biol. Environ. 24, 103110.
  • 17
    De Guidi, G., S. Giuffrida, S. Monti, P. S. Pisu, S. Sortino and L. L. Costanzo (1999) Molecular mechanisms of photosensitization induced by drugs XIV: Two different behaviours in the photochemistry and photosensitization of antibacterials containing a fluoroquinolone like chromophore. Int. J. Photoenergy 1, 16.
  • 18
    Iwamoto, Y., T. Itoyama, K. Yasuda, T. Uzuhashi, H. Tanizawa, Y. Takino, T. Oku, H. Hashizume and Y. Yanagihara (1992) Photodynamic deoxyribonucleic acid (DNA) strand breaking activities of enoxacin and afloqualone. Chem. Pharm. Bull. 40, 18681870.
  • 19
    Iwamoto, Y., A. Kurita, T. Shimizu, T. Masuzawa, K. Uno, M. Yagi, T. Kitagawa, T. Oku and Y. Yanagihara (1994) DNA strand-breaking activities of quinolone antimicrobial agents under visible-light irradiation. Biol. Pharm. Bull. 17, 654657.
  • 20
    Martinez, L. and C. F. Chignell (1998) Photocleavage of DNA by the fluoroquinolone antibacterials. J. Photochem. Photobiol. B, Biol. 45, 5159.
  • 21
    Sortino, S., G. Condorelli, G. De Guidi and S. Giuffrida (1998) Molecular mechanism of photosensitization—XI. Membrane damage and DNA cleavage photoinduced by enoxacin. Photochem. Photobiol. 68, 652659.
  • 22
    Umezawa, N., K. Arakane, A. Ryu, S. Mashiko, M. Hirobe and T. Nagano (1997) Participation of reactive oxygen species in phototoxicity induced by quinolone antibacterial agents. Arch. Biochem. Biophys. 342, 275281.
  • 23
    Yamamoto, T., Y. Tsurumaki, M. Takei, M. Hosaka and Y. Oomori (2001) In vitro method for prediction of the phototoxic potentials of fluoroquinolones. Toxicol. In Vitro 15, 721727.
  • 24
    Lhiaubet-Vallet, V., M. C. Cuquerella, J. V. Castell, F. Bosca and M. A. Miranda (2007) Triplet excited fluoroquinolones as mediators for thymine cyclobutane dimer formation in DNA. J. Phys. Chem. B 111, 74097414.
  • 25
    Miolo, G., G. Viola, D. Vedaldi, F. Dall’Acqua, A. Fravolini, O. Tabarrini and V. Cecchetti (2002) In vitro phototoxic properties of new 6-desfluoro and 6-fluoro-8-methylquinolones. Toxicol. In Vitro 16, 683693.
  • 26
    Spratt, T. E., S. S. Schultz, D. E. Levy, D. Chen, G. Schluter and G. M. Williams (1999) Different mechanisms for the photoinduced production of oxidative DNA damage by fluoroquinolones differing in photostability. Chem. Res. Toxicol. 12, 809815.
  • 27
    Marrot, L. and C. Agapakis-Causse (2000) Differences in the photogenotoxic potential of two fluoroquinolones as shown in diploid yeast strain (Saccharomyces cerevisiae) and supercoiled plasmid DNA. Mutat. Res. 468, 19.
  • 28
    Bosca, F., V. Lhiaubet-Vallet, M. C. Cuquerella, J. V. Castell and M. A. Miranda (2006) The triplet energy of thymine in DNA. J. Am. Chem. Soc. 128, 63186319.
  • 29
    Lhiaubet-Vallet, V., Z. Sarabia, D. Hernandez, J. V. Castell and M. A. Miranda (2003) In vitro studies on DNA-photo sensitization by different drug stereoisomers. Toxicol. In Vitro 17, 651656.
  • 30
    Viola, G., L. Facciolo, M. Canton, D. Vedaldi, F. Dall’Acqua, G. G. Aloisi, M. Amelia, A. Barbafina, F. Elisei and L. Latterini (2004) Photophysical and phototoxic properties of the antibacterial fluoroquinolones levofloxacin and moxifloxacin. Chem. Biodivers. 1, 782801.
  • 31
    Sayama, K., Y. Kobayashi, H. Fujita, A. Ito, Y. Tokura and M. Sasaki (2005) Determination of action spectrum for sparfloxacin-photosensitized single-strand breaks in plasmid pBR322 DNA. Photodermatol. Photoimmunol. Photomed. 21, 287292.
  • 32
    Sayama, K., K. Ishikawa, R. Yamada, H. Fujita, A. Ito and M. Sasaki (2002) In vitro evaluation of preventive ability of commercial sunscreens against induction of photosensitivity with sparfloxacin. Photomed. Photobiol. 24, 4346.
  • 33
    Hiraku, Y. and S. Kawanishi (2000) Distinct mechanisms of guanine-specific DNA photodamage induced by nalidixic acid and fluoroquinolone antibacterials. Arch. Biochem. Biophys. 382, 211218.
  • 34
    Saito, I., T. Nakamura, K. Nakatani, Y. Yoshioka, K. Yamaguchi and H. Sugiyama (1998) Mapping of the hot spots for DNA damage by one-electron oxidation: Efficacy of GG doublets and GGG triplets as a trap in long-range hole migration. J. Am. Chem. Soc. 120, 1268612687.
  • 35
    Rosen, J. E., D. Chen, A. K. Prahalad, T. E. Spratt, G. Schluter and G. M. Williams (1997) A fluoroquinolone antibiotic with a methoxy group at the 8 position yields reduced generation of 8-oxo-7,8-dihydro-2′-deoxyguanosine after ultraviolet-A irradiation. Toxicol. Appl. Pharmacol. 145, 381387.
  • 36
    Verna, L. K., D. Chen, G. Schluter and G. M. Williams (1998) Inhibition by singlet oxygen quenchers of oxidative damage to DNA produced in cultured cells by exposure to a quinolone antibiotic and ultraviolet A irradiation. Cell Biol. Toxicol. 14, 237242.
  • 37
    Rosen, J. E. (1997) Proposed mechanism for the photodynamic generation of 8-oxo-7,8-dihydro-2′-deoxyguanosine produced in cultured cells by exposure to lomefloxacin. Mutat. Res. 381, 117129.
  • 38
    Rosen, J. E., A. K. Prahalad, G. Schluter, D. Chen and G. M. Williams (1997) Quinolone antibiotic photodynamic production of 8-oxo-7,8-dihydro-2′-deoxyguanosine in cultured liver epithelial cells. Photochem. Photobiol. 65, 990996.
  • 39
    Belvedere, A., F. Bosca, A. Catalfo, M. C. Cuquerella, G. De Guidi and M. A. Miranda (2002) Type II guanine oxidation photoinduced by the antibacterial fluoroquinolone rufloxacin in isolated DNA and in 2′-deoxyguanosine. Chem. Res. Toxicol. 15, 11421149.
  • 40
    Cuquerella, M. C., F. Bosca, M. A. Miranda, A. Belvedere, A. Catalfo and G. De Guidi (2003) Photochemical properties of ofloxacin involved in oxidative DNA damage: A comparison with rufloxacin. Chem. Res. Toxicol. 16, 562570.
  • 41
    Hiraku, Y., K. Ito, K. Hirakawa and S. Kawanishi (2007) Photosensitized DNA damage and its protection via a novel mechanism. Photochem. Photobiol. 83, 205212.
  • 42
    Jeffrey, A. M., L. Shao, S. Y. Brendler-Schwaab, G. Schluter and G. M. Williams (2000) Photochemical mutagenicity of phototoxic and photochemically carcinogenic fluoroquinolones in comparison with the photostable moxifloxacin. Arch. Toxicol. 74, 555559.
  • 43
    Martinez, L. J., G. Li and C. F. Chignell (1997) Photogeneration of fluoride by the fluoroquinolone antimicrobial agents lomefloxacin and fleroxacin. Photochem. Photobiol. 65, 599602.
  • 44
    Cuquerella, M. C., M. A. Miranda and F. Bosca (2006) Generation of detectable singlet aryl cations by photodehalogenation of fluoroquinolones. J. Phys. Chem. B 110, 64416443.
  • 45
    Lovdahl, M. J. and R. S. Priebe (2000) Characterization of clinafloxacin photodegradation products by LC-MS/MS and NMR. J. Pharm. Biomed. 23, 521534.
  • 46
    Morimura, T., K. Kohno, Y. Nobuhara and H. Matsukura (1997) Photoreaction and active oxygen generation by photosensitization of a new antibacterial fluoroquinolone derivative, orbifloxacin, in the presence of chloride ion. Chem. Pharm. Bull. 45, 18281832.
  • 47
    Cuquerella, M. C., F. Bosca and M. A. Miranda (2004) Photonucleophilic aromatic substitution of 6-fluoroquinolones in basic media: Triplet quenching by hydroxide anion. J. Org. Chem. 69, 72567261.
  • 48
    Fasani, E., F. F. Barberis Negra, M. Mella, S. Monti and A. Albini (1999) Photoinduced C-F bond cleavage in some fluorinated 7-amino-4-quinolone-3-carboxylic acids. J. Org. Chem. 64, 53885395.
  • 49
    Albini, A. and S. Monti (2003) Photophysics and photochemistry of fluoroquinolones. Chem. Soc. Rev. 32, 238250.
  • 50
    Lorenzo, F., S. Navaratnam, R. Edge and N. S. Allen (2008) Primary photophysical properties of moxifloxacin—A fluoroquinolone antibiotic. Photochem. Photobiol. 84, 11181125.
  • 51
    Sortino, S. and G. Condorelli (2002) Complexes between fluoroquinolones and calf thymus DNA: Binding mode and photochemical reactivity. New J. Chem. 26, 250258.