Showing papers on "Porphyrin published in 1986"
TL;DR: The literature in the field of porphyrin photosensitization has been growing with an increasing rate since the last yearly review on the topic was published in this journal, and this field will receive significant attention in the present review.
Abstract: The literature in the field of porphyrin photosensitization has been growing with an increasing rate since the last yearly review on the topic was published in this journal (Kessel, 1984). The reason for this growth is mainly to be found in the development of photodynamic cancer therapy (PDT), and this field will receive significant attention in the present review, which mainly covers the period July 1984December 1985. During this period several reviews have appeared on the same or closely related topics (Jori and Spikes, 1984; Dougherty, 1984; Spikes, 1984; Spikes, 1985; Spikes and Straight, 1985) and I will try not to overlap these reviews too much. A more complete list of recent, as well as older literature, can be found elsewhere (Kessel, 1985).
303 citations
TL;DR: In this paper, the reaction conditions of pyrrole and an aromatic aldehyde at room temperature affords the corresponding tetraarylporphyrinogen in high yield at thermodynamic equilibrium.
282 citations
TL;DR: In this paper, a polycarbonate aliphatique de distribution etroite controlee par copolymerisation vivante et alternee is presented as an example.
Abstract: Premier exemple d'obtention d'un polycarbonate aliphatique de distribution etroite controlee par copolymerisation vivante et alternee
207 citations
TL;DR: The present work demonstrates unambiguously that a short, ca.
Abstract: Extended X-ray absorption fine structure spectroscopy has been utilized to determine the structural environment of the heme iron sites in horseradish peroxidase compounds I and II. For comparison, analogous studies have been undertaken on putative ferryl (Fe/sup IV/=O) porphyrin model compounds and on crystallographically characterized Cr/sup IV/=O and Cr/sup V/ identical with N porphyrins. In a preliminary communication, they suggested that a short ca. 1.6 A Fe-O bond is present in the high valent forms of both the enzyme and the synthetic porphyrins. The present work demonstrates unambiguously that a short, ca. 1.64 A, Fe-O bond length is present both in HRP compounds I and II and in their synthetic analogues. This structure is consistent only with an oxo-ferryl (Fe=O) complex as the active oxygen species in horseradish peroxidase. The structural details, their implications for heme protein mediated oxygen activation, and the difference between their results and those recently published by other workers.
202 citations
136 citations
TL;DR: Cells of the line NHIK 3025 were incubated with the tumor-localizing porphyrin preparation DHE (Photofrin II) and several independent estimations indicate that bleaching may play a role in clinical situations.
131 citations
TL;DR: The higher efficiency of cationic porphyrins (as compared to anionic ones) is due to their greater affinity for DNA as shown by experiments carried out at either high ionic strength or in the presence of the surfactant, sodium dodecyl sulfate.
Abstract: In the presence of oxygen and visible light, various synthetic water-soluble porphyrins cleave pBR 322 plasmid supercoiled DNA (form I) producing relaxed (form II) and linear (form III) DNA corresponding to single-strand and double-strand breaks respectively. Large variations are observed in the efficiency of the porphyrins containing a diamagnetic metal or no metal at all. Singlet oxygen (1O2) seems to be involved in the mechanism of cleavage consistent with the inhibitory effect of the azide anion, N–3. The higher efficiency of cationic porphyrins (as compared to anionic ones) is due to their greater affinity for DNA as shown by experiments carried out at either high ionic strength or in the presence of the surfactant, sodium dodecyl sulfate.
124 citations
114 citations
TL;DR: The results indicate that porphyrins produced by the bacteria are important for the light sensitivity of these bacteria.
Abstract: —Propionibacterium acnes (P. acnes), grown on Eagles medium with different pH. were irradiated with monochromatic light in the range 320 to 440 nm. Different pH leads to different porphyrin concentrations in the cells. The light sensitivity of the bacteria was estimated from the reduction in their ability to form colonies after radiation. The sensitivity was highest for the lowest wavelength (320 nm). and decreased continuously with increasing wavelength up to 380 nm. In the region between 380 and 440 nm there was a second maximum (at 415 nm) which corresponds to the maximum absorption ol the fluorescing porphyrins in P. acnes. The sensitivity to 415 nm light was found to be dependent on the endogenous porphyrin concentration in the cells. while the sensitivity to 320 nm radiation was independent of the amount of porphyrin present. These results indicate that porphyrins produced by the bacteria are important for the light sensitivity of these bacteria.
111 citations
TL;DR: In this paper, different anion selectivities were observed for the Co(III and Mn(III) porphyrins for different anions in the 5,10,15,20,20-tetrakis [4-(hexyloxycarbonyl)phenyl]porphyrin.
Abstract: Lipophilic Co(III) and Mn(III) complexes of 5,10,15,20-tetrakis[4-(hexyloxycarbonyl)phenyl]porphyrin act as positively charged carriers for anions and induce anion selectivities in membranes clearly deviating from the sequence of classical anion exchangers. Different anion selectivities are observed for the Co(III) and Mn(III) porphyrins.
110 citations
TL;DR: The effects of hydrophobicity and charges of dicarboxylic porphyrins upon their interactions with membrane model systems are investigated and the hypothesis of a possible role of pH in the preferential uptake of p Morphyrins by tumors is discussed.
TL;DR: The efficiency of several porphyrins at 10 μM and 83 μM as sensitizers of the photooxidation of 0.1 mM tryptophan and histidine via a singlet oxygen‐mechanism was studied and laser flash photolysis studies showed that the micelle‐incorporation of the above mentioned porphyrs brought about only minor changes in their photophysical properties, including the relative yield of O2(1Δg) generation.
Abstract: The efficiency of several porphyrins at 10 μM and 83 μM as sensitizers of the photooxidation of 0.1 mM tryptophan and histidine via a singlet oxygen-mechanism was studied in pH 7.4-buffered aqueous solutions and in aqueous dispersions of Triton X-100 micelles. The porphyrins were either solubilized in the bulk aqueous medium or associated with the micellar phase, whereas the amino acids were always located in the aqueous phase. With those porphyrins, such as uroporphyrin I, meso-tetra (4-sulfonatophenyl)porphine, meso-tetra(4-carboxyphenyl)porphine and meso-tetra)N,N,N-trimethylanilinium)porphine, which are > 98% monomeric in both media, the efficiency of histidine photooxidation was independent of the site of O2(1Δg) generation, as shown by the closely similar values for the photooxidation rate constant and oxygen-consumption quantum yield in the presence and absence of Triton micelles; the same indications were provided by photokinetic experiments with tryptophan. Actually, laser flash photolysis studies showed that the micelle-incorporation of the above mentioned porphyrins brought about only minor changes in their photophysical properties, including the relative yield of O2(1Δg) generation. On the other hand, hematoporphyrin IX, its Zn2+-complex, and coproporphyrin III are largely aggregated in homogeneous aqueous solution; their incorporation into Triton micelles caused an increase of the triplet quantum yield and an enhancement of the oxygen-consumption quantum yield and photooxidation rate constant for both histidine and tryptophan. The lower photosensitizing efficiency of aggregated porphyrin species in comparison with the corresponding monomeric porphyrin was confirmed by measuring the initial rate and quantum yield of oxygen consumption upon irradiation of 1 mM histidine and tryptophan in the presence of different hematoporphyrin concentrations within the 0.3-100μM range.
TL;DR: Analysis of the mechanism of porphyrin-mediated strand breakage in terms of the DNA cleavage mechanism of methidium-propyl-iron-EDTA and Fe-bleomycin, the potential of the cationic metalloporphyrins as footprinting probes and as new "reporter ligands" for DNA is presented and discussed.
Abstract: The ability of a group of water-soluble metalloporphyrins to cleave DNA has been investigated. Incubation of Mn3+, Fe3+, or Co3+ complexes of meso-tetrakis(N-methyl-4-pyridiniumyl)porphine (H2T4MPyP) with DNA in the presence of ascorbate, superoxide ion, or iodosobenzene results in DNA breakage. Comparisons between the rates of porphyrin autodestruction with the rates of strand scission of covalently closed circular PM2 DNA indicate that the porphyrins remain intact during the cleavage process. Analysis of the porphyrin-mediated strand scissions on a 139-base-pair restriction fragment of pBR322 DNA using gel electrophoresis/autoradiography/microdensitometry reveals that the minimum porphyrin cleavage site is (A X T)3. The cleavage pattern within a given site was found to be asymmetric, indicating that porphyrin binding and the strand scission process are highly directional in nature. In addition to an analysis of the mechanism of porphyrin-mediated strand breakage in terms of the DNA cleavage mechanism of methidium-propyl-iron-EDTA and Fe-bleomycin, the potential of the cationic metalloporphyrins as footprinting probes and as new "reporter ligands" for DNA is presented and discussed.
TL;DR: The ionic strength dependences of the binding of tetrakis to poly(dG-dC) and calf thymus DNA and the avidity of binding does decrease with increasing [Na+] as predicted, but of greater interest is the relocation of the porphyrin from GC-rich regions to AT- rich regions as the ionsic strength increases.
Abstract: The ionic strength dependences of the binding of tetrakis (4-N-methylpyridyl)porphine (H2TMpyP) to poly(dG-dC) and calf thymus DNA have been determined. For the former system the results are typical of other intercalators, i.e., a plot of log K vs log [Na+] is linear albeit with a slope which suggests that the "effective charge" of the porphyrin is closer to two than the formal charge of +4. For calf thymus DNA, the binding profile is not completely compatible with the predictions of condensation theory. Whereas the avidity of binding does decrease with increasing [Na+] as predicted, of greater interest is the relocation of the porphyrin from GC-rich regions to AT-rich regions as the ionic strength increases.
TL;DR: Intraperitoneal injection of the liposome-bound porphyrins to mice bearing a MS-2 fibrosarcoma results in remarkably more efficient tumour targeting than that obtained by administration of the same porphyrs dissolved in homogeneous aqueous solution.
Abstract: Unilamellar liposomes of dipalmitoyl-phosphatidylcholine can incorporate various porphyrins in either the phospholipid bilayer or the internal aqueous compartment depending on the water-/lipo-solubility of the drug. Intraperitoneal injection of the liposome-bound porphyrins to mice bearing a MS-2 fibrosarcoma results in remarkably more efficient tumour targeting than that obtained by administration of the same porphyrins dissolved in homogeneous aqueous solution. Moreover, also water-insoluble porphyrins can be transported to the tumour via liposomes. Fractionation of liver and neoplastic cells indicates that the subcellular distribution of liposome-delivered porphyrins is also dependent on their solubility properties: thus, relatively polar porphyrins, such as tetra(4-sulfonatophenyl)porphine and uroporphyrin, are mainly recovered from the soluble fraction, whereas hydrophobic porphyrins, such as haematoporphyrin or porphyrin esters, preferentially partition in the cytoplasmic membrane. As a consequence, different subcellular sites can be targeted by porphyrins and possibly photodamaged through a suitable choice of the drug-carrier system.
TL;DR: In this paper, a series of covalently linked Zn-H2 porphyrin dimers has been synthesized, which consists of a flexible alkoxy chain of variable length.
Abstract: A series of covalently linked Zn–H2 porphyrin dimers has been synthesized. The linkage consists of a flexible alkoxy chain of variable length. Absorption spectroscopy shows that there is some exciton coupling between the two porphyrin rings, whilst fluorescence spectroscopy shows that the ZnP unit transfers singlet-state excitation energy to the H2P. From time-resolved fluorescence studies it is concluded that the dimers exist in solution in different, non-equilibrating conformations. A partially closed form permits reasonably close approach of the two porphyrin rings so that Forster energy transfer is efficient. In a fully extended form the two porphyrins are held too far apart for energy transfer to compete effectively with non-radiative decay of the ZnP excited singlet state. Triplet energy transfer is not observed, owing to unfavourable orientations for exchange coupling, whilst redox ion intermediates are not seen, even in polar solvent.
TL;DR: Synthese de la porphyrine du titre et de son complexe de Zn, ses proprietes electrochimiques et oxydation de cette porphyre en cation porphryine ferricenium as mentioned in this paper.
Abstract: Synthese de la porphyrine du titre et de son complexe de Zn, ses proprietes electrochimiques et oxydation de cette porphyrine en cation porphyrine ferricenium
01 Jan 1986
TL;DR: It was shown that hyperthermia given shortly after the light exposure gave a synergistic killing effect and in spite of some loss of porphyrins from the cells, the light sensitivity increased 20 min after a light irradiation and the cells apparently repaired some of the photodynamic damage at 37°C.
Abstract: Terje Christensen*, Lars Smedshammer, Anne Wahl and Johan Moan Norsk Hydro's Institute for Cancer Research The Norwegian Radium Hospital Montebello, 0310 Oslo 3, Norway Cells from the established human line NHIK** 3025 were labelled with hematoporphyrin derivative in vitro. Subsequently, the cells were treated with light and hyperthermia:--The cells could be irradiated either before, during or after the incubation at a hyperthermic temperature. It was shown that hyperthermia given shortly after the light exposure gave a synergistic killing effect. In spite of some loss of porphyrins from the cells, the light sensitivity increased 20 min after a light irradiation. At later times, the cells apparently repaired some of the photodynamic damage at 37°C. At higher temperatures, the repair was inhibited.
TL;DR: The authors report the first observation of a direct four-electron reduction of dioxygen catalyzed by Ir(OEP)H adsorbed on graphite in acidic electrolyte solution.
Abstract: The electrocatalytic reduction of dioxygen by macrocyclic transition-metal complexes adsorbed on electrodes has been studied extensively in conjunction with the search for an inexpensive cathode material for oxygen fuel cells. The authors and other laboratories have shown that dicobalt cofacial porphyrin dimers can catalyze dioxygen reduction to water without producing significant amounts of hydrogen peroxide. To our knowledge, however, no monomeric macrocyclic metal complex has been reported to catalyze the direct four-electron reduction of dioxygen in acidic solution. In a survey of electrocatalytic oxygen reduction by various metalloporphyrins adsorbed on activated carbon, iridium complexes were reported to be the most active catalysts. Since the reduction product and the reaction pathway had not been elucidated in that work, they were prompted to study the electrocatalytic activity of iridium porphyrins toward dioxygen reduction. Here they report the first observation of a direct four-electron reduction of dioxygen catalyzed by Ir(OEP)H adsorbed on graphite in acidic electrolyte solution.
TL;DR: In this article, a non-metalated chlorophyll derivative has been isolated from Darwinella oxeata (Bergquist) and its structure determined by physical and X-ray measurements.
TL;DR: In this article, the excited state properties of heterodimers oftetra(4-carboxyphenyl)porphyrin and tetra(N-methylpyridyl) porphyrin (TMPyP) are studied by absorption and emission spectroscopy, EPR and zero-field ODMR.
TL;DR: Une solution toluenique de polymethacrylate de butyle et de CoPIm ({α,α',α'',α'''-meso-tetrabis [o-pivalamidophenyl] porphinato} cobalt-methyl-1 imidazole), est coulee sur une plaque de Teflon puis sechee as discussed by the authors
Abstract: Une solution toluenique de polymethacrylate de butyle et de CoPIm ({α,α',α'',α'''-meso-tetrabis [o-pivalamidophenyl] porphinato} cobalt-methyl-1 imidazole), est coulee sur une plaque de Teflon puis sechee
TL;DR: In this article, the authors derive mphenylene-5,5' bisporphyrine a partir d'isophtaladehyde, and dimethyl-3,5 propyl-4-and ethyl-3 methyl-4 pyrrolecarboxylates-2 d'ethyle.
Abstract: Synthese d'un derive de m-phenylene-5,5' bis-porphyrine a partir d'isophtaladehyde, et de dimethyl-3,5 propyl-4- et ethyl-3 methyl-4 pyrrolecarboxylates-2 d'ethyle
TL;DR: The spectroscopic properties of porphyrins incorporated into unilamellar liposomes of dipalmitoylphos‐phatidylcholine have been studied with the aim to assess the distribution of p Morphyrins within the various liposomal compartments.
Abstract: — The spectroscopic properties of hematoporphyrin, hematoporphyrin-dimethyl ester, uroporphyrin and uroporphyrinoctamethyl ester, incorporated into unilamellar liposomes of dipalmitoylphos-phatidylcholine, have been studied with the aim to assess the distribution of porphyrins within the various liposomal compartments.
The results obtained indicate that the highly hydrosoluble uroporphyrin is partitioned in the endoliposomal aqueous pool while its octamethylester is homogeneously distributed in the inner lipid monolayer. Hematoporphyrin and its dimethylester show an heterogeneous distribution within the phospholipid bilayer. At T = 25°C these porphyrins are preferentially located in the outer phospholipid monolayer.
Detailed studies on hematoporphyrin indicate that the distribution between the inner and outer phospholipid monolayer is a function of temperature and liposome dimensions. In particular, the increase of temperature above the critical temperature for the liquid-gel phase transition of the liposomes causes a partial shift of the porphyrin molecules toward the inner phospholipid monolayer. Moreover, the increase of liposome dimensions leads to a greater accessibility of porphyrin to the external medium.
TL;DR: Using this procedure, it is shown that one characteristic of chilling induced chlorosis involves a non-lethal alteration in the ability of etiolated tissue to synthesize chlorophylls.
TL;DR: Carbon dioxide is trapped by aluminum porphyrin and activated enough to undergo a catalytic reaction involving secondary amine and epoxide to afford dialkylcarbamic ester under atmospheric pressure at room temperature.
Abstract: Carbon dioxide is trapped by (5,10,15,20-tetraphenylporphinato) aluminum acetate in the presence of a secondary amine in the form of an aluminum carbamate on the opposite side to the acetate group with respect to the porphyrin plane. Carbon dioxide thus trapped by aluminum porphyrin is activated enough to undergo a catalytic reaction involving secondary amine and epoxide to afford dialkylcarbamic ester under atmospheric pressure at room temperature. 15 references, 2 figures, 2 tables.