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At least 19 recordsLinked to original sources
PubMed1990

Oxidative cleavage of DNA mediated by hybrid metalloporphyrin-ellipticine molecules and functionalized metalloporphyrin precursors.

The nuclease activity of functionalized metalloporphyrins 1-8 and hybrid metalloporphyrin-ellipticine molecules 10-16 in the presence of potassium monopersulfate (KHSO5) or magnesium monoperoxyphthalate (MMPP), water-soluble oxygen atom donors at physiological pH, toward double-stranded phi X174 DNA is reported. The DNA cleavage efficiency as a function of the nature of functionalized metalloporphyrins, the length of the linkage between the two parts of the hybrid molecule, viz., metalloporphyrin and 9-methoxyellipticine, the nature of the central metal atom (Mn, Fe, or Zn) the ionic strength, and the nature of the oxygen donor has been studied. Single-strand breaks (SSBs) are observed on double-stranded DNA with a short incubation time of 2 min in the presence of manganese derivatives of both metalloporphyrins and hybrid molecules. Owing to their cytotoxic and nuclease activity, these new water-soluble hybrid molecules may be considered as efficient bleomycin models based on cationic metalloporphyrins.

Bacteriophage phi X 174↗
PubMed1997

Influence of the nature of the porphyrin ligand on the nuclease activity of metalloporphyrin-oligonucleotide conjugates designed with cationic, hydrophobic or anionic metalloporphyrins.

The synthesis of metalloporphyrin-oligonucleotide conjugates with different metalloporphyrin moieties are described as well as the comparison of their in vitro nuclease efficiency toward a single-stranded DNA target. Between cationic, anionic and hydrophobic manganese porphyrins covalently linked to the oligonucleotide, the best nuclease activity was obtained with the cationic ones, suggesting that the affinity of the cleaver to the DNA target is a key factor.

Anions↗
PubMed1994

Monoclonal antibodies against metalloporphyrins. Specificity of interaction with structurally different metalloporphyrins.

Monoclonal antibodies against Pd-coproporphyrin I have been obtained. The antibody specificity for free as well as for conjugated Pd-coproporphyrin I is characterized. Affinity constants are estimated for 3 monoclonal antibodies effectively interacting with free Pd-coproporphyrin I. A comparative study on the binding of monoclonal antibodies with analogues and derivatives of Pd-coproporphyrin I has revealed that the antigen is mainly located inside the antibody paratope. The protein adjoins complementary to the metalloporphyrin in such a manner that antibodies obtained discern only isomer I, and to some degree, isomer III of coproporphyrin.

Animals↗
PubMed2003

Metalloporphyrins for treatment of unconjugated hyperbilirubinemia in neonates.

BACKGROUND: Metalloporphyrins are heme analogues that inhibit heme oxygenase, the rate-limiting enzyme in the catabolism of heme to bilirubin. By preventing the formation of bilirubin, they have the potential to reduce the level of unconjugated bilirubin in neonates and thereby reduce the risk of neonatal encephalopathy and long term neurodevelopmental impairment from bilirubin toxicity to the nervous system. OBJECTIVES: 1. To determine the efficacy of metalloporphyrins in reducing bilirubin levels, reducing the need for phototherapy or exchange transfusion and reducing the incidence of bilirubin encephalopathy in neonates with unconjugated hyperbilirubinemia when compared to placebo, phototherapy or exchange transfusion. 2. To determine the nature and frequency of side effects of metalloporphyrins when used to treat unconjugated hyperbilirubinemia in neonates. SEARCH STRATEGY: We searched Medline (1966 - January 2003) and the Cochrane Controlled Trials Register (CCTR) from the Cochrane Library (2003, issue 1). We hand-searched the articles cited in each publication obtained. We hand searched the abstracts of the Society for Pediatric Research (USA) (published in Pediatric Research) for the years 1985 - 2002. SELECTION CRITERIA: We included only randomized controlled studies, in which preterm or term neonates (age 28 days of life or less) with unconjugated hyperbilirubinemia due to any cause were randomly allocated to receive a metalloporphyrin in the treatment arm(s), and to receive a placebo or a conventional treatment (phototherapy or exchange transfusion) or no treatment for hyperbilirubinemia in the comparison arm(s). Any preparation of metalloporphyrin could be used, in any form, by any route, at any dose. DATA COLLECTION AND ANALYSIS: Two authors extracted data independently. Data were entered into Revman by one author and checked by a second author. Prespecified subgroup analyses were planned in term versus preterm infants, hemolytic versus non-hemolytic causes of jaundice and according to the type of metalloporphyrin used. MAIN RESULTS: Three small studies, enrolling a total of 170 infants, were eligible for inclusion in this review. None blinded intervention or outcome assessment. In all three studies some patients were excluded after randomization. Metalloporphyrin-treated infants appeared to have short-term benefits compared to controls, including a lower maximum plasma bilirubin level in one study, a lower frequency of severe hyperbilirubinemia in one study, a decreased need for phototherapy, fewer plasma bilirubin measurements and a shorter duration of hospitalization. None of the enrolled infants required an exchange transfusion in the two studies that described this outcome. None of the studies reported on neonatal kernicterus, death, long-term neurodevelopmental outcomes or iron deficiency anemia. Though a small number of metalloporphyrin-treated as well as control infants developed a photosensitivity rash, the trials were too small to rule out an increase in the risk of photosensitivity or other adverse effects from metalloporphyrin treatment. No subgroup analyses were possible due to the small number of included trials. REVIEWER'S CONCLUSIONS: Treatment of neonatal unconjugated hyperbilirubinemia with metalloporphyrins may reduce neonatal bilirubin levels and decrease the need for phototherapy and hospitalization. There is no evidence to support or refute the possibility that treatment with a metalloporphyrin decreases the risk of neonatal kernicterus or of long-term neurodevelopmental impairment due to bilirubin encephalopathy. There is no evidence to support or refute the possibility that cutaneous photosensitivity is increased with metalloporphyrin treatment. Routine treatment of neonatal unconjugated hyperbilirubinemia with a metalloporphyrin cannot be recommended at present.

Humans↗
PubMed2006

Comparison of activity of immobilised and soluble metalloporphyrins by NO release of oximes by chemiluminescence.

The ongoing interest in very efficient systems for the imitation of cytochrome P-450-dependent monooxygenase reactions, consisting of metalloporphyrin and oxygen donor, prompted us to develop a method to compare the catalytic activity of soluble metalloporphyrins with those which have been immobilised on different silica surfaces. In this article, we describe a method which allows direct comparison between the catalytic activities of soluble and immobilised metalloporphyrins by measuring the NO release of cyclohexanone oxime. We observed that all metalloporphyrins are able to enhance the NO release of cyclohexanone oxime in the presence of iodosobenzene as oxygen donor. In case of cationic metalloporphyrins, no difference in the catalytic activity was determined. In contrast, for perfluorinated metalloporphyrins we ascertained a major loss of activity after immobilisation. These results led us to the assumption that it is not easy to compare quantitative results of NO releases if soluble and immobilised metalloporphyrins were used.

Buffers↗
PubMed2006

Unconventional neuroprotection against Ca2+ -dependent insults by metalloporphyrin catalytic antioxidants.

We evaluated whether both inert and catalytically active metalloporphyrin antioxidants, meso-substituted with either phenyl-based or N-alkylpyridinium-based groups, suppress Ca(2+)-dependent neurotoxicity in cell culture models of relevance to cerebral ischemia. Representatives from both metalloporphyrin classes, regardless of antioxidant strength, protected cultured cortical neurons or PC-12 cultures against the Ca(2+) ionophores ionomycin or A23187, by suppressing neurotoxic Ca(2+) influx. Some metalloporphyrins suppressed excitotoxic Ca(2+) influx indirectly induced by the Ca(2+) ionophores in cortical neurons. Metalloporphyrins did not quench intracellular fluorescence, suggesting localization to the plasma membrane interface and/or interference with Ca(2+) ionophores. Metalloporphyrins suppressed ionomycin-induced Mn(2+) influx, but did not protect cortical neurons against pyrithione, a Zn(2+) ionophore. In other Ca(2+)-dependent paradigms, Ca(2+) influx via plasma membrane depolarization, but not through reversal of plasmalemmal Na(+)/Ca(2+) exchangers, was modestly suppressed by Mn(III)meso-tetrakis(4-benzoic acid)porphyrin (Mn(III)TBAP) or by an inert analog, Zn(II)TBAP. Mn(III)TBAP and Zn(II)TBAP potently protected cortical neurons against long-duration oxygen-glucose deprivation (OGD), performed in the presence of antagonists of NMDA, alpha-amino-3-hydroxy-5-methylisoxazole-4-propionate and L-type voltage-gated Ca(2+) channels, raising the possibility of an unconventional mode of blockade of transient receptor protein melastatin 7 channels by a metalloTBAP family of metalloporphyrins. The present study extends the range of Ca(2+)-dependent insults for which metalloporphyrins demonstrate unconventional neuroprotection. MetalloTBAPs appear capable of targeting an OGD temporal continuum.

Animals↗
PubMed2004

Metalloporphyrin solubility: a trigger for catalyzing reductive dechlorination of tetrachloroethylene.

Metalloporphyrins are well known for their electron-transfer roles in many natural redox systems. In addition, several metalloporphyrins and related tetrapyrrole macrocycles complexed with various core metals have been shown to catalyze the reductive dechlorination of certain organic compounds, thus demonstrating the potential for using naturally occurring metalloporphyrins to attenuate toxic and persistent chlorinated organic pollutants in the environment. However, despite the great interest in reductive dechlorination reactions and the wide variety of natural and synthetic porphyrins currently available, only soluble porphyrins, which comprise a small fraction of this particular family of organic macrocycles, have been used as electron-transfer shuttles in these reactions. Results from the present study clearly demonstrate that metalloporphyrin solubility is a key factor in their ability to catalyze the reductive dechlorination of tetrachloroethylene and its daughter compounds. Additionally, we show that certain insoluble and nonreactive metalloporphyrins can be activated as catalysts merely by changing solution conditions to bring about their dissolution. Furthermore, once a metalloporphyrin is fully dissolved and activated, tetrachloroethylene transformation proceeds rapidly, giving nonchlorinated and less toxic alkenes as the major reaction products. Results from the present study suggest that if the right environmental conditions exist or can be created, specific metalloporphyrins may provide a solution for cleaning up sites that are contaminated with chlorinated organic pollutants.

Catalysis↗
PubMed2005

[Effect of photodynamic therapy with metalloporphyrin compound on human prostate cancer PC-3 cells in vitro].

OBJECTIVE: To investigate the effect of the photodynamic therapy (PDT) with the new water-soluble metalloporphyrin compound on human prostate cancer PC-3 cells in vitro and the anticancer mechanism of PDT. METHODS: The new water-soluble manganese, 5,10,15, 20-tetra (N-methyl4-pyridyl) porphinato (2-) tetraiodide salt, was synthesized. The PC-3 cells were treated with the compound of serial concentrations(0, 0.1, 1, 1.0 micromol/L) followed by irradiation of different dosages of visible light. The techniques of MTT and Annexin-V/propidium iodide double-labeled flow cytometry (FCM) were applied to measuring the inhibitory effect of the compound on the growth activity and apoptosis of the cells. RESULTS: When the metalloporphyrin compound concentration was within 10 micromol/L and the irradiation time was within 30 min, the water-soluble metalloporphyrin compound had a significant inhibitory effect on the proliferation of PC-3 cells and induced PC-3 cell apoptosis, and the effects depended greatly on metalloporphyrin concentration and illumination dosages. Higher concentrations and dosages induced the death of the majority of PC-3 cells. CONCLUSION: The PDT of the water-soluble metalloporphyrin compound followed by light irradiation has a distinctive killing effect on PC-3 cells in vitro, and the rates of proliferation inhibition and cell apoptosis are correlated with metalloporphyrin concentration and the dosages of light irradiation. The results suggest that the mechanism of metalloporphyrin PDT may be involved with the induction of apoptosis in human prostate cancer cells.

Apoptosis↗
PubMed2002

Mapping of the chick heme oxygenase-1 proximal promoter for responsiveness to metalloporphyrins.

Heme oxygenase (HO) catalyzes the rate-controlling step of physiologic heme catabolism, namely, the oxidation of the alpha-methene bridge of the macrocycle with formation of CO, Fe, and biliverdin. HO-1, the first isoform of HO to be identified, is highly inducible by a large number of physical and chemical factors. Many of these factors cause oxidative or other stresses to cells. In this work, we have studied the regulation of the chick HO-1 gene, using selected promoter--reporter constructs of the gene transiently or stably transfected into primary cultures of chick embryo liver cells or into the LMH line of chicken hepatoma cells. By use of deletional and mutational analyses, DNase protection, and electromobility shift DNA-binding assays, we identified a heretofore undefined regulatory region in the 5'-UTR of the chick HO-1 gene which confers up-regulation of reporter gene (luciferase) expression in the presence of heme and other selected metalloporphyrins. This new metalloporphyrin-responsive element (MPRE) was localized to a 200-bp region 3.8 to 3.6 kb upstream of the transcription starting point of the chick HO-1 gene. It responded particularly to heme and cobalt protoporphyrin with maximal inductions at 10-15 microM concentrations and 15-18 h of exposure. In contrast, sodium arsenite, a prototypical stress-type inducer of HO-1, led to down-regulation of the reporter gene down stream of MPRE. DNase analysis identified an 18-mer oligonucleotide that was required for the metalloporphyrin response (5'-(-3711)TATTGCAGCTGTGTGGGG-3'). Mutations at any of four sites within this oligonucleotide abrogated the metalloporphyrin-dependent up-regulation of reporter gene expression. Nuclear protein extracts of cells treated with heme or cobalt protoporphyrin showed specific enhanced binding to this 18-mer. We conclude that the chick HO-1 promoter region contains a unique sequence that subserves up-regulation of the gene by metalloporphyrins and propose the name "metalloporphyrin-responsive element" for this sequence.

Animals↗
PubMed2006

A fluorescence enhancement-based sensor using glycosylated metalloporphyrin as a recognition element for levamisole assay.

A fluorescence sensor based on the supermolecular recognition by glycosylated metalloporphyrin for levamisole (LEV) assay is reported. For the preparation of a LEV-sensitive active material, 5, 10, 15, 20-tetrakis[2-(2, 3, 4, 6-tetraacetyl-beta-D-glucopyranosyl)-1-O-phenyl] porphyrin and its metal complexes were synthesized and used in an optode membrane prepared by including glycosylated metalloporphyrin in chitosan matrice. The immobilized glycosylated metalloporphyrin is shown to be weakly fluorescent as a result of the inhibiting of the electron tansfer by central metal. The fluorescence enhancement of the metalloporphyrin modified optode membrane by LEV is based on the complexation with the central metal moiety of metalloporphyrin and weakening the inhibiting of the electron tansfer for metalloporphyrin. The glycosylated metalloporphyrin/chitosan optode membrane showed excellent selectivity toward LEV with respect to a number of interferents and exhibited stable response. The calibration graph obtained with the proposed sensor was linear over the range of 1.3x10(-5)-3.5x10(-7)ML(-1), with a detection limit of 3.5x10(-7)ML(-1) for LEV. The prepared sensor is applied for the determination of LEV in pharmaceutical preparations and the results agreed with the values obtained by the pharmacopoeia method.

Biosensing Techniques↗
PubMed2000

Origin of non-Nernstian anion response slopes of metalloporphyrin-based liquid/polymer membrane electrodes.

The origin of the non-Nernstian potentiometric anion response behavior exhibited by several metalloporphyrin-based liquid/polymeric membrane electrodes is examined. UV-visible spectrophotometry of organic-phase solutions and thin plasticized PVC films containing In(III) and Ga(III) octaethylporphyrins suggests that, in the absence of preferred axial coordination anions, the metalloporphyrins form hydroxide ion bridged dimers within the organic phases, as indicated by a significant blue shift of the Soret band in the visible spectrum. As increasing levels of the preferred anions are added, the degree of dimerization decreases and the intensity of the Soret band corresponding to the monomer species increases. Observation of Nernstian responses with membranes doped with picket fence-type In(III) and Ga(III) porphyrins not capable of forming hydroxide bridged structures (as determined by UV-visible spectroscopy) confirms that dimerization is likely responsible for the super-Nernstian slopes of membrane electrodes formulated with the non-picket fence species. A phase boundary model based on simultaneous binding equilibria of hydroxide ions with two metalloporphyrins to form the dimeric species, while the target anions bind with metalloporphyrins to form neutral 1:1 complexes, is shown to fully predict the observed non-Nernstian behavior. The prospect of utilizing this anion-dependent dimer-monomer metalloporphyrin equilibrium to fabricate anion-selective optical sensors using thin films of metalloporphyrin-doped polymers is also discussed.

Electrodes↗
PubMed2000

Oxidative damage generated by an oxo-metalloporphyrin onto the human telomeric sequence.

The cationic metalloporphyrin Mn-TMPyP activated by KHSO(5) has been used as cleaver of an oligonucleotide containing the four human telomere repeats of 5'-GGGTTA. This oligonucleotide formed an intramolecular quadruplex DNA under 200 mM KCl as probed by DMS footprinting and could fold into different quadruplex structures under 200 mM NaCl. We found that the oxo-metalloporphyrin was able to mediate efficient oxidative cleavage of the quadruplex. The location of damage showed that the metalloporphyrin was able to bind to the last G-tetrad of the quadruplex structure via an external interaction. This metalloporphyrin-G-tetrad interaction needs a relatively high flexibility of the single-stranded linker regions to allow the partial stacking of the metalloporphyrin with the last G-tetrad planar structure. The oxidative damage consisted of guanine oxidation within the interacting G-tetrad together with an 1'-carbon hydroxylation of deoxyribose residues of the thymidine residues located on the neighboring single-stranded loop. So the high-valent oxo-metalloporphyrin is able to mediate both electron-abstraction or H-abstraction on G or T residues, respectively, within the DNA quadruplex target.

Base Sequence↗
PubMed1997

Mechanism of induction of heme oxygenase by metalloporphyrins in primary chick embryo liver cells: evidence against a stress-mediated response.

Heme oxygenase catalyzes the first and rate-controlling step in heme catabolism. One of the two forms of heme oxygenase (heme oxygenase-1) has been shown to be increased by heme, metals, and in some systems, by certain environmental stresses. However, it remains uncertain whether heme induces hepatic heme oxygenase-1 by a general stress response, or a specific heme-dependent cellular response. The work communicated here explores this issue by examining possible mechanisms whereby heme and other metalloporphyrins induce heme oxygenase-1 in normal liver cells. Primary cultures of chick embryo liver cells were tested for their ability to increase heme oxygenase mRNA after exposure to selected metalloporphyrins (heme, chromium mesoporphyrin, cobalt protoporphyrin and manganese protoporphyrin). The ability of antioxidants to decrease metalloporphyrin-mediated induction of heme oxygenase-1 mRNA was also tested. Our results indicate that: 1) the increase in heme oxygenase-1 mRNA mediated by heme or other metalloporphyrins may involve a short-lived protein(s) since the increase was prevented by several inhibitors of protein synthesis; and 2) in normal liver cells, heme-dependent oxidative stress does not play a key role in the heme-mediated induction of heme oxygenase-1. We conclude that heme and other non-heme metalloporphyrins induce heme oxygenase-1 through a mechanism requiring protein synthesis, not because metalloporphyrins increase cellular oxidative or other stress.

Animals↗
PubMed1999

Retinoic acid in association with tin-metalloporphyrins influences heme metabolism in vivo in rats.

In the current study we report the perturbation of key enzymes of the heme metabolic pathway, i.e. delta-amino levulinic acid synthase, heme oxygenase and biliverdin reductase, in vivo by administration of retinoic acid (RA) and retinoic acid in association with tin-metalloporphyrins, viz., tin-protoporphyrin (SnPP) and tin-mesoporphyrin (SnMP) in the liver, spleen, heart and lung of rats. RA at a dosing regimen of 50,000 I.U. stimulated splenic ALA-S activity, whereas co-administration of tin-metalloporphyrins with RA antagonised the RA mediated induction of ALA-S. In the other tissues viz., liver, heart and lung our results showed a diminution of ALA-S activity on RA administration, the level of repression was further attenuated when tin-metalloporphyrins were co-administered with RA. This marked suppression of ALA-S brought forth by concurrent administration of RA and tin-metalloporphyrins is suggestive of the beneficial effect of this formulation in acute attacks of porphyria, similar to heme. Furthermore, our results emphasize that the combined dosing of RA with tin-metalloporphyrins leads to a substantial decline in bilirubin levels due to a profound inhibition of HMOX in the probed tissues. The features of the combined action of RA and tin-metalloporphyrins in vivo lead to a substantial suppression of formation of the potentially toxic metabolite bilirubin, and the enhancement of disposal of the untransformed substrate (heme) of the enzyme that is inhibited. These results define some of the characteristics of a therapeutically useful formulation and represent a new therapeutic approach for the amelioration and management of hyperbilirubinemia.

5-Aminolevulinate Synthetase↗
PubMed1999

The connection domain is implicated in metalloporphyrin binding and inhibition of HIV reverse transcriptase.

We have shown that heme and zinc protoporphyrin inhibit both human immunodeficiency virus type 1 (HIV-1) and type 2 (HIV-2) reverse transcriptases (RTs) and, in combination with other nucleoside and non-nucleoside inhibitors, exert an additive effect on HIV-1 RT inhibition. Screening of a phage peptide library against heme resulted in the isolation of a peptide with sequence similarity to sequence 398-407 from the connection subdomain of both HIV-1 and HIV-2 RTs, suggesting that this highly conserved region of HIV RTs corresponds to the binding site for metalloporphyrins and a new site for inhibition of enzyme activity. Inclusion of a synthetic peptide corresponding to the exact sequence 398-407 of HIV-1 RT in RT inhibition assays had a protective effect on metalloporphyrin inhibition, as it was able to reverse the inhibitory effect of both metalloporphyrins on HIV-1 RT activity. Furthermore, intrinsic fluorescence assays indicated that these metalloporphyrins bind to synthetic peptide 398-407 as well as to intact dimeric HIV-1 RT. The identification of this novel inhibition site will help to expand our understanding of the mode of action of metalloporphyrins in RT inhibition and will assist in the design and development of more potent metalloporphyrin RT inhibitors for the management of HIV infection.

Amino Acid Sequence↗
PubMed2005

An alternative Ca2+-dependent mechanism of neuroprotection by the metalloporphyrin class of superoxide dismutase mimetics.

This study challenges the conventional view that metalloporphyrins protect cultured cortical neurons in models of cerebral ischemia by acting as intracellular catalytic antioxidants [superoxide dismutase (SOD) mimetics]. High SOD-active Mn(III)porphyrins meso-substituted with N,N'-dimethylimidazolium or N-alkylpyridinium groups did not protect neurons against oxygen-glucose deprivation (OGD), although lower SOD-active and -inactive para isomers protected against N-methyl-D-aspartate (NMDA) exposure. Mn(III)meso-tetrakis(4-benzoic acid)porphyrin (Mn(III)TBAP), as well as SOD-inactive metalloTBAPs and other phenyl ring- or beta-substituted metalloporphyrins that contained redox-insensitive metals, protected cultures against OGD and NMDA neurotoxicity. Crucially, neuroprotective metalloporphyrins suppressed OGD- or NMDA-induced rises in intracellular Ca2+ concentration in the same general rank order as observed for neuroprotection. Results from paraquat toxicity, intracellular fluorescence quenching, electrophysiology, mitochondrial Ca2+, and spontaneous synaptic activity experiments suggest a model in which metalloporphyrins, acting at the plasma membrane, protect neurons against OGD by suppressing postsynaptic NMDA receptor-mediated Ca2+ rises, thereby indirectly preventing accumulation of neurotoxic mitochondrial Ca2+ levels. Though neuroprotective in a manner not originally intended, SOD-inactive metalloporphyrins may represent promising therapeutic agents in diseases such as cerebral ischemia, in which Ca2+ toxicity is implicated. Conventional syntheses aimed at improving the catalytic antioxidant capability and/or intracellular access of metalloporphyrins may not yield improved efficacy in some disease models.

Animals↗
PubMed1998

Electrospray ionization mass spectrometry of metalloporphyrins.

The magnesium, nickel, copper, zinc and vanadium metalloporphyrins from octaethylporphyrin, etioporphyrin I and tetraphenylporphyrin were characterized using electrospray ionization mass spectrometry (ESI-MS). The ion abundance of each of the porphyrins present in binary mixtures was monitored as a function of the porphyrin concentration and is dependent on the metalloporphyrin oxidation potential. It was found that, for binary mixtures of metalloporphyrins whose oxidation potentials differ by less than 0.1 V, the resulting ion abundance of each species is directly proportional to the concentration of each analyte in the mixture. For binary mixtures whose oxidation potentials differ by more than 0.1 V, relative abundances of the radical cations of each metalloporphyrin are determined by the oxidation potential and concentration of each metalloporphyrin with the analyte of lowest oxidation potential being ionized preferentially. The ability to ionize selectively one porphyrin over another in a binary mixture offers the potential to use ESI-MS for the qualitative analysis of porphyrins present in complex mixtures.

Electrochemistry↗