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Thomas AH, Catalá Á, Vignoni M. Soybean phosphatidylcholine liposomes as model membranes to study lipid peroxidation photoinduced by pterin. BIOCHIMICA ET BIOPHYSICA ACTA 2016; 1858:139-45. [PMID: 26551322 DOI: 10.1016/j.bbamem.2015.11.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 10/15/2015] [Accepted: 11/05/2015] [Indexed: 11/16/2022]
Abstract
Oxidized pterins, efficient photosensitizers under UVA irradiation, accumulate in the skin of patients suffering from vitiligo, a chronic depigmentation disorder. Soybean phosphatidylcholine (SoyPC) liposomes were employed as model membranes to investigate if pterin (Ptr), the parent compound of oxidized pterins, is able to photoinduced lipid peroxidation. Size exclusion chromatography and dialysis experiments showed that Ptr is not encapsulated inside the liposomes and the lipid membrane is permeable to this compound. The formation of conjugated dienes and trienes, upon UVA irradiation, was followed by absorption at 234 and 270 nm, respectively. The photoproducts were characterized by mass spectrometry and oxygenation of SoyPC was demonstrated. In addition, analysis of MS/MS spectra suggested the formation hydroperoxides. Finally, the biological implications of the findings are discussed.
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Affiliation(s)
- Andrés H Thomas
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, Casilla de Correo 16, Sucursal 4, (1900) La Plata, Argentina
| | - Ángel Catalá
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, Casilla de Correo 16, Sucursal 4, (1900) La Plata, Argentina
| | - Mariana Vignoni
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, Casilla de Correo 16, Sucursal 4, (1900) La Plata, Argentina.
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Histidine oxidation photosensitized by pterin: pH dependent mechanism. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2015; 153:483-9. [DOI: 10.1016/j.jphotobiol.2015.10.026] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2015] [Revised: 09/28/2015] [Accepted: 10/11/2015] [Indexed: 11/20/2022]
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53
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Laura Dántola M, Zurbano BN, Thomas AH. Photoinactivation of tyrosinase sensitized by folic acid photoproducts. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2015; 149:172-9. [DOI: 10.1016/j.jphotobiol.2015.06.002] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2015] [Revised: 05/11/2015] [Accepted: 06/03/2015] [Indexed: 02/08/2023]
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54
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Serrano MP, Lorente C, Borsarelli CD, Thomas AH. Unraveling the Degradation Mechanism of Purine Nucleotides Photosensitized by Pterins: The Role of Charge-Transfer Steps. Chemphyschem 2015; 16:2244-52. [PMID: 26017933 DOI: 10.1002/cphc.201500219] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Indexed: 11/09/2022]
Abstract
Photosensitized reactions contribute to the development of skin cancer and are used in many applications. Photosensitizers can act through different mechanisms. It is currently accepted that if the photosensitizer generates singlet molecular oxygen ((1) O2 ) upon irradiation, the target molecule can undergo oxidation by this reactive oxygen species and the reaction needs dissolved O2 to proceed, therefore the reaction is classified as (1) O2 -mediated oxidation (type II mechanism). However, this assumption is not always correct, and as an example, a study on the degradation of 2'-deoxyguanosine 5'-monophosphate photosensitized by pterin is presented. A general mechanism is proposed to explain how the degradation of biological targets, such as nucleotides, photosensitized by pterins, naturally occurring (1) O2 photosensitizers, takes place through an electron-transfer-initiated process (type I mechanism), whereas the contribution of the (1) O2 -mediated oxidation is almost negligible.
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Affiliation(s)
- Mariana P Serrano
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, Casilla de Correo 16, Sucursal 4, (1900) La Plata (Argentina)
| | - Carolina Lorente
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, Casilla de Correo 16, Sucursal 4, (1900) La Plata (Argentina)
| | - Claudio D Borsarelli
- Laboratorio de Cinética y Fotoquímica (LACIFO), Centro de Investigaciones y Transferencia de Santiago del Estero (CITSE-CONICET) Universidad Nacional de Santiago del Estero (UNSE), Casilla de Correo 23, Bs. As. 252, G4200AQF, Santiago del Estero (Argentina)
| | - Andrés H Thomas
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, Casilla de Correo 16, Sucursal 4, (1900) La Plata (Argentina).
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55
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Quici S, Casoni A, Foschi F, Armelao L, Bottaro G, Seraglia R, Bolzati C, Salvarese N, Carpanese D, Rosato A. Folic acid-conjugated europium complexes as luminescent probes for selective targeting of cancer cells. J Med Chem 2015; 58:2003-14. [PMID: 25602505 DOI: 10.1021/jm501945w] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
We report the synthesis of three optical probes (Eu(3+)⊂1, Eu(3+)⊂2, and Eu(3+)⊂3) having a luminescent Eu complex (signaling unit) bonded in different positions to folic acid (FA), the folate receptor (FR) targeting unit. The structures of the two regioisomers Eu(3+)⊂1 and Eu(3+)⊂2 were assigned by mass spectrometric experiments. The optical properties and stability of these probes were assessed in phosphate-buffered saline, cell culture medium, rat serum, and cellular lysate, and results indicated that they are chemically and photophysically stable. Cytotoxicity was studied with ovarian cancer cells having high (SKOV-3), intermediate (OVCAR-3), low (IGROV-1), or null (A2780) expression of FRs. The internalized probe, evaluated in SKOV-3, IGROV-1, and A2780 cells, was in the order Eu(3+)⊂2 > Eu(3+)⊂1 > Eu(3+)⊂3. No internalization was observed for A2780 cells. Such results, together with those obtained in competition experiments of FA versus Eu(3+)⊂2 and FA or Eu(3+)⊂2 versus (3)H-FA, indicate that internalization is receptor-mediated and that Eu(3+)⊂2 shows high selectivity and specificity for FR.
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Affiliation(s)
- Silvio Quici
- Istituto di Scienze e Tecnologie Molecolari, Consiglio Nazionale delle Ricerche , Via C. Golgi 19, 20133 Milano, Italy
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Miñán A, Lorente C, Ipiña A, Thomas AH, Fernández Lorenzo de Mele M, Schilardi PL. Photodynamic inactivation induced by carboxypterin: a novel non-toxic bactericidal strategy against planktonic cells and biofilms of Staphylococcus aureus. BIOFOULING 2015; 31:459-468. [PMID: 26133959 DOI: 10.1080/08927014.2015.1055731] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Microbial related contamination is of major concern and can cause substantial economic losses. Photodynamic inactivation (PDI) has emerged as a suitable approach to inhibit microorganism proliferation. In this work, PDI induced by 6-carboxypterin (Cap), a biocompatible photosensitizer (PS), was analyzed. The growth inhibition of Staphylococcus aureus exposed to artificial UV-A radiation and sunlight in the presence of Cap was investigated. After UV-A irradiation, 50 μM Cap was able to decrease by three orders (with respect to the initial value) the number of S. aureus cells in early biofilms. However, this concentration was 500 times higher than that needed for eradicating planktonic cells. Importantly, under solar exposure, 100 μM Cap was able to suppress sessile bacterial growth. Thus, this strategy is able to exert a bactericidal effect on sessile bacteria and to eradicate planktonic cells by exposing the Cap-containing sample to sunlight.
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Affiliation(s)
- Alejandro Miñán
- a Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), CONICET - Facultad de Ciencias Exactas , Universidad Nacional de La Plata , La Plata , Argentina
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Thomas AH, Zurbano BN, Lorente C, Santos J, Roman EA, Laura Dántola M. Chemical changes in bovine serum albumin photoinduced by pterin. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2014; 141:262-8. [DOI: 10.1016/j.jphotobiol.2014.10.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2014] [Revised: 09/23/2014] [Accepted: 10/14/2014] [Indexed: 11/28/2022]
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58
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Liu L, Yang D, Li P. pH-Related and Site-Specific Excited-State Proton Transfer from Pterin to Acetate. J Phys Chem B 2014; 118:11707-14. [DOI: 10.1021/jp5082017] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Lei Liu
- State Key Laboratory of Molecular
Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- State Key Laboratory
of Fine Chemicals, Dalian University of Technology, Dalian 116024, China
| | - Dapeng Yang
- State Key Laboratory of Molecular
Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- Physics Laboratory, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
| | - Peng Li
- State Key Laboratory of Molecular
Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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59
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Buglak AA, Telegina TA, Lyudnikova TA, Vechtomova YL, Kritsky MS. Photooxidation of tetrahydrobiopterin under UV irradiation: possible pathways and mechanisms. Photochem Photobiol 2014; 90:1017-26. [PMID: 24773158 DOI: 10.1111/php.12285] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 04/24/2014] [Indexed: 12/16/2023]
Abstract
Tetrahydrobiopterin (H4 Bip) is a cofactor for several key enzymes, including NO synthases and aromatic amino acid hydroxylases (AAHs). Normal functioning of the H4 Bip regeneration cycle is extremely important for the work of AAHs. Oxidized pterins may accumulate if the H4 Bip regeneration cycle is disrupted or if H4 Bip autoxidation occurs. These oxidized pterins can photosensitize the production of singlet molecular oxygen (1)O2 and thus cause oxidative stress. In this context, we studied the photooxidation of H4 Bip in phosphate buffer at pH 7.2. We found that UV irradiation of H4 Bip affected its oxidation rate (quantum yield Φ300 = (2.7 ± 0.4) × 10(-3)). The effect of UV irradiation at λ = 350 nm on H4 Bip oxidation was stronger, especially in the presence of biopterin (Bip) (Φ350 = (9.7 ± 1.5) × 10(-3)). We showed that the rate of H4 Bip oxidation linearly depends on Bip concentration. Experiments with KI, a selective quencher of triplet pterins at micromolar concentrations, demonstrated that the oxidation is sensitized by the triplet state biopterin (3) Bip. Apparently, electron transfer sensitization (Type-I mechanism) is dominant. Energy transfer (Type-II mechanism) and singlet oxygen generation play only a secondary role. The mechanisms of H4 Bip photooxidation and their biological meaning are discussed.
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Affiliation(s)
- Andrey A Buglak
- A. N. Bach Institute of Biochemistry, Russian Academy of Sciences, Moscow, Russia
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60
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Wolcan E. On the origins of the absorption spectroscopy of pterin and Re(CO)3(pterin)(H2O) aqueous solutions. A combined theoretical and experimental study. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 129:173-183. [PMID: 24727177 DOI: 10.1016/j.saa.2014.03.022] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2013] [Revised: 03/10/2014] [Accepted: 03/16/2014] [Indexed: 06/03/2023]
Abstract
The origins of the absorption spectroscopy of pterin and Re(CO)3(pterin)(H2O) complex as a function of pH is studied using the hybrid functional B3LYP and PBE0 in combination with 6-311++G(d,p) and LanL2TZ(f) basis sets. A natural bond analysis was performed to the principal molecular orbitals involved in the electronic transitions of the studied compounds. The low energy band of pterin, which is described as a H→L electronic transition, can be interpreted as an admixture of π→π(*), n→π(*) and n→n electronic transitions involving π(C2-N1, C6-N5, C9-C10) and n(C2) orbitals of the HOMO and π(*)(C6-N5, C7-N8) and n(C4) orbitals of the LUMO. The low energy band of Re(CO)3(pterin)(H2O) can be described as a combination of different MLLCT transitions where electron density residing on different π orbitals of carbonyl-Re bonds and lone pairs of Re is transferred to pterin moiety. Besides MLLCT transitions, IL, LLCT and LLMCT transitions contribute the absorptions of the Re(I) complex in the wavelength region corresponding to the high energy bands. The calculated electronic spectra of the acid and base forms of pterin and Re(CO)3(pterin)(H2O) were simulated from the theoretical results and compared to the experimental absorption spectra with great accuracy both in position and relative intensities of the absorption bands.
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Affiliation(s)
- Ezequiel Wolcan
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA, UNLP, CCT La Plata-CONICET), Diag. 113 y 64, (B1906ZAA) La Plata, Argentina.
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61
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Roca-Sanjuán D, Galván IF, Giussani A, Lindh R. A theoretical analysis of the intrinsic light-harvesting properties of xanthopterin. COMPUT THEOR CHEM 2014. [DOI: 10.1016/j.comptc.2014.03.029] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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62
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Pauszek RF, Kodali G, Stanley RJ. Excited state electronic structures of 5,10-methenyltetrahydrofolate and 5,10-methylenetetrahydrofolate determined by Stark spectroscopy. J Phys Chem A 2014; 118:8320-8. [PMID: 24814224 DOI: 10.1021/jp501143u] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Folates are ubiquitous cofactors that participate in a wide variety of critical biological processes. 5,10-Methenyltetrahydrofolate and its photodegradation product 5,10-methylenetetrahydrofolate are both associated with the light-driven DNA repair protein DNA photolyase and its homologues (e.g., cryptochromes). The excited state electronic properties of these folate molecules have been studied here using Stark spectroscopy and complementary quantum calculations. The tetrahydrofolates have relatively large difference dipole moments (ca. 6-8 Debye) and difference polarizabilities (ca. 100 Å(3)). This extensive excited state charge redistribution appears to be due largely to the pendant p-aminobenzoic acid group, which helps shuttle charge over the entirety of the molecule. Simple calculations based on the experimental difference dipole moments suggest that tetrahydrofolates should have large two photon cross sections sufficient to enable two photon microscopy to selectively detect and follow folate-containing proteins both in vitro and in vivo.
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Affiliation(s)
- Raymond F Pauszek
- Department of Chemistry, Temple University , Philadelphia, Pennsylvania 19122, United States
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63
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Synchronous Luminescence Spectroscopic Characterization of Urine of Normal Subjects and Cancer Patients. J Fluoresc 2014; 24:1199-205. [DOI: 10.1007/s10895-014-1401-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2013] [Accepted: 04/29/2014] [Indexed: 10/25/2022]
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64
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Bahng SH, Kwon NH, Kim HC, Siddique AB, Kang HJ, Lee JY, Kim J, Kim S, Kim J. Simple synthesis of water-dispersible and photoactive titanium dioxide nanoparticles using functionalized poly(ethylene oxide)s. Macromol Res 2014. [DOI: 10.1007/s13233-014-2062-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
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65
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Determination of pterins in urine by HPLC with UV and fluorescent detection using different types of chromatographic stationary phases (HILIC, RP C8, RP C18). J Pharm Biomed Anal 2014; 91:37-45. [DOI: 10.1016/j.jpba.2013.12.012] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 12/10/2013] [Accepted: 12/12/2013] [Indexed: 11/19/2022]
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66
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Denofrio MP, Ogilby PR, Thomas AH, Lorente C. Selective quenching of triplet excited states of pteridines. Photochem Photobiol Sci 2014; 13:1058-65. [DOI: 10.1039/c4pp00079j] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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67
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Castaño C, Lorente C, Martins-Froment N, Oliveros E, Thomas AH. Degradation of α-melanocyte-stimulating hormone photosensitized by pterin. Org Biomol Chem 2014; 12:3877-86. [DOI: 10.1039/c4ob00434e] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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68
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Thomas AH, Serrano MP, Rahal V, Vicendo P, Claparols C, Oliveros E, Lorente C. Tryptophan oxidation photosensitized by pterin. Free Radic Biol Med 2013; 63:467-75. [PMID: 23747929 DOI: 10.1016/j.freeradbiomed.2013.05.044] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2012] [Revised: 05/22/2013] [Accepted: 05/30/2013] [Indexed: 10/26/2022]
Abstract
Pterins are normal components of cells and they have been previously identified as good photosensitizers under UV-A irradiation, inducing DNA damage and oxidation of nucleotides. In this work, we have investigated the ability of pterin (Ptr), the parent compound of oxidized pterins, to photosensitize the oxidation of another class of biomolecules, amino acids, using tryptophan (Trp) as a model compound. Irradiation of Ptr in the UV-A spectral range (350 nm) in aerated aqueous solutions containing Trp led to the consumption of the latter, whereas the Ptr concentration remained unchanged. Concomitantly, hydrogen peroxide (H₂O₂) was produced. Although Ptr is a singlet oxygen ((1)O₂) sensitizer, the degradation of Trp was inhibited in O₂-saturated solutions, indicating that a (1)O₂-mediated process (type II oxidation) was not an important pathway leading to Trp oxidation. By combining different analytical techniques, we could establish that a type I photooxidation was the prevailing mechanism, initiated by an electron transfer from the Trp molecule to the Ptr triplet excited state, yielding the corresponding radical ions (Trp(·+)/Trp(-H)· and Ptr(·-)). The Trp reaction products that could be identified by UPLC-mass spectrometry are in agreement with this conclusion.
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Affiliation(s)
- Andrés H Thomas
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET, Boulevard 113 y 64, 1900 La Plata, Argentina
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69
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Juzeniene A, Thu Tam TT, Iani V, Moan J. The action spectrum for folic acid photodegradation in aqueous solutions. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2013; 126:11-6. [DOI: 10.1016/j.jphotobiol.2013.05.011] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 05/08/2013] [Accepted: 05/29/2013] [Indexed: 12/14/2022]
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70
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Serrano MP, Borsarelli CD, Thomas AH. Type I photosensitization of 2'-deoxyadenosine 5'-monophosphate (5'-dAMP) by biopterin and its photoproduct formylpterin. Photochem Photobiol 2013; 89:1456-62. [PMID: 23837607 DOI: 10.1111/php.12134] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2013] [Accepted: 07/03/2013] [Indexed: 11/30/2022]
Abstract
Biopterin (Bip) and its photoproducts 6-formylpterin (Fop) and 6-carboxypterin (Cap) accumulate in the skin of patients suffering from vitiligo, a chronic depigmentation disorder where the protection against UV radiation fails because of the lack of melanin. These compounds absorb in the UV-A inducing a potential photosensitizing action that can cause damage to DNA and other biomolecules. In this work, we have investigated the capability of these pterin derivatives (Pt) to act as photosensitizers under UV-A irradiation for the degradation of 2'-deoxyadenosine 5'-monophosphate (5'-dAMP) in aqueous solutions, as model DNA target. Steady-state and time-resolved experiments were performed and the effect of pH was evaluated. The results showed that photosensitized degradation of 5'-dAMP was only observed under acidic conditions, and a mechanistic analysis revealed the participation of the triplet excited state of the pterin derivatives ((3)Pt*) by electron transfer yielding the corresponding pair of radical ions (Pt(•-) and 5'-dAMP(•+)), with successive photosensitizer recovery by electron transfer from Pt(•-) to O2. Finally, 5'-dAMP(•+) participates in subsequent reactions to yield degradation products.
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Affiliation(s)
- Mariana P Serrano
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, La Plata, Argentina
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71
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Castaño C, Dántola ML, Oliveros E, Thomas AH, Lorente C. Oxidation of Tyrosine Photoinduced by Pterin in Aqueous Solution. Photochem Photobiol 2013; 89:1448-55. [DOI: 10.1111/php.12099] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Accepted: 05/07/2013] [Indexed: 12/01/2022]
Affiliation(s)
- Carolina Castaño
- Departamento de Química; Facultad de Ciencias Exactas; Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA); Universidad Nacional de La Plata; CCT La Plata-CONICET; La Plata Argentina
| | - María L. Dántola
- Departamento de Química; Facultad de Ciencias Exactas; Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA); Universidad Nacional de La Plata; CCT La Plata-CONICET; La Plata Argentina
| | - Esther Oliveros
- Laboratoire des Interactions Moléculaires Réactivité Chimique et Photochimique (IMRCP); UMR 5623-CNRS/UPS; Université Toulouse III (Paul Sabatier); Toulouse Cédex France
| | - Andrés H. Thomas
- Departamento de Química; Facultad de Ciencias Exactas; Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA); Universidad Nacional de La Plata; CCT La Plata-CONICET; La Plata Argentina
| | - Carolina Lorente
- Departamento de Química; Facultad de Ciencias Exactas; Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA); Universidad Nacional de La Plata; CCT La Plata-CONICET; La Plata Argentina
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72
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Sakai KI, Nagahara K, Yoshii Y, Hoshino N, Akutagawa T. Structural and Spectroscopic Study of 6,7-Dicyano-Substituted Lumazine with High Electron Affinity and Proton Acidity. J Phys Chem A 2013; 117:3614-24. [DOI: 10.1021/jp401528c] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Ken-ichi Sakai
- Department of Bio- and Material
Photonics, Chitose Institute of Science and Technology (CIST), Chitose 066-8655, Japan
| | - Kenta Nagahara
- Department of Bio- and Material
Photonics, Chitose Institute of Science and Technology (CIST), Chitose 066-8655, Japan
| | - Yuuya Yoshii
- Polymer Hybrid Materials Research
Center, Institute of Multidisciplinary Research for Advanced Materials
(IMRAS), Tohoku University, Sendai 980-8577,
Japan
| | - Norihisa Hoshino
- Polymer Hybrid Materials Research
Center, Institute of Multidisciplinary Research for Advanced Materials
(IMRAS), Tohoku University, Sendai 980-8577,
Japan
| | - Tomoyuki Akutagawa
- Polymer Hybrid Materials Research
Center, Institute of Multidisciplinary Research for Advanced Materials
(IMRAS), Tohoku University, Sendai 980-8577,
Japan
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73
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Fluorescence modulation and associative behavior of lumazine in hydrophobic domain of micelles and bovine serum albumin. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2013; 121:37-45. [DOI: 10.1016/j.jphotobiol.2013.02.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/16/2012] [Revised: 02/13/2013] [Accepted: 02/13/2013] [Indexed: 11/21/2022]
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74
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Thomas AH, Lorente C, Roitman K, Morales MM, Dántola ML. Photosensitization of bovine serum albumin by pterin: A mechanistic study. JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY 2013; 120:52-8. [DOI: 10.1016/j.jphotobiol.2013.01.008] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2012] [Revised: 01/14/2013] [Accepted: 01/15/2013] [Indexed: 10/27/2022]
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75
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Ragone F, Ruiz GT, Piro OE, Echeverría GA, Cabrerizo FM, Petroselli G, Erra-Balsells R, Hiraoka K, García Einschlag FS, Wolcan E. Water-Soluble (Pterin)rhenium(I) Complex: Synthesis, Structural Characterization, and Two Reversible Protonation-Deprotonation Behavior in Aqueous Solutions. Eur J Inorg Chem 2012. [DOI: 10.1002/ejic.201200681] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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76
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Serrano MP, Lorente C, Vieyra FEM, Borsarelli CD, Thomas AH. Photosensitizing properties of biopterin and its photoproducts using 2'-deoxyguanosine 5'-monophosphate as an oxidizable target. Phys Chem Chem Phys 2012; 14:11657-65. [PMID: 22825359 DOI: 10.1039/c2cp41476g] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
UV-A radiation (320-400 nm) induces damage to the DNA molecule and its components through photosensitized reactions. Biopterin (Bip) and its photoproducts 6-formylpterin (Fop) and 6-carboxypterin (Cap) accumulate in the skin of human beings suffering from vitiligo, a depigmentation disorder where the protection against UV radiation fails because of the lack of melanin. This study was aimed to evaluate the photosensitizing properties of oxidized pterins present in the skin and to elucidate the mechanisms involved in the photosensitized oxidation of purine nucleotides by pterins in vitro. For this purpose, steady-state and time-resolved experiments in acidic (pH 5.0-5.8) aqueous solution were performed using Bip, Fop and Cap as photosensitizers and the nucleotide 2'-deoxyguanosine 5'-monophosphate (dGMP) as an oxidizable target. The three pterin derivatives are able to photosensitize dGMP, being Fop the most efficient sensitizer. The reactions proceed through two competing pathways: (1) electron transfer from dGMP to triplet excited-state of pterins (type I mechanism) and (2) reaction of dGMP with (1)O(2) produced by pterins (type II mechanism). Kinetic analysis revealed that the electron transfer pathway is the main mechanism and the interaction of dGMP with the triplet excited-state of pterins and the formation of the corresponding dGMP radicals were demonstrated by laser flash photolysis experiments. The biological implications of the results obtained are also discussed.
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Affiliation(s)
- Mariana P Serrano
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (UNLP), CCT La Plata-CONICET, La Plata, Argentina
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77
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Laura Dántola M, Gojanovich AD, Thomas AH. Inactivation of tyrosinase photoinduced by pterin. Biochem Biophys Res Commun 2012; 424:568-72. [DOI: 10.1016/j.bbrc.2012.06.155] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2012] [Accepted: 06/29/2012] [Indexed: 10/28/2022]
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78
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Li G, Magana D, Dyer RB. Photoinduced electron transfer in folic acid investigated by ultrafast infrared spectroscopy. J Phys Chem B 2012; 116:3467-75. [PMID: 22364409 PMCID: PMC3311227 DOI: 10.1021/jp300392a] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Conformational control of excited-state intramolecular electron transfer (ET) in folic acid (FA) has been investigated using femtosecond time-resolved infrared (TRIR) spectroscopy. Ultrafast excited-state ET between the pterin and the 4-aminobenzoyl subunits of FA is observed for the anionic form (at pH 10.0). An ET lifetime of 2.5 ps is estimated from Marcus theory for FA in the "U" conformation, in close agreement with the observed lifetime of 2.0 ps. Return to the ground state through the reverse ET reaction happens almost as rapidly, within 5 ps, resulting in rapid quenching of the singlet excited state. In mixed water:dimethyl sulfoxide solvent, ET becomes more unfavorable as FA adopts a more open conformation, thereby increasing the effective donor-acceptor distance and reducing the coupling energy. In contrast, no ET is observed for the cationic form of FA at low pH (6.0). In this case, the initial singlet excited state is localized on the pterin moiety of FA, and the excited-state charge distribution evolves with time. The charge redistribution in the pterin that occurs with intersystem crossing to the triplet state is characterized by changes in the transient IR spectrum. The excited-state lifetime is much longer in the absence of an ET quenching pathway. These results provide new insight into the mechanism of photodegradation and toxicity of FA. Ultrafast intramolecular ET in closed conformations of FA rapidly quenches the excited state and prevents efficient triplet state formation. Thus, conformations of FA that allow ultrafast intra-ET and rapid quenching of the singlet excited state play a key role in inhibiting pathological pathways following photoexcitation of FA.
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Affiliation(s)
- Guifeng Li
- Department of Chemistry, Emory University, Atlanta, Georgia, 30322, United States
| | - Donny Magana
- Department of Chemistry, Emory University, Atlanta, Georgia, 30322, United States
| | - R. Brian Dyer
- Department of Chemistry, Emory University, Atlanta, Georgia, 30322, United States
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79
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Cui G, Yang W. Conical intersections in solution: formulation, algorithm, and implementation with combined quantum mechanics/molecular mechanics method. J Chem Phys 2011; 134:204115. [PMID: 21639432 PMCID: PMC3124537 DOI: 10.1063/1.3593390] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 05/04/2011] [Indexed: 11/14/2022] Open
Abstract
The significance of conical intersections in photophysics, photochemistry, and photodissociation of polyatomic molecules in gas phase has been demonstrated by numerous experimental and theoretical studies. Optimization of conical intersections of small- and medium-size molecules in gas phase has currently become a routine optimization process, as it has been implemented in many electronic structure packages. However, optimization of conical intersections of small- and medium-size molecules in solution or macromolecules remains inefficient, even poorly defined, due to large number of degrees of freedom and costly evaluations of gradient difference and nonadiabatic coupling vectors. In this work, based on the sequential quantum mechanics and molecular mechanics (QM/MM) and QM/MM-minimum free energy path methods, we have designed two conical intersection optimization methods for small- and medium-size molecules in solution or macromolecules. The first one is sequential QM conical intersection optimization and MM minimization for potential energy surfaces; the second one is sequential QM conical intersection optimization and MM sampling for potential of mean force surfaces, i.e., free energy surfaces. In such methods, the region where electronic structures change remarkably is placed into the QM subsystem, while the rest of the system is placed into the MM subsystem; thus, dimensionalities of gradient difference and nonadiabatic coupling vectors are decreased due to the relatively small QM subsystem. Furthermore, in comparison with the concurrent optimization scheme, sequential QM conical intersection optimization and MM minimization or sampling reduce the number of evaluations of gradient difference and nonadiabatic coupling vectors because these vectors need to be calculated only when the QM subsystem moves, independent of the MM minimization or sampling. Taken together, costly evaluations of gradient difference and nonadiabatic coupling vectors in solution or macromolecules can be reduced significantly. Test optimizations of conical intersections of cyclopropanone and acetaldehyde in aqueous solution have been carried out successfully.
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Affiliation(s)
- Ganglong Cui
- Department of Chemistry, Duke University, Durham, North Carolina 27708, USA
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80
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Serrano MP, Vignoni M, Dántola ML, Oliveros E, Lorente C, Thomas AH. Emission properties of dihydropterins in aqueous solutions. Phys Chem Chem Phys 2011; 13:7419-25. [PMID: 21409193 DOI: 10.1039/c0cp02912b] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Pterins belong to a class of heterocyclic compounds present in a wide range of living systems and accumulate in the skin of patients affected by vitiligo, a depigmentation disorder. The study of the emission of 7,8-dihydropterins is difficult because these compounds are more or less unstable in the presence of O(2) and their solutions are contaminated with oxidized pterins which have much higher fluorescence quantum yields (Φ(F)). In this work, the emission properties of six compounds of the dihydropterin family (6-formyl-7,8-dihydropterin (H(2)Fop), sepiapterin (Sep), 7,8-dihydrobiopterin (H(2)Bip), 7,8-dihydroneopterin (H(2)Nep), 6-hydroxymethyl-7,8-dihydropterin (H(2)Hmp), and 6-methyl-7,8-dihydropterin (H(2)Mep)) have been studied in aqueous solution. The fluorescence characteristics (spectra, Φ(F), lifetimes (τ(F))) of the neutral form of these compounds have been investigated using the single-photon-counting technique. Φ(F) and τ(F) values obtained lie in the ranges 3-9 × 10(-3) and 0.18-0.34 ns, respectively. The results are compared to those previously reported for oxidized pterins.
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Affiliation(s)
- Mariana P Serrano
- INIFTA, Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET., C.C. 16, Suc. 4, (1900) La Plata, Argentina
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81
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Denofrio MP, Thomas AH, Lorente C. Oxidation of 2'-deoxyadenosine 5'-monophosphate photoinduced by lumazine. J Phys Chem A 2011; 114:10944-50. [PMID: 20873833 DOI: 10.1021/jp1061336] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
UV radiation induces damages to the DNA molecule and its components through photosensitized reactions. Among these processes, photosensitized oxidations may occur through electron transfer or hydrogen abstraction (type I mechanism) and/or the production of singlet molecular oxygen ((1)O(2)) (type II mechanism). Lumazines are an important family of heterocyclic compounds present in biological systems as biosynthetic precursors and/or products of metabolic degradation. To evaluate the capability of lumazines to act as photosensitizers through type I mechanism, we have investigated the oxidation of 2'-deoxyadenosine 5'-monophosphate (dAMP) photosensitized by the specific compound called lumazine (pteridine-2,4(1,3H)-dione; Lum) in aqueous solutions under UV irradiation. The photochemical reactions were followed by UV/vis spectrophotometry, HPLC, electrochemical measurement of dissolved O(2), and an enzymatic method for H(2)O(2) determination. The effect of pH was evaluated and the participation of oxygen was investigated. In aerated solutions, oxidation of dAMP photoinduced by the acid form of Lum (pH 5.5) takes place through a type I mechanism, in which the excitation of Lum is followed by an electron transfer from dAMP molecule to the Lum triplet excited state. During the process, O(2) is consumed and H(2)O(2) is generated, whereas the photosensitizer is not consumed. In contrast, no evidence of a photochemical reaction induced by the basic form of Lum (pH 10.5) was observed.
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Affiliation(s)
- M Paula Denofrio
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET, Boulevard 113 y 64, 1900 La Plata, Argentina
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82
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Paula Denofrio M, Lorente C, Breitenbach T, Hatz S, Cabrerizo FM, Thomas AH, Ogilby PR. Photodynamic Effects of Pterin on HeLa Cells. Photochem Photobiol 2011; 87:862-6. [DOI: 10.1111/j.1751-1097.2011.00922.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. Paula Denofrio
- Departamento de Química, Facultad de Ciencias Exactas, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata, CCT La Plata‐CONICET, La Plata, Argentina
| | - Carolina Lorente
- Departamento de Química, Facultad de Ciencias Exactas, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata, CCT La Plata‐CONICET, La Plata, Argentina
| | - Thomas Breitenbach
- Department of Chemistry, Center for Oxygen Microscopy and Imaging, University of Aarhus, Århus, Denmark
| | - Sonja Hatz
- Department of Chemistry, Center for Oxygen Microscopy and Imaging, University of Aarhus, Århus, Denmark
| | - Franco M. Cabrerizo
- Instituto de Investigaciones Biotecnológicas, Instituto Tecnológico de Chascomús (IIB‐INTECH), Universidad Nacional de San Martín, CONICET, Camino Circunv., Chascomús, Argentina
| | - Andrés H. Thomas
- Departamento de Química, Facultad de Ciencias Exactas, Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Universidad Nacional de La Plata, CCT La Plata‐CONICET, La Plata, Argentina
| | - Peter R. Ogilby
- Department of Chemistry, Center for Oxygen Microscopy and Imaging, University of Aarhus, Århus, Denmark
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83
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Scurachio RS, Skibsted LH, Metzker G, Cardoso DR. Photodegradation of Folate Sensitized by Riboflavin. Photochem Photobiol 2011; 87:840-5. [DOI: 10.1111/j.1751-1097.2011.00916.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Regina S. Scurachio
- Instituto de Quimica de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
| | - Leif H. Skibsted
- Food Chemistry, Department of Food Science, Faculty of Life Sciences, University of Copenhagen, Frederiksberg C, Denmark
| | - Gustavo Metzker
- Instituto de Quimica de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
| | - Daniel R. Cardoso
- Instituto de Quimica de São Carlos, Universidade de São Paulo, São Carlos, São Paulo, Brazil
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84
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Belen’kii L, Gramenitskaya V, Evdokimenkova Y. The Literature of Heterocyclic Chemistry, Part X, 2005–2007. ADVANCES IN HETEROCYCLIC CHEMISTRY 2011. [DOI: 10.1016/b978-0-12-385464-3.00001-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
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85
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Vignoni M, Serrano MP, Oliveros E, Thomas AH. Photodimerization of 7,8-Dihydroneopterin in Aqueous Solution Under UV-A Irradiation. Photochem Photobiol 2010; 87:51-5. [DOI: 10.1111/j.1751-1097.2010.00833.x] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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86
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Petroselli G, Dántola ML, Cabrerizo FM, Lorente C, Braun AM, Oliveros E, Thomas AH. Quenching of the fluorescence of aromatic pterins by deoxynucleotides. J Phys Chem A 2010; 113:1794-9. [PMID: 19199487 DOI: 10.1021/jp8101496] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Steady-state and time-resolved studies of the fluorescence of four aromatic unconjugated pterins (pterin (Ptr), 6-(hydroxymethyl)pterin (Hmp), 6-methylpterin (Mep), and 6,7-dimethylpterin (Dmp)) in aqueous solutions in the presence of different nucleotides (2'-deoxyguanosine 5'-monophosphate (dGMP), 2'-deoxyadenosine 5'-monophosphate (dAMP), and 2'-deoxycytosine 5'-monophosphate (dCMP)) have been performed using the single-photon counting technique. The singlet excited states of acid forms of pterins are deactivated by purine nucleotides (dGMP and dAMP) via a combination of dynamic and static processes. The efficiency of the dynamic quenching is high, independently of the nature of the purine base of the nucleotide and of the chemical structure of the substituents linked to the pterin moiety. Analysis of the static quenching indicates that ground-state association between pterins and purine nucleotides takes place, but the formation of the corresponding complexes is significant only at relatively high reactant concentrations. The quenching of the fluorescence of acid forms of pterin derivatives by dCMP, a pyrimidine nucleotide, is slightly less efficient than the quenching by purine nucleotides and is purely dynamic. In alkaline media, the fluorescence quenching is much less efficient than in acidic media, the deactivation by purine nucleotides being purely dynamic, whereas quenching by dCMP is negligible. Possible mechanisms for the quenching of fluorescence of pterin derivatives by the different nucleotides are discussed.
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Affiliation(s)
- Gabriela Petroselli
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas, Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET, Boulevard 113 y 64, 1900 La Plata, Argentina
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87
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Dántola ML, Denofrio MP, Zurbano B, Gimenez CS, Ogilby PR, Lorente C, Thomas AH. Mechanism of photooxidation of folic acid sensitized by unconjugated pterins. Photochem Photobiol Sci 2010; 9:1604-12. [PMID: 20922252 DOI: 10.1039/c0pp00210k] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Folic acid, or pteroyl-l-glutamic acid (PteGlu), is a precursor of coenzymes involved in the metabolism of nucleotides and amino acids. PteGlu is composed of three moieties: a 6-methylpterin (Mep) residue, a p-aminobenzoic acid (PABA) residue, and a glutamic acid (Glu) residue. Accumulated evidence indicates that photolysis of PteGlu leads to increased risk of several pathologies. Thus, a study of PteGlu photodegradation can have significant ramifications. When an air-equilibrated aqueous solution of PteGlu is exposed to UV-A radiation, the rate of the degradation increases with irradiation time. The mechanism involved in this "auto-photo-catalytic" effect was investigated in aqueous solutions using a variety of tools. Whereas PteGlu is photostable under anaerobic conditions, it is converted into 6-formylpterin (Fop) and p-aminobenzoyl-l-glutamic acid (PABA-Glu) in the presence of oxygen. As the reaction proceeds and enough Fop accumulates in the solution, a photosensitized electron-transfer process starts, where Fop photoinduces the oxidation of PteGlu to Fop, and H(2)O(2) is formed. This process also takes place with other pterins as photosensitizers. The results are discussed with the context of previous mechanisms for processes photosensitized by pterins, and their biological implications are evaluated.
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Affiliation(s)
- M Laura Dántola
- INIFTA, Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET. C.C. 16, Suc. 4, (1900), La Plata, Argentina
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88
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89
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90
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Vignoni M, Cabrerizo FM, Lorente C, Claparols C, Oliveros E, Thomas AH. Photochemistry of dihydrobiopterin in aqueous solution. Org Biomol Chem 2010; 8:800-10. [PMID: 20135037 DOI: 10.1039/b913095k] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Dihydrobiopterin (H(2)Bip) and its oxidized analogue, biopterin (Bip), accumulate in the skin of patients suffering from vitiligo, a chronic depigmentation disorder in which the protection against UV radiation fails. The photochemistry of H(2)Bip was studied in neutral aqueous solutions upon UV-A irradiation (320-400 nm) at room temperature. The photochemical reactions were followed by UV/vis spectrophotometry, HPLC and enzymatic methods for hydrogen peroxide (H(2)O(2)) determination. Photoproducts were analyzed by means of electrospray ionization mass spectrometry. Under anaerobic conditions, excitation of H(2)Bip leads to the formation of at least two isomeric dimers with molecular masses equal to exactly twice the molecular mass of the reactant. This reaction takes place from the singlet excited state of the reactant. To the best of our knowledge, this is the first time that the photodimerization of a dihydropterin is reported. In the presence of air, the dimers are again the main photoproducts at the beginning of the reaction, but a small proportion of the reactant is converted into Bip. As the reaction proceeds and enough Bip accumulates in the solution, a photosensitized process starts, where Bip photoinduces the oxidation of H(2)Bip to Bip, and H(2)O(2) is formed. As a consequence, the rates of H(2)Bip consumption and Bip formation increase as a function of irradiation time, resulting in an autocatalytic photochemical process. In this process, Bip in its triplet excited state reacts with the ground state of H(2)Bip. The mechanisms involved are analyzed and the biological implications of the results are discussed.
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Affiliation(s)
- Mariana Vignoni
- Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas (INIFTA), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET, Casilla de Correo 16, Sucursal 4, (1900) La Plata, Argentina
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91
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92
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Goswami S, Hazra A, Jana S, Fun HK. Recognition study of substituted benzoic acids by 7-substituted pterin receptors in solution and solid phases. CrystEngComm 2010. [DOI: 10.1039/b917092h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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93
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Martínez A, Vargas R. Electron donor–acceptor properties of metal atoms interacting with pterins. NEW J CHEM 2010. [DOI: 10.1039/b9nj00805e] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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94
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Mori H, Nishinaka Y, Nonogawa M, Sommani P, Makino K, Yamashita K, Arai T. Substituent Effects of Pterin Derivatives on Singlet Oxygen Scavenging Activity. Biol Pharm Bull 2010; 33:905-8. [DOI: 10.1248/bpb.33.905] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Hiroko Mori
- Department of Anesthesia, Higashiyama Takeda Hospital
| | - Yoko Nishinaka
- School of Health Science, Faculty of Medicine, Kyoto University
| | | | | | | | - Kouhei Yamashita
- Department of Hematology and Oncology, Kyoto University Hospital
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95
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Dántola ML, Thomas AH, Oliveros E, Lorente C. Visible-light photochemistry of 6-formyl-7,8-dihydropterin in aqueous solution. J Photochem Photobiol A Chem 2010. [DOI: 10.1016/j.jphotochem.2009.11.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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96
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Denofrio MP, Hatz S, Lorente C, Cabrerizo FM, Ogilby PR, Thomas AH. The photosensitizing activity of lumazine using 2'-deoxyguanosine 5'-monophosphate and HeLa cells as targets. Photochem Photobiol Sci 2009; 8:1539-49. [PMID: 19862412 DOI: 10.1039/b9pp00020h] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Lumazines are an important family of heterocyclic compounds present in biological systems as biosynthetic precursors and/or products of metabolic degradation. Upon UV irradiation, the specific compound called lumazine (pteridine-2,4(1,3H)-dione) is able to generate singlet oxygen (1O2), which is one of the main chemical species responsible for photodynamic effects. To further assess the photosensitizing capability of lumazine (Lum) experiments were performed using the nucleotide 2'-deoxyguanosine 5'-monophosphate (dGMP) and, independently, cervical cancer cells (HeLa cell line) as targets. In the dGMP experiments, the data revealed that dGMP indeed undergoes oxidation/oxygenation photoinduced by Lum. Moreover, dGMP disappearance proceeds through two competing pathways: (1) electron transfer between dGMP and excited-state Lum (Type I process) and (2) reaction of dGMP with 1O2 produced by Lum (Type II process). The multistep processes involved are convoluted and susceptible to changes in experimental conditions. The independent studies with HeLa cells included fluorescence analysis of cell extracts and phototoxicity experiments performed at the single-cell level. Results showed that, upon Lum uptake and irradiation, photodynamic effects occur. In particular, the mitochondria and cell membrane were perturbed, both of which reflect key stages in cell death. The data reported herein illustrate how the irradiation of an endogenous biological compound can have various effects which, depending on the system, can be manifested in different ways.
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Affiliation(s)
- M Paula Denofrio
- INIFTA, Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, CCT La Plata-CONICET. C.C. 16, Suc. 4, (1900), La Plata, Argentina
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97
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Jaramillo P, Coutinho K, Canuto S. Solvent Effects in Chemical Processes. Water-Assisted Proton Transfer Reaction of Pterin in Aqueous Environment. J Phys Chem A 2009; 113:12485-95. [DOI: 10.1021/jp903638n] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Paula Jaramillo
- Instituto de Física, Universidade de São Paulo, CP 66318, 05314-970, São Paulo, SP, Brazil
| | - Kaline Coutinho
- Instituto de Física, Universidade de São Paulo, CP 66318, 05314-970, São Paulo, SP, Brazil
| | - Sylvio Canuto
- Instituto de Física, Universidade de São Paulo, CP 66318, 05314-970, São Paulo, SP, Brazil
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98
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Mercader AG, Duchowicz PR, Fernández FM, Castro EA, Cabrerizo FM, Thomas AH. Predictive modeling of the total deactivation rate constant of singlet oxygen by heterocyclic compounds. J Mol Graph Model 2009; 28:12-9. [DOI: 10.1016/j.jmgm.2009.03.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Revised: 03/04/2009] [Accepted: 03/07/2009] [Indexed: 11/29/2022]
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99
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Tyagi A, Penzkofer A, Batschauer A, Wolf E. Fluorescence behaviour of 5,10-methenyltetrahydrofolate, 10-formyltetrahydrofolate, 10-formyldihydrofolate, and 10-formylfolate in aqueous solution at pH 8. Chem Phys 2009. [DOI: 10.1016/j.chemphys.2009.05.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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100
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Effect of methyl substitution in a ligand on the selectivity and binding affinity for a nucleobase: A case study with isoxanthopterin and its derivatives. Bioorg Med Chem 2009; 17:351-9. [DOI: 10.1016/j.bmc.2008.10.062] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2008] [Revised: 10/27/2008] [Accepted: 10/27/2008] [Indexed: 11/21/2022]
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