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PubMed1989

Dehalogenation of lindane by a variety of porphyrins and corrins.

The dehalogenation of lindane by a range of hemoproteins, porphyrins, and corrins has been tested under reducing conditions in the presence of dithiothreitol. In addition, a series of porphyrin-metal ion complexes have been prepared and have also been screened for the capacity to dehalogenate lindane. Hemoglobin, hemin, hematin, and chlorophyll alpha all catalyzed the dehalogenation of lindane, as did all of the corrins tested. The porphyrins which did not contain metal centers--coproporphyrin, hematoporphyrin, protoporphyrin, and uroporphyrin--were inactive. However, when these porphyrins were then complexed with Co, Fe, Mg, Mo, Ni, or V, lindane dehalogenation was observed. In all cases, the reaction proceeded by an initial dechlorination to produce tetrachlorocyclohexene, which was further dehalogenated to yield chlorobenzene as the end product.

Chlorophyll↗
PubMed1978

Comparative studies of porphyrin production in Propionibacterium acnes and Propionibacterium granulosum.

Porphyrin production by Propionibacterium acnes and that by Propionibacterium granulosum were compared. Porphyrin synthesized by both organisms was identified as coproporphyrin III on the bases of absorption and fluorescence spectra and behavior on paper chromatography and thin-layer chromatography. Quantitative, rather than qualitative, differences in production were found between these organisms. In general, P. granulosum produced significantly greater amounts (P less than 0.001) of porphyrin than did P. acnes. delta-Aminolevulinic acid synthetase appeared to be the rate-limiting enzyme of the heme biosynthetic pathway in both organisms. The increased porphyrin production in P. granulosum is apparently associated with increased delta-aminolevulinic acid synthetase activity.

5-Aminolevulinate Synthetase↗
PubMed1991

Gender differences and time course of castration-induced changes in porphyrins, indoles, and proteins in the Harderian glands of the Syrian hamster.

Sexual differences and the effects of orchidectomy were determined for porphyrin and melatonin concentrations and for the activities of the enzymes N-acetyltransferase and hydroxyindole-O-methyltransferase, which synthesize melatonin from serotonin, in the Harderian glands of the Syrian hamster. Porphyrin concentrations in intact males were about 1/400th those of intact females. Castration for 1 week increased male Harderian porphyrin concentrations 10-fold; by 3 weeks, castrated male porphyrin levels were 140 times those of control values. N-Acetyltransferase activity in intact male Harderian glands was about 4 times that of females. Castration led to a drop in N-acetyltransferase activity to female levels within 2 weeks. Hydroxyindole-O-methyltransferase activity was 7 times higher in females than in males and castration had no effect on male Harderian hydroxyindole-O-methyltransferase activity. Neither gender nor castration influenced Harderian melatonin concentrations. Soluble proteins in Harderian glands from male and female hamsters and from male hamsters castrated for 1 and 4 weeks were examined by sodium dodecyl sulfate--polyacrylamide gel electrophoresis. The gel profiles revealed several differences among the protein distribution in male and female gland lysates. Orchidectomy led to a female protein pattern within 4 weeks.

Androgens↗
PubMed1981

Drugs affecting porphyrin and lipid metabolism in rats: effects exerted by allylisopropylacetamide and related molecules.

Allylisopropylacetamide (AIA), a drug known to cause lesions in porphyrin and lipid metabolism, and drugs with structure related to AIA [propylisopropylacetamide (PIA) and 2-isopropyl-4-hydroxyvaleric acid] were injected subcutaneously into rats. Measurements were taken of the effect of these compounds on the levels of 5-aminolevulinic acid synthetase (ALA synthetase) and hepatic porphyrins and on the values of hepatic and plasmatic triglycerides and plasma free fatty acids. To a different degree, both AIA and PIA increase the activity of ALA synthetase, and also increase the levels of hepatic porphyrins and hepatic and plasmatic triglycerides, while they both initially lower the levels of plasmatic free fatty acids (FFAs). The administration of 2-isopropyl-4-hydroxyvaleric acid has no effect on the parameters studied. The findings seem to suggest that the activity affecting porphyrin and lipid metabolism is connected in both cases with the presence of the amide function.

5-Aminolevulinate Synthetase↗
PubMed2002

Atomic force microscopic observation of the molecular orientation in ultrathin films of alkanoic acid-derivatized porphyrins on a mica surface.

The observation of the molecular orientation of alkanoic acid-derivatized porphyrins in ultrathin films deposited on mica was carried out by atomic force microscopy. It was observed that the tetraacid derivative 5, 10, 15, 20-tetra(N-10-carboxydecyl-pyridinium-4-yl) porphyrin was arranged as a monolayer with the porphyrin macrocycle oriented coplanar to the mica surface. On the other hand, the diacid derivative protoporphyrin IX Zn(II) formed a bilayer with the hydrophobic part inside and the hydrophilic part in the periphery. Therefore, in this case, the porphyrin macrocycle is roughly perpendicular to the mica surface.

Aluminum Silicates↗
PubMed1990

Antioxidative effect of several porphyrins on lipid peroxidation in rat liver homogenates.

The effect of several porphyrins on Fe2(+)-ascorbic acid-stimulated lipid peroxidation was examined in rat liver homogenates. Not only protoporphyrin IX (PP) but also mesoporphyrin IX and hematoporphyrin inhibited the lipid peroxidation. Some porphyrins, in which 6- and 7-carboxyethyl groups were esterified with a methyl group, such as protoporphyrin IX dimethyl ester and mesoporphyrin IX dimethyl ester, had no antioxidative effect. Hemin and zinc protoporphyrin IX, which are metal-chelated porphyrins, inhibited the lipid peroxidation while cobalt protoporphyrin IX and tin protoporphyrin IX showed no antioxidative effect. Thus, some of the porphyrins used in the present study showed an antioxidative effect as did PP, but the others did not show such an effect.

Animals↗
PubMed2001

Solution properties and photonuclease activity of cationic bis-porphyrins linked with a series of aliphatic diamines.

The development of efficient photo-induced DNA cleavage agents has been of particular interest for biomedical applications such as cancer photodynamic therapy (PDT). Toward this objective, we synthesized a series of cationic bis-porphyrins with various lengths of diamino alkyl linkage, N,N'-bis[4-[10,15,20-tris(1-methylpyridinium-4-yl)porphyrin-5-yl]benzoyl]oligomethylenediamine hexaiodide. They were expected to show more efficient photocleavage of DNA than unichromophore meso-tetrakis(4-N-methylpyridiniumyl)porphine (TMPyP), which is well known to cleave DNA effectively on illumination. The cationic bis-porphyrins were found to self-aggregate in aqueous solution, and the aggregation property was accounted for by the formation of an intermolecular dimer. Because conservative-type circular dichroism spectra of the bis-porphyrins were induced in the Soret region on binding to calf thymus DNA, we assigned their binding mode to outside self-stacking on the DNA surface. Their photonuclease activity using plasmid DNA decreased as the number of their linker hydrocarbons increased, and was well correlated with their tendency for dimerization. The inhibitory effect of azide anion, N3-, and the enhancement effect of D2O suggest that singlet oxygen was probably involved in the photocleavage of DNA.

Circular Dichroism↗
PubMed2001

Efficient photocleavage of DNA by cationic porphyrin-acridine hybrids with the effective length of diamino alkyl linkage.

Positively charged porphyrins bearing an acridine with various lengths of diamino alkyl linkage, 5-[4-[(6-chloro-2-methoxy-9-acridyl)aminoalkylaminocarbonyl]phenyl]-10,15,20-tris(4-N-methylpyridiniumyl)porphine triiodide, alkyl=ethyl, butyl, hexyl, or octyl, were synthesized. They exhibited more enhanced photocleavage activity of pUC18 plasmid DNA than TMPyP, meso-tetrakis(4-N-methylpyridiniumyl)porphine, which is well known to bind to DNA tightly and to cleave DNA effectively; the hybrid linked with the hexamethylene chain showed particularly high activity. An equilibrium dialysis experiment demonstrated that the binding ability of the hybrids to calf thymus (CT) DNA correlated quantitatively with the photocleavage activity. The lack of the substantial red-shift of the Soret maxima of the hybrids through the titration with CTDNA denied the intercalative binding of the porphyrin part. In their circular dichroism (CD) spectral change on binding to CTDNA, two negative peaks appeared at 275 nm and at 285-290 nm in the UV range. The latter negative peak was observed for hybrids, but not for TMPyP, and thus we assigned it to induced CD (ICD) derived from intercalation of acridine chromophore. In the visible range, the hybrids showed only a positive peak around their Soret maxima, and this feature suggested the porphyrin moiety lay in the DNA groove. In addition, the length of the linker markedly influenced the ellipticity of their visible ICD, suggesting that the proximity of the porphyrin moiety to DNA was greatly affected by the linker.

Acridines↗
PubMed2004

Plasma fluorescence scanning and fecal porphyrin analysis for the diagnosis of variegate porphyria: precise determination of sensitivity and specificity with detection of protoporphyrinogen oxidase mutations as a reference standard.

BACKGROUND: Variegate porphyria (VP) is the autosomal dominant disorder associated with deficiency of the enzyme protoporphyrinogen oxidase (PPOX). Plasma fluorescence scanning has been reported to be a more sensitive test for VP than traditional fecal chromatography. Previous comparisons of these techniques predated identification of the PPOX gene. We assessed these techniques in a large group of patients characterized for VP at the DNA level. METHODS: We evaluated all patients for whom the genotype and a plasma scan or fecal porphyrin result were available. Mutations were detected by restriction digest analysis. Plasma fluorescence scanning was conducted according to published methods. Fecal porphyrins were identified and quantified by thin-layer chromatography. RESULTS: Plasma fluorescence scanning was assessed in 679 patients (205 with VP who were carriers of a PPOX mutation, either with disease symptoms or asymptomatic) and fecal analysis in 473 (190 with VP). Sensitivity and specificity of both tests were higher in adults than in children and higher for adults with disease symptoms than for asymptomatic carriers. In a direct comparison in 168 adults (73 with VP), plasma scanning was significantly more sensitive than fecal porphyrin analysis [sensitivity, 0.96 (95% confidence interval, 0.89-0.99) vs 0.77 (0.66-0.85)]. Fecal coproporphyrin [area under the curve, 0.87 (0.83-0.90)] was a better predictor of VP than protoporphyrin [0.80 (0.76-0.84)]. CONCLUSIONS: Plasma scanning is a more sensitive and specific test for VP than fecal porphyrin analysis. Neither test is sensitive in children, and both are less sensitive in asymptomatic carriers than in symptomatic cases. DNA analysis therefore remains the preferred method for the identification of carriers, particularly in children.

Adolescent↗
PubMed1976

Total plasma porphyrins in renal disease.

Thirty patients suffering from chronic kidney disease were examined for urinary, fecal and total plasma porphyrins. Twenty patients had nitrogen retention whereas the remaining ten patients displayed normal values. Urinary coproporphyrin excretion and total plasma porphyrin levels were comparatively less pronounced in patients with nitrogen retention. Such changes in porphyrin metabolism could be explained by a diminished capacity for kidney excretion. It is concluded that the total amount of porphyrins synthesized in the body is decreased as a result of nitrogen retention.

Adolescent↗
PubMed1985

"Glucose effect" and rate limiting function of uroporphyrinogen synthase on porphyrin metabolism in hepatocyte culture: relationship with human acute hepatic porphyrias.

The effect of glucose on drug-promoted induction of porphyrin synthesis was studied in chick embryo liver cell culture with and without the addition of exogenous delta-aminolaevulinic acid (ALA). Induction of ALA synthase was abolished by haemin or glucose. Less than 10% of porphobilinogen is converted into protoporphyrin. Protoporphyrin synthesis cannot be enhanced by high ALA concentrations. The conversion of exogenous ALA into porphyrins decreases with increasing concentrations of ALA from 0.1 to 2.0 mmol/l, whereas porphobilinogen accumulates, thus reflecting the rate limiting function of uroporphyrinogen synthase, which is not influenced by glucose. This needle-eye-like function of uroporphyrinogen synthase within the porphyrin biosynthetic chain explains the urinary increase of ALA and porphobilinogen in the acute phase of variegate and coproporphyria, similar to that in acute intermittent porphyria. The "glucose effect" was also investigated in vivo in humans in 32 courses of hereditary acute hepatic porphyrias (acute intermittent porphyria, variegate porphyria, coproporphyria and porphobilinogen synthase defect porphyria). Patients were treated with high carbohydrate intake (approximately 500 g/24 h), mainly in the form of glucose infusions. There was a resulting consistent and highly significant decrease of porphyrin biosynthesis metabolites, accompanied by clinical improvement in most of the patients.

5-Aminolevulinate Synthetase↗
PubMed1995

Evaluation of a first-line spectrophotometric screening test for increased faecal porphyrin concentration.

We compared a spectrophotometric screening test measuring faecal porphyrin concentration with an HPLC method. There was a good overall correlation between both methods although some scatter was observed. ROC plot analysis of the screening test leads to a cut-off value of 35 nmol porphyrin per g faeces, wet weight with a sensitivity of 97% and a specificity of 96%. These results indicate that the screening test is quite useful for detection of increased total faecal porphyrin concentration, but less useful in accurate measurement of increased total faecal porphyrin concentration.

Adolescent↗
PubMed2000

On accuracy and precision of a HPLC method for measurement of urine porphyrin concentrations.

We studied the accuracy and precision of a HPLC method for determination of porphyrins in urine. A commercial standard solution appeared to contain less porphyrins than indicated by the manufacturer, since calibration resulted in lower concentrations of uroporphyrin and coproporphyrin: 16% and 8%, respectively. Coefficients of variation for the measurement of uro-, hepta-, copro I and copro III porphyrins in samples of patients with and without porphyria were often much less than 15%. Comparison of measurements with and without calibrated standards revealed differences for uroporphyrin and coproporphyrin of 27% and 5%, respectively. Recovery of added uroporphyrin and coproporphyrin was 99%. The main cause of the variability in test results was apparently the improperly calibrated standard solutions. The precision of porphyrin measurements was not influenced by the type of porphyria.

Calibration↗
PubMed2002

Do liposome-binding constants of porphyrins correlate with their measured and predicted partitioning between octanol and water?

We tested correlations between lipophilicity parameters and the partitioning of sensitizers into membranes. For this purpose we investigated 17 porphyrins and two chlorins having various chemical structures. Some of these compounds possess an amphiphilic structure (including hematoporphyrin, deuteroporphyrin, mesoporphyrin, chlorin e6 and more). The others are very symmetrical sensitizers [meso-tetra(N-methyl-4-pyridyl)porphyrin, tetra-benzoporphyrin, coproporphyrin I dihydrochloride (CP), meso-tetra(4-carboxyphenyl)porphyrin (TCP) and meso-tetra(m-hydroxyphenyl)chlorin]. Our investigation also included two series of hematoporphyrins and protoporphyrins with varying lengths of alkylcarboxylate side groups. The partitioning of these compounds between the bulk aqueous phase and liposomes was studied by fluorescence methods, and a liposome-binding constant, Kb, was obtained. It was found that CP and TCP do not incorporate into the lipid phase at pH 7.3. An n-octanol-water partition coefficient (log P) and a distribution coefficient (log D) were predicted with a modeling software. The values of log D were also obtained experimentally. We found that for the studied molecules, the predicted log D correlated well with the measured values. The values of log D as well as log P, in turn, did not correlate nicely, for the whole group of studied compounds, with the binding constants to liposomes. However, in the case of porphyrins that share a similar structure, the Kb showed good linear correlation with both log P and log D. For the series of hematoporphyrins and protoporphyrins with different lengths of alkylcarboxyl groups, it was shown that prolongation of this group caused an increase in the lipophilicity and the liposome-binding constant. This effect is more pronounced for the proto- than for the hematoporphyrin series. The results highlight the possible use, as well as limitations, of lipophilicity parameters for the prediction of membrane binding.

1-Octanol↗
PubMedDate not supplied

Porphyrin-fullerene C60 dyads with high ability to form photoinduced charge-separated state as novel sensitizers for photodynamic therapy.

The photodynamic activities of a porphyrin-C60 dyad (P-C60) and its metal complex with Zn(II) (ZnP-C60) were compared with 5-(4-acetamidophenyl)-10,15,20-tris(4-methoxyphenyl)porphyrin (P), both in homogeneous medium-bearing photooxidizable substrates and in vitro on the Hep-2-human-larynx-carcinoma cell line. This study represents the first evaluation of dyads, with a high capacity to form a photoinduced charge-separated state, to act as agents to inactivate cells by photodynamic therapy (PDT). Absorption and fluorescence spectroscopic studies were performed in toluene and N,N-dimethylformamide (DMF). The emission of the porphyrin moiety in the dyads is strongly quenched by the attached fullerene C60 moiety. The singlet molecular oxygen, O2(1delta(g)), productions (phi(delta)) were determined using 9,10-dimethylanthracene (DMA). The values of phi(delta) were strongly dependent on the solvent's polarity. Comparable phi(delta) values were found for dyads and P in toluene, while O2(1delta(g)) production was significantly diminished for the dyads in DMF. In more polar solvent, the stabilization of charge-transfer state takes place, decreasing the efficiency of porphyrin triplet-state formation. Also, both dyads photosensitize the decomposition of L-tryptophan in DMF. In biological medium, no dark cytotoxicity was observed using sensitizer concentrations < or = 1 microM and 24 h of incubation. The uptake of sensitizers into Hep-2 was studied using 1 microM of sensitizer and different times of incubation. Under these conditions, a value of approximately 1.5 nmol/10(6) cells was found between 4 and 24 h of incubation. The cell survival after irradiation of the cells with visible light was dependent upon light-exposure level. A higher photocytotoxic effect was observed for P-C60, which inactivates 80% of cells after 15 min of irradiation. Moreover, both dyads keep a high photoactivity even under argon atmosphere. Thus, depending on the microenvironment where the sensitizer is localized, these compounds could produce biological photodamage through either an O2(1delta(g))-mediated photoreaction process or a free-radicals mechanism under low oxygen concentration. These results show that molecular dyads, which can form a photoinduced charge-separated state, are a promising model for phototherapeutic agents, with potential applications in cell inactivation by PDT.

Fullerenes↗
PubMedDate not supplied

A large entropic term due to water rearrangement is concomitant with the photoproduction of anionic free-base porphyrin triplet states in aqueous solutions.

The enthalpy change, DeltaTH, and volume change, DeltaTV, associated with triplet state formation upon excitation of free-base meso-tetra-(4-sulfonatophenyl)porphyrin, TSPP4-, its Zn derivative, ZnTSPP4-, and meso-tetra-(4-carboxyphenyl)porphyrin, TCPP4-, were obtained in aqueous solutions by the application of laser-induced optoacoustics spectroscopy in the presence of phosphate salts of various monovalent cations (Li+, Na+, K+, NH4+ and Cs+). A linear correlation was found between DeltaTH and DeltaTV at different phosphate concentrations for the free-base porphyrins. The intercepts (132 +/- 8 kJ mol(-1) for TSPP4- and 164 +/- 23 kJ mol(-1) for TCPP4-) of these plots correspond to the respective value of the triplet energy content obtained from phosphorescence at 77 K (140 and 149 kJ mol(-1)). This suggests that DeltaTG for the triplet state formation is independent of the medium and an enthalpy-entropy compensation is responsible for the much smaller and salt-dependent DeltaTH values obtained at room temperature. The Gibbs energy for triplet state formation of the free-base porphyrins at room temperature is thus mainly determined by the entropic term due to solvent rearrangement. The DeltaTH values for 3ZnTSPP4- at different buffer concentrations and different cations are all between 130 and 150 kJ mol(-1), close to the triplet energy obtained from phosphorescence (E(T) = 155 kJ mol(-1)). The solvent structure and the nature of the counterion have a negligible influence on the 3ZnTSPP4-formation due to the blockage of the electron pairs on the central N atoms. Thus, the small DeltaTV value should be due to intrinsic bond changes upon 3ZnTSPP4- formation and no correlation between DeltaTH and DeltaTV should be expected in this case. The enthalpy change determines the Gibbs energy for 3ZnTSPP4-formation at room temperature.

Electrons↗
PubMed2006

New derivatives of 5-aminolevulinic acid for photodynamic therapy: chemical synthesis and porphyrin production in in vitro and in vivo biological systems.

Photodynamic therapy (PDT) has become a new treatment for several oncological and nononcological disorders. This procedure involves systemic or topical administration of a lesion-localizing photosensitizer or prodrug, followed by irradiation with visible light to cause singlet oxygen-induced damage to the target tissue. 5-aminolevulinic acid (ALA) is an endogenous precursor for several photosensitizing porphyrins formed by heme biosynthesis, and has been studied for PDT with promising results for some superficial diseases of the skin and hollow internal organs. Hydrophilic ALA has a limited ability to penetrate certain biological barriers and has a relatively low selectivity for lesions. In addition, its ability to induce intracellular porphyrins has been shown to be low compared to most esters of ALA. This stimulated a search for lipophilic derivatives of ALA to overcome the shortcomings of ALA. Thirty-two new esters of ALA were prepared and their ability to induce porphyrin formation was assessed in the WiDr human carcinoma cell line in vitro and in the normal skin of Balb/c nude mice in vivo. Branched-chain alkyl esters and substituted benzyl esters were found to be the most efficient porphyrin precursors of the compounds studied.

Aminolevulinic Acid↗
PubMed2006

Mechanism of porphyrin-induced sonodynamic effect: possible role of hyperthermia.

The biological effects of ultrasound have been investigated vigorously for various applications including the thermal coagulation of tissues, the opening of tight junctions, and localized gene or drug introduction. The synergistic cell killing effect of ultrasound and porphyrin derivatives, the so-called sonodynamic effect, holds promise for cancer treatment. Although several models to explain the sonodynamic effect have been proposed, its exact mechanism, especially in vivo, remains unknown. We examined the effect of a porphyrin derivative, protoporphyrin IX, on ultrasound-induced killing of HeLa cells. In some experiments, the intracellular protoporphyrin IX concentration was increased by 5-aminolevulinic acid treatment of the cells. Although extracellular protoporphyrin IX showed an enhanced cell killing effect by microbubble-enhanced ultrasound, intracellular protoporphyrin IX did not. On the other hand, intracellular protoporphyrin IX enhanced the cell killing effect of hyperthermia, which can be produced by ultrasound exposure, in a moderately acidic environment (pH 6.6). Because porphyrin derivatives are generally imported into the intracellular component in vivo, our results suggest that hyperthermia caused by ultrasound may play an important role in the sonodynamic effect induced by porphyrin derivatives.

Aminolevulinic Acid↗