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PubMed2003

Novel heterotopic colloids of anionic porphyrins entangled in cationic amphiphilic cyclodextrins: spectroscopic investigation and intracellular delivery.

The entanglement process between water-soluble 5,10,15,20-tetrakis(4-sulfonatophenyl)-21H,23H-porphine and the amphiphilic cyclodextrin (CD) heptakis(2-omega-amino-O-oligo(ethylene oxide)-6-hexylthio)-beta-CD and the occurrence of various species at different porphyrin:CD ratios were studied by a combination of UV/Vis absorption, fluorescence anisotropy, time-resolved fluorescence, resonance light scattering, and circular dichroism. The effect of the entanglement process on the mean vesicle diameter was investigated over a wide concentration range by quasielastic light-scattering techniques. The experimental results indicate that the presence of porphyrins in this colloidal system promotes some structural rearrangements, essentially driven by charge interaction, which are responsible for a sensitive change of vesicle dimensions. In the range of porphyrin:CD molar ratios between 1:10 and 1:50, the porphyrin is solubilized in monomeric form (tau(1)=11.5 ns) and photosensitizes the production of singlet oxygen ((1)O(2)). At the same molar ratio the ability of this amphiphilic cyclodextrin to transport porphyrins into tumor cells indicates specificity at the nuclear-compartment level. These findings may be of potential interest for the of development agents for photodynamic therapy of tumors.

Animals↗
PubMed2003

Molecular energy and electron transfer assemblies made of self-organized lipid-porphyrin bilayer vesicles.

Novel molecular energy and electron transfer assemblies in vesicular form, which are made of self-organized amphiphilic porphyrins bearing phospholipid-like substituents (lipid-porphyrins), have been photochemically characterized. Tetraphenylporphyrin (TPP) derivatives with four dialkylphosphocholine groups [free-base (1 a), Zn(2+) complex (1 b), and Fe(3+) complex (1 c)] are spontaneously associated in water to form spherical unilamellar vesicles with a diameter of 100-150 nm. Exciton calculations based on the bilayered sheet model of 1 b, which has a porphyrin packing similar to that seen in the triclinic unit cell of the Zn(2+)TPP crystals, reproduced the Soret band bathochromic shift appearing in the aqueous solution of 1 b well. The UV/Vis absorption spectrum of the 1 a/1 b hybrid vesicles (molar ratio: 1/1) showed no electronic interaction between the two porphyrin chromophores in the ground state, but efficient intermolecular singlet-singlet energy transfer took place from the excited 1 b donors to the 1 a acceptor within the vesicle. Near-field scanning optical microspectroscopy of the 1 a/1 b vesicles on a graphite surface also showed only free-base porphyrin fluorescence. The efficiency of the energy transfer was 0.81 and the rate constant was 3.1 x 10(9) s(-1). On the other hand, protoporphyrin IX bearing two alkylphosphocholine propionates (2) was incorporated into the 1 a or 1 c bilayer vesicles (ca. 100 nm phi, molar ratio: 1 a/2 or 1 c/2=10). The UV/Vis absorption spectrum showed that 2 was successfully anchored into the fluid alkylene region of the membrane without stacking. Photoirradiation (lambda(ex): 390 nm) of the 1 c/2 vesicles in the presence of triethanolamine led a vectorial electron transfer from the outer aqueous phase to the membrane center, which allowed reduction of the ferric ion of the Fe(3+)TPP platform.

Electron Transport↗
PubMed2006

Electrochemical characterization of self-assembled thiol-porphyrin monolayers on gold electrodes by SECM.

Herein, the scanning electrochemical microscopy (SECM) approach is applied to study the formation of thiol-porphyrin self-assembled monolayer (SAMs). Using cyclic voltammetry (CV), the formation process is characterized adopting different probe molecules. The observed phenomena indicate that the formation process is affected by solution properties and the molecular structure of the probe molecules. In K(3)Fe(CN)(6) , the SAMs show a strong electron-transfer (ET) blocking effect on a pure porphyrin-modified electrode. However, addition of metal ions to the porphyrin molecules leads to ET. A consistent tendency is observed throughout the modification process using CV and SECM methods. Furthermore, k(eff) values, the apparent heterogeneous rate constants, obtained for different modification periods affirm the validity of these results. SECM images are used to collect surface information in the course of the modification process when the substrate potential is 0.5 V versus Ag/AgCl. The effect of the substrate potential indicates that the oxidation of the porphyrin molecules is supported by more positive potentials because of the similar bimolecular reaction of the porphyrin ring with positive charge and the probe molecules with negative charge.

Electrochemistry↗
PubMed2005

Characterization of dinitroporphyrin zinc complexes by electrospray ionization tandem mass spectrometry. Unusual fragmentations of beta-(1,3-dinitroalkyl) porphyrins.

The zinc complexes of diaryl bis(p-nitrophenyl)porphyrins and beta-(1,3-dinitroalkyl)tetraphenylporphyrins were studied by electrospray ionization (ESI) tandem mass spectrometry (MS/MS). All porphyrins showed the protonated molecule under ESI conditions. The protonated molecules were induced to fragment and the corresponding ESI tandem mass spectra were analysed. Porphyrins with two p-nitrophenyl groups showed, as expected, characteristic fragmentations including either loss of one nitro group, as the major fragment of the tandem mass spectra, and loss of both nitro groups. In contrast, MS/MS of the beta-(1,3-dinitroalkyl)porphyrins provided interesting and unexpected results such as the absence (or in insignificant abundance) of the ions formed by loss of one nitro group. However, these porphyrins show an abundant fragment due to combined loss of the two nitro groups. Also, the typical beta-cleavage of the alkyl chain is not observed per se, only when combined with loss of HNO2 or *NO2. Instead, alpha-cleavage, with loss of the beta-pyrrolic substituent, is the most favourable process.

Nitro Compounds↗
PubMed1993

Pharmaceutics and drug delivery aspects of heme and porphyrin therapy.

The importance of porphyrins and metalloporphyrins as therapeutic drugs has increased significantly over the last decade. This review highlights some of the challenges faced by pharmaceutical scientists in formulating these drugs into stable, effective, and safe dosage forms. Most activity in the clinic has focused on three areas: photodynamic therapy of cancer (e.g., hematoporphyrin derivatives), porphyrias and hematological diseases (e.g., heme), and various forms of jaundice (e.g., tin porphyrins). The biodistribution, stability, aggregation, toxicology, and analytical methodology of porphyrin drugs are all important considerations in the pharmaceutical development of porphyrin drugs. The utility of delivery systems such as liposomes hold promise of increasing the therapeutic potential of these drugs. Future prospects for therapeutic applications of porphyrin drugs are also discussed.

Animals↗
PubMed2004

Identification of monovinyl tripropionic acid porphyrins and metabolites from faeces of patients with hereditary coproporphyria by high-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry.

Harderoporphyrin (2-vinyl-4,6,7-tripropionic acid porphyrin) and its metabolites in faeces of patients with hereditary coproporphyria (HCP) have been separated and characterized by high-performance liquid chromatography/electrospray ionization quadrupole time-of-flight tandem mass spectrometry (HPLC/ESI-Q-TOFMS/MS). The metabolites identified were 2-ethyl-4,6,7-tripropionic acid porphyrin, 2-hydro-4,6,7-tripropionic acid porphyrin, 2-methoxyethyl-4,6,7-tripropionic acid porphyrin and 2-acetyl-4,6,7-tripropionic acid porphyrin. Isomers of harderoporphyrin derived from isomerization of harderoporphyrinogen were also detected.

Chromatography, High Pressure Liquid↗
PubMed1993

Porphyrin induced calcium release from skeletal muscle sarcoplasmic reticulum.

Micromolar concentrations of the porphyrin mesotetra(4-N-methylpyridyl)porphine tetraiodide is shown to induce rapid release of Ca2+ from skeletal muscle sarcoplasmic reticulum vesicles. Porphyrin-induced Ca2+ release is stimulated by ATP (KdATP = 100 microM) and Ca2+ (KdCa = 1 microM) and is inhibited by Mg2+ (KI = 220 microM) and ruthenium red (KI = 7 nM). The porphyrin is also shown to stimulate high affinity [3H]ryanodine binding by decreasing the dissociation constant (kd) and increasing the binding capacity (Bmax). Moreover, in the presence of Mg2+, receptor binding is sensitized to activation by Ca2+, and porphyrin-stimulated channel activity is sensitized to activation by Ca2+. These observations show that porphyrin-induced Ca2+ release is due to a direct interaction with the Ca2+ release protein from sarcoplasmic reticulum.

Adenosine Triphosphate↗
PubMed1997

Cytochrome P450 induction, uroporphyrinogen decarboxylase depression, porphyrin accumulation and excretion, and gender influence in a 3-week rat model of porphyria cutanea tarda.

An experimental model of porphyria cutanea tarda, consisting of depressed hepatic uroporphyrinogen decarboxylase (URO-D) activity and accumulation of highly carboxylated porphyrins in the liver, was produced in 3 weeks in Fischer 344 rats. A single administration of a polychlorinated biphenyl mixture (Aroclor 1254) to iron-loaded female rats maintained continuously on delta-aminolevulinic acid supplemented drinking water produced the porphyric state. Without iron loading, URO-D activity appeared slightly less inhibited (33% of normal vs 23% of normal) but porphyrin accumulation was dramatically less (70 vs 605 micrograms porphyrin/g liver). Similar treatment in male rats produced URO-D activities of 54 and 70% of normal with and without iron loading, respectively, and porphyrin concentrations of 76 and 17 micrograms/g. When hexachlorobenzene was substituted for Aroclor 1254 treatment in female rats, URO-D activity was 61 and 69% of normal (with and without iron loading, respectively) and liver porphyrin concentrations were 96 and 25 micrograms/g, respectively. Hexachlorobenzene did not produce significant porphyric effects in male rats. Aroclor 1254 induced CYP1A to a greater extent in females than in males and to a greater extent than hexachlorobenzene, which showed a greater propensity to induce CYP2B. Overall correlation between URO-D activity depression and porphyrin accumulation was highest when fitted to an exponential curve, indicating the importance of the extreme of the depression URO-D activity in evoking experimental porphyria cutanea tarda.

Animals↗
PubMed1994

Evidence for the interference of aluminum with bacterial porphyrin biosynthesis.

Aluminum (0.74 mM) was found to retard bacterial growth, and enhance porphyrin formation and excretion in Arthrobacter aurescens RS-2. Coproporphyrin III was shown to be the main porphyrin excreted by aluminum-exposed A. aurescens RS-2 cultures and by RS-2 cultures grown under anoxic conditions. Synthesis and excretion of porphyrins in A. aurescens RS-2 increased in a dose-dependent manner when the bacteria were exposed to increasing aluminum concentrations. Incubation of A. aurescens RS-2 with delta-aminolevulinic acid (delta-ALA, 1.2 mM) brought about the intense formation and excretion of porphyrins by the cells, in the presence or absence of aluminum. delta-ALA slightly enhanced the toxicity of aluminum towards RS-2 bacteria. Furthermore, the intracellular concentration of heme was reduced by 63.9 +/- 8.67% in aluminum-exposed RS-2 bacteria when compared with control cultures. The results are discussed in light of the recent finding concerning aluminum toxicity and porphyrin biosynthesis in microorganisms.

Aluminum↗
PubMed1996

The effects of bromocriptine and prolactin on porphyrin biosynthesis and morphology in the female hamster harderian gland.

Porphyrin biosynthesis was examined in the Harderian gland of the female golden hamster by fluorometric assays of gland porphyrin content and by measuring the activity of a rate-limiting enzyme for haem biosynthesis, delta-aminolaevulinic acid synthase. Both porphyrin content and enzyme activity are high in normal female glands. Enzyme activity was lowered in females ovariectomised for 6 weeks, and both enzyme activity and porphyrin content were greatly lowered in ovariectomised females given the dopamine agonist bromocriptine; this suppression could be prevented by simultaneous prolactin administration. Bromocriptine (but not ovariectomy alone) also masculinised the morphology of the Harderian gland, resulting in the appearance of type II cells and polytubular complexes; again, the simultaneous administration of prolactin prevented masculinisation. The results support the hypothesis that while androgens have an inhibitory effect on porphyrin synthesis within this model, prolactin may have a major facilitatory role.

5-Aminolevulinate Synthetase↗
PubMed1982

Patterns of porphyrin-excretion in female estrogen-induced porphyria cutanea tarda.

It has been suggested that the urinary profile of porphyrins excreted by female patients with estrogen-induced porphyria cutanea tarda is peculiar in that heptacarboxylic porphyrin equals or exceeds uroporphyrin. The chromatographic pattern of urinary porphyrin excretion was studied in nine females with porphyria cutanea tarda precipitated by estrogens, 129 porphyric males, and nine females, whose porphyria was not hormone-induced. Both female porphyric groups showed absolutely the same urinary chromatographic pattern and looked quite similar to the pattern observed in male patients. None of our female porphyric patients, whether treated with estrogens or not, showed percentage values for the heptacarboxylic porphyrin higher or equal to the uroporphyrin values. Our results do not support the hypothesis that the profile of urinary porphyrin excretion found in estrogen-induced porphyria cutanea tarda is atypical.

Adult↗
PubMed1976

[Erythropoietic protoporphyria: porphyrin content of a gall-stone (author's transl)].

In the case of a 48 year old woman with characteristic signs of erythropoetic protoporphyria, a solitary gall-stone which had persisted over a period of 10 years was removed. Porphyrin-concentration of this gall-stone was found to be 22.6 mcg/g, which is almost twenty times the concentration of other cholestrol-stones. Besides protoporphyrin, porphyrins with a higher degree of carboxylation were discovered in four different samples by thin layer chromatography. It is postulated that the increased bile-concentration of protoporphyrin in the liver causes the cristallisation of cholestrol and the formation and growth of gall-stones. The biochemical finding of porphyrins with a higher degree of carboxylation indicates that the porphyrins of the gall-stone may not only come from hemolysed erythrocytes but possibly also from metabolites of disturbed hepatic porphyrin biosynthesis.

Cholelithiasis↗
PubMed1993

Effect of diphenyl ether herbicides and oxadiazon on porphyrin biosynthesis in mouse liver, rat primary hepatocyte culture and HepG2 cells.

The effects of the herbicides fomesafen, oxyfluorfen, oxadiazon and fluazifop-butyl on porphyrin accumulation in mouse liver, rat primary hepatocyte culture and HepG2 cells were investigated. Ten days of herbicide feeding (0.25% in the diet) increased the liver porphyrins in male C57B1/6J mice from 1.4 +/- 0.6 to 4.8 +/- 2.1 (fomesafen) 16.9 +2- 2.9 (oxyfluorfen) and 25.9 +/- 3.1 (oxadiazon) nmol/g wet weight, respectively. Fluazifop-butyl had no effect on liver porphyrin metabolism. Fomesafen, oxyfluorfen and oxadiazon increased the cellular porphyrin content of rat hepatocytes after 24 h of incubation (control, 3.2 pmol/mg protein, fomesafen, oxyfluorfen and oxadiazon at 0.125 mM concentration 51.5, 54.3 and 44.0 pmol/mg protein, respectively). The porphyrin content of HepG2 cells increased from 1.6 to 18.2, 10.6 and 9.2 pmol/mg protein after 24 h incubation with the three herbicides. Fluazifop-butyl increased hepatic cytochrome P450 levels and ethoxy- and pentoxyresorufin O-dealkylase (EROD and PROD) activity, oxyfluorfen increased PROD activity. Peroxisomal palmitoyl CoA oxidation increased after fomesafen and fluazifop treatment to about 500% of control values both in mouse liver and rat hepatocytes. Both rat hepatocytes and HepG2 cells can be used as a test system for the porphyrogenic potential of photobleaching herbicides.

Animals↗
PubMed1991

Heme biosynthesis and porphyrin studies in chronic renal failure patients following kidney transplantation.

El-Far and Sobh were the first to describe abnormalities in porphyrin metabolism in Egyptian patients with chronic renal failure (CRF). Our results were confirmed by others. The present investigation aims to study and discuss the nature of those abnormalities and changes in porphyrin metabolism in CRF patients following kidney transplantation. Blood samples and urine were collected from patients (with and without polycythaemia) as well as from normal controls. The activity of heme enzymes such as ALA-S, ALA-D, URO-S, PBGase and URO-D were assayed. Total blood porphyrins as well as enzyme activities such as ALA-S and URO-S were found to be highly significantly increased in all patients, while URO-D activity remained within normal range. The observed elevated erythrocyte porphyrins may be mainly due to increased activity of ALA-S, the rate-limiting enzyme in heme synthesis. The present study is the first of its kind which clearly demonstrates that successful kidney transplantation does not correct or rectify the abnormalities in porphyrin metabolism.

5-Aminolevulinate Synthetase↗
PubMed1987

Effects of lighting conditions and of hormone replacement on the level of porphyrins in the rat Harderian gland.

The effects of lighting conditions and/or gonadal secretions on the porphyrins of rat Harderian glands were studied. In female rats, exposure to constant light (= LL) induced a 50% decrease of porphyrin in the Harderian gland. Ovariectomy in these animals caused an increase to levels comparable to those found in intact controls. In males, exposure to constant darkness (= DD) produced a marked increase in the glandular porphyrins together with greatly decreased weights of accessory sexual organs. Further, orchidectomy remarkably increased porphyrin levels in rats kept under conditions of LL or DD. Administration of testosterone propionate to castrated male rats significantly decreased the porphyrin contents in the gland, although estradiol benzoate and progesterone treatments had no effect on the levels. Similar results were obtained in female rats.

Animals↗
PubMed1996

Porphyrins as biomarkers of methylmercury and PCB exposure in experimental quail.

Chemicals such as heavy metals and polyhalogenated hydrocarbons have a high capacity to interfere with the enzymatic processes responsible for haem biosynthesis. These compounds can produce accumulation in tissues and organs and increased elimination of porphyrins in excreta (Andrew et al, 1990). The development of fast and easy analytical methods and the wide variety of biological media in which porphyrins can be detected have suggested their use as biomarkers of environmental pollution (Akins et al, 1993; De Matteis and Lim 1994). The analysis of porphyrins in the excreta is of special interest because it enables nondestructive monitoring of wild animals in the assessment of threatened or endangered species (Fossi et al, 1994). Methylmercury and PCBs are ubiquitous global pollutants and there is evidence they accumulate in terminal consumers, particularly those belonging to marine trophic chain (Renzoni et al, 1986; Yamashita et al, 1993). There have been some reports on methylmercury-induced (e.g. Woods et al, 1991; Bowers et al, 1992; Miller and Woods 1993) and PCB-induced porphyria (e.g. Vos and Pennings, 1971; Miranda et al, 1987; Elliot et al, 1990; Miranda et al, 1992) but little data on their combined effect. In order to investigate the quality of porphyrins as biomarkers we performed an experiment in which Japanese quail were fed a diet containing methylmercury and polychlorobyphenyls (PCBs as Arochlor 1260) individually or combined in different ratios. The present study aims to provide preliminary data on liver and fecal levels of porphyrins in response to methylmercury and PCB administration, and on whether the indicator is sensitive to synergism or antagonism between the two compounds, administered simultaneously.

Animals↗
PubMed2004

Synthesis of novel types of copper-bipyridyl porphyrins and characterization of their interactions and reactivity with DNA.

The inherent ability to interact with DNA makes cationic metallo-porphyrins attractive targets as antitumor drugs. Many studies describe their interaction with DNA and the mechanism by which they induce DNA cleavage. Since porphyrins can be used as anchors for chemically reactive groups, it is possible to modify them to generate a family of compounds with specific functions. In the present work, we used chemical groups such as copper-bipyridinium (Cu-bpy), which hydrolyze phosphodiester bonds, and a porphyrin core to synthesize two novel Cu(2)-bpy-porphyrins. Their interactions with DNA have been characterized using classic spectroscopic methods, and their oxidative and hydrolytic reactivity toward supercoiled plasmid DNA has been studied in vitro. Our results show that Cu(2)-bpy-porphyrins interact with DNA via external association and intercalation and that their ability to cleave DNA and the mechanisms depends on the experimental conditions.

2,2'-Dipyridyl↗
PubMed2005

The axial ligand effect of oxo-iron porphyrin catalysts. How does chloride compare to thiolate?

We have performed density functional theory calculations on an oxo-iron porphyrin catalyst with chloride as an axial ligand and tested its reactivity toward propene. The reactions proceed via multistate reactivity on competing doublet and quartet spin surfaces. Close-lying epoxidation and hydroxylation mechanisms are identified, whereby in the gas phase the epoxidation reaction is dominant, while in environments with a large dielectric constant the hydroxylation pathways become competitive. By contrast to reactions with thiolate as an axial ligand all low-lying pathways have small ring-closure and rebound barriers, so it is expected that side products and rearrangements will be unlikely with Fe=O(porphyrin)Cl, whereas with Fe=O(porphyrin)SH some side products were predicted. The major differences in the electronic configurations of Fe=O(porphyrin)Cl and Fe=O(porphyrin)SH are due to strong mixing of thiolate orbitals with iron 3d orbitals, a mixing which is much less with chloride as an axial ligand. Predictions of the reactivity of ethylbenzene-h (12) versus ethylbenzene-d (12) are made.

Chlorides↗