Edgardo Durantini | Universidad Nacional de Rio Cuarto (original) (raw)
Papers by Edgardo Durantini
Photochemistry and Photobiology, 2004
The photodynamic activities of novel asymmetrically meso-substituted cationic porphyrins, 5,10-di... more The photodynamic activities of novel asymmetrically meso-substituted cationic porphyrins, 5,10-di(4-methylphenyl)-15,20-di(4-trimethylammoniumphenyl)porphyrin iodide 1 and 5-(4-trifluorophenyl)-10,15,20-tris(4-trimethylammoniumphenyl)porphyrin iodide 2 and its metal complex with Pd(II) 3, have been investigated in both homogeneous medium bearing photooxidizable substrates and in vitro on a typical gram-negative bacterium Escherichia coli. The amphiphilic character of porphyrin 2 was increased by the presence of a high-lipophilic trifluoromethyl group and its photophysical properties changed by forming a complex with Pd(II). Absorption and fluorescence spectroscopic studies were compared in different media. Fluorescence quantum yields (phi(F)) of 0.16 for 1 in tetrahydrofuran and 0.08 for 2 in N, N-dimethylformamide (DMF) were calculated, whereas no significant emission was detected for Pd(II) porphyrin 3. The singlet molecular oxygen, O(2)((1)Delta(g)), production was evaluated using 9,10-dimethylanthracene in DMF yielding relative values of 1, 0.55 and 0.47 for porphyrins 3, 2 and 1, respectively. A faster decomposition of l-tryptophan was obtained using Pd(II) porphyrin 3 as sensitizer with respect to the free-base porphyrins 1 and 2. In biological medium, the behavior of cationic porphyrins 1-3 were compared with that of 5-(4-carboxyphenyl)-10,15,20-tris(4-methylphenyl)porphyrin 4, which was used as a noncationic sensitizer. These porphyrins are rapidly bound to E. coli cells in 5 min and the amount of cell-bound sensitizer is not appreciably changed incubating the cultures for longer times. The recovered porphyrin 2 after one washing step reaches a value of approximately 2.9 nmol/10(6) cells and this amount remains high even after three washes, indicating that this sensitizer is tightly bound to cells. Photosensitized inactivation of E. coli was analyzed using cells without and with one washing step. In both cases, a higher photoinactivation of cells was found for tricationic porphyrin 2 and 3, causing a approximately 5.5 log (99.999%) decrease of cell survival, when treated with 10 microM of sensitizer. Under these conditions, a lower effect was found for porphyrin 1 (approximately 4 log) whereas sensitizer 4 did not produce appreciable photodamage. The results were also confirmed by growth delay experiments. These studies show that the amphiphilic tricationic porphyrin 2 and 3 bearing a trifluoromethyl group can be a promising model for phototherapeutic agents with potential applications in inactivation of bacteria by photodynamic therapy.
Photochemistry and Photobiology, 2015
The photoreaction type I/type II pathways mediated by zinc(II) 2,9,16,23-tetrakis[4-(N-methylpyri... more The photoreaction type I/type II pathways mediated by zinc(II) 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]phthalocyanine (ZnPPc(4+) ) was studied in Candida albicans cells. This photosensitizer was strongly bound to C. albicans cells at short times. After 30 min irradiation, 5 μM ZnPPc(4+) produced ~5 log decrease in cell viability. Different probes were used to detect reactive oxygen species (ROS) in cell suspensions (~10(6) CFU mL(-1) ). Singlet molecular oxygen, O2 ((1) Δg ), was observed by the reaction with 9,10-dimethylanthracene (DMA) and tetrasodium 2,2-(anthracene-9,10-diyl)bis(methylmalonate) (ABMM), whereas the nitro blue tetrazolium (NBT) method was used to sense superoxide anion radical (O2·-). Moreover, the effects produced by an anoxic atmosphere and cell suspensions in D2 O, as well as the addition of sodium azide and mannitol as ROS trapping were evaluated in the PDI of C. albicans. These investigation indicates that O2 ((1) Δg ) is generated in the cells, although a minor extension other radical species can also be involved in the PDI of C. albicans mediated by ZnPPc(4+) .
Electrochimica Acta, 2015
ABSTRACT A photoactive interface is formed between an electrochemical generated organic polymer f... more ABSTRACT A photoactive interface is formed between an electrochemical generated organic polymer film and CdSe quantum dots. The specifically designed and synthesized 3,4 ethylenedioxythiophene electroactive monomer, holding C60 buckminsterfullerene, allows the formation of thin films containing both, electron acceptor and hole transport moieties. The generation of photoinduced heterogeneous charge transfer in CdSe quantum dots-electropolymer system was characterized by time resolved and spectral dependent surface photovoltage. In films containing C60 moieties whose surface was modified with 5 nm CdSe quantum dots, the illumination generated photovoltage values around twenty times larger than those obtained without nanoparticles decoration. The results show that this organic-inorganic hybrid interface is a potential structure for the development of optoelectronic devices.
Journal of the Chemical Society, Perkin Transactions 2, 1996
Cellular and molecular biology (Noisy-le-Grand, France), 2009
The photodynamic activity of three photosensitizers (PS): AL-induced PPIX, the porphyrin derivati... more The photodynamic activity of three photosensitizers (PS): AL-induced PPIX, the porphyrin derivative 5-(4-trimethylammoniumphenyl)-10, 5, 20-tris (2,4,6- trimethoxyphenyl) porphyrin (CP) and the molecular dyad porphyrin-C(60) (P-C(60)), the last two incorporated into liposomal vesicles, was evaluated on Hep-2 human larynx carcinoma cell line. ALA-induced accumulation of the endogenous PS PPIX, reached saturation values between 5 and 24 h incubation time; the maximal PPIX content was 5.7 nmol/106 cells. The same intracellular level was accumulated when the cationic porphyrin CP was used, while the amount of P-C(60) attained was 1.5 nmol/106 cells. Under violet-blue exciting light, the fluorescence of PPIX and P-C(60) was found in the cytoplasm showing a granular appearance indicating lysosomal localization. CP was mainly detected as a filamentous pattern characteristic of mitochondrial localization. No dark cytotoxicity was observed using 1mM ALA, 5 microM CP and 1 microM P-C(60) afte...
Nature, Jan 2, 1998
Energy-transducing membranes of living organisms couple spontaneous to non-spontaneous processes ... more Energy-transducing membranes of living organisms couple spontaneous to non-spontaneous processes through the intermediacy of protonmotive force (p.m.f.)--an imbalance in electrochemical potential of protons across the membrane. In most organisms, p.m.f. is generated by redox reactions that are either photochemically driven, such as those in photosynthetic reaction centres, or intrinsically spontaneous, such as those of oxidative phosphorylation in mitochondria. Transmembrane proteins (such as the cytochromes and complexes I, III and IV in the electron-transport chain in the inner mitochondrial membrane) couple the redox reactions to proton translocation, thereby conserving a fraction of the redox chemical potential as p.m.f. Many transducer proteins couple p.m.f. to the performance of biochemical work, such as biochemical synthesis and mechanical and transport processes. Recently, an artificial photosynthetic membrane was reported in which a photocyclic process was used to transport...
Plants are invaluable sources of pharmaceutical products and Brazil, in particular, has yielded a... more Plants are invaluable sources of pharmaceutical products and Brazil, in particular, has yielded an incredible array of plant and animal products that have drawn the attention of ethnopharmacologists from around the world. Ouratea is a genus of tropical plants within the Ochnaceae. Ouratea is widespread throughtout the tropics, with species in Costa Rica, Brazil, Jamaica, and Kenya. The search for compounds with antimicrobial activity is urgent and indispensable for the treatment of infectious diseases caused by microorganisms resistant to traditional antimicrobial drugs. A screening was conducted with organic extracts from two species, from roots and leaves of Ouratea hexasperma var. planchonii Engl. and leaves and branches of Ouratea parviflora Engl., to identify plant extracts with antifungal properties against Candida albicans. Initially, minimal inhibitory concentrations (MICs) were determined in C. albicans cellular suspension in Sabouraud medium, in a range of 0.060-3.0 mg/ml....
Journal of Physical Chemistry B, 1997
We have used a series of metalloporphyrin compounds to test for a relationship between the contra... more We have used a series of metalloporphyrin compounds to test for a relationship between the contrast of STM images and the electrochemical properties of the molecules. Molecules were tethered to a gold (111) surface by means of an isothiocyano linkage and both ...
Photodiagnosis and Photodynamic Therapy, 2015
The effect of divalent cations, EDTA and chitosan (CS) on the uptake and photoinactivation of Esc... more The effect of divalent cations, EDTA and chitosan (CS) on the uptake and photoinactivation of Escherichia coli produced by 5,10,15,20-tetrakis(4-N,N,N-trimethylammoniumphenyl)porphyrin (TMAP(4+)), 5,10-di(4-methylphenyl)-15,20-di(4-N,N,N-trimethylammoniumphenyl)porphyrin (MPAP(2+)) and 5,10,15,20-tetra(4-sulphonatophenyl)porphyrin (TPPS(4-)) were examined under different conditions. These porphyrins were rapidly bound to E. coli cells (<2.5min) and the uptake of photosensitizers was not dependent on incubation temperature, reaching values of 0.61, 0.18 and 0.08nmol/10(8) cells for TMAP(4+), MPAP(2+) and TPPS(4-), respectively. The addition of Ca(2+) or Mg(2+) to the cultures enhanced the uptake of MPAP(2+) and TPPS(4-) by cells. In contrast, the amount of TMAP(4+) bound to cells was decreased. The presence of EDTA produced an increase in the uptake of porphyrins by cells, while CS mainly enhanced the amount of TPPS(4-) bound to E. coli. The photoinactivation of E. coli cells mediated by TMAP(4+) was highly effective even at low concentration (1μM) and short irradiation period (5min). However, a reduction in the phototoxicity was found for TMAP(4+) in presence of Ca(2+) and Mg(2+). In contrast, the phototoxic activity mediated by MPAP(2+) and TPPS(4-) was increased. Addition of EDTA did not show effect on the photoinactivation induced by cationic porphyrins, while a small enhance was found for TPPS(4-). Moreover, inactivation of E. coli cells was achieved in the presence CS. This cationic polymer was antimicrobial by itself in the dark. Using a slightly toxic CS concentration, the phototoxic activity induced by TMAP(4+) was diminished. This effect was mainly observed at lower concentration of TMAP(4+) (0.5-1μM). In contrast, an increase in E. coli photoinactivation was obtained for MPAP(2+) and TPPS(4-) in presence of CS. Thus, this natural polymeric destabilizer agent mainly benefited the photoinactivation mediated by TPPS(4-).
Journal of Photochemistry and Photobiology A-chemistry, 2008
The interaction of amphiphilic cationic porphyrins, containing different patterns of meso-substit... more The interaction of amphiphilic cationic porphyrins, containing different patterns of meso-substitution by 4-(3-N,N,N-trimethylammoniumpropoxy)phenyl (A) and 4-(trifluoromethyl)phenyl (B) groups, with guanosine 5′-monophosphate (GMP) and calf thymus DNA have been studied by optical methods in phosphate buffer solution. The properties of these synthetic porphyrins were compared with those of representative standard of anionic 5,10,15,20-tetra(4-sulphonatophenyl)porphyrin (TPPS44−) and cationic 5,10,15,20-tetra(4-N,N,N-trimethylammonium phenyl)porphyrin (TMAP4+). Stable complexes
Journal of Organic Chemistry - J ORG CHEM, 1999
ABSTRACT The nucleophilic aromatic substitution SNAr reaction of 1-fluoro-2,4-dinitrobenzene with... more ABSTRACT The nucleophilic aromatic substitution SNAr reaction of 1-fluoro-2,4-dinitrobenzene with n-butylamine and piperidine was studied in n-hexane and AOT/n-hexane/water reverse micelle media. The kinetic profile of the reactions was investigated as a function of variables such as AOT and the amine concentration and the amount of water dispersed in the reverse micelles, W0 = [H2O]/[AOT]. The reactions are faster in the micellar medium than in the pure solvent. The overall reactions are accelerated by increasing the AOT concentration until a value of [AOT] 0.1 M, where saturation in the micellar interface is reached and no further micellar catalysis is observed. The reactions are base catalyzed in n-hexane but not in a micellar medium. Thus, despite the partition of the reactants in both pseudophases the reactions effectively take place at the interface of the aggregates. The kinetic behavior can be quantitatively explained by taking into account the distribution of the substrate and the nucleophile between the bulk solvent and the micelle interface. The results were used to evaluate the amine distribution constant between the micellar pseudophase and organic solvent and the intrinsic second-order rate coefficient of the SNAr reaction in the interface. A mechanism to rationalize the kinetic results is proposed.
The Journal of Physical Chemistry B, 2005
Free-base (P), Zn(II) (P(Zn)), Cu(II) (P(Cu)), Pd(II) (P(Pd)), Ni(II) (P(Ni)), and Co(II) (P(Co))... more Free-base (P), Zn(II) (P(Zn)), Cu(II) (P(Cu)), Pd(II) (P(Pd)), Ni(II) (P(Ni)), and Co(II) (P(Co)) 5-(4-carboxyphenyl)-10,15,20-tris(4-methylphenyl) porphyrins were designed and synthesized to be employed as spectral senzitizers in photoelectrochemical cells. The dyes were studied adsorbed on SnO(2) nanocrystalline semiconductor and also in Langmuir-Blodgett film ITO electrodes in order to disclose the effect of molecular packing on the studied properties. Electron injection yields were obtained by fluorescence quenching analysis comparing with the dyes adsorbed on a SiO(2) nanocrystalline insulator. Back electron-transfer kinetics were measured by using laser flash photolysis. The unmetallized and metallized molecules have different singlet state energies, fluorescence quantum yields, and redox properties. The quantum yields of sensitized photocurrent generation are shown to be highly dependent on the identity of the central metal. It is shown that P(Ni) and P(Co) do not present a photoelectric effect. The other porhyrins present reproducible photocurrent, P(Pd) being the one that gives the highest quantum yield even in closely packet ITO/LB films. Photocurrent quantum yields increase as the dye ground-state oxidation potential becomes more anodic, which is in agreement with the observation, obtained by laser flash photolysis, that back electron-transfer kinetics decrease with the increase in the driving force for the recombination process. This effect could be exploited as a design element in the development of new and better sensitizers for high-efficiency solar cells involving porphyrins and related dyes.
The Journal of Physical Chemistry B, 1999
A conducting atomic force microscope was used to measure the electrical properties of carotenoid ... more A conducting atomic force microscope was used to measure the electrical properties of carotenoid molecules attached to a gold electrode. The thiolated carotene molecules were embedded in insulating n-alkanethiol self-assembled monolayers. At a contact force of a few nanoNewtons, a carotenoid molecule behaves ohmically with a resistance of approximately 4.2 ( 0.7 GΩ, over a million times more conductive than an alkane chain of similar length. Modes of electron transport are discussed.
The Journal of Physical Chemistry B, 2008
The spectroscopic properties and the photodynamic activity of a highly water soluble zinc(II)tetr... more The spectroscopic properties and the photodynamic activity of a highly water soluble zinc(II)tetramethyltetrapyridino[2,3-b:2',3'-g:2",3"-l:2"',3'''-q]porphyrazinium salt (ZnTM2,3PyPz) were investigated in aqueous homogeneous solution and in biomimetic reverse micelles medium bearing photooxidizable biological substrates. Absorption and fluorescence spectroscopic studies indicate that ZnTM2,3PyPz is dissolved as monomer in water and in n-heptane/sodium bis(2-ethylhexyl)sulfosuccinate (AOT, 0.1 M)/water (W0 = 30) micellar system. Fluorescence quantum yields (phi F) of 0.29 and 0.27 were calculated for ZnTM2,3PyPz in water and in AOT micelles, respectively. Spectroscopic analysis at different AOT concentrations showed interaction between ZnTM2,3PyPz and AOT reverse micelles with a binding constant (Kb) of 1.7 x 10(3) M(-1). The photosensitization ability of ZnTM2,3PyPz was evaluated using 9,10-dimethylanthracene (DMA). Singlet molecular oxygen, O2(1 delta g), production yielded values of phi(delta) = 0.65 for ZnTM2,3PyPz in AOT micelles. Also, ZnTM2,3PyPz induced efficiently the decomposition of the amino acid L-tryptophan (Trp) and the nucleotide guanosine 5'-monophosphate (GMP) in both media. A value of approximately 3.6 x 10(7) s(-1) M(-1) was found for the second order rate constant of Trp (k(r)(Trp)) decomposition in the AOT system, which is near to that found in pure water. Moreover, ZnTM2,3PyPz formed stable complexes with GMP with a binding constant of K(GMP) = 1.0 x 10(3) M(-1). 1H NMR studies indicated that ZnTM2,3PyPz interacts mainly with the guanine moiety more than the sugar part of GMP. On the other hand, the photodynamic activity of ZnTM2,3PyPz produced decomposition of GMP. Quantification of GMP by HPLC indicates that the nucleotide is photooxidized with a k(obs)(GMP) = 2.6 x 10(-4) s(-1) in water. Photooxidation of GMP considerably increases in deuteriated water indicating that ZnTM2,3PyPz appears to perform its photosensitizing action via the intermediacy of O2(1delta g). Also, efficient sensitized decomposition was observed in micellar media resembling that in pure water. These results provide a better understanding of the effective photodynamic action produced by ZnTM2,3PyPz like a potential phototherapeutic agent for the treatment of neoplastic diseases by photodynamic therapy.
Journal of Physical Chemistry B, 2002
The generation of photoelectrical effects through the spectral sensitization of wide band gap (Sn... more The generation of photoelectrical effects through the spectral sensitization of wide band gap (SnO 2 ) nanostructured semiconductor electrode by the excitation of a novel porphyrin-fullerene (P-C 60 ) dyad is reported. P-C 60 was synthesized from 5-(4-amidophenyl)-10,15,20-tris(4-methoxylphenyl) porphyrin (P) linked to 1,2-dihydro-1,2-methoxyphenyl [60]-61-carboxilic acid (acid-C 60 ) by an amide bond. Anodic photocurrents and photovoltages are observed under visible irradiation of ITO/SnO 2 / P-C 60 electrodes, although the porphyrin fluorescence is strongly quenched by the C 60 moiety in the dyad. The photocurrent generation quantum yield of the dyad P-C 60 is around twice higher than the yield of the porphyrin moiety at the same wavelength (Soret band). A mechanism involving the formation of an intramolecular photoinduced charge-transfer state is proposed to explain the efficiency in the generation of photoelectrical effect. Figure 1. Structures of the dyad P-C60 and its monomers.
The Journal of Physical Chemistry B, 2001
... This was inferred by comparing the experimental current function (i pI /ACv 1/2 , where A is ... more ... This was inferred by comparing the experimental current function (i pI /ACv 1/2 , where A is the electrode area and C is the H 2 APC concentration) with that obtained for N,N,N',N'-tetramethyl-1,1'-naphthidine (TMN), which gives a well-characterized two-electron oxidation wave. ...
The International Journal of Biochemistry & Cell Biology, 2006
The photokilling activity of a porphyrin-C(60) (P-C(60)) dyad was evaluated on a Hep-2 human lary... more The photokilling activity of a porphyrin-C(60) (P-C(60)) dyad was evaluated on a Hep-2 human larynx-carcinoma cell line. This study represents the first evaluation of a dyad, with high capacity to form a photoinduced charge-separated state, to act as agent to inactivate cells by photodynamic therapy (PDT). Cell treatment was carried out with 1 microM P-C(60) incorporated into liposomal vesicles. No dark cytotoxicity was observed using 1 microM P-C(60) concentration and during long incubation time (24h). The uptake of sensitizer into Hep-2 was studied at different times of incubation. Under these conditions, a value of 1.5 nmol/10(6)cells was found after 4h of incubation showing practically no change even after 24h. The cell survival after irradiation of the cells with visible light was dependent upon light exposure level. A high photocytotoxic effect was observed for P-C(60), which inactivated 80% of the cells after 54 J/cm(2) of irradiation. Moreover, the dyad kept a high photoactivity even under argon atmosphere. Thus, depending on the microenvironment where the sensitizer is localized, this compound could produce a biological photodamage through either a (1)O(2)-mediated photoreaction process or a free radical mechanism under low oxygen concentration. The mechanism of cell death was analyzed by Hoechst-33258, toluidine blue staining, TUNEL and DNA fragmentation. Cell cultures treated for 24h with P-C(60) and irradiated with a dose of 54 J/cm(2) showed a great amount of apoptotic cells (58%). Moreover, changes in cell morphology were analyzed using fluorescence microscopy with Hoechst-33258 under low oxygen concentration. Under this anaerobic condition, necrotic cellular death predominated on apoptotic pathway. There were more apoptotic cells under air irradiation condition than under argon irradiation condition. To determine the apoptotic pathway, caspase-3 activation was studied by caspase-3 activity detection kits. The last results showed that P-C(60) induced apoptosis by caspase-3-dependent pathway. These results indicated that molecular dyad, which can form a photoinduced charge-separated state, is a promising model for phototherapeutic agents and they have potential application in cell inactivation by PDT.
The International Journal of Biochemistry & Cell Biology, 2005
The photokilling activity of 5-(4-trimethylammoniumphenyl)-10,15,20-tris(2,4,6-trimethoxyphenyl)p... more The photokilling activity of 5-(4-trimethylammoniumphenyl)-10,15,20-tris(2,4,6-trimethoxyphenyl)porphyrin (CP) was evaluated on a Hep-2 human larynx-carcinoma cell line. Cell treatment was carried out with 5 microM CP incorporated into liposomal vesicles. Under violet-blue exciting light, the red fluorescence of CP was mainly detected as a filamentous pattern characteristic of mitochondrial localization. Similar pattern was also observed using rhodamine 123 in Hep-2 cells. No dark cytotoxicity was observed using 5 microM CP concentration and long incubation time (24 h). Using Hoechst-33258 and caspase-3 immunostaining methods, cell cultures treated for 24 h with CP and exposed to light for 7.5 min (27 J/cm2) showed a great amount of apoptotic cells (40%). In contrast, necrotic cells (58%) were observed using the same drug concentration but irradiated for 15 min (54 J/cm2). The results show that CP can induce different mechanisms of cell death depending on irradiation doses in the photodynamic treatments, which makes this agent an interesting sensitizer with potential application in photodynamic tumor therapy.
Synthetic Communications, 1996
Page 1. SYNTHETIC COMMUNICATIONS, 26(20), 3849-3858 (1996) SYNTHESIS OF SUBSTITUTED DIPHENYLAMMES... more Page 1. SYNTHETIC COMMUNICATIONS, 26(20), 3849-3858 (1996) SYNTHESIS OF SUBSTITUTED DIPHENYLAMMES UNDER PHASE TRANSFER CATALYSIS Edgardo N. Durantini, Stella M. Chiacchiera and Juana J. Silber ...
Synthetic Communications, 1999
... Braz. Chem. SOC. 1996, 7, 19. 9. Gust, D.; Moore, T. A.; Moore, A. L.; Liddel, P. A. Methods ... more ... Braz. Chem. SOC. 1996, 7, 19. 9. Gust, D.; Moore, T. A.; Moore, A. L.; Liddel, P. A. Methods of Enzymology 1992,115,2081. 10. Lee CH.; Lindsey, J. S . ; Tetrahedron 1994,50, 11427. 11. Wallace, DM; Leung, S. H.; Senge, M. 0.; Smith, KM; J Org, Chem. 1993.58,7245. 12. ...
Photochemistry and Photobiology, 2004
The photodynamic activities of novel asymmetrically meso-substituted cationic porphyrins, 5,10-di... more The photodynamic activities of novel asymmetrically meso-substituted cationic porphyrins, 5,10-di(4-methylphenyl)-15,20-di(4-trimethylammoniumphenyl)porphyrin iodide 1 and 5-(4-trifluorophenyl)-10,15,20-tris(4-trimethylammoniumphenyl)porphyrin iodide 2 and its metal complex with Pd(II) 3, have been investigated in both homogeneous medium bearing photooxidizable substrates and in vitro on a typical gram-negative bacterium Escherichia coli. The amphiphilic character of porphyrin 2 was increased by the presence of a high-lipophilic trifluoromethyl group and its photophysical properties changed by forming a complex with Pd(II). Absorption and fluorescence spectroscopic studies were compared in different media. Fluorescence quantum yields (phi(F)) of 0.16 for 1 in tetrahydrofuran and 0.08 for 2 in N, N-dimethylformamide (DMF) were calculated, whereas no significant emission was detected for Pd(II) porphyrin 3. The singlet molecular oxygen, O(2)((1)Delta(g)), production was evaluated using 9,10-dimethylanthracene in DMF yielding relative values of 1, 0.55 and 0.47 for porphyrins 3, 2 and 1, respectively. A faster decomposition of l-tryptophan was obtained using Pd(II) porphyrin 3 as sensitizer with respect to the free-base porphyrins 1 and 2. In biological medium, the behavior of cationic porphyrins 1-3 were compared with that of 5-(4-carboxyphenyl)-10,15,20-tris(4-methylphenyl)porphyrin 4, which was used as a noncationic sensitizer. These porphyrins are rapidly bound to E. coli cells in 5 min and the amount of cell-bound sensitizer is not appreciably changed incubating the cultures for longer times. The recovered porphyrin 2 after one washing step reaches a value of approximately 2.9 nmol/10(6) cells and this amount remains high even after three washes, indicating that this sensitizer is tightly bound to cells. Photosensitized inactivation of E. coli was analyzed using cells without and with one washing step. In both cases, a higher photoinactivation of cells was found for tricationic porphyrin 2 and 3, causing a approximately 5.5 log (99.999%) decrease of cell survival, when treated with 10 microM of sensitizer. Under these conditions, a lower effect was found for porphyrin 1 (approximately 4 log) whereas sensitizer 4 did not produce appreciable photodamage. The results were also confirmed by growth delay experiments. These studies show that the amphiphilic tricationic porphyrin 2 and 3 bearing a trifluoromethyl group can be a promising model for phototherapeutic agents with potential applications in inactivation of bacteria by photodynamic therapy.
Photochemistry and Photobiology, 2015
The photoreaction type I/type II pathways mediated by zinc(II) 2,9,16,23-tetrakis[4-(N-methylpyri... more The photoreaction type I/type II pathways mediated by zinc(II) 2,9,16,23-tetrakis[4-(N-methylpyridyloxy)]phthalocyanine (ZnPPc(4+) ) was studied in Candida albicans cells. This photosensitizer was strongly bound to C. albicans cells at short times. After 30 min irradiation, 5 μM ZnPPc(4+) produced ~5 log decrease in cell viability. Different probes were used to detect reactive oxygen species (ROS) in cell suspensions (~10(6) CFU mL(-1) ). Singlet molecular oxygen, O2 ((1) Δg ), was observed by the reaction with 9,10-dimethylanthracene (DMA) and tetrasodium 2,2-(anthracene-9,10-diyl)bis(methylmalonate) (ABMM), whereas the nitro blue tetrazolium (NBT) method was used to sense superoxide anion radical (O2·-). Moreover, the effects produced by an anoxic atmosphere and cell suspensions in D2 O, as well as the addition of sodium azide and mannitol as ROS trapping were evaluated in the PDI of C. albicans. These investigation indicates that O2 ((1) Δg ) is generated in the cells, although a minor extension other radical species can also be involved in the PDI of C. albicans mediated by ZnPPc(4+) .
Electrochimica Acta, 2015
ABSTRACT A photoactive interface is formed between an electrochemical generated organic polymer f... more ABSTRACT A photoactive interface is formed between an electrochemical generated organic polymer film and CdSe quantum dots. The specifically designed and synthesized 3,4 ethylenedioxythiophene electroactive monomer, holding C60 buckminsterfullerene, allows the formation of thin films containing both, electron acceptor and hole transport moieties. The generation of photoinduced heterogeneous charge transfer in CdSe quantum dots-electropolymer system was characterized by time resolved and spectral dependent surface photovoltage. In films containing C60 moieties whose surface was modified with 5 nm CdSe quantum dots, the illumination generated photovoltage values around twenty times larger than those obtained without nanoparticles decoration. The results show that this organic-inorganic hybrid interface is a potential structure for the development of optoelectronic devices.
Journal of the Chemical Society, Perkin Transactions 2, 1996
Cellular and molecular biology (Noisy-le-Grand, France), 2009
The photodynamic activity of three photosensitizers (PS): AL-induced PPIX, the porphyrin derivati... more The photodynamic activity of three photosensitizers (PS): AL-induced PPIX, the porphyrin derivative 5-(4-trimethylammoniumphenyl)-10, 5, 20-tris (2,4,6- trimethoxyphenyl) porphyrin (CP) and the molecular dyad porphyrin-C(60) (P-C(60)), the last two incorporated into liposomal vesicles, was evaluated on Hep-2 human larynx carcinoma cell line. ALA-induced accumulation of the endogenous PS PPIX, reached saturation values between 5 and 24 h incubation time; the maximal PPIX content was 5.7 nmol/106 cells. The same intracellular level was accumulated when the cationic porphyrin CP was used, while the amount of P-C(60) attained was 1.5 nmol/106 cells. Under violet-blue exciting light, the fluorescence of PPIX and P-C(60) was found in the cytoplasm showing a granular appearance indicating lysosomal localization. CP was mainly detected as a filamentous pattern characteristic of mitochondrial localization. No dark cytotoxicity was observed using 1mM ALA, 5 microM CP and 1 microM P-C(60) afte...
Nature, Jan 2, 1998
Energy-transducing membranes of living organisms couple spontaneous to non-spontaneous processes ... more Energy-transducing membranes of living organisms couple spontaneous to non-spontaneous processes through the intermediacy of protonmotive force (p.m.f.)--an imbalance in electrochemical potential of protons across the membrane. In most organisms, p.m.f. is generated by redox reactions that are either photochemically driven, such as those in photosynthetic reaction centres, or intrinsically spontaneous, such as those of oxidative phosphorylation in mitochondria. Transmembrane proteins (such as the cytochromes and complexes I, III and IV in the electron-transport chain in the inner mitochondrial membrane) couple the redox reactions to proton translocation, thereby conserving a fraction of the redox chemical potential as p.m.f. Many transducer proteins couple p.m.f. to the performance of biochemical work, such as biochemical synthesis and mechanical and transport processes. Recently, an artificial photosynthetic membrane was reported in which a photocyclic process was used to transport...
Plants are invaluable sources of pharmaceutical products and Brazil, in particular, has yielded a... more Plants are invaluable sources of pharmaceutical products and Brazil, in particular, has yielded an incredible array of plant and animal products that have drawn the attention of ethnopharmacologists from around the world. Ouratea is a genus of tropical plants within the Ochnaceae. Ouratea is widespread throughtout the tropics, with species in Costa Rica, Brazil, Jamaica, and Kenya. The search for compounds with antimicrobial activity is urgent and indispensable for the treatment of infectious diseases caused by microorganisms resistant to traditional antimicrobial drugs. A screening was conducted with organic extracts from two species, from roots and leaves of Ouratea hexasperma var. planchonii Engl. and leaves and branches of Ouratea parviflora Engl., to identify plant extracts with antifungal properties against Candida albicans. Initially, minimal inhibitory concentrations (MICs) were determined in C. albicans cellular suspension in Sabouraud medium, in a range of 0.060-3.0 mg/ml....
Journal of Physical Chemistry B, 1997
We have used a series of metalloporphyrin compounds to test for a relationship between the contra... more We have used a series of metalloporphyrin compounds to test for a relationship between the contrast of STM images and the electrochemical properties of the molecules. Molecules were tethered to a gold (111) surface by means of an isothiocyano linkage and both ...
Photodiagnosis and Photodynamic Therapy, 2015
The effect of divalent cations, EDTA and chitosan (CS) on the uptake and photoinactivation of Esc... more The effect of divalent cations, EDTA and chitosan (CS) on the uptake and photoinactivation of Escherichia coli produced by 5,10,15,20-tetrakis(4-N,N,N-trimethylammoniumphenyl)porphyrin (TMAP(4+)), 5,10-di(4-methylphenyl)-15,20-di(4-N,N,N-trimethylammoniumphenyl)porphyrin (MPAP(2+)) and 5,10,15,20-tetra(4-sulphonatophenyl)porphyrin (TPPS(4-)) were examined under different conditions. These porphyrins were rapidly bound to E. coli cells (<2.5min) and the uptake of photosensitizers was not dependent on incubation temperature, reaching values of 0.61, 0.18 and 0.08nmol/10(8) cells for TMAP(4+), MPAP(2+) and TPPS(4-), respectively. The addition of Ca(2+) or Mg(2+) to the cultures enhanced the uptake of MPAP(2+) and TPPS(4-) by cells. In contrast, the amount of TMAP(4+) bound to cells was decreased. The presence of EDTA produced an increase in the uptake of porphyrins by cells, while CS mainly enhanced the amount of TPPS(4-) bound to E. coli. The photoinactivation of E. coli cells mediated by TMAP(4+) was highly effective even at low concentration (1μM) and short irradiation period (5min). However, a reduction in the phototoxicity was found for TMAP(4+) in presence of Ca(2+) and Mg(2+). In contrast, the phototoxic activity mediated by MPAP(2+) and TPPS(4-) was increased. Addition of EDTA did not show effect on the photoinactivation induced by cationic porphyrins, while a small enhance was found for TPPS(4-). Moreover, inactivation of E. coli cells was achieved in the presence CS. This cationic polymer was antimicrobial by itself in the dark. Using a slightly toxic CS concentration, the phototoxic activity induced by TMAP(4+) was diminished. This effect was mainly observed at lower concentration of TMAP(4+) (0.5-1μM). In contrast, an increase in E. coli photoinactivation was obtained for MPAP(2+) and TPPS(4-) in presence of CS. Thus, this natural polymeric destabilizer agent mainly benefited the photoinactivation mediated by TPPS(4-).
Journal of Photochemistry and Photobiology A-chemistry, 2008
The interaction of amphiphilic cationic porphyrins, containing different patterns of meso-substit... more The interaction of amphiphilic cationic porphyrins, containing different patterns of meso-substitution by 4-(3-N,N,N-trimethylammoniumpropoxy)phenyl (A) and 4-(trifluoromethyl)phenyl (B) groups, with guanosine 5′-monophosphate (GMP) and calf thymus DNA have been studied by optical methods in phosphate buffer solution. The properties of these synthetic porphyrins were compared with those of representative standard of anionic 5,10,15,20-tetra(4-sulphonatophenyl)porphyrin (TPPS44−) and cationic 5,10,15,20-tetra(4-N,N,N-trimethylammonium phenyl)porphyrin (TMAP4+). Stable complexes
Journal of Organic Chemistry - J ORG CHEM, 1999
ABSTRACT The nucleophilic aromatic substitution SNAr reaction of 1-fluoro-2,4-dinitrobenzene with... more ABSTRACT The nucleophilic aromatic substitution SNAr reaction of 1-fluoro-2,4-dinitrobenzene with n-butylamine and piperidine was studied in n-hexane and AOT/n-hexane/water reverse micelle media. The kinetic profile of the reactions was investigated as a function of variables such as AOT and the amine concentration and the amount of water dispersed in the reverse micelles, W0 = [H2O]/[AOT]. The reactions are faster in the micellar medium than in the pure solvent. The overall reactions are accelerated by increasing the AOT concentration until a value of [AOT] 0.1 M, where saturation in the micellar interface is reached and no further micellar catalysis is observed. The reactions are base catalyzed in n-hexane but not in a micellar medium. Thus, despite the partition of the reactants in both pseudophases the reactions effectively take place at the interface of the aggregates. The kinetic behavior can be quantitatively explained by taking into account the distribution of the substrate and the nucleophile between the bulk solvent and the micelle interface. The results were used to evaluate the amine distribution constant between the micellar pseudophase and organic solvent and the intrinsic second-order rate coefficient of the SNAr reaction in the interface. A mechanism to rationalize the kinetic results is proposed.
The Journal of Physical Chemistry B, 2005
Free-base (P), Zn(II) (P(Zn)), Cu(II) (P(Cu)), Pd(II) (P(Pd)), Ni(II) (P(Ni)), and Co(II) (P(Co))... more Free-base (P), Zn(II) (P(Zn)), Cu(II) (P(Cu)), Pd(II) (P(Pd)), Ni(II) (P(Ni)), and Co(II) (P(Co)) 5-(4-carboxyphenyl)-10,15,20-tris(4-methylphenyl) porphyrins were designed and synthesized to be employed as spectral senzitizers in photoelectrochemical cells. The dyes were studied adsorbed on SnO(2) nanocrystalline semiconductor and also in Langmuir-Blodgett film ITO electrodes in order to disclose the effect of molecular packing on the studied properties. Electron injection yields were obtained by fluorescence quenching analysis comparing with the dyes adsorbed on a SiO(2) nanocrystalline insulator. Back electron-transfer kinetics were measured by using laser flash photolysis. The unmetallized and metallized molecules have different singlet state energies, fluorescence quantum yields, and redox properties. The quantum yields of sensitized photocurrent generation are shown to be highly dependent on the identity of the central metal. It is shown that P(Ni) and P(Co) do not present a photoelectric effect. The other porhyrins present reproducible photocurrent, P(Pd) being the one that gives the highest quantum yield even in closely packet ITO/LB films. Photocurrent quantum yields increase as the dye ground-state oxidation potential becomes more anodic, which is in agreement with the observation, obtained by laser flash photolysis, that back electron-transfer kinetics decrease with the increase in the driving force for the recombination process. This effect could be exploited as a design element in the development of new and better sensitizers for high-efficiency solar cells involving porphyrins and related dyes.
The Journal of Physical Chemistry B, 1999
A conducting atomic force microscope was used to measure the electrical properties of carotenoid ... more A conducting atomic force microscope was used to measure the electrical properties of carotenoid molecules attached to a gold electrode. The thiolated carotene molecules were embedded in insulating n-alkanethiol self-assembled monolayers. At a contact force of a few nanoNewtons, a carotenoid molecule behaves ohmically with a resistance of approximately 4.2 ( 0.7 GΩ, over a million times more conductive than an alkane chain of similar length. Modes of electron transport are discussed.
The Journal of Physical Chemistry B, 2008
The spectroscopic properties and the photodynamic activity of a highly water soluble zinc(II)tetr... more The spectroscopic properties and the photodynamic activity of a highly water soluble zinc(II)tetramethyltetrapyridino[2,3-b:2',3'-g:2",3"-l:2"',3'''-q]porphyrazinium salt (ZnTM2,3PyPz) were investigated in aqueous homogeneous solution and in biomimetic reverse micelles medium bearing photooxidizable biological substrates. Absorption and fluorescence spectroscopic studies indicate that ZnTM2,3PyPz is dissolved as monomer in water and in n-heptane/sodium bis(2-ethylhexyl)sulfosuccinate (AOT, 0.1 M)/water (W0 = 30) micellar system. Fluorescence quantum yields (phi F) of 0.29 and 0.27 were calculated for ZnTM2,3PyPz in water and in AOT micelles, respectively. Spectroscopic analysis at different AOT concentrations showed interaction between ZnTM2,3PyPz and AOT reverse micelles with a binding constant (Kb) of 1.7 x 10(3) M(-1). The photosensitization ability of ZnTM2,3PyPz was evaluated using 9,10-dimethylanthracene (DMA). Singlet molecular oxygen, O2(1 delta g), production yielded values of phi(delta) = 0.65 for ZnTM2,3PyPz in AOT micelles. Also, ZnTM2,3PyPz induced efficiently the decomposition of the amino acid L-tryptophan (Trp) and the nucleotide guanosine 5'-monophosphate (GMP) in both media. A value of approximately 3.6 x 10(7) s(-1) M(-1) was found for the second order rate constant of Trp (k(r)(Trp)) decomposition in the AOT system, which is near to that found in pure water. Moreover, ZnTM2,3PyPz formed stable complexes with GMP with a binding constant of K(GMP) = 1.0 x 10(3) M(-1). 1H NMR studies indicated that ZnTM2,3PyPz interacts mainly with the guanine moiety more than the sugar part of GMP. On the other hand, the photodynamic activity of ZnTM2,3PyPz produced decomposition of GMP. Quantification of GMP by HPLC indicates that the nucleotide is photooxidized with a k(obs)(GMP) = 2.6 x 10(-4) s(-1) in water. Photooxidation of GMP considerably increases in deuteriated water indicating that ZnTM2,3PyPz appears to perform its photosensitizing action via the intermediacy of O2(1delta g). Also, efficient sensitized decomposition was observed in micellar media resembling that in pure water. These results provide a better understanding of the effective photodynamic action produced by ZnTM2,3PyPz like a potential phototherapeutic agent for the treatment of neoplastic diseases by photodynamic therapy.
Journal of Physical Chemistry B, 2002
The generation of photoelectrical effects through the spectral sensitization of wide band gap (Sn... more The generation of photoelectrical effects through the spectral sensitization of wide band gap (SnO 2 ) nanostructured semiconductor electrode by the excitation of a novel porphyrin-fullerene (P-C 60 ) dyad is reported. P-C 60 was synthesized from 5-(4-amidophenyl)-10,15,20-tris(4-methoxylphenyl) porphyrin (P) linked to 1,2-dihydro-1,2-methoxyphenyl [60]-61-carboxilic acid (acid-C 60 ) by an amide bond. Anodic photocurrents and photovoltages are observed under visible irradiation of ITO/SnO 2 / P-C 60 electrodes, although the porphyrin fluorescence is strongly quenched by the C 60 moiety in the dyad. The photocurrent generation quantum yield of the dyad P-C 60 is around twice higher than the yield of the porphyrin moiety at the same wavelength (Soret band). A mechanism involving the formation of an intramolecular photoinduced charge-transfer state is proposed to explain the efficiency in the generation of photoelectrical effect. Figure 1. Structures of the dyad P-C60 and its monomers.
The Journal of Physical Chemistry B, 2001
... This was inferred by comparing the experimental current function (i pI /ACv 1/2 , where A is ... more ... This was inferred by comparing the experimental current function (i pI /ACv 1/2 , where A is the electrode area and C is the H 2 APC concentration) with that obtained for N,N,N',N'-tetramethyl-1,1'-naphthidine (TMN), which gives a well-characterized two-electron oxidation wave. ...
The International Journal of Biochemistry & Cell Biology, 2006
The photokilling activity of a porphyrin-C(60) (P-C(60)) dyad was evaluated on a Hep-2 human lary... more The photokilling activity of a porphyrin-C(60) (P-C(60)) dyad was evaluated on a Hep-2 human larynx-carcinoma cell line. This study represents the first evaluation of a dyad, with high capacity to form a photoinduced charge-separated state, to act as agent to inactivate cells by photodynamic therapy (PDT). Cell treatment was carried out with 1 microM P-C(60) incorporated into liposomal vesicles. No dark cytotoxicity was observed using 1 microM P-C(60) concentration and during long incubation time (24h). The uptake of sensitizer into Hep-2 was studied at different times of incubation. Under these conditions, a value of 1.5 nmol/10(6)cells was found after 4h of incubation showing practically no change even after 24h. The cell survival after irradiation of the cells with visible light was dependent upon light exposure level. A high photocytotoxic effect was observed for P-C(60), which inactivated 80% of the cells after 54 J/cm(2) of irradiation. Moreover, the dyad kept a high photoactivity even under argon atmosphere. Thus, depending on the microenvironment where the sensitizer is localized, this compound could produce a biological photodamage through either a (1)O(2)-mediated photoreaction process or a free radical mechanism under low oxygen concentration. The mechanism of cell death was analyzed by Hoechst-33258, toluidine blue staining, TUNEL and DNA fragmentation. Cell cultures treated for 24h with P-C(60) and irradiated with a dose of 54 J/cm(2) showed a great amount of apoptotic cells (58%). Moreover, changes in cell morphology were analyzed using fluorescence microscopy with Hoechst-33258 under low oxygen concentration. Under this anaerobic condition, necrotic cellular death predominated on apoptotic pathway. There were more apoptotic cells under air irradiation condition than under argon irradiation condition. To determine the apoptotic pathway, caspase-3 activation was studied by caspase-3 activity detection kits. The last results showed that P-C(60) induced apoptosis by caspase-3-dependent pathway. These results indicated that molecular dyad, which can form a photoinduced charge-separated state, is a promising model for phototherapeutic agents and they have potential application in cell inactivation by PDT.
The International Journal of Biochemistry & Cell Biology, 2005
The photokilling activity of 5-(4-trimethylammoniumphenyl)-10,15,20-tris(2,4,6-trimethoxyphenyl)p... more The photokilling activity of 5-(4-trimethylammoniumphenyl)-10,15,20-tris(2,4,6-trimethoxyphenyl)porphyrin (CP) was evaluated on a Hep-2 human larynx-carcinoma cell line. Cell treatment was carried out with 5 microM CP incorporated into liposomal vesicles. Under violet-blue exciting light, the red fluorescence of CP was mainly detected as a filamentous pattern characteristic of mitochondrial localization. Similar pattern was also observed using rhodamine 123 in Hep-2 cells. No dark cytotoxicity was observed using 5 microM CP concentration and long incubation time (24 h). Using Hoechst-33258 and caspase-3 immunostaining methods, cell cultures treated for 24 h with CP and exposed to light for 7.5 min (27 J/cm2) showed a great amount of apoptotic cells (40%). In contrast, necrotic cells (58%) were observed using the same drug concentration but irradiated for 15 min (54 J/cm2). The results show that CP can induce different mechanisms of cell death depending on irradiation doses in the photodynamic treatments, which makes this agent an interesting sensitizer with potential application in photodynamic tumor therapy.
Synthetic Communications, 1996
Page 1. SYNTHETIC COMMUNICATIONS, 26(20), 3849-3858 (1996) SYNTHESIS OF SUBSTITUTED DIPHENYLAMMES... more Page 1. SYNTHETIC COMMUNICATIONS, 26(20), 3849-3858 (1996) SYNTHESIS OF SUBSTITUTED DIPHENYLAMMES UNDER PHASE TRANSFER CATALYSIS Edgardo N. Durantini, Stella M. Chiacchiera and Juana J. Silber ...
Synthetic Communications, 1999
... Braz. Chem. SOC. 1996, 7, 19. 9. Gust, D.; Moore, T. A.; Moore, A. L.; Liddel, P. A. Methods ... more ... Braz. Chem. SOC. 1996, 7, 19. 9. Gust, D.; Moore, T. A.; Moore, A. L.; Liddel, P. A. Methods of Enzymology 1992,115,2081. 10. Lee CH.; Lindsey, J. S . ; Tetrahedron 1994,50, 11427. 11. Wallace, DM; Leung, S. H.; Senge, M. 0.; Smith, KM; J Org, Chem. 1993.58,7245. 12. ...