Drug-Photosensitized Protein Modification:  Identification of the Reactive Sites and Elucidation of the Reaction Mechanisms with Tiaprofenic Acid/Albumin as Model System

Miranda, Miguel A.; Castell, José V.; Hernández, Daniel E.; Gómez-Lechón, Marı́a José; Boscá, Francisco; Morera, Isabel M.; Sarabia, Zaideth

doi:10.1021/tx970082d

Cited by 48 publications

(37 citation statements)

References 21 publications

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“…Tryptophan solutions (100 µM) were irradiated in the presence of the test compounds and analysed as described for BSA. Histidine solutions were irradiated for various time intervals and the resulting samples were analysed for His content as described by Figureido et al 28 Tyrosine solutions (1 mM) were also irradiated in PBS and the resulting samples were analysed for Tyr content as described 29 . Analogous experiments were performed by bubbling with nitrogen before and during the irradiation and also using deuterated phosphate buffer.…”

Section: Methodsmentioning

confidence: 99%

Photoinduced modifications by fluoroquinolone drugs in bovine serum albumin (BSA) and ribonuclease A (RNAse) as model proteins

Dall’Acqua¹,

Viola²,

Vedaldi³

et al. 2007

Arkivoc

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Photosensitized protein oxidation by drugs, with the consequent modification of their structure is thought to be responsible for the occurrence of phototoxic phenomena such as photoallergy and loss of biological functions. In this paper we have investigated in detail the interaction of four fluoroquinolones namely ciprofloxacin, lomefloxacin, norfloxacin and ofloxacin with two proteins such as Bovine Serum Albumin (BSA) and Ribonuclease A (RNAse A) chosen as models. The interactions between the four drugs and the proteins, were studied by absorption and emission spectroscopy. Photophysical experiments were carried out in aqueous solutions by stationary and time-resolved fluorimetry and by laser flash photolysis, in the absence and in the presence of the proteins to obtain information on the various decay pathways of the excited states of the drugs and on transient species formed upon irradiation. In parallel we have investigated by a series of biochemical assays the photoinduced modifications exerted by the four drugs. The obtained results showed that the four drugs are able to photooxidize proteins with the formation of protein-protein cross-link. This effect was also confirmed in isolated erythrocyte membranes. Furthermore the effect of the fluoroquinolones was also evaluated on isolated aromatic aminoacids. In this context the four drugs are able to photodamage in particular tyrosine and histidine. These results are important in the light of the growing interest for the comprehension of the mechanism of phototoxicity induced by these antibacterial drugs.

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Section: Methodsmentioning

confidence: 99%

Photoinduced modifications by fluoroquinolone drugs in bovine serum albumin (BSA) and ribonuclease A (RNAse) as model proteins

Dall’Acqua¹,

Viola²,

Vedaldi³

et al. 2007

Arkivoc

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“…The resulting photoantigen may trigger a hypersensitivity reaction of the immune system. Besides, the photosensitized modifications of proteins may also produce extensive structural changes associated with loss of biological function [17]. Hence, a precise knowledge of the involved active sites and reaction mechanisms is required to understand the phototosensitizing potential of a given drug.…”

Section: Photosensitized Reactions Of Proteinsmentioning

confidence: 99%

“…In this context, the changes taking place upon irradiation of purified bovine serum albumin (BSA) in the presence of TPA have been thoroughly investigated as a model system for drug-photosensitized protein modifications [17]. Acid hydrolysis of the photolysates followed by amino acid analysis shows a dramatic decrease of His and Tyr with respect to nonirradiated controls.…”

Section: Photosensitized Reactions Of Proteinsmentioning

confidence: 99%

Photosensitization by drugs

Miranda

2001

Pure and Applied Chemistry

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Certain drugs are known to elicit photosensitivity side effects. A satisfactory understanding of the involved mechanistic aspects is necessary to anticipate the photosensitizing potential. We have used tiaprofenic acid (TPA), a photosensitizing nonsteroidal antiinflammatory drug, to illustrate the methodology followed to address this problem. After studying the photophysical and photochemical properties of TPA, the attention has been directed towards the reactivity of its lowest lying π−π* triplet with biomolecules. Photosensitized lipid peroxidation occurs by a mixed type I (radicals) and type II (singlet oxygen) mechanism. In the case of proteins, the photosensitized reactions include Tyr, Trp, and His photodegradation, protein-protein photocrosslinking and drug-protein photobinding. This involves direct quenching of the drug triplet by the amino acid residues (Tyr and Trp) or by oxygen, followed by singlet oxygen oxidation (His and Trp). With DNA, the studies have included comet assay, induction of single-strand breaks in supercoiled DNA, and reaction with 2'-deoxyguanosine and thymidine. Product studies, together with time-resolved measurements, have shown that the fastest reaction occurs with purine bases, by a mechanism involving both radical and singlet oxygen processes. The employed methodology can be of general use to investigate the mechanistic aspects of photosensitization by drugs. PHOTOSENSITIVITY SIDE EFFECTSThe combined action of drugs and sunlight on patients can produce both desired and undesired effects [1]. Thus, PUVA-therapy (psoralenes plus UVA-radiation) has long been employed for the treatment of psoriasis, while porphyrins are currently being introduced for the photodynamic therapy (PDT) of cancer or other diseases. By contrast, there is also a significant number of reports indicating that a variety of drugs can elicit undesired side effects, such as phototoxicity, photoallergy, or photocarcinogenicity [2,3].The photobiological risk associated with the use of drugs depends on environmental and individual factors (climate, height on the sea level, type of skin, etc.). On the other hand, the photosensitizing potential is enhanced in the case of topically administered drugs or when the field of application is dermatology or ophthalmology. Considering all these factors, in a number of cases it may be advisable to evaluate the photobiological risk of a new drug candidate before its introduction in the market [3]. The mechanistic approach to risk predictionIn order to anticipate the appearance of photosensitivity side effects, a mechanistic understanding of the involved phenomena is necessary. Absorption of sunlight by drugs leads to their excited states. These can proceed further to afford drug-derived reactive intermediates or, under aerobic conditions, reactive oxygen species. Any of the above short-lived chemical entities may be able to interact with biological *Lecture presented at the

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“…Soc. 1072 biomolecules [18][19][20][21] and, for the DNA case, this process can be responsible for photogenotoxicity. [22][23][24][25] Of special importance is the effect of triplet carbonyl compounds on the photoxidative process of tyrosine and tryptophan, nucleic acid constituents containing a phenol or an indole group, respectively, since this type of reaction can result in high photoallergic activity when several drugs containing the carbonyl group are employed.…”

Section: Introductionmentioning

confidence: 99%

“…17 This photosensitization process involves direct interaction between the triplet excited state of the sensitizer (the triplet carbonyl) and the biological substrate through the formation of an encounter complex. This species leads to an electron transfer reaction followed by a proton transfer, resulting in the formation of the corresponding radical pair sensitizer/ biological substrate with the consequent damage of several biomolecules [18][19][20][21] and, for the DNA case, this process can be responsible for photogenotoxicity. [22][23][24][25] Of special importance is the effect of triplet carbonyl compounds on the photoxidative process of tyrosine and tryptophan, nucleic acid constituents containing a phenol or an indole group, respectively, since this type of reaction can result in high photoallergic activity when several drugs containing the carbonyl group are employed.…”

Section: Introductionmentioning

confidence: 99%

Phenolic hydrogen abstraction by the triplet excited state of thiochromanone: a laser flash photolysis study

Ribeiro¹,

Bertoti²,

Netto‐Ferreira³

2010

J. Braz. Chem. Soc.

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O estado excitado triplete de cetonas pode oxidar substratos biológicos acarretando danos a diversas biomoléculas como aminoácidos, nucleosídeos e mesmo DNA. Como parte de nossos estudos acerca da interação entre carbonilas e fenóis, foi investigada a reatividade do estado excitado triplete de tiocromanona (1) frente a fenóis, em acetonitrila, empregando a técnica de fotólise por pulso de laser de nanossegundo. As constantes de velocidade de supressão obtidas variaram de (1,1 ± 0,1) × 10 8 L mol -1 s -1 (4-cianofenol) a (5,8 ± 1,0) × 10 9 L mol -1 s -1 (hidroquinona). Um gráfico de Hammett para a reação do triplete de 1 com uma série de fenóis contendo substituintes polares resultou em uma constante de reação r = -0,90. Este valor negativo para a constante de reação r está plenamente de acordo com um mecanismo envolvendo uma transferência acoplada elétron/ próton no processo de transferência de hidrogênio do fenol para a carbonila triplete.Triplet ketones are known to oxidize biological substrates which can lead to damage of several biomolecules such as amino acids, nucleosides and DNA. As part of our systematic study on the interaction between carbonyl compounds and phenols, the triplet reactivity of thiochromanone (1) towards substituted phenols, in acetonitrile, was investigated employing the laser flash photolysis technique. The quenching rate constants ranged from (1.1 ± 0.1) × 10 8 L mol -1 s -1 (4-cyanophenol) to (5.8 ± 1.0) × 10 9 L mol -1 s -1 (hydroquinone). A Hammett plot for the reaction of triplet 1 with phenols containing polar substituents resulted in a reaction constant r = -0.90. This negative value observed for the reaction constant r is in accord with a mechanism in which the hydrogen transfer from phenols to the triplet carbonyl involves a coupled electron/proton transfer.Keywords: thiochromanone, laser flash photolysis, triplet excited state, hydrogen donors IntroductionIn the last few years the phenolic hydrogen abstraction by carbonyl compounds in the triplet excited state has been extensively studied employing experimental and theoretical methods. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] The mechanism for this process is now well established and involves the initial formation of a hydrogen-bonded exciplex in the triplet excited state, followed by electron transfer and, subsequently, an ultrafast proton transfer. 4,9-16 DFT calculations clearly showed that for the triplet complex (exciplex) ketone-phenol the hydrogen transfer is predominantly occurring. 8 The very fast quenching rate constants of triplet carbonyls towards phenols is consequence of both the low reduction potential of the former as well as the low oxidation potential of the later. 4,16 Experimentally, this coupled electron/proton transfer mechanism ultimately results in the formation of the ketyl-aryloxyl radical pair.Triplet ketones are known to oxidize biological substrates such as amino acids, nucleosides and DNA. Due to this, topical or systemic administration of drugs containing the carbonyl chromophore c...

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Drug-Photosensitized Protein Modification: Identification of the Reactive Sites and Elucidation of the Reaction Mechanisms with Tiaprofenic Acid/Albumin as Model System

Cited by 48 publications

References 21 publications

Photoinduced modifications by fluoroquinolone drugs in bovine serum albumin (BSA) and ribonuclease A (RNAse) as model proteins

Photoinduced modifications by fluoroquinolone drugs in bovine serum albumin (BSA) and ribonuclease A (RNAse) as model proteins

Photosensitization by drugs

Phenolic hydrogen abstraction by the triplet excited state of thiochromanone: a laser flash photolysis study

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