Protoporphyrin IX-induced structural and functional changes in human red blood cells, haemoglobin and myoglobin.
TL;DR: Spectrophotometric studies reveal that protoporphyrin IX interacts with haemoglobin and myoglobin forming ground state complexes, which may have a role in establishing efficacy of therapeutic uses of porphyrins as well as in elucidating their mechanisms of action as therapeutic agents.
Abstract: Protoporphyrin IX and its derivatives are used as photosensitizers in the photodynamic therapy of cancer. Protoporphyrin IX penetrates into human red blood cells and releases oxygen from them. This leads to a change in the morphology of the cells. Spectrophotometric studies reveal that protoporphyrin IX interacts with haemoglobin and myoglobin forming ground state complexes. For both proteins, the binding affinity constant decreases, while the possible number of binding sites increases, as the aggregation state of the porphyrin is increased. The interactions lead to conformational changes of both haemoglobin and myoglobin as observed in circular dichroism studies. Upon binding with the proteins, protoporphyrin IX releases the heme-bound oxygen from the oxyproteins, which is dependent on the stoichiometric ratios of the porphyrin : protein. The peroxidase activities of haemoglobin and myoglobin are potentiated by the protein-porphyrin complexation. Possible mechanisms underlying the relation between the porphyrin-induced structural modifications of the heme proteins and alterations in their functional properties have been discussed. The findings may have a role in establishing efficacy of therapeutic uses of porphyrins as well as in elucidating their mechanisms of action as therapeutic agents.
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TL;DR: The results indicated that Photofrin® incorporated with IONPs could be considered as a modality to improve cytotoxicity in photodynamic therapy and/or reduces the inhabitation effect.
Abstract: The present study aims to measure the temperature-dependence of in vitro continuous photohemolysis (CPH) photosensitized by Photofrin® in the presence or absence of Iron Oxide Nanoparticles (IONPs) and to evaluate the results using Gompertz function. Red Blood Cells (RBCs) were isolated from human healthy volunteers blood; they were then incubated with Photofrin® only or with IONPs for 45 minutes at 37 °C and then irradiated to a range of temperatures (441°C). The results show that Photosensitization of RBCs by Photofrin® with IONPs presence reduces the inhabitation effect of Photofrin® at the same irradiation temperature since the decreasing in activation energy and increment in t R 50 R were obvious evidence for such result as well as the applicability of Gompertz function to the fractional photohemolysis ratio (a) and the rate of fractional photohemolysis (b), is found to be the most appropriate model to fit the experimental data with minimum parameters and minimum errors, Parameter (a) and the curves steepness were found to be temperatureindependent. On the other hand, values of parameter (b) increased as irradiation temperature increased with or without IONPs presence. The apparent activation energy was found to be 18.85 ± 0.72 kcal/mol in the absence of IONPs and 17.29 ± 0.71 kcal/mol in the presence of IONPs. Our results indicated that Photofrin® incorporated with IONPs could be considered as a modality to improve cytotoxicity in photodynamic therapy and/or reduces the inhabitation effect.
5 citations
Cites background from "Protoporphyrin IX-induced structura..."
...Human erythrocytes were shown to be a primary target in PDT because they have a relatively simple structured model which enables the compounds to create photooxidation process, and the released haemoglobin, due to membrane damage, can be easily measured through spectrophotometrey (Ben-hur et al., 1986)....
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...Therefore, molecular Oxygen existence is a key point in PDT (Henderson et al., 2000; Sil et al., 2004)....
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...Keywords: Continuous Photohemolysis (CPH), Gompartz parameters, Iron Oxide Nanoparticles (IONPs), Irradiation temperatures, Photodynamic Therapy (PDT) * Corresponding author. e-mail: alakmoh@just.edu.jo....
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...Photodynamic Therapy (PDT) is a promising treatment modality that has been successfully used in treating localized tumours, providing tumour selectivity and normal tissue sparing with almost no serious side effects....
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...PDT employs the combination of light and photosensitizers to damage localized cancer cells (Sternberg et al., 1997; Dougherty et al., 1998)....
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17 May 2018
TL;DR: It was shown that, for the transferrin-porphyrin complexes, singlet oxygen luminescence is significantly decreased due to the presence of transferrin amino acids which are efficient quenchers of singletoxy.
Abstract: In photodynamic therapy (PDT) of tumors, targeted therapy is one of the most successful directions. The goal of the present work was to study the formation of new potential photosensitizers, based on transferrin (Tf) and cationic porphyrins, for targeted binding with transferrin receptors of cancer cells. We studied non-covalent binding of three cationic porphyrins 1) meso-tetra [4-N-(2'-oxyethtyl) pyridyl] porphyrin (TOEt4PyP) 2) Zn-TOEt4PyP and 3) Zn-mesotetra [4-N-butyl pyridyl] porphyrin (Zn-TBut4PyP) with human transferrin by absorption and fluorescent spectroscopy as well as by gel filtration methods. It was shown that the investigated porphyrins and metalloporphyrins bind stably enough to the protein molecule. It was found that the porphyrins having Zn ion in porphyrin core as well as the peripheral OH - groups are linked better to the transferrin molecules. It can be apparently explained by Zn coordination with transferrin amino acids and the formation of the hydrogen bonds between OH - groups of the porphyrin and transferrin amino acids. It was shown that, for the transferrin-porphyrin complexes, singlet oxygen luminescence is significantly decreased due to the presence of transferrin amino acids which are efficient quenchers of singlet oxygen.
4 citations
Cites background from "Protoporphyrin IX-induced structura..."
...At the same time, it was shown that cationic porphyrins also bind to another important blood protein - hemoglobin, which can serve as their carrier.(9,10) A great interest is to study the binding of porphyrins to the blood protein - transferrin, which carries iron ions....
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01 Jan 2011
TL;DR: A photon subsurface scattering method to simulate light transport in human colon tissue and to collect the data containing the effect of fluorescence to find the best position of endoscope during cancer seeking and recognition.
Abstract: This paper introduces a photon subsurface scattering method to simulate light transport in human colon tissue. First the theoretical model and parameters of human tissue including autofluorescence phenomenon was presented. Then it was described the Monte-Carlo model of steadystate light transport in multi-layered colon. The goal of this investigation is to simulate the light propagation in tissue and to collect the data containing the effect of fluorescence. This information will be used to generate images. Pictures taken for different adjustment of light parameters should define a configuration for which cancerous structures are visible quickly and precisely. Real medical devices can adjust their parameters to the simulated ones and help with efficient diagnosis and recognition of diseased structures. 2. A. Zacher: Initial angle of light rays and their influence on the total distribution, scattering and absorption in human tissue. Studia Informatica, 4(87):37-52, 2009. Abstract: This paper describes the method of light transport in human colon tissue. The structure is treated as a turbid medium, so that subsurface scattering model can be applied. Extended photon mapping algorithm is utilized to add a contribution of fluorescence phenomenon and finally generate images. The quantitative dependencies between photon’s angle of incidence and their distribution in the tissue are going to be shown. This investigation can be later used to find the best position of endoscope during cancer seeking and recognition. This paper describes the method of light transport in human colon tissue. The structure is treated as a turbid medium, so that subsurface scattering model can be applied. Extended photon mapping algorithm is utilized to add a contribution of fluorescence phenomenon and finally generate images. The quantitative dependencies between photon’s angle of incidence and their distribution in the tissue are going to be shown. This investigation can be later used to find the best position of endoscope during cancer seeking and recognition. 3. A. Zacher: Mathematical model of human tissue in photodynamic cancer recognition, Studia Informatica, 4(87):53-66, 2009. Abstract: This paper presents the method of light propagation in human tissue. Subsurface scattering model together with photon mapping is applied to generate images. Surface and volumetric photon maps were used to fully describe the fluorescence phenomenon. The qualitative comparison between images will be presented to find the best camera angle of incidence. Moreover, multi-spectral images rendered during simulations are verified with real, scientific images. This paper presents the method of light propagation in human tissue. Subsurface scattering model together with photon mapping is applied to generate images. Surface and volumetric photon maps were used to fully describe the fluorescence phenomenon. The qualitative comparison between images will be presented to find the best camera angle of incidence. Moreover, multi-spectral images rendered during simulations are verified with real, scientific images. 4. A. Zacher: Utilization of Multi-spectral Images in Photodynamic Diagnosis. Lecture Notes in Computer Science, 6375:367-375, 2010.
4 citations
Cites background from "Protoporphyrin IX-induced structura..."
...Photodynamic diagnosis is of great interest for medicine [6]....
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TL;DR: This study shows that bioallethrin forms a stable complex with human Hb which may lead to loss of Hb function in the body.
Abstract: Abstract Bioallethrin is an insecticide that is widely used in households resulting in human exposure. Bioallethrin is cytotoxic to human erythrocytes. Here we have studied the interaction of bioallethrin with human hemoglobin (Hb) using in silico and biophysical approaches. Incubation of Hb (5 μM) with bioallethrin (1–50 µM) led to increase in absorbance at 280 nm while the Soret band at 406 nm was slightly reduced. The intrinsic fluorescence of Hb was enhanced with the appearance of a new peak around 305 nm. Synchronous fluorescence showed that the binding of bioallethrin to Hb mainly affects the tyrosine microenvironment. The structural changes in Hb were confirmed with a significant shift in CD spectra and about 25% loss of α-helix. Molecular docking and visualisation through Discovery studio confirmed the formation of Hb-bioallethrin complex with a binding energy of –7.3 kcal/mol. Molecular simulation showed the stability and energy dynamics of the binding reaction between bioallethrin and Hb. The structural changes induced by bioallethrin led to inhibition of the esterase activity of Hb. In conclusion, this study shows that bioallethrin forms a stable complex with human Hb which may lead to loss of Hb function in the body. Communicated by Ramaswamy H. Sarma Graphical representation showing structural changes, enzymatic alteration upon complex formation between BA and Hb with different in vitro and in silico approaches. This study shows that a stable Hb:BA complex is formed which results in structural changes in human Hb and also inhibits its esterase activity. These changes will further affect the normal functioning of Hb and may cause blood related clinical issues in the BA exposed population.
4 citations
TL;DR: In this paper , chitosan nanoparticles were synthesized by ionic gelation and conjugated by coacervation with a pDNA rabies vaccine to test their attachment efficiency.
Abstract: In Mexico, urban rabies has been reduced during the last decade thanks to intensive canine control and vaccination campaigns; however, rabies transmitted by wild animals, especially by bats, has been increasing due to vampire bats feeding on livestock. Vampire bat populations has been controlled by culling with vampiricides, reducing indiscriminately other bat species. Hence, bat vaccination for rabies offers an alternative for culling. Nevertheless, available rabies vaccines are not suitable for their use in wildlife from emerging countries. This project presents an alternative for the use of plasmid vaccines using bio-nanotechnology, to create low-cost and accessible vaccines. To accomplish this goal, chitosan nanoparticles were synthesized by ionic gelation and conjugated by coacervation with a pDNA rabies vaccine to test their attachment efficiency. Also, the conjugate was functionalized with Protoporphyrin IX and Folic acid as biomarkers. The nanoparticles complex was characterized by ultraviolet visible spectroscopy, infrared spectroscopy, transmission electron microscopy, dynamic light scattering, and the Z potential was obtained. In vitro tests were performed on cell viability and transfection. The nanoparticles possessed a low polydispersity, a mean size of 118.5 ± 13.6 nm and a Z potential of 17.3 mV. The attachment efficiency was of 100% independent of pDNA added. In contrast to functionalized nanoparticles which showed a max attachment efficiency of 99.6% dependent of pDNA concentration and the method of functionalization. The conjugate did not influence the viability and they improved the transfection efficiency. Results suggest that these nanoparticles are easy to prepare, inexpensive, and exhibit potential for plasmid delivery as it improves transfection efficiency of pDNA vaccines.
4 citations
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01 May 1988
TL;DR: A comprehensive review of mechanisms of subcellular and tumor localization of photosensitizing agents, as well as of molecular, cellular, and tumor responses associated with photodynamic therapy, are discussed.
Abstract: Photodynamic therapy involves administration of a tumor-localizing photosensitizing agent, which may require metabolic synthesis (i.e., a prodrug), followed by activation of the agent by light of a specific wavelength. This therapy results in a sequence of photochemical and photobiologic processes that cause irreversible photodamage to tumor tissues. Results from preclinical and clinical studies conducted worldwide over a 25-year period have established photodynamic therapy as a useful treatment approach for some cancers. Since 1993, regulatory approval for photodynamic therapy involving use of a partially purified, commercially available hematoporphyrin derivative compound (Photofrin) in patients with early and advanced stage cancer of the lung, digestive tract, and genitourinary tract has been obtained in Canada, The Netherlands, France, Germany, Japan, and the United States. We have attempted to conduct and present a comprehensive review of this rapidly expanding field. Mechanisms of subcellular and tumor localization of photosensitizing agents, as well as of molecular, cellular, and tumor responses associated with photodynamic therapy, are discussed. Technical issues regarding light dosimetry are also considered.
4,580 citations
1,853 citations
"Protoporphyrin IX-induced structura..." refers methods in this paper
...The αhelical contents of the protein in the presence and absence of the porphyrin were estimated from the spectra according to the relation (Chen et al 1972): Fraction of α-helix = ([θ ]222 + 2340)/– 30300, where [θ ]222 is the ellipticity at 222 nm. 2.9 Assay of peroxidase activities of Hb and…...
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TL;DR: Can the superoxide radical exert deleterious effects independent of participating with H2O2 in the production of the hydroxyl radical?
1,433 citations
"Protoporphyrin IX-induced structura..." refers background in this paper
...Superoxide radicals are generated in HRP/H2O2/NAD(P)H system (Takayama and Nakano 1977) and these radicals may inhibit the peroxidase activity of HRP (Fridovich 1986)....
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...…radicals are generated in HRP/H2O2/NAD(P)H system (Takayama and Nakano 1977) and these radicals may inhibit the peroxidase activity of HRP (Fridovich 1986). van Steveninck et al (1987, 1988) have postulated that superoxide radical generation is prevented by the porphyrin hematoporphyrin…...
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...Interaction of PP with HRP as demonstrated from this laboratory (Sil and Chakraborti 1997) may be involved in this process, because potentiation of HRP activity has a positive correlation with the extent of binding of the protein with the porphyrin....
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...Drug-protein binding; haemoglobin; myoglobin; protoporphyrin IX; red blood cells ________________ Abbreviations used: cd, Circular dichroism; EPP, erythropoietic protoporphyria; Hb, haemoglobin; HRP, horseradish peroxidase; Mb, oxymyoglobin; PDT, photodynamic therapy; PP, protoporphyrin; RBC, red blood cells; ZPP, zinc protoporphyrin....
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...It is not yet known how porphyrins remove or inhibit generation of superoxide radicals in HRP system....
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TL;DR: Studies have shown that a higher accumulation of ALA‐derived PpIX in rapidly proliferating cells may provide a biologic rationale for clinical use of ALa‐based PDT and diagnosis, however, no review updating the clinical data has appeared so far.
Abstract: BACKGROUND
Photodynamic therapy (PDT) for cancer patients has developed into an important new clinical treatment modality in the past 25 years PDT involves administration of a tumor-localizing photosensitizer or photosensitizer prodrug (5-aminolevulinic acid [ALA], a precursor in the heme biosynthetic pathway) and the subsequent activation of the photosensitizer by light Although several photosensitizers other than ALA-derived protoporphyrin IX (PpIX) have been used in clinical PDT, ALA-based PDT has been the most active area of clinical PDT research during the past 5 years Studies have shown that a higher accumulation of ALA-derived PpIX in rapidly proliferating cells may provide a biologic rationale for clinical use of ALA-based PDT and diagnosis However, no review updating the clinical data has appeared so far
METHODS
A review of recently published data on clinical ALA-based PDT and diagnosis was conducted
RESULTS
Several individual studies in which patients with primary nonmelanoma cutaneous tumors received topical ALA-based PDT have reported promising results, including outstanding cosmetic results However, the modality with present protocols does not, in general, appear to be superior to conventional therapies with respect to initial complete response rates and long term recurrence rates, particularly in the treatment of nodular skin tumors Topical ALA-PDT does have the following advantages over conventional treatments: it is noninvasive; it produces excellent cosmetic results; it is well tolerated by patients; it can be used to treat multiple superficial lesions in short treatment sessions; it can be applied to patients who refuse surgery or have pacemakers and bleeding tendency; it can be used to treat lesions in specific locations, such as the oral mucosa or the genital area; it can be used as a palliative treatment; and it can be applied repeatedly without cumulative toxicity Topical ALA-PDT also has potential as a treatment for nonneoplastic skin diseases Systemic administration of ALA does not seem to be severely toxic, but the advantage of using this approach for PDT of superficial lesions of internal hollow organs is still uncertain The ALA-derived porphyrin fluorescence technique would be useful in the diagnosis of superficial lesions of internal hollow organs
CONCLUSIONS
Promising results of ALA-based clinical PDT and diagnosis have been obtained The modality has advantages over conventional treatments However, some improvements need to be made, such as optimization of parameters of ALA-based PDT and diagnosis; increased tumor selectivity of ALA-derived PpIX; better understanding of light distribution in tissue; improvement of light dosimetry procedure; and development of simpler, cheaper, and more efficient light delivery systems Cancer 1997; 79:2282-308 © 1997 American Cancer Society
1,000 citations