Porphyrin Compounds Research Articles

Assembly structures and electronic properties of truxene–porphyrin compounds studied by STM/STS

The self-assembly of functional molecules into uniform nanostructures with innovational properties has attracted extensive research interest. In the present work, the assembly structures and electronic properties of a novel type of truxene derivative, e.g. truxene-porphyrin derivatives, were studied, for the first time, on a highly oriented pyrolytic graphite (HOPG) surface. Scanning tunneling microscopy (STM) images revealed that the truxene-porphyrin compounds could be parallelly arranged into long-ranged lamellar patterns. Density functional theory (DFT) calculations helped explain the assembly mechanisms further. Besides, order distribution of the smaller compound 1T1P in the 1,3,5-tris(10-carboxydecyloxy)-benzene (TCDB) host network was achieved, which is a reflection of the dimensional effect in the host-guest assembly. Furthermore, together with theoretical analyses, scanning tunneling spectroscopy (STS) measurements were conducted to investigate the electronic properties of truxene-porphyrin compounds. Results showed that the metalation of the porphyrin units could have a significant effect on the band gap and the position of the gap center. The study enhances our understanding of the assembly mechanism of truxene derivatives at the molecular level and paves the way towards fabricating truxene-based functional nanodevices.

Insight into the Interaction of Cationic Porphyrin-Anthraquinone Hybrids with Hsp90: In Silico Analysis

Heat shock protein 90 (Hsp90) is responsible for the correct folding of many cellular proteins. Several Hsp90 inhibitors have been developed for cancer treatment. The present in silico study aimed to evaluate the potential of several porphyrin derivatives conjugated with anthraquinone groups as Hsp90 inhibitors by using simulation of molecular docking and molecular dynamics. The binding mode of porphyrin hybrids to Hsp90, which was examined by using AutoDock 4.2, showed that all six porphyrin compounds fit well in the binding pocket of Hsp90. The pi-cationic interactions with Lys58 were exclusively observed in the interaction of each porphyrin hybrid. Stabilities of porphyrin-Hsp90 complexes were confirmed by 40-ns MD simulation, which was carried out with the help of AMBER16. Prediction of ligand affinity by using the MM-PBSA method showed that all complexes were energetically favorable as indicated by a negative binding free energy. The predicted affinities of tris−H2PyP−AQ, tris−H2PzP−AQ, bis−H2PzP−AQ, and mono−H2PzP−AQ are better than those of geldanamycin, a known inhibitor of Hsp90, which shows the importance of the electrostatic and van der Waals energies for ligand binding.

Supramolecular Adducts of Anionic Porphyrins and a Biocompatible Polyamine: Effect of Photodamage-on Human Red Blood Cells.

Supramolecular adducts obtained by interaction between the anionic porphyrin meso-tetrakis(4-carboxyphenyl)porphyrin (TPPC) or its zinc(II) derivative (ZnTPPC) with a biocompatible amino-terminated polypropylene or poly(ethylene oxide)s (Jeffamines) has been investigated. The interaction with the polymer allows the stabilization of the porphyrins in their monomeric form under physiological conditions. The photodynamic properties of the supramolecular adducts were explored by typical 1O2 indirect detection. Their photodynamic action were evaluated in vitro using human red blood cells (HRBCs) under different experimental conditions. The morphology of erythrocytes was investigated by optical microscopy after incubation with porphyrin compounds and light irradiation. The images show loss of their normal biconcave profile and an incoming spiny configuration with blebs evident on their surfaces.

An optical sensor of acidity in fuels based on a porphyrin derivative

The measure of the acid concentration in an organic media is a common issue in chemistry. With the aim to overcome this problem in a facile and inexpensive way, the spectroscopic properties of a PEGylate porphyrin derivative, the 5,10,15,20-p-(ω-methoxypolyethyleneoxyphenyl) porphyrin (P), as an acidity sensor were tested.Its behaviour was analysed in toluene and several fuels through acid titration experiments. In each case, examining UV–vis and fluorescence spectroscopic data, the disappearance of the free-base porphyrin derivative Uv–vis signals (B- and Q-bands) and the increasing of new bands, as a consequence of the added acid, was monitored.On the basis of these data it was possible to evaluate the presence of acid in several organic media as toluene, gasoline, diesel, and jet fuel, using our porphyrin derivative in very low amount (about 3 ppm).Finally, in order to exclude the risk of a negative contribution of P in ash formation, the complete oxidation of the porphyrin compound under common engine's combustion conditions was also ascertained.

Porphyrins to restrict progression of pancreatic cancer by stabilizing KRAS G-quadruplex: In silico, in vitro and in vivo validation of anticancer strategy

KRAS, a frequently mutated G-quadruplex forming proto-oncogene is responsible for almost every type of cancer which can form a parallel G-quadruplex structure in the promoter region. G-quadruplex structure is one of the most important drug targets for modern cancer therapy for their unique structure and specificity. Here, we have screened several synthetic porphyrin-based compounds as potential KRAS G-quadruplex stabilizing ligands, using molecular modeling and docking studies. Two novel porphyrins: Porphyrin-1(Cobalt containing) and Porphyrin-2 (Palladium containing) evidenced high affinity towards KRAS-promoter/G-quadruplex. As KRAS mutation is prevalent in pancreatic cancer, the efficacy of these ligands against human pancreatic ductal carcinoma cell line PANC-1 and MiaPaCa2 were examined. Both the Porphyrins exhibited significant cytotoxicity and block metastasis by inhibiting Epithelial to messenchymal transition. In vivo studies confirmed both porphyrin compounds to be effective against EAC tumors along with significantly low toxicity against normal Swiss albino mice. The expression of KRAS gene in porphyrin-treated PANC-1, MiaPaCa2 and tumor-derived EAC cells were drastically reduced at both protein and RNA levels. Thus interaction of porphyrin-based ligands with G-quadruplex DNA at the promoter region of KRAS, might be utilized as a target for anticancer therapeutic strategy.

ELECTROCHEMICAL BEHAVIOUR OF PORPHYRINS AND THEIR METAL COMPLEXES

This study aims to establish a group of heterogeneous organic compounds of porphyrin and derived compounds. This is useful for many medical fields such as phototherapy or industrial therapy such as dyes and OLED screens. On this basis, we assembled a group of six compounds and a group of their compounds with different metals such as Zn and Co, and studied their properties by spectral methods. We conducted an electrochemical study through the voltmeter ring to study the effect of alternatives and the quality of the metal on the oxidation and for a group of six porphyrin compounds and enables us to study future applications of vehicles obtained and developed in OLED light emitting it.

Functionalized Zinc Porphyrins with Various Peripheral Groups for Interfacial Electron Injection Barrier Control in Organic Light Emitting Diodes.

Here, we use a simple and effective method to accomplish energy level alignment and thus electron injection barrier control in organic light emitting diodes (OLEDs) with a conventional architecture based on a green emissive copolymer. In particular, a series of functionalized zinc porphyrin compounds bearing π-delocalized triazine electron withdrawing spacers for efficient intramolecular electron transfer and different terminal groups such as glycine moieties in their peripheral substitutes are employed as thin interlayers at the emissive layer/Al (cathode) interface to realize efficient electron injection/transport. The effects of spatial (i.e., assembly) configuration, molecular dipole moment and type of peripheral group termination on the optical properties and energy level tuning are investigated by steady-state and time-resolved photoluminescence spectroscopy in F8BT/porphyrin films, by photovoltage measurements in OLED devices and by surface work function measurements in Al electrodes modified with the functionalized zinc porphyrins. The performance of OLEDs is significantly improved upon using the functionalized porphyrin interlayers with the recorded luminance of the devices to reach values 1 order of magnitude higher than that of the reference diode without any electron injection/transport interlayer.

Early detection of colorectal adenocarcinoma: a clinical decision support tool based on plasma porphyrin accumulation and risk factors

BackgroundAn increase in naturally-occurring porphyrins has been described in the blood of subjects bearing different kinds of tumors, including colorectal, and this is probably related to a systemic alteration of heme metabolism induced by tumor cells. The aim of our study was to develop an artificial neural network (ANN) classifier for early detection of colorectal adenocarcinoma based on plasma porphyrin accumulation and risk factors.MethodsWe measured the endogenous fluorescence of blood plasma in 100 colorectal adenocarcinoma patients and 112 controls using a conventional spectrofluorometer. Height, weight, personal and family medical history, use of alcohol, red meat, vegetables and tobacco were all recorded. An ANN model was built up from demographic data and from the integral of the fluorescence emission peak in the range 610–650 nm. We used the Receiver Operating Characteristic (ROC) curve to assess performance in distinguishing colorectal adenocarcinoma patients and controls. A liquid chromatography-high resolution mass spectrometry (LC-HRMS) analytical method was employed to identify the agents responsible for native fluorescence.ResultsThe fluorescence analysis indicated that the integral of the fluorescence emission peak in the range 610–650 nm was significantly higher in colorectal adenocarcinoma patients than controls (p < 0.0001) and was weakly correlated with the TNM staging (Spearman’s rho = 0.224, p = 0.011). LC-HRMS measurements showed that the agents responsible for the fluorescence emission were mainly protoporphyrin-IX (PpIX) and coproporphyrin-I (CpI). The overall accuracy of our ANN model was 88% (87% sensitivity and 90% specificity) with an area under the ROC curve of 0.83.ConclusionsThese results confirm that tumor cells accumulate a diagnostic level of endogenous porphyrin compounds and suggest that plasma porphyrin concentrations, indirectly measured through fluorescence analysis, may be useful, together with risk factors, as a clinical decision support tool for the early detection of colorectal adenocarcinoma. Our future efforts will be aimed at examining how plasma porphyrin accumulation correlates with survival and response to therapy.

Features of interaction of tetraiodide meso-tetra(N-methyl-3-pyridyl)porphyrin with bovine serum albumin

The interaction processes spectral study of tetraiodide meso-tetra(N-methyl-3-pyridyl)porphyrin with blood serum albumin has been carried out. The results obtained are considered in comparison with similar data for tetraphenylporphyrin and tetraiodide meso-tetra(N-methyl-4-pyridyl)porphyrin. It is established that interaction of albumin with the porphyrins under study leads to a change in the secondary structure of the protein accompanied by a decrease in the proportion of disordered fragments of the protein and an increase in β-structuring within the complexes. NCH3+ group isomerism position in the porphyrin compound significantly affects binding to albumin. Adding of the substituent in meta-position of the phenyl ring contributes to the increased affinity of protein to the cationic porphyrin, compared to the pair-substituted counterpart.

Triazine-Substituted Zinc Porphyrin as an Electron Transport Interfacial Material for Efficiency Enhancement and Degradation Retardation in Planar Perovskite Solar Cells

Motivated by the excellent electron-transfer capability of porphyrin molecules in natural photosynthesis, we introduce here the first application of a porphyrin compound to improve the performance of planar perovskite solar cells. The insertion of a thin layer consisting of a triazine-substituted Zn porphyrin between the TiO2 electron transport layer and the CH3NH3PbI3 perovskite film significantly augmented electron transfer toward TiO2 while also sufficiently improved the morphology of the perovskite film. The devices employing porphyrin-modified TiO2 exhibited a significant increase in the short-circuit current densities and a small increase in the fill factor. As a result, they delivered a maximum power conversion efficiency (PCE) of 16.87% (average 14.33%), which represents a 12% enhancement compared to 15.01% (average 12.53%) of the reference cell. Moreover, the porphyrin-modified cells exhibited improved hysteretic behavior and a higher stabilized power output of 14.40% compared to 10.70% of the re...

Photo-induced antibacterial activity of a porphyrin derivative isolated from the harmful dinoflagellate Heterocapsa circularisquama

The dinoflagellate Heterocapsa circularisquama is highly toxic to bivalves. However, significant toxicity to finfish species has not been reported. We previously found that H. circularisquama has light-dependent haemolytic agents. Purification and chemical structural analyses revealed that the haemolytic agent H2-a is a porphyrin derivative, which exhibits light-dependent cytotoxicity toward tumour cells. To clarify the biological activity of H2-a further, its antibacterial activities against Gram-positive and Gram-negative bacteria were investigated in this study. A fraction (F5) equivalent to H2-a purified from the methanol extract of H. circularisquama showed potent light-dependent bactericidal activity toward Staphylococcus aureus, and the activity was concentration- and light illumination time-dependent; however, Escherichia coli was highly resistant to F5. Electron microscopic observation suggested that F5 induces morphological changes in S. aureus in a light-dependent manner. Further analysis using other bacterial species showed that the Gram-positive bacterium Bacillus subtilis was more sensitive than the Gram-negative bacteria Pseudomonas aeruginosa and Vibrio alginolyticus. These results indicate that F5 is a photo-induced antibacterial agent with relatively higher specificity to Gram-positive bacteria. Iodometric assay suggested that singlet oxygen was generated from light-illuminated F5. Histidine, a specific singlet oxygen scavenger, markedly inhibited the photosensitising antibacterial activity of F5 against S. aureus, suggesting the involvement of singlet oxygen in antibacterial activity. The antibacterial spectrum of F5 was evidently different from that of 5,10,15,20-tetra (N,N,N-trimethylanilinium) porphyrin tetratosylate, a commercially available porphyrin compound with antibacterial activity. Our results demonstrate that H. circularisquama has a novel antibacterial photosensitiser, a porphyrin derivative, with relatively higher specificity to Gram-positive bacteria. To the best of our knowledge, this is the first study to discover a porphyrin derivative with antibacterial activity in marine microalga.

The Transcriptional Coactivator TAZ Is a Potent Mediator of Alveolar Rhabdomyosarcoma Tumorigenesis.

Purpose: Alveolar rhabdomyosarcoma (aRMS) is a childhood soft tissue sarcoma driven by the signature PAX3-FOXO1 (P3F) fusion gene. Five-year survival for aRMS is <50%, with no improvement in over 4 decades. Although the transcriptional coactivator TAZ is oncogenic in carcinomas, the role of TAZ in sarcomas is poorly understood. The aim of this study was to investigate the role of TAZ in P3F-aRMS tumorigenesis.Experimental Design: After determining from publicly available datasets that TAZ is upregulated in human aRMS transcriptomes, we evaluated whether TAZ is also upregulated in our myoblast-based model of P3F-initiated tumorigenesis, and performed IHC staining of 63 human aRMS samples from tissue microarrays. Using constitutive and inducible RNAi, we examined the impact of TAZ loss of function on aRMS oncogenic phenotypes in vitro and tumorigenesis in vivo Finally, we performed pharmacologic studies in aRMS cell lines using porphyrin compounds, which interfere with TAZ-TEAD transcriptional activity.Results: TAZ is upregulated in our P3F-initiated aRMS model, and aRMS cells and tumors have high nuclear TAZ expression. In vitro, TAZ suppression inhibits aRMS cell proliferation, induces apoptosis, supports myogenic differentiation, and reduces aRMS cell stemness. TAZ-deficient aRMS cells are enriched in G2-M phase of the cell cycle. In vivo, TAZ suppression attenuates aRMS xenograft tumor growth. Preclinical studies show decreased aRMS xenograft tumor growth with porphyrin compounds alone and in combination with vincristine.Conclusions: TAZ is oncogenic in aRMS sarcomagenesis. While P3F is currently not therapeutically tractable, targeting TAZ could be a promising novel approach in aRMS. Clin Cancer Res; 24(11); 2616-30. ©2018 AACR.

Biocatalysis mechanisms and characterization of a novel denitrification process with porphyrin compounds based on the electron transfer chain

In this research, the nitrate reduction rate increased 2–3 fold in the presence of five different porphyrin compounds (0.25 mM), among which hemin expressed the best accelerating effectiveness. Therefore, hemin was used to explore the catalytic characteristics and mechanisms during denitrification. The relationship between hemin concentrations (Chemin) and nitrate reduction rates (k) could be best described by the equation k = 8.7463 + 0.44528ln (Chemin-0.00993) (R2 = 0.9908). Furthermore, the activation energy decreased 87% compared to the hemin-free system. Two active centers of hemin, the Fe3+ atom and the porphyrin ligand, might be involved in catalyzing the denitrification process. Additionally, the accelerating site of hemin in the denitrification electron transfer chain was elucidated by different metabolic inhibitors. This study provides a better understanding of porphyrin compounds in bio-multistage redox reactions and is a promising strategy for its practice application.

Plant Sunscreen and Co(II)/(III) Porphyrins for UV-Resistant and Thermally Stable Perovskite Solar Cells: From Natural to Artificial.

The poor UV, thermal, and interfacial stability of perovskite solar cells (PSCs) makes it highly challenging for their technological application, and has drawn increasing attention to resolving the above issues. In nature, plants generally sustain long exposure to UV illumination without damage, which is attributed to the presence of the organic materials acting as sunscreens. Inspired by the natural phenomenon, a natural plant sunscreen, sinapoyl malate, an ester derivative of sinapic acid, is employed to modify the surface of electron transport materials (ETMs). The interfacial modification successfully resolved the UV stability and reduced the poor interfacial contact between ETM and perovskite. The best efficiency of fabricated PSCs is up to 19.6%. Furthermore, we employed a mixture of Co(II) and Co(III)-based porphyrin compounds containing the excellent Co(II)/Co(III) redox couple to substitute the commonly used hole transport material, 2,2',7,7'-tetrakis(N,N-di-p-methoxyphenylamine)-9,9-spiro-bifluorene (spiro-OMeTAD), to resolve the thermal degradation of PSCs noted at and above 80 °C that originates from ion diffusion of I- and CH3 NH3+ (MA+ ) ions from perovskite into spiro-OMeTAD. Finally, the stable PSCs with the best efficiency up to 20.5% are successfully fabricated.

Production of Formamides from CO and Amines Induced by Porphyrin Rhodium(II) Metalloradical.

It is of fundamental importance to transform carbon monoxide (CO) to petrochemical feedstocks and fine chemicals. Many strategies built on the activation of C≡O bond by π-back bonding from the transition metal center were developed during the past decades. Herein, a new CO activation method, in which the CO was converted to the active acyl-like metalloradical, [(por)Rh(CO)]• (por = porphyrin), was reported. The reactivity of [(por)Rh(CO)]• and other rhodium porphyrin compounds, such as (por)RhCHO and (por)RhC(O)NH nPr, and corresponding mechanism studies were conducted experimentally and computationally and inspired the design of a new conversion system featuring 100% atom economy that promotes carbonylation of amines to formamides using porphyrin rhodium(II) metalloradical. Following this radical based pathway, the carbonylations of a series of primary and secondary aliphatic amines were examined, and turnover numbers up to 224 were obtained.

Fabrication of Visible-light Responsive N-doped TiO2 Nanothin Films via a Top–down Sol–gel Deposition Method Using NH4TiOF3 Single Crystals

We report a novel coating method for TiO2 anatase thin-film fabrication via a top–down sol–gel deposition method using NH4TiOF3 single crystals. A cationic nitrogen-rich porphyrin compound was used to fabricate N-doped TiO2 nanofilms that showed highly efficient photocatalytic activity under visible-light irradiation.

Molecular modeling on porphyrin derivatives as β5 subunit inhibitor of 20S proteasome

The ubiquitin-proteasome system plays an important role in protein quality control. Currently, inhibition of the proteasome has been validated as a promising approach in anticancer therapy. The 20S core particle of the proteasome harbors β5 subunit which is a crucial active site in proteolysis. Targeting proteasome β5 subunit which is responsible for the chymotrypsin-like activity of small molecules has been regarded as an important way for achieving therapeutics target. In the present study, a series of porphyrin derivatives bearing either pyridine or pyrazole rings as meso-substituents were designed and evaluated as an inhibitor for the β5 subunit of the proteasome by employing molecular docking and dynamics simulations. The molecular docking was performed with the help of AutoDock 4.2, while molecular dynamics simulation was done using AMBER 14. All compounds bound to the proteasome with similar binding modes, and each porphyrin-proteasome complex was stable during 30 ns MD simulation as indicated by root-mean-square-deviation (RMSD) value. An analysis on protein residue fluctuation of porphyrin binding demonstrates that in all complexes, porphyrin binding produces minor fluctuation on amino acid residues. The molecular mechanics Poisson-Boltzmann surface area (MM-PBSA) free energy calculation shows that the binding affinities of mono-H2PyP, bis-H2PzP, and tetra-H2PyP were comparable with that of the potential inhibitor, HU10. It is noted that the electrostatic interaction increases with the number of meso-substituents, which was favourable for porphyrin binding. The present study shows that both electrostatic and van der Waals interaction are the main force which controls the interaction of porphyrin compounds with the proteasome.

Mitochondrial Reactive Oxygen Species Accelerated Cancer Specific Porphyrin Accumulation to Enhance Photodynamic Therapeutic Effect in Gastric Epithelial Cells

Photodynamic therapy is useful for the treatment of cancer because it is minimally invasive for patients. Certain porphyrin compounds and their derivatives have been used as the photosensitizer because they accumulate specifically in cancerous tissues. However, the detailed mechanism of this phenomenon has not been clarified. We previously reported that a proton-coupled folate transporter, HCP1, transported porphyrins and that regulation of the protein was associated with cancer-specific reactive oxygen species from mitochondria (mitROS) (Hiyama K et al. J PorphPhtal. 2013; 17: 36–43). Therefore, over-generation of mitROS could increase HCP1 expression and the effect of photodynamic therapy. We investigated whether pretreatment with indomethacin influenced photodynamic therapy by using a rat normal gastric mucosal cell line, RGM1, its cancer-like mutated cell line, RGK1, and a manganese superoxide dismutase (MnSOD)-overexpressed RGK cell line, RGK-MnSOD. Indomethacin promotes the generation of cellular mitROS by inhibiting the electron transport chain, and MnSOD scavenges the mitROS. We elucidated that hyperthemia enhanced cancer-specific mitROS generation and increased HCP1 expression. Furthermore, RGK1 cells showed higher cellular incorporation of hemato-porphyrin and better therapeutic effect with indomethacin treatment whereas RGK-MnSOD cells did not show a difference. Thus, we concluded that hyperthermia improved the effect of photodynamic therapy by inducing increased mitROS generation in cancer cells.

DFT studies on solvent dependence of electronic absorption spectra of free-base and protonated porphyrin

Abstract The nature of the solvent and composition of the solution in which optical absorption spectra are acquired can substantially affect the structures of analytes as well as spectra and relative intensities of spectral features. We have computed the effects of the solvent for dilute solutions on the electronic absorption spectra and structures of a prototypical porphyrin—free-base porphyrin (herein referred to as FBP and H2FBP)—and its protonated form (H4FBP) in the ground and the lowest triplet states, both important in device and medical applications. Density functional theory (DFT) and time-dependent-DFT (TD-DFT) have been employed to investigate solvent effects on structure and singlet-singlet (S0 → Sn) and triplet-triplet (T1 → Tn) absorption spectra. We also calculated the solvent dependence of energy gaps between optically allowed singlet and nearest triplet states for the species. Soret band positions are found to be strongly solvent dependent, but less so are Q bands. The finding of dependence of the spectroscopic features of the porphyrin on the dielectric constant of the solvent, from 1.00 (gas-phase) to about 20.493 (acetone)—with the features becoming stable for polar solvents with the dielectric constants e > 20—can be used to monitor micro environmental changes of porphyrin (and its derivatives) embedded in biological systems and nanoparticles; such composites may also be suitable to study and monitor modifications of the chemical environment in different solutions and interactions with biological systems and nanoparticles. This is first systematical study on the solvent-dependence of the porphyrin compounds.

Third-order optical measurements of porphyrin compounds using Dark-field and D4σ-Z scan imaging techniques

The newly introduced imaging techniques D4σ and Dark-field Z-scan (DFZ-scan) are very much appropriate to measure the third-order nonlinear (NL) refractive index in the presence of high nonlinear absorption (NLA) in condensed matter. To demonstrate the large potential of both techniques we prepared and characterized porphyrins solutions in chlorobenzene and report here on the NL optical properties of 5,10,15,20-Tetraphenyl-21H,23H-porphyrin (TPP), 5,10,15,20-Tetraphenyl-21H,23H-zinc porphyrin (ZnTPP), 5,10,15,20-tetraphenyl-21H,23H-porphyrin cobalt(II) (CoTPP) and 5,10,15,20-tetrakis(4-methoxyphenyl)−21H,23H-porphyrin cobalt(II) (MCoTPP). The measurements were performed with a laser delivering low repetition rate linearly polarized single picosecond pulses at 1064 nm and 532 nm.