Home About us Contact
|
Home About us Contact | ||
|
|
||
Porphyrin Derivatives (porphyrin + derivative)
Selected AbstractsPorphyrin derivatives as photosensitizers for the inactivation of Bacillus cereus endosporesJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2009A. Oliveira Abstract Aims:, In this study, we propose (i) to study the photodynamic inactivation (PDI) efficiency of neutral and cationic porphyrin derivatives, (ii) to characterize the kinetics of the inactivation process using Bacillus cereus as a model endospore-producing bacterium and (iii) to conclude on the applicability of porphyrin derivatives in the inactivation of bacterial endospores. Methods and Results:, The study of PDI of Bacillus cereus endospores, taken as model-endospores, using porphyrin derivatives differing in the number of positive charges and in the meso-substituent groups, showed that neutral, monocationic and dicationic porphyrins are quite ineffective, in contrast with the tri- and tetra-cationic molecules. The most effective porphyrin is a tricationic porphyrin with a meso-pentafluorophenyl group. With this photosensitizer (PS), at 0·5 ,mol l,1, a reduction of 3·5 log units occurs after only 4 min of irradiation. None of the porphyrin derivatives showed toxicity in the absence of light. Conclusions:, Some porphyrin derivatives are efficient PSs for the inactivation of bacterial endospores and should be considered in further studies. Small modifications in the substituent groups, in addition to charge, significantly improve the effectiveness of the molecule as a PS for endospore inactivation. Significance and Impact of the Study:, Tetrapyrrolic macrocycles should be regarded as worthy to explore for the PDI of spore-producing gram-positive bacteria. The development of molecules, more selective and effective, emerges as a new objective. [source] Thermal Behavior of Free-Base and Core-Modified Bicyclo[2.2.2]octadiene-Fused PorphyrinsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2008Hidemitsu Uno Abstract Multistep thermal fragmentation of quadruply bicyclo[2.2.2]octadiene-fused porphyrins giving tetrabenzoporphyrins was examined in detail. After the first extrusion of an ethylene molecule from the porphyrin derivative, the opposite bicyclo[2.2.2]octadiene moiety preferentially underwent the second retro-Diels,Alder reaction to give an opp -dibenzoporphyrin derivative rather than an adj -dibenzoporphyrin derivative. These two benzoporphyrin derivatives then decomposed to give a tribenzoporphyrin derivative in similar rates. The temperature regions of these fragmentations could not be distinguished by thermogravimetric analysis. In contrast, the third and the fourth fragmentations obviously occurred stepwise. There was a temperature region where the tribenzoporphyrin derivative preferentially existed. In the case of the 21,23-dithiaporphyrin derivative, opp -21,23-dithiadibenzoporphyrin, possessing benzo moieties fused at the pyrrole parts of the core-modified porphyrin chromophore was predominantly formed during the fragmentation. In the case of the 21-thiaporphyrin derivative, an ethylene molecule was extruded selectively from the bicyclo[2.2.2]octadiene moiety adjacent to the thiophene part to give 21-thiabenzo[q]porphyrin and then 21-thiabenzo[g,q]porphyrin derivatives. In these cases, the last ethylene extrusion also occurred very slowly. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Cytotoxic action mode of a novel porphyrin derivative isolated from harmful red tide dinoflagellate Heterocapsa circularisquamaJOURNAL OF BIOCHEMICAL AND MOLECULAR TOXICOLOGY, Issue 3 2008Daekyung Kim Abstract Heterocapsa circularisquama is known to cause lethal effect on bivalves, but toxic effect on fish has not been reported yet. Recently, we have found that H. circularisquama has potent light-dependent hemolytic toxins. Based on the chemical structural analysis, one of the hemolytic toxins named H2-a was found to be a novel porphyrin derivative with similar structure to pyropheophorbide a methyl ester (PME), a well-known photoactive hemolytic agent (Miyazaki et al., Aquatic Toxicol. 2005;73:382--393). To clarify the cytotoxic action mode of H2-a, we examined the effects of H2-a on HeLa cells in comparison with PME. The cytotoxicities of both reagents were strictly light dependent, and no significant cytotoxic effects including cellular morphological changes were induced without light illumination. The dose response curves revealed that H2-a showed stronger cytotoxicity to HeLa cells than PME. Fluorescence microscopic observation suggested that H2-a tends to accumulate in the plasma membrane, whereas PME seems to distribute entire cytoplasm. Although PME induced typical apoptotic nuclear morphological changes and DNA fragmentation in HeLa cells, no such apoptosis-inducing ability of H2-a was observed. Among the radical scavengers, histidine significantly inhibited the cytotoxic activity of H2-a, suggesting the involvement of singlet oxygen in the cytotoxicity. These results suggest that the cytotoxic mechanism of H2-a is necrotic rather than apoptosis differing from PME, even though these are structurally quite similar to each other. The relatively high affinity of H2-a to the plasma membrane might result in the potent and quick cytotoxicity without induction of apoptotic signal transduction. © 2008 Wiley Periodicals, Inc. J Biochem Mol Toxicol 22:158,165, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jbt.20216 [source] Circular dichroism spectroscopic study of non-covalent interactions of poly- L -glutamic acid with a porphyrin derivative in aqueous solutionsJOURNAL OF PEPTIDE SCIENCE, Issue 9 2005Palivec Abstract The interactions of poly- L -glutamic acid and a cationic porphyrin derivative in aqueous solutions were studied by the combination of vibrational circular dichroism (VCD) and electronic circular dichroism (ECD) spectroscopies. It was found that non-covalent interactions between both agents influence the structure of the polymeric matrix and the guest porphyrins and vice versa, but the physico-chemical properties of the solutions, especially the pH and the relative permittivity of the solvent, play a key role in the structure of the polypeptide part of the formed complexes. It was shown that the interaction with porphyrins prevents the precipitation of poly- L -glutamic acid in aqueous solution at acidic pH. In special conditions, the porphyrins attached to the polypeptide probably possess face-to-face interaction as demonstrated by the enhancement of the characteristic ECD signal and the appearance of sidebands on its short and long wavelength sides. Copyright © 2005 European Peptide Society and John Wiley & Sons, Ltd. [source] Thermal Behavior of Free-Base and Core-Modified Bicyclo[2.2.2]octadiene-Fused PorphyrinsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 1 2008Hidemitsu Uno Abstract Multistep thermal fragmentation of quadruply bicyclo[2.2.2]octadiene-fused porphyrins giving tetrabenzoporphyrins was examined in detail. After the first extrusion of an ethylene molecule from the porphyrin derivative, the opposite bicyclo[2.2.2]octadiene moiety preferentially underwent the second retro-Diels,Alder reaction to give an opp -dibenzoporphyrin derivative rather than an adj -dibenzoporphyrin derivative. These two benzoporphyrin derivatives then decomposed to give a tribenzoporphyrin derivative in similar rates. The temperature regions of these fragmentations could not be distinguished by thermogravimetric analysis. In contrast, the third and the fourth fragmentations obviously occurred stepwise. There was a temperature region where the tribenzoporphyrin derivative preferentially existed. In the case of the 21,23-dithiaporphyrin derivative, opp -21,23-dithiadibenzoporphyrin, possessing benzo moieties fused at the pyrrole parts of the core-modified porphyrin chromophore was predominantly formed during the fragmentation. In the case of the 21-thiaporphyrin derivative, an ethylene molecule was extruded selectively from the bicyclo[2.2.2]octadiene moiety adjacent to the thiophene part to give 21-thiabenzo[q]porphyrin and then 21-thiabenzo[g,q]porphyrin derivatives. In these cases, the last ethylene extrusion also occurred very slowly. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] The Synthesis of the Dimethyl Ester of Quino[4,4a,5,6- efg]-Annulated 7-Demethyl-8-deethylmesoporphyrin and Three of Its Isomers with Unprecedented peri -Condensed Quinoline Porphyrin Structures.EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 19 2004Molecules with Outstanding Properties as Sensitizers for Photodynamic Therapy in the Far-Red Region of the Visible Spectrum Abstract The mesoporphyrin dimethyl ester nickel complex has been formylated via the Vilsmeier method. The four possible mono meso-formyl derivatives were isolated and characterized. Wadsworth,Emmons coupling with the anion of (diethylphosphono)acetonitrile converted these aldehydes into the four novel meso acrylonitriles. Brief treatment of these acrylonitrile systems in hot trichloroacetic acid resulted in the formation of four achiral porphyrin derivatives with unprecedented nickel complexes of quino-fused porphyrins. Subsequent removal of the nickel gave four quino-porphyrin free bases: quino[4,4a,5,6- efg]-annulated 7-demethyl-8-deethylmesoporphyrin dimethyl ester 6a, 2,-(methoxycarbonyl)quino[4,4a,5,6- jkl]-annulated 12-demethyl-13-de[2,-(methoxycarbonyl)ethyl]mesoporphyrin dimethyl ester 6b, 2,-(methoxycarbonyl)quino[4,4a,5,6- qrs]-annulated 18-demethyl-17-de(2,-methoxycarbonylethyl)mesoporphyrin dimethyl ester 6c and quino[4,5,6,7- abt]-annulated 2-demethyl-3-deethylmesoporphyrin dimethyl ester 6d. The structures of these systems were unambiguously determined via mass spectroscopy and a plethora of NMR techniques. In the same way, etioporphyrin and octaethylporphyrin were converted into the corresponding peri -condensed quinoporphyrins as products, which shows that the formation of novel pericondensed quino-porphyrins is a general reaction in the porphyrin series and will have a wide scope in this field. Also, a plausible reaction mechanism for the formation of the quinoporphyrin systems was derived. As a first test for the use of these systems as sensitizers in far-red phototherapy, the quantum yield of singlet oxygen generation by 6a in toluene was studied. This quantum yield is 0.77, which is even higher than the singlet oxygen generation by sensitized meso-tetraphenylporphyrin. Secondly, when Chinese Hamster ovary (CHO) cells were incubated in medium which contained up to 15 ,g/ml of 6a, the survival rate of the cells in the dark is complete within experimental error, showing that under these conditions, 6a is not toxic to CHO cells. When CHO cells incubated in medium containing 6a in concentrations of 1 ,g/ml and higher were treated with white light of intensity 30 mW/cm2 for 15 minutes, complete cell death was observed. Based on these facts, we expect that all four achiral systems will show very promising properties to form the basis of a photodynamic therapy in far-red light. The fact that these systems are achiral is an additional bonus for medical applications. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Porphyrin derivatives as photosensitizers for the inactivation of Bacillus cereus endosporesJOURNAL OF APPLIED MICROBIOLOGY, Issue 6 2009A. Oliveira Abstract Aims:, In this study, we propose (i) to study the photodynamic inactivation (PDI) efficiency of neutral and cationic porphyrin derivatives, (ii) to characterize the kinetics of the inactivation process using Bacillus cereus as a model endospore-producing bacterium and (iii) to conclude on the applicability of porphyrin derivatives in the inactivation of bacterial endospores. Methods and Results:, The study of PDI of Bacillus cereus endospores, taken as model-endospores, using porphyrin derivatives differing in the number of positive charges and in the meso-substituent groups, showed that neutral, monocationic and dicationic porphyrins are quite ineffective, in contrast with the tri- and tetra-cationic molecules. The most effective porphyrin is a tricationic porphyrin with a meso-pentafluorophenyl group. With this photosensitizer (PS), at 0·5 ,mol l,1, a reduction of 3·5 log units occurs after only 4 min of irradiation. None of the porphyrin derivatives showed toxicity in the absence of light. Conclusions:, Some porphyrin derivatives are efficient PSs for the inactivation of bacterial endospores and should be considered in further studies. Small modifications in the substituent groups, in addition to charge, significantly improve the effectiveness of the molecule as a PS for endospore inactivation. Significance and Impact of the Study:, Tetrapyrrolic macrocycles should be regarded as worthy to explore for the PDI of spore-producing gram-positive bacteria. The development of molecules, more selective and effective, emerges as a new objective. [source] Theoretical study of the interaction between a high-valent manganese porphyrin oxyl-(hydroxo)-Mn(IV)-TMPyP and double-stranded DNAJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 7 2003Philippe Arnaud Abstract Cationic porphyrin derivatives such as meso-tetrakis(4- N -methylpyridinium)porphyrin, TMPyP, have been shown to interact with double-stranded DNA. The manganese derivative, Mn(III)-TMPyP, activated by an oxygen donor like potassium monopersulfate, provides an efficient DNA-cleaving system. Previous experimental work1 has shown that DNA cleavage by the Mn(III)-TMPyP/KHSO5 system was due to an oxidative attack, within the minor groove of B-DNA, at the C5, or C1, carbons of deoxyribose units. The aim of this study was to use molecular modeling to elucidate the specificity of the interactions between the transient active species oxyl-Mn(IV)-TMPyP and the DNA target. Geometric parameters, charges, and force field constants consistent with the AMBER 98 force field were calculated by DFT methods. Molecular modeling (mechanics and dynamic simulations) were performed for oxyl-(hydroxo)-Mn(IV)-TMPyP bound in the minor groove of the dodecamer d(5,-TCGTCAAACCGC)-d(5,-GCGGTTTGACGA). Geometry, interactions, and binding energy of the metalloporphyrin located at the A.T triplet region of the dodecamer were analyzed. These studies show no significant structural change of the DNA structure upon ligand binding. Mobility of the metalloporphyrin in the minor groove was restrained by the formation of a hydrogen bond between the hydroxo ligand trans to the metal-oxyl and a DNA phosphate, restricting the access of the oxyl group to the (pro-S) H atom at C5,. © 2003 Wiley Periodicals, Inc. J Comput Chem 24: 797,805, 2003 [source] Vehicles for oligonucleotide delivery to tumoursJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 1 2002Crispin R. Dass The vasculature of a tumour provides the most effective route by which neoplastic cells may be reached and eradicated by drugs. The fact that a tumour's vasculature is relatively more permeable than healthy host tissue should enable selective delivery of drugs to tumour tissue. Such delivery is relevant to carrier-mediated delivery of genetic medicine to tumours. This review discusses the potential of delivering therapeutic oligonucleotides (ONs) to tumours using cationic liposomes and cyclodextrins (CyDs), and the major hindrances posed by the tumour itself on such delivery. Cationic liposomes are generally 100,200 nm in diameter, whereas CyDs typically span 1.5 nm across. Cationic liposomes have been used for the introduction of nucleic acids into mammalian cells for more than a decade. CyD molecules are routinely used as agents that engender cholesterol efflux from lipid-laden cells, thus having an efficacious potential in the management of atherosclerosis. A recent trend is to employ these oligosaccharide molecules for delivering nucleic acids in cells both in-vitro and in-vivo. Comparisons are made with other ON delivery agents, such as porphyrin derivatives (< 1 nm), branched chain dendrimers (, 10 nm), polyethylenimine polymers (, 10 nm), nanoparticles (20,1000 nm) and microspheres (> 1 ,m), in the context of delivery to solid tumours. A discourse on how the chemical and physical properties of these carriers may affect the uptake of ONs into cells, particularly in-vivo, forms a major basis of this review. [source] Synthesis and white electroluminescent properties of multicomponent copolymers containing polyfluorene, oligo(phenylenevinylene), and porphyrin derivativesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2009Hui Li Abstract Two novel multicomponent copolymers (P1 and P2) containing polyfluorene (PF), oligo(phenylenevinylene) (OPV), and porphyrin (Por) derivatives were synthesized according to the Suzuki polymerization method. The structures, optical, and electrochemical properties of the two model compounds (OPV and Por) and multicomponent copolymers were characterized by 1H NMR, FTIR, elemental analysis, UV,vis spectroscopy, photoluminescence, and cyclic voltammetry, respectively. Both of the copolymers exhibit thermotropic liquid crystalline properties and represent the characteristic Schlieren textures in a wide temperature range. Electroluminescence spectra of these copolymers exhibit broadband emissions covering the entire visible region from 400 to 700 nm. The single layer polymer light emitting diodes device based on P2 with a configuration of indium tin oxide/poly(ethylenedioxythiophene):poly(styrenesulfonic acid)/polymers/Ca/Al emits white light with the Commission Internationale de l,Eclairage chromaticity coordinates of (0.29, 0.30), maximum brightness of 443 cd/m2. The white-light-emitting devices based on the novel multicomponent copolymers exhibit low turn-on voltage, and good color stability at different driving voltages as well. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5291,5303, 2009 [source] Computational study of dimethyl- and trimethyl-tin(IV) complexes of porphyrin derivativesAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 7 2001Dario Duca Abstract The molecular geometry, energetics and electronic charge distribution of diorgano- and triorgano-tin(IV) complexes of [protoporphyrin-IX] and [meso -tetra(4-carboxyphenyl)porphine] derivatives were determined at semi-empirical and ab initio levels. To study the molecular details of the complexes, simpler molecule models were calculated by the ab initio pseudo-potential method. The molecular properties of these complexes are essentially independent of the presence of the peripheral tin atoms. Agreement was always found among the results of the different computational approaches, as well as between the theoretical and the experimental findings on the molecular geometry of the hypothesized complexes. Interaction modes between water and the organo-tin systems considered were affected strongly by the presence of peripheral tin atoms. Copyright © 2001 John Wiley & Sons, Ltd. [source] A General Method for Constructing Optically Active Supramolecular Assemblies from Intrinsically Achiral Water-Insoluble Free-Base PorphyrinsCHEMISTRY - A EUROPEAN JOURNAL, Issue 6 2008Yiqun Zhang Abstract We have developed a general method to construct optically active porphyrin supramolecular assemblies by using a simple air,water interfacial assembly process. The method involved the in situ diprotonation of the free-base porphyrins at the air,water interface and subsequent assembly under compression. We showed that two intrinsically achiral water-insoluble free-base porphyrin derivatives, 2,3,7,8,12,13,17,18-octaethyl-21H,23H -porphine (H2OEP) and 5,10,15,20-tetra- p -tolyl-21H,23H -porphine (H2TPPMe), could be diprotonated when spread onto a 2.4,M hydrochloric acid solution surface, and the Langmuir,Schaefer (LS) films fabricated from the subphase exhibited strong circular dichroism (CD) absorption, whereas those fabricated from pure Milli-Q water subphase did not. The experimental data suggested that the helical stacking of the achiral porphyrin building blocks was responsible for the supramolecular chirality of the assemblies. Interestingly, such a method was successfully applied to a series of other intrinsically achiral free-base porphyrins such as 5,10,15,20-tetrakis(4-methoxyphenyl)-21H,23H -porphine (H2TPPOMe), 5,10,15,20-tetraphenyl-21H,23H -porphine (H2TPP), 5,10,15,20-tetrakis(4-(allyloxy)phenyl)-21H,23H -porphine (H2TPPOA), and 5,10,15,20-tetrakis(3,5-dimethoxyphenyl)-21H,23H -porphine (H2TPPDOMe). A possible mechanism has been proposed. The method provides a facile way to obtain optically active porphyrin supramolecular assemblies by using intrinsically achiral water-insoluble free-base porphyrin derivatives. [source] Circular dichroism and the interactions of water soluble porphyrins with DNA,A minireviewCHIRALITY, Issue 4 2003Robert F. Pasternack Abstract The size, sign, and profile of induced circular dichroism (CD) features in the Soret region are reliable indicators of the binding modes of porphyrins and metalloporphyrins to DNA. Porphyrins shown (using such CD criteria) to be intercalators in monodispersed DNA duplexes prove extremely useful for the detection and characterization of organized, condensed forms of nucleic acids (,-condensates). In addition, certain select porphyrin derivatives can form extended assemblies on nonaggregated DNA templates. A combination of CD and resonance light scattering (RLS) measurements allows for sensitive detection and characterization of these porphyrin arrays. Chirality 15:329,332, 2003. © 2003 Wiley-Liss, Inc. [source] | ||||||||||