Preliminary research on metalized phthalocyanines synthesis. Evaluation as potential photosensitizer in photodynamic therapy

SUMMARY Introduction: Phthalocyanines are porphyrin-based dyes. They have plenty applications in different fields, including biomedical and chemical research. From a chemical point of view, Phthalocyanines are macrocyclictetraaza compounds, which mainly are made up of isoindol groups that confer aromaticity and planarity on Phthalocyanine structure. Unlike other kinds of porphyrin compounds, Phthalocyanine structure is able to chelate a lot of metals, which more often contribute to their huge variety of functions, including ROS generation, fluorescence, absorption spectra, and others. Aim: To evaluate phthalocyanines compounds owing their excellent photochemical and pharmaceutical properties that explain their wide use at the clinical and medical level. Methodology: We have carried out a meticulous search for scientific works related to the subject between April 2020 and April 2021, the most of them were written in English. As a result, we can say that, for studying Phthalocyanines' properties, the work can be separated into two issues: synthesis of the metalized phthalocyanines and photochemical and photobiological properties. Results: Phthalocyanines have plenty properties that are desirable to biomedical and pharmaceutical research. Because of their photochemical and photobiological properties, as well as ROS generation, Phthalocyanines are one of the photosenstitizers most widely used in photodynamic therapy. They also have antibacterial, antiviral and anticancer activities. In this sense, Phthalocyanine synthesis and in vitro studies are a very important scientific issue.

Introducción: las ftalocianinas son tintes porfirínicos. Tienen muchas aplicaciones en diferentes campos, incluida la investigación biomédica y química. Desde el punto de vista químico, las ftalocianinas son compuestos macrocíclicos de tetraaza. Se componen principalmente de grupos isoindol que confieren aromaticidad y planaridad a la estructura de la ftalocianina. Esta última es capaz de quelar muchos metales, que con mayor frecuencia contribuyen a su gran variedad de funciones, incluida la generación de EROS, la fluorescencia, los espectros de absorción y otros. Objetivo: evaluar algunos derivados de ftalocianinas gracias a las excelentes propiedades fotoquímicas y farmacéuticas que explican su amplio uso a nivel clínico y médico. Metodología: hemos realizado una búsqueda minuciosa de trabajos científicos relacionados con el tema entre abril de 2020 y abril de 2021, la mayoría de ellos escritos en inglés. Como resultado, podemos decir que, para estudiar las propiedades de las ftalocianinas, el trabajo se puede dividir en dos temas: síntesis de las ftalocianinas metalizadas y propiedades fotoquímicas y ffotobiológicas. Resultados: las ftalocianinas tienen muchas propiedades que son deseables para la investigación biomédica y farmacéutica. Por sus propiedades fotoquímicas y fotobiológicas, así como por la generación de EROS, las ftalocianinas son uno de los fotosensibilizadores más utilizados en terapia fotodinámica. También tienen actividades antibacterianas, antivirales y anticancerígenas. En este sentido, la síntesis de ftalocianina y los estudios in vitro son un tema científico muy importante.

Introdução: as ftalocianinas são corantes à base de porfirinas. Eles têm muitas aplicações em diferentes campos, incluindo pesquisas biomédicas e químicas. Do ponto de vista químico, as ftalocianinas são compostos macrocíclicos tetraaza, que são constituídos principalmente por grupos isoindol que conferem aromaticidade e planaridade à estrutura das ftalocianinas. Ao contrário de outros tipos de compostos de porfirina, a estrutura da ftalocianina é capaz de quelar uma grande quantidade de metais, que mais frequentemente contribuem para sua enorme variedade de funções, incluindo geração de ROS, fluorescência, espectro de absorção e outros. Objetivo: avaliar alguns derivados de ftalocianinas graças às excelentes propriedades fotoquímicas e farmacêuticas que explicam a sua ampla utilização a nível clínico e médico. Metodologia: efetuamos uma busca minuciosa de trabalhos científicos relacionados ao assunto entre abril de 2020 e abril de 2021, a maioria deles redigidos na língua inglesa. Como resultado, podemos dizer que, para estudar as propriedades das ftalocianinas, o trabalho pode ser dividido em duas questões: síntese das ftalocianinas metalizadas e propriedades fotoquímicas e fotobiológicas. Resultados: as ftalocianinas têm muitas propriedades desejáveis para a pesquisa biomédica e farmacêutica. Pelas suas propriedades fotoquímicas e fotobiológicas, além da geração de ROS, as ftalocianinas são um dos ffotossensibilizantes mais amplamente utilizados na terapia fotodinàmica e processos fototóxicos. Eles também têm atividades antibacteriana, antiviral e anticàncer. Nesse sentido, a síntese de ftalocianina e os estudos in vitro são uma questão científica muito importante.

Progress in application and detection of riboflavin singlet oxygen photochemistry / 中国输血杂志

Photodynamic therapy (PDT), which uses photosensitizers to produce singlet oxygen to kill bacteria, was first discovered by scientists over 100 years ago and has been widely used in clinical treatment. Riboflavin is an endogenous and the most commonly used photosensitizer.A large number of studies have shown that riboflavin can produce singlet oxygen through photodynamic reaction(typeⅡ) after illumination.This method is currently widely used to kill pathogens such as bacteria and viruses in blood, and singlet oxygen is considered to be the key factor in the photodynamic effect.Singlet oxygen can induce cell apoptosis, necrosis and autophagy.At present, there are direct and indirect methods to detect singlet oxygen, but both with some limitations.This paper reviews production mechanism, action mechanism and detection of singlet oxygen produced by riboflavin during photodynamic therapy, which provides a basis for further application of photodynamic therapy in clinical practice and searching for a more suitable detection method for singlet oxygen.

An in vitro study on the clearance effect of oxygen-releasing photodynamic therapy on Enterococcus faecalis in the root canal / 口腔疾病防治

Objective@#To investigate the clearance effect of photodynamic therapy (PDT) with an oxygen-releasing photosensitizer methylene blue (MB) formula on Enterococcus faecalis in the root canal.@*Methods @# Groups were divided into the MB group and oxygen release MB group. Samples in the MB group were mixed with 50 μmol/L MB solution, and samples in the oxygen release MB group were mixed with 50 μmol/L MB in oxygen release emulsion. N-acetyl-L-tryptophan amide (NATA) and 1,3-diphenylisobenzofuran (DPBF) were used to detect the oxidative activity and singlet oxygen generation of different formulas of MB (MB group, oxygen-releasing MB group), and the oxygen-releasing capacity of the oxygen-releasing photosensitizer formula was analyzed. The single root canal anterior teeth were collected, and the Enterococcus faecalis root canal infection model of isolated teeth was constructed. The distribution of Enterococcus faecalis in the root canal was observed by scanning electron microscopy. The isolated teeth with Enterococcus faecalis root canal infection were divided into three groups: the conventional root canal therapy group, MB-PDT therapy group, and oxygen-releasing MB-PDT therapy group, with 10 teeth in each group. Bacterial samples in the root canals of each group were obtained, the number of colonies was analyzed(CFU/mL) after 24 h of in vitro culture, and the clearance rate of Enterococcus faecalis in the root canal by photodynamic therapy was evaluated. The remaining isolated teeth with Enterococcus faecalis root canal infection were divided into 3 groups, with 5 samples in each group. Bacterial samples at a depth of 1 000 μm in the dentin tubules of the upper root, middle root and lower root segment were obtained and cultured in vitro for 24 h for calculations. The number of colonies (CFU/mL) was analyzed, and the clearance rate of Enterococcus faecalis in the dentin tubules of different segments of the root canals in each group was analyzed. @*Results @#The oxidation activity and singlet oxygen generation capacity in the oxygen-releasing MB group were stronger than those in the MB group. Scanning electron microscope detection showed that Enterococcus faecalis was distributed in dentinal tubules, indicating that the model of root canal infection in vitro was successfully constructed. The clearance rate of Enterococcus faecalis in the oxygen-releasing MB-PDT therapy group was higher than that in the conventional therapy group and the MB-PDT therapy group (P<0.05). Oxygen-releasing PDT significantly improved the bactericidal effect in the lower dentinal tubules, and the clearance rate of Enterococcus faecalis was better than in the other two groups (P<0.05).@*Conclusion@#Photodynamic therapy with the oxygen-releasing photosensitizer MB can achieve a better root canal bactericidal effect and can significantly improve the clearance effect of Enterococcus faecalis in the deep dentin of the lower root segment.

Oxidative foliar photo-necrosis produced by the bacteria Pseudomonas cedrina

BACKGROUND: Although bioactive metabolites capable of causing oxidative photo-necrosis in plant tissues have been identified in fungi, little is known about this type of mechanism in bacteria. These metabolites act as photosensitizers that generate reactive oxygen species (ROS) capable of causing damage to cells. In addition, these metabolites can pass into an energetically excited state when they receive some luminous stimulus, a condition in which they interact with other molecules present in the environment, such as molecular oxygen (O2), also known as triplet oxygen (3 O2), generating ROS. RESULTS: The suspension of the bacterial culture of Pseudomonas cedrina was shown to produce foliar necrosis in papaya leaves (Carica papaya L.) only in the presence of sunlight, which is evidence of photosensitizing mechanisms that generate singlet oxygen (1 O2). From the chemical study of extracts obtained from this bacteria, 3-(4-(2-carboxipropyl) phenyl) but-2-enoic acid (1) was isolated. This compound, in the presence of light and triplet oxygen (3 O2), was able to oxidize ergosterol to its peroxide, since it acted as a photosensitizer producing 1 O2, with which it was corroborated that a photosensitization reaction occurs, mechanism by which this bacterium could prove to cause oxidative foliar photo-necrosis. CONCLUSIONS: P. cedrina was able to induce oxidative foliar photo-necrosis because of its potential ability to produce photosensitizing metabolites that generate singlet oxygen in the plants it colonizes. Based on the above, it can be proposed that some bacteria can cause oxidative foliar photo-necrosis as an important mechanism in the pathogenesis of host species.

Research progress of sonodynamic therapy in the field of stomatology / 口腔疾病防治

@#Sonodynamic therapy (SDT) is a cutting-edge method for the biological effects of ultrasound combined with sound-sensitive agents. In recent years, SDT has been a concern of experts and scholars in the oral field, and a series of experimental studies has been carried out. We will introduce the progress of SDT in the field of stomatology from three aspects: the therapeutic mechanism of SDT, the application of SDT in the oral field, and the current situation and future of SDT in the treatment of oral diseases. It is currently believed that singlet oxygen theory, cavitation effects, and induction of apoptosis are the main therapeutic mechanisms. The research of SDT on oral disease prevention mainly focuses on oral tumors (especially squamous cell carcinoma and osteosarcoma) and infectious diseases (such as periodontitis, maxillofacial infection, and oral mucosal disease). Although the current research is still in the experimental stage, with the continuous exploration of sonosensitizers and nanotechnology, SDT will provide great help for the clinical prevention and treatment of oral diseases in the future.

Biodegradable micelles for two-photon photodynamic therapy in a mouse model of breast cancer / 药学学报

Photodynamic therapy (PDT) is one of the new approaches for cancer treatment with high efficacy. However, applications of current photosensitizers are restricted to skin and superficial tumor due to poor in vivo targeting ability, poor water solubility and short wavelength excitement, which limits penetration therefore therapeutic depth. Here, a biodegradable polymeric micelle, methoxy poly(ethylene glycol)-polylactide copolymer (mPEG-PDLLA), is employed as drug delivery system to co-encapsulate strong two-photon absorption compound (LTPA) and photosensitizers. This delivery system is designed to target tumor passively, resulting in near infrared light with an approximately 808 nm wavelength becoming able to indirectly excite photosensitizers through fluorescence resonance energy transfer. Tumor cells and microvessels could be damaged by the generated singlet oxygen. The average size of drug loaded micelles was approximately 55 nm and showed a spherical shape. Both compounds could be released simultaneously from micelles under either weak acid and neutral pH conditions. Reactive oxygen species was produced intracellularly during two-photon PDT process and induced cell apoptosis/necrosis, which was quantified by Annexin-V/FITC assays. Time-dependent ex vivo organ distribution and in vivo anticancer efficacy results suggested that the drug carriers could accumulate in tumors and suppress tumor growth by two-photon PDT. All animals experiments were performed in line with national regulations and approved by the Animal Experiments Ethical Committee of College of Pharmaceutical Sciences, Southwest University. In summary, we have employed two-photon PDT for breast cancer treatment successfully in a mouse model and have demonstrated the significance of delivery system in such therapeutics.

Experimental study of a novel photosensitizer mediated photodynamic therapy on resistant gastric cancer / 中国药理学通报

Aim To investigate the therapeutic efficacy of DTP-mediated photodynamic therapy (PDT) on SGC7901/VCR human vincristine ( VCR )-resistant gastric cancer cells, and to reveal the relationship between DTP-PDT and P-gp. Methods MTT assay was employed to evaluate the cytotoxicity of DTP-PDT and combination treatment with DTP-PDT and VCR. A SGC7901/VCR-bearing nude mouse model was established, and the tumor volume was measured to draw the growth curve. Cell apoptosis was detected by flow cytometry, and the yield of intracellular singlet oxygen (O2) was determined after DTP-PDT. The expression of MDR1 mRNA and P-gp was determined by qPCR and flow cytometry, respectively. Results DTP-PDT demonstrated significant cytotoxicity on SGC7901/VCR cells and the nude mice transplanted tumor. DTP-PDT could induce the apoptosis of SGC7901/VCR cells and the generation of intracellular O2. DTP-PDT could inhibit the expression of MDR1 mRNA and P-gp, which could be reduced by a-tocopherol. Combined treatment with DTP-PDT and VCR demonstrated synergistic efficacy on resistant cells, which could be reduced by or-tocopherol. Conclusions O2 generated by DTP-me-diated PDT could inhibit the growth of SGC7901/VCR cells and induce cell apoptosis. Meanwhile, it inhibits the over-expression of P-gp on cell membranes, leading to reduced efflux of VCR and synergistic efficacy with DTP-PDT and VCR eventually.

Intracellular location of severe fever with thrombocytopenia syndrome bunyavirus NP protein with correlative light and electron microscopy based on miniSOG / 中华实验和临床病毒学杂志

Objective@#To study the intracellular location and characteristic of SFTSV NP protein in different phases using mini singlet oxygen generator (miniSOG) labeling technique.@*Methods@#MiniSOG is a recently-invented genetically-encoded tag for EM. MiniSOG-fused SFTSV NP (NPSOG) gene was cloned by PCR, and inserted into pcDNA3.0 plasmid to form pTPL-NPSOG, which was used to transfect 293 cells. The transfected cells of different phases were fixed in 2.5% glutaraldehyde in situ, stained with DAB through the photooxidation activity of miniSOG, and used to prepare ultrathin sections. Intracellular location and characteristic of SFTSV NP protein in different phases were studied by observing the sections under transmission electron microscope.@*Results@#After transfecting the plasmid with NPSOG to 293 cells, NP protein was expressed in cytoplasm and peri nucleus, and gradually aggregated, which connected with endoplasmic reticulum and Golgi apparatus to form larger volume and irregular inclusion bodies in cytoplasm. No obvious subcellular structure changes were found.@*Conclusions@#The SFTSV nucleoprotein can be expressed separately to form inclusion bodies without the assistance of other viral proteins. The formation of inclusion bodies requires the directional movement and aggregation of a certain number of NP proteins, which may involve the interaction of NP protein and host organelles during this period.

Preparation and evaluation of photo-sensitive reactive oxygen species responsive liposomes / 药学学报

Photo-sensitive reactive oxygen species (ROS) responsive liposomes loaded with 1,4,8,11,15, 18,22,25-octabutoxypalladium phthalocyanine[PdPC(OBu)8] and doxorubicin hydrochloride (DOX) (LPD) were prepared by (NH4)2SO4-gradient method. LPD was characterized with transmission electron microscopy (TEM), dynamic light scattering particle size, zeta potentials, photo-sensitive ROS-responsive DOX release behaviors and the serum stability in vitro. LPD cytotoxicity, DOX uptake and singlet oxygen production in MCF-7 cells were evaluated. The results showed that the particle size of LPD was (169.3 ±1.2) nm, PDI of LPD was 0.198 ±0.003 and zeta potentials of LPD was (-39.8 ±0.8) mV. The accumulated release of DOX reached 95.5% in 5 min under 730 nm laser irradiation (300 mW·cm-2). The DOX uptake of liposome was increased and 1O2 was generated. The half inhibition concentration (IC50) of DOX in LPD with irradiation group was decreased by 85.7% and no irradiation group was decreased by 67.9% compared with free DOX group in MCF-7 cells. Therefore, photo-sensitive ROS-responsive liposomes would be a promising drug delivery system for tumor therapy.

Recent progress of reactive oxygen species-responsive drug delivery systems / 药学学报

Excessive reactive oxygen species (ROS) is associated with an array of pathological conditions, including cancer, diabetes, cardiovascular diseases, and neurodegenerative diseases. However, ROS-responsive materials have drawn attention in the development of drug delivery systems. There are many types of ROS-responsive materials explored in drug delivery applications, including sulfur-based responsive polymers, selenium-based responsive polymers, tellurium-based responsive polymers, oxalate ester-containing polymers, phenylboronic ester-containing polymers and unsaturated lipids. When integrated with ROS-responsive drug delivery systems, a photosensitizer is used as a light-sensitive element to generate ROS, mainly singlet oxygen (1O2), which in turn activates the ROS-triggered drug delivery.

Kinetic study of the quenching of singlet oxygen by naringin isolated from peels of the fruit of bitter orange (Citrus aurantium I)

Introduction: antioxidant activity is the capacity of a substance to inhibit oxidative degradation, mainly through its ability to react with both radical and non-radical species (e.g. singlet oxygen). Interest by scientific communities in the study of the antioxidant capacity of natural compounds has increased in recent years, due to their possible applications in the pharmaceutical, cosmetic and food industries. Objective: estimate the antioxidant capacity of naringin against singlet oxygen using the rubrene method. Methods: naringin was isolated from peels of the fruit of bitter orange (Citrus aurantium) and characterized using several spectroscopic techniques (UV-Vis and FTIR). The global rate constant for the reaction of 1O2 with naringin was determined with the Stern-Volmer plot derived from a stationary kinetic state based on the competition reaction with rubrene. Results: results showed that naringin acted as singlet oxygen quenching agent with a global rate constant of 2.1 x 107 M-1s-1 (derived from the linear relationship of Stern-Volmer). Conclusion: the kinetic study conducted suggests that naringin could be used as a singlet oxygen quenching agent in biological systems to protect them from oxidative damage(AU)

Introducción: la actividad antioxidante es la capacidad de una sustancia para inhibir la degradación oxidativa y actúa principalmente a través de su capacidad para reaccionar con las especies de radicales y no radicales (por ejemplo, oxígeno singulete). En los últimos años, se han incrementado el interés de las comunidades científicas en el estudio de la capacidad antioxidante de los compuestos naturales debido a sus posibles aplicaciones en la industria farmacéutica, cosmética y alimentaria. Objetivo: estimar la capacidad antioxidante de la naringina contra el oxígeno singulete usando el método de rubreno. Métodos: la naringina se aisló de cáscaras del fruto de la naranja agria (Citrus aurantium) y se caracterizó por algunas técnicas espectroscópicas (UV-Vis y FT-IR). La constante de velocidad global para la reacción de 1O2 con la naringina se determinó por medio del gráfico de Stern-Volmer derivado de una cinética en estado estacionario basada en la reacción de competición con el rubreno. Resultados: los resultados mostraron que la naringina actuó como un quenching del oxígeno singulete con una constante de velocidad global de 2.1 x 10 7 M-1s-1 (derivado de la relación lineal de Stern-Volmer). Conclusión: el estudio cinético sugiere que la naringina se podría utilizar como un quenching del oxígeno singulete en sistemas biológicos y protegerlos del daño oxidativo(AU)

9-[(E)-2-feniletenil]antraceno Y 9-[(E)-2-(naftalen-2-il)etenil] antraceno COMO TRAMPAS PARA OXÍGENO SINGULETE: OXIDACIÓN FOTOSENSIBILIZADA Y EFECTO FOTODINÁMICO SOBRE PARÁSITOS Leishmania tarentolae / 9-[(E)-2-phenylethenyl]anthracene AND 9-[(E)-2-(naphthalen-2-yl)ethenyl] anthracene AS TRAPS FOR SINGLET OXYGEN: PHOTOSENSITIZED OXIDATION AND PHOTODYNAMIC EFFECT ON Leishmania tarentolae PARASITES

Introducción: El oxígeno singulete es una especie reactiva que se obtiene mediante transferencia energética usando un fotosensibilizador. Su cuantificación directa requiere de instrumentación costosa, por lo cual es necesario recurrir a métodos indirectos que tengan suficiente selectividad y bajo costo. Estos procedimientos se basan en la interceptación química del oxígeno singulete produciendo una especie que se pueda detectar por métodos analíticos convencionales. En este artículo se describe la utilización del 9-[(E)-2-feniletenil] antraceno 1 (PEA) y del 9-[(E)-2-(naftalen-2-il) etenil]antraceno 2 (NEA), como alternativas viables y económicas para la cuantificación indirecta del oxígeno singulete, en medios acuosos. Su ventaja radica en la fácil detección de la desactivación de su fluorescencia una vez son oxidados por el oxígeno singulete. Materiales y Métodos: Los compuestos se sintetizaron y caracterizaron siguiendo procedimientos previamente reportados. Su capacidad para atrapar oxígeno singulete se determinó siguiendo su oxidación fotosensibilizada en solución de H2O/THF y en parásitos de Leishmania tarentolae, empleando azul de metileno o rosa bengala como fotosensibilizadores. Las muestras experimentales se iluminaron con una lámpara de emisión de luz visible, y se utilizaron métodos espectroscópicos (absorción UV-Vis, fluorescencia, RMN-1H) y espectrometría de masas para monitorear el atrapamiento y fotooxidación. Resultados y Discusión: Las pruebas espectroscópicas demostraron la capacidad que tienen los compuestos PEA 1 y NEA 2 para atrapar oxígeno singulete en solución acuosa y dentro de parásitos de L. tarentolae. Estudios de viabilidad parasitaria demuestran que PEA 1 es citotóxico en la oscuridad y cuando los cultivos son expuestos a la luz, mientras que NEA 2 no es citotóxico en la oscuridad, pero sí lo es cuando el cultivo es expuesto a la luz. En conclusión, los compuestos estudiados pueden servir como sondas para detectar y medir la producción de oxígeno singulete en medio acuoso y potencialmente en cultivos celulares, aunque es recomendable evaluar su actividad citotóxica en la oscuridad y bajo iluminación en estos casos.

Introduction: Singlet oxygen is a reactive species obtained via energy transfer using a photosensitizer. Its direct quantification requires expensive instrumentation, so it is necessary to use indirect methods having sufficient selectivity and low cost. These procedures are based on the chemical interception of singlet oxygen producing a species that can be detected using conventional analytical methods. This article describes the utilization of 9-[(E)-2-phenylethenyl]anthracene 1 (PEA) and 9-[(E)-2-(naphtalen-2-yl)ethenyl]anthracene 2 (NEA) as suitable and economic alternatives for the indirect quantification of singlet oxygen in aqueous media. Their advantage is the easy detection of their fluorescence once they are oxidized by singlet oxygen. Materials and Methods: Compounds were synthesized and characterized following procedures previously reported. Their capacity to trap singlet oxygen was determined by monitoring their photosensitized oxidation in either a H2O/THF solution or within Leishmania tarentolae parasites, utilizing methylene blue or rose bengal as photosensitizers. Experimental samples were illuminated with a lamp emitting visible light, while spectroscopical techniques (absorption, fluorescence, 1 H-NMR) and mass spectrometry were used to monitor trapping and photooxidation. Results and Discussion: Spectroscopical evidence demonstrates that both PEA 1 and NEA 2 are capable of trapping singlet oxygen in both aqueous media and within L. tarentolae parasites. Viability studies demonstrate that PEA 1 is cytotoxic in the dark and when parasite cultures were exposed to light, while NEA 2 does not show dark cytotoxicity, but is toxic when cultures were exposed to light. It can be concluded that both compounds under study may be utilized as probes to detect and quantify the production of singlet oxygen in aqueous media and potentially in cell cultures, although it is recommended to evaluate their cytotoxic activity both in the dark and upon light exposure in these cases.

Discovery of direct inhibitors of Keap1-Nrf2 protein-protein interaction as potential therapeutic and preventive agents

The Keap1-Nrf2-ARE pathway is an important antioxidant defense mechanism that protects cells from oxidative stress and the Keap1-Nrf2 protein-protein interaction (PPI) has become an important drug target to upregulate the expression of ARE-controlled cytoprotective oxidative stress response enzymes in the development of therapeutic and preventive agents for a number of diseases and conditions. However, most known Nrf2 activators/ARE inducers are indirect inhibitors of Keap1-Nrf2 PPI and they are electrophilic species that act by modifying the sulfhydryl groups of Keap1׳s cysteine residues. The electrophilicity of these indirect inhibitors may cause "off-target" side effects by reacting with cysteine residues of other important cellular proteins. Efforts have recently been focused on the development of direct inhibitors of Keap1-Nrf2 PPI. This article reviews these recent research efforts including the development of high throughput screening assays, the discovery of peptide and small molecule direct inhibitors, and the biophysical characterization of the binding of these inhibitors to the target Keap1 Kelch domain protein. These non-covalent direct inhibitors of Keap1-Nrf2 PPI could potentially be developed into effective therapeutic or preventive agents for a variety of diseases and conditions.

Photodynamic Therapy – The Pragmatic Paradigm.

Photodynamic therapy (PDT), also known as photo-radiation therapy, phototherapy, or photo-chemotherapy, involves the use of a photoactive dye (photosensitizer) that is activated by exposure to light of a specific wavelength in the presence of oxygen. The transfer of energy from the activated photosensitizer to available oxygen results in the formation of toxic oxygen species, such as singlet oxygen and free radicals which damages proteins, lipids, nucleic acids and other cellular components.PDT has wide range of applications in Dentistry ranging from antimicrobial chemotherapy to the diagnosis & treatment of premalignant and malignant conditions. Its application in Periodontics represents a novel therapeutic approach in the management of oral biofilms with consequent alterations in plaque homeostasis. An improved post surgical healing with reduced periodontal inflammation and tissue damage are the hallmarks of PDT. Its scope has been extended in Implantology to promote osseointegration and to prevent peri-implantitis. With such myriad of applications PDT has a promising future depending on the interactions between clinical applications and technological innovations. The paper appraises the various scopes that PDT envisages beyond the horizon.

Photodynamic therapeutic effect of iminodiacetic acid modified tetraphenylporphyrin in mice bearing H22 liver cancer / 国际生物医学工程杂志

Objective To explore the physical/chemical properties and effect of photodynamic therapy (PDT) of iminodiacetic acid modified tetraphenylporphyrin on mice bearing H22 liver cancer.Methods The UV absorbance spectrum,singlet oxygen yield and lipid-water partition coefficient were measured by UV spectrophotometry.Mice bearing H22 liver cancer as animal model were divided into control group (no drug,no light),light treated group (no drug,only light),drug treated group (only drug,no light),experimental once group (with drug and light,once) and experimental twice group (with drug and light,twice,PDT twice).Tumor inhibition rate and index of liver,spleen,lung,thymus of the mice were calculated to evaluate the antitumor activity of iminodiacetic acid modified tetraphenyl porphyrin-PDT.Results The iminodiacetic acid modified tetraphenylporphyrin had absorption at 650 nm,while its singlet oxygen yield and lipid-water partition coefficient were 2.30 and 0.52,respectively.No antitumor effect on mice bearing H22liver cancer for light treated group and drug treated group respectively.However,significant antitumor effect (P＜0.001)was found at experimental group.The maximum tumor inhibition rate could be 95.15％ for PDT twice group.No significant differences were observed on weight gain and liver,lung,spleen,thymus index in each group.Conclusion Iminodiacetic acid modified tetraphenylporphyrin with high singlet oxygen yield,low toxicity and significant in vivo anti-tumor activity,is suitable to be developed as an anti-tumor drug candidate for photodynamic therapy.

Photodynamic therapy of oral pathogenic bacteria and its potential application / 国际生物医学工程杂志

Photodynamic therapy (PDT) has been wildly used in the treatment of tumors and dermatologic diseases,especially,when the traditional therapies are ineffective or bring side effects.Moreover,with the deepening of the studies,its effects in anti-microbial has been found.PDT in the treatment of infectious diseases has attracted more and more attention of scholars.In this review,we discussed the mechanism of the PDT,studies in the sterilization of a variety of oral pathogenic bacteria by the PDT and its potential applications in clinic.

Photodynamic antimicrobial chemotherapy (PACT) for the treatment of malaria, leishmaniasis and trypanosomiasis

A photodynamic effect occurs when photosensitiser molecules absorb light and dissipate the absorbed energy by transferring it to biological acceptors (usually oxygen), generating an excess of reactive species that are able to force cells into death pathways. Several tropical diseases present physiopathological aspects that are accessible to the application of a photosensitiser and local illumination. In addition, disease may be transmitted through infected blood donations, and many of the aetiological agents associated with tropical diseases have been shown to be susceptible to the photodynamic approach. However, there has been no systematic investigation of the application of photoantimicrobial agents in the various presentations, whether to human disease or to the disinfection of blood products or even as photo-insecticides. We aim in this review to report the advances in the photoantimicrobial approach that are beneficial to the field of anti-parasite therapy and also have the potential to facilitate the development of low-cost/high-efficiency protocols for underserved populations.

Estudo do reparo das lesões induzidas no DNA de Escherichia coli pela radiação ultravioleta C (UVC) / Study of repair of induced lesions in the DNA of Escherichia coli by ultraviolet C (UVC)

Didaticamente, podemos dividir o espectro da radiação ultravioleta (UV) em três faixas: UVA (400 a 320 nm), UVB (320 a 290 nm) e UVC (290 a 100 nm). Apesar do UVC ou UV-curto ser eficientemente filtrado pela camada de ozônio da Terra e sua atmosfera, este é uma das faixas do espectro de UV mais usadas para explorar as consequências de danos causados ao DNA, já que a letalidade induzida por este agente está relacionada aos danos diretos no genoma celular, como as lesões dímero de pirimidina, que são letais se não reparadas. Contudo, demonstrou-se que a radiação UVC pode gerar espécies reativas de oxigênio (ERO), como o oxigênio singleto (1O2). Embora, o radical hidroxil (•OH) cause modificações oxidativas nas bases de DNA, alguns trabalhos indicam que o 1O2 também está envolvido nos danos oxidativos no DNA. Esta ERO é produzida por vários sistemas biológicos e reações fotossensibilização, quando cromóforos são expostos à luz visível ou são excitados pela luz UV, permitindo que essa energia possa ser transferida para o oxigênio sendo convertido em 1O2, que é conhecido por modificar resíduos de guanina, gerando 8-oxoG, que caso não seja reparada pode gerar uma transversão GC-TA. O objetivo deste trabalho foi o de elucidar a participação de ERO nos efeitos genotóxicos e mutagênicos gerados pela radiação UVC, assim como as enzimas envolvidas no processo de reparação destas lesões em células de Escherichia coli. Nos ensaios as culturas foram irradiadas com o UVC (254 nm; 15W General Electric G15T8 germicidal lamp, USA). Nossos resultados mostram que o uso de quelantes de ferro não alterou a letalidade induzida pelo UVC. A azida sódica, um captador de 1O2, protegeu as cepas contra os danos genotóxicos gerados pelo UVC e também diminuiu a frequência de mutações induzidas no teste com rifampicina. A reversão específica GC-TA foi induzida mais de 2,5 vezes no ensaio de mutagênese. A cepa deficiente na proteína de reparo Fpg, enzima que corrige a lesão 8-oxoG...

Didactically, we can divide the ultraviolet radiation (UV) spectrum into three bands: UVA (400 to 320 nm), UVB (320-290 nm) and UVC (290-100 nm). Despite the UVC or far-UV be efficiently filtered by Earth´s ozone layer and its atmosphere, this is one of bands of UV spectrum used to explore the consequences of DNA damages, since the UVC-induced lethality is related to direct damage in genome cells, such as pyrimidine dimers, which are lethal if not repaired. However, it was shown that UVC radiation can generate reactive oxygen species (ROS) such as singlet oxygen (1O2). Although hydroxyl radical (•OH) cause oxidative modifications in DNA bases, some works suggests that 1O2 is also involved in oxidative DNA damage. This ROS is produced by several biological systems and photosensitivity reactions when chromophores are exposed to visible light or excited by UV light, allowing that energy can be transferred to the oxygen being converted to 1O2, which is known to modify guanine residues, generating 8-oxoG, if not repaired can lead to a GC-TA transversion. The objective of this work was to elucidate the ROS involvement in the genotoxic and mutagenic effects generated by UVC radiation, as well as the enzymes involved in the repair process of these lesions in Escherichia coli cells. In the assays, cultures were irradiated with UVC (254 nm, 15 W General Electric germicidal lamp G15T8, USA). Our results show that the use of iron chelators did not affect the UVC-induced lethality. The sodium azide, a 1O2 quencher, protected strains against the genotoxic damage produced by UVC and also decreased the frequency of mutations induced in rifampicin assay. Reversal specific GC-TA was induced more than 2.5 fold in the mutagenesis assay. The deficient strain in the repair protein Fpg, an enzyme that corrects 8-oxoG lesions, had less DNA breakage than the wild strain in electrophoresis alkaline assay. The UVC-induced lethality was increased in mutants transformed with the pFPG...

Irradiation at 635/670nm in 5-aminolevulinic acid-mediated photodynamic therapy: The anti-tumor effect / 第二军医大学学报

Objective To increase the anti-tumor effect of 5-ALA-mediated photodynamic therapy, PDT was performed at 635nm followed by an additional irradiation at 670nm, and the effectiveness was studied. Methods PDT was performed at single irradiation (635nm or 670nm), and symphysial irradiation (635nm+670nm), and its effectiveness was studied using PpIXsolutions, tumor cells (9L and HeLa), andHeLa tumor-bearing mice. Results When a Pp IX solution was irradiated at 635 nm or 670nm, singlet oxygen counts were almost similar. Symphysial irradiation -mediated singlet oxygen generation was higher in 9L cells than HeLa cells and it did not produce an additional PDT effect in HeLa tumors. Conclusion It was suggested as the low uptake of 5-ALA in HeLa cells, and the symphysial irradiation can't increase the anti-tumor effects in 5-ALA-mediated PDT. Further study is necessary to obtain the irradiation method for the efficient application of PDT.

Oxidación de anrraceno con oxígeno singulete geerado químicamente por el sisteema molibdato de sodio/peróxido de hiróógeno / Oxidaion of anthhracene with singlet xigen generated chemically by tthe sodium molibdate/hydrogen peroxidessystem / Oxidção de antraaceno com oxigênio snglete gerados quimicamente pello sistema molibdato de sódio / peróxido de hidrogênio

La oxidación del antraceno con oxígeno singulete, generado químicamente por el sistema molibdato de sodio/peróxido de hidrógeno (Na2MoO4/H2O2), fue estudiada en una microemulsión tipo micela invertida (agua/aceite). El seguimiento de la reacción se realizó midiendo la absorbancia en la banda de 375 nm por espectrofotometría UV-Vis. Se identificaron como productos de la oxidación: la antraquinona, el endoperóxido- 9,10-antraceno, la 9-hidroxiantrona, la antrona y el 9,10-dihidrodihidroxiantraceno mediante cromatografía de gases-espectrometría de masas (CG-EM). Los tres primeros productos son el resultado de la cicloadición [4+2] del oxígeno singulete sobre el antraceno. La antrona y el 9,10-dihidrodihidroxiantraceno pueden ser generados por la presencia de un radical generado en el medio de reacción. En las condiciones de reacción usadas se determinó una constante de la velocidad de la oxidación con oxígeno singulete.

The oxidation of anthracene with singlet oxygen, chemically generated by sodium molybdate/hydrogen peroxide system (Na2MoO4/H2O2), was studied in an inverted mycelle-type microemulsion (Oil/ Water). The tracking of the reaction was carried out by measuring the absorbance at the 375 nm band, using UV-Vis spectrophotometry. Oxidation products (anthraquinone, endoperoxide-9,10-anthracene, 9-hydroxyanthrone, anthrone and 9,10-dihydrodihydroxianthracene) were identified by gas chromatography massspectrometry (GC-MS). The first three products come of the singlet oxygen [4+2] cycloaddition on the anthracene. Anthrone and 9,10-dihydrodihydroxianthracene can be generated by the presence of a radical that is produced in the reaction. Under the used reaction conditions it was determined the rate constant of the oxidation with oxygen singlet.

A oxidação do antraceno com o oxigênio singlete, gerado quimicamente pelo sistema sódio molibdato / peróxido de hidrogênio (Na2MoO4/H2O2); foi estudada numa microemulsão tipo, mycelle - invertida (água /óleo ). O acompanhamento da reação foi feito, pela absorvância na banda em 375 nm, utilizando espectrofotometria UV-Vis. Depois da a oxidacao; e utilizando as ténicas de, cromatografia gasosa, GC, e espectrometria de massa, MS; foram identificados os seguintes produtos: antraquinona, endoperóxido- 9,10-antraceno, 9-hidroxiantrona, antrona e 9,10- dihidrodihidroxiantraceno. Os três primeiros, sao provenientes da cicloadicao [4 +2] do oxigênio singlete sobre o antraceno. Antrone e 9,10 -dihidrodihidroxianthracene, podem ser gera- dos pela presença de um radical que é produzido na própria reação. Das condições utilizadas na reação, foi determinada uma taxa constante de oxidação com oxigênio singlete.