Presence Of Photosensitizer Research Articles

An Efficient Photodynamic Therapy Treatment for Human Pancreatic Adenocarcinoma.

To date, pancreatic adenocarcinoma (ADKP) is a devastating disease for which the incidence rate is close to the mortality rate. The survival rate has evolved only 2–5% in 45 years, highlighting the failure of current therapies. Otherwise, the use of photodynamic therapy (PDT), based on the use of an adapted photosensitizer (PS) has already proved its worth and has prompted a growing interest in the field of oncology. We have developed a new photosensitizer (PS-FOL/PS2), protected by a recently published patent (WO2019 016397-A1, 24 January 2019). This photosensitizer is associated with an addressing molecule (folic acid) targeting the folate receptor 1 (FOLR1) with a high affinity. Folate binds to FOLR1, in a specific way, expressed in 100% of ADKP or over-expressed in 30% of cases. The first objective of this study is to evaluate the effectiveness of this PS2-PDT in four ADKP cell lines: Capan-1, Capan-2, MiapaCa-2, and Panc-1. For this purpose, we first evaluated the gene and protein expression of FOLR1 on four ADKP cell lines. Subsequently, we evaluated PS2’s efficacy in our cell lines and we assessed the impact of PDT on the secretome of cancer cells and its impact on the immune system. Finally, we evaluate the PDT efficacy on a humanized SCID mouse model of pancreatic cancer. In a very interesting way, we observed a significant increase in the proliferation of activated-human PBMC when cultured with conditioned media of ADKP cancer cells subjected to PDT. Furthermore, to evaluate in vivo the impact of this new PS, we analyzed the tumor growth in a humanized SCID mice model of pancreatic cancer. Four conditions were tested: Untreated, mice (nontreated), mice with PS (PS2), mice subjected to illumination (Light only), and mice subjected to illumination in the presence of PS (PDT). We noticed that the mice subjected to PDT presented a strong decrease in the growth of the tumor over time after illumination. Our investigations have not only suggested that PS2-PDT is an effective therapy in the treatment of PDAC but also that it activates the immune system and could be considered as a real adjuvant for anti-cancer vaccination. Thus, this new study provides new treatment options for patients in a therapeutic impasse and will provide a new arsenal in the fight against PDAC.

Determination and photodegradation of sertraline residues in aqueous environment

Sertraline is an antidepressant drug that has been frequently reported in the aquatic environment and biota. While the research has mostly dealt with its occurrence and toxicity, there is a lack of information pertaining to its environmental transformation. The present study aimed to fill in these gaps by giving an insight into mechanisms of sertraline phototransformation in surface waters, which was recognized as the main transformation pathway for this contaminant.We performed photodegradation experiments in presence of photosensitizers or reaction quenchers to determine rate constants and used them to predict sertraline phototransformation kinetics by “Aqueous Photochemistry of Environmentally occurring Xenobiotics” (APEX) software. It was established that sertraline degrades by pseudo-first order kinetics mostly dominated by direct photolysis, while the presence of certain reactive species including •OH, CO3−• and 3CDOM* further accelerate the compound’s breakdown rate. To validate the predicted results, sertraline-spiked surface water was irradiated by sunlight, where the half-life of sertraline at around 1.4 days was estimated. While following the photodegradation kinetics, we also identified five transformation products, of which three were determined in Slovenian surface waters. According to the ECOSAR toxicity prediction, these transformation products will either have comparable or lower toxicity than their parent compound.

Efficacy of blue LED in microbial inactivation: Effect of photosensitization and process parameters

Efficacy of blue (462 ± 3 nm) Light emitting diode (LED) illumination to inactivate the foodborne pathogens like Escherichia coli and Staphylococcus aureus in the presence of exogenous photosensitizer (curcumin) was studied in vitro. The effect of temperature, concentration of photosensitizer and incubation time with photosensitizer for microbial inactivation was investigated and sublethal injury of cells was determined. Mechanism of inactivation by the combination of photosensitizer and blue light was also examined. A maximum reduction of 5.94 ± 0.22 and 5.91 ± 0.20 log CFU/ml was obtained for E. coli and S. aureus, respectively, when treated with photosensitizer (20 μM) at 13 J/cm2 of blue light. There was no significant change in the inactivation of these pathogens both at 9 °C and 27 °C in the presence of photosensitizer. Even, the incubation with the photosensitizer didn't show any significant difference on the inactivation of these food-borne pathogens. Sublethal injury (>90% injury) was also observed for the cells treated with photosensitizer and blue light simultaneously. Confocal laser scanning microscopy analysis revealed that membrane integrity was disturbed due to photodynamic activity of curcumin in both the bacteria. Further, both cells produced intracellular reactive oxygen species by the action of photosensitizer and blue light. Scanning electron microscopy of E. coli and S. aureus cells treated with photosensitizer and blue light showed morphological changes in the cell wall compared to untreated group. The study indicated that photodynamic inactivation of foodborne pathogens using LED-based photosensitization can be explored as a potential technique for food safety.

Singlet oxygen modification abolishes voltage-dependent inactivation of the sea urchin spHCN channel.

Photochemically or metabolically generated singlet oxygen (1O2) reacts broadly with macromolecules in the cell. Because of its short lifetime and working distance, 1O2 holds potential as an effective and precise nanoscale tool for basic research and clinical practice. Here we investigate the modification of the spHCN channel that results from photochemically and chemically generated 1O2 The spHCN channel shows strong voltage-dependent inactivation in the absence of cAMP. In the presence of photosensitizers, short laser pulses transform the gating properties of spHCN by abolishing inactivation and increasing the macroscopic current amplitude. Alanine replacement of a histidine residue near the activation gate within the channel's pore abolishes key modification effects. Application of a variety of chemicals including 1O2 scavengers and 1O2 generators supports the involvement of 1O2 and excludes other reactive oxygen species. This study provides new understanding about the photodynamic modification of ion channels by 1O2 at the molecular level.

A Possible Role of Human Herpes Viruses Belonging to the Subfamily Alphaherpesvirinae in the Development of Some Cancers.

Seroepidemiological studies suggest that human herpes simplex virus type 1 (HSV-1) and 2 (HSV-2) are linked with several types of cancer; however, they do not appear to play a direct role and are considered to be cofactors. The abilities of HSV-1 and -2 to transform cells in vitro can be demonstrated by suppressing their lytic ability via irradiation with a specific dose of ultraviolet light, photoinactivation in the presence of photosensitizers (e.g., neutral red or methylene blue), and culture under specific conditions. Several mechanisms have been proposed to explain the actions of these viruses. According to the hit-and-run mechanism, viral DNA initiates transformation by interacting with cellular DNA and thereby inducing mutations and epigenetic changes, but is not involved in other stages of neoplastic progression. By contrast, according to the hijacking mechanism, viral products in infected cells can activate signaling pathways and thereby cause uncontrolled proliferation. Such products include RR1PK, an oncoprotein that activates the Ras pathway and is encoded by the HSV-2 gene ICP10. Virus-encoded microRNAs may act as cofactors in tumorigenesis of serous ovarian carcinoma and some prostate tumors. Herpes virus-associated growth factors that facilitate or suppress transformation may play important roles in tumor formation. Finally, there is much evidence that HSV-2 increases the risk of cervical cancer after infection of human papilloma viruses. Key words: HSV-1 - HSV-2 - cancer - mechanisms of transformation This work was supported by APVV 0621-12. The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Submitted: 29. 11. 2016 Accepted: 20. 3. 2018.

Global Profiling of the Oxidative Stress Induced Effects on RNA Modifications by Liquid Chromatography‐Tandem Mass Spectrometry

The goal of this work was to profile the oxidative damage exerted by ultraviolet‐A radiation (UVA, 370 nm) or H2O2 on RNA modifications by liquid chromatography‐tandem mass spectrometry (LC‐MS/MS). Oxidative damage to RNA impacts biological systems due to its association with metabolic, mitochondrial, neurological diseases and cancer.1,2 In the presence of photosensitizer (e.g., riboflavin), UVA radiation induces the production of reactive oxygen species (ROS, O2•, HOO•, HO•) in vivo.3 Likewise, H2O2 generates ROS under physiological conditions, and formation of radicals is accelerated via Fenton reactions in the presence of catalysts (e.g., Fe2+, Cu2+).4Oxidation pathways of canonical nucleosides are well documented.5 However, the effect of ROS on modified ribonucleosides is not well known, and information about RNA damage is largely extrapolated from studies on DNA. More than 160 modified nucleosides have been reported in various types of RNA of different organisms.6 E. coli with 46 modifications in its tRNA serve as a good model system to investigate the stress‐induced effects. Apart from the known oxidative products arising from canonical nucleosides, we have documented a list of modified nucleosides that are adversely affected by UVA or H2O2. To understand the oxidative environment generated by UVA exposure, we exposed E. coli total tRNA with or without a photosensitizer for defined period of time. In a similar manner, the effect of H2O2 on RNA modifications was investigated by incubating E. coli total tRNA and H2O2, with or without the presence of transition metal ion catalysts. The oxidative damage observed on various modifications was measured by subjecting it to LC‐MS/MS following complete hydrolysis of tRNA. We will present data that describes the susceptibility of various functional groups of these modifications and underlying patterns. Further, these studies also document a range of RNA photoproducts and chemical alterations arising due to the oxidative conditions.Support or Funding InformationFinancial support of this work was provided by the NSF (CHE1507357) and DTRA (HDTRA1‐15‐1‐0033), both to Patrick A. Limbach, and the University of Cincinnati.This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.

Blue/violet laser inactivates methicillin-resistant Staphylococcus aureus by altering its transmembrane potential

The resistance of methicillin-resistant Staphylococcus aureus to antibiotics presents serious clinical problems that prompted the need for finding alternative or combination therapies. One such therapy is irradiation with blue light. To determine the alterations in metabolic processes implicated in the observed antimicrobial effects of blue light, we investigated the changes in membrane potential and the presence of free-radical-producing photo-acceptor molecules. Bacterial cultures irradiated with one or two doses of 405nm laser light (each consisting of 121J/cm2) were imaged with spectrally resolved laser-scanning microscopes to detect endogenous fluorescent species as well as the voltage sensitive dye 3,3′-Diethyloxacarbocyanine iodide. The endogenous fluorescence indicated the presence of photosensitizers (i.e., porphyrins, NADH, FAD) in the cells, while the exogenous signal allowed us to monitor rapid changes in transmembrane potential following treatment with light. The changes were drastic within the first 5min after irradiation with the first dose and continued slowly after the second irradiation. These results suggest that the early antimicrobial activity of blue light results from alteration of membrane integrity with a consequent decrease in membrane polarization and rapid alteration of vital cellular functions. The observation of an early antimicrobial activity of light is very encouraging, as it suggests that treatment does not necessarily have to be administered over a long period of time.

Antimicrobial Photodynamic Therapy against Endodontic Enterococcus faecalis and Candida albicans Mono and Mixed Biofilms in the Presence of Photosensitizers: A Comparative Study with Classical Endodontic Irrigants.

Endodontic biofilms eradication from the infected root canal system remains as the primary focus in endodontic field. In this study, it was assessed the efficacy of antimicrobial Photodynamic Therapy (aPDT) with the Zn(II)chlorin e6 methyl ester (Zn(II)e6Me) activated by red light against monospecies and mixed biofilms of Enterococcus faecalis and Candida albicans. The results were compared with the ones obtained with Rose Bengal (RB), Toluidine Blue-O (TBO), the synthetic tetracationic porphyrin (TMPyP) as well as classical endodontic irrigants (3% NaOCl, 17% EDTA and 2% CHX). The antimicrobial efficacy of aPDT toward monospecies and mixed biofilms was quantified resorting to safranin red method. The changes of biofilm organization and of cellular ultrastructure were evaluated through several microscopy techniques (light, laser confocal and transmission electron microscopy). Zn(II)e6Me once activated with light for 60 or 90 s was able to remove around 60% of the biofilm’s biomass. It was more efficient than TBO and RB and showed similar efficiency to TMPyP and classical irrigants, CHX and EDTA. As desirable in a PS, Zn(II)e6Me in the dark showed smaller activity than TMPyP. Only NaOCl revealed higher efficiency, with 70–90% of the biofilm’s biomass removal. The organization of biofilms and the normal microbial cell ultrastructure were extensively damaged by the presence of Zn(II)e6Me. aPDT with Zn(II)e6Me showed to be an efficient antimicrobial strategy deserving further studies leading to a future clinical usage in endodontic disinfection.

A comparison of antibacterial and antibiofilm efficacy of phenothiazinium dyes between Gram positive and Gram negative bacterial biofilm

BackgroundAntimicrobial photodynamic therapy (APDT) is a process that generates reactive oxygen species (ROS) in presence of photosensitizer, visible light and oxygen which destroys the bacterial cells. We investigated the photoinactivation efficiency of phenothiazinium dyes and the effect of ROS generation on Gram positive and Gram negative bacterial cell as well as on biofilm. Material and methodsEnterococcus faecalis and Klebsiella pneumonia were incubated with all the three phenothiazinium dyes and exposed to 630nm of light. After PDT, colony forming unit (CFU) were performed to estimate the cell survival fraction. Intracellular reactive oxygen species (ROS) was detected by DCFH-DA. Crystal violet (CV) assay and extracellular polysaccharides (EPS) reduction assay were performed to analyze antibiofilm effect. Confocal laser electron microscope (CLSM) scanning electron microscope (SEM) was performed to assess the disruption of biofilm. Results8log10 reduction in bacterial count was observed in Enterococcus faecalis while 3log10 in Klebsiella pneumoniae. CV and EPS reduction assay revealed that photodynamic inhibition was more pronounced in Enterococcus faecalis. In addition to this CLSM and SEM study showed an increase in cell permeability of propidium iodide and leakage of cellular constituents in treated preformed biofilm which reflects the antibiofilm action of photodynamic therapy. ConclusionWe conclude that Gram-positive bacteria (Enterococcus faecalis) are more susceptible to APDT due to increased level of ROS generation inside the cell, higher photosensitizer binding efficiency and DNA degradation. Phenothiazinium dyes are proved to be highly efficient against both planktonic and biofilm state of cells.

In vitro inactivation of Enterococcus faecalis with a led device

Non-coherent light-emitting diodes (LEDs) are effective in a large variety of clinical indications; however, the bactericidal activity of LEDs is unclear, although the effectiveness of such lights is well known. Currently, no studies have examined the effects of NIR-LED on bacteria. The aims of this study were to verify the antibacterial activity of 880-nm LED irradiation on a bacterial suspension of Enterococcus faecalis and to compare it with the actions of sodium hypochlorite (NaOCl) and the concurrent use of both treatments. Before we proceeded with the main experiment, we first performed preliminary tests to evaluate the influence of such parameters as the distance of irradiation, the energy density, the irradiation time and the presence of photosensitizers on the antimicrobial effects of LEDs.After treatment, the colony forming units per milliliter (CFU/mL) was recorded and the data were submitted to ANOVA and Bonferroni post hoc tests at a level of significance of 5%.The results showed that LED irradiation, at the parameters used, is able to significantly decrease E. faecalis viability in vitro. The total inhibition of E. faecalis was obtained throughout concurrent treatment of LED and NaOCl (1%) for 5min.The same antimicrobial activity was confirmed in all of the experiments (p<0.05), but no statistically significant differences were found by varying such parameters as the distance of irradiation (from 0.5mm to 10mm), energy density (from 2.37 to 8.15mJ/s), irradiation time (from 5min to 20min) or by adding toluidine blue O (TBO).

Significant role of UV and carbonate radical on the degradation of oxytetracycline in UV-AOPs: Kinetics and mechanism

Carbonate radical (CO3•−), a selective oxidant, reacts readily with electron-rich compounds through electron transfer and/or hydrogen abstraction. In this study, the role of CO3•− in degrading oxytetracycline (OTC) by UV only, UV/H2O2 and UV/persulfate (UV/PS) advanced oxidation processes (AOPs) in the presence of HCO3− or CO32− was investigated. For UV only process, the presence of photosensitizers, i.e., nitrate (NO3−) and natural organic matter (NOM), had different impacts on OTC degradation, i.e., an enhancing effect by NO3− due to the generation of HO• and a slight inhibiting effect by NOM possibly due to a light scattering effect. Differently for UV/H2O2 and UV/PS processes, the presence of NO3− hardly influenced the destruction of OTC. Generation of CO3•− presented a positive role on OTC degradation by UV/NO3−/HCO3−. Such influence was also observed in the two studied AOPs in the presence of both bicarbonate and other natural water constituents. When various natural water samples from different sources were used as reaction matrices, UV only and UV/H2O2 showed an inhibiting effect while UV/PS demonstrated a comparable or even promoting effect in OTC decomposition. After elucidating the potential contribution of UV direct photolysis via excited state OTC* at an elevated reaction pH condition, putative OTC transformation byproducts via CO3•− reaction were identified by ultra-high definition accurate-mass quadrupole time-of-flight tandem mass spectrometry (QTOF/MS). Five different reaction pathways were subsequently proposed, including hydroxylation (+16 Da), quinonization (+14 Da), demethylation (−14 Da), decarbonylation (−28 Da) and dehydration (−18 Da). The significant role of UV at high pH and CO3•− on OTC removal from contaminated water was therefore demonstrated both kinetically and mechanistically.

Synthesis and evaluation of methylene blue oligonucleotide conjugates for DNA interstrand cross-linking

Abstract Efficient DNA interstrand cross-linking can be achieved with furan containing oligonucleotide probes upon activation by singlet oxygen ( 1 O 2 ). Previously, we have described how this can be achieved by irradiation of these furan probes with visible light in the presence of photosensitizers. Now, in an effort to explore cross-linking under conditions that are representative for experiments in cellular context, the furan mediated oligonucleotide cross-linking was investigated at low oligonucleotide concentrations, ensuring a sufficiently high local concentration of singlet oxygen by attaching the sensitizing methylene blue moiety to the oligonucleotide complementary to the furan modified strand. Four methylene blue-oligonucleotide conjugates were synthesized, each with a different positioning of methylene blue with respect to the furan unit present on the complementary strand. The conjugates were evaluated for singlet oxygen generation and subsequent cross-linking ability. It was observed that not only the distance of the 1 O 2 source to the furan unit, but also the specific interaction of methylene blue moiety with the duplex, which is position dependent, influences cross-linking yields.

Case Report of a Patient with partial Trisomy 13q21.1qter

Introduction: Trisomy 13 (Patau syndrome) is one of the most common autosomal trisomies and is characterized by craniofacial dysmorphologies as well as cardiac and central nervous system abnormalities. Life expectancy is reduced. Most of the children die within the first days and months after birth. However, approximately 10% of the children with total trisomy 13 survive beyond 1 year. In up to 50% of the cases, Patau syndrome is accompanied by epilepsy. Typical features are an early onset and a generally good seizure control. Common types of seizures are infantile spasms and myoclonic jerks. EEG recordings show nonspecific findings, although photosensitivity has been an often reported EEG feature. Recent studies show that the epilepsy can just be poorly controlled by antiepileptic medication in the presence of photosensitivity. Method: We describe a 13-month-old boy with a partial trisomy 13q21.1qter who was born at 36 weeks with a distinct growth retardation. Postnatally, a malalignment-ventricular septum defect and an infundibular pulmonary stenosis plus a tracheo- and laryngomalacia as well as postaxial hexadactyly became apparent. Furthermore, a pronounced cognitive and motoric retardation developed over the course of time. At the age of 7 months, myoclonic jerks occurred. The EEG revealed multifocal and generalized sharp and (poly-) spike waves. Photosensitivity was not detected. Initial treatment with sultiam and ethosuximide failed to improve the epileptic situation. The introduction of valproate decreased the frequency of seizures significantly. Summary: For our patient, semiology and EEG findings match data in literature for children with total trisomy 13. However, despite the absence of photosensitivity, the epilepsy seems difficult to treat. For patients with trisomy 13 and epilepsy, valproate is the first-line treatment. Keywords: trisomy 13, epilepsy, EEG, photosensitivity, valproate.

Synergic phototoxic effect of visible light or Gallium-Arsenide laser in the presence of different photo-sensitizers on Porphyromonas gingivalis and Fusobacterium nucleatum.

Background:According to the development of resistant strains of pathogenic bacteria following treatment with antimicrobial chemotherapeutic agents, alternative approaches such as lethal photosensitization are being used. The aim of this study was to evaluate the effect of visible light and laser beam radiation in conjugation with three different photosensitizers on the survival of two main periodontopathogenic bacteria including Porphyromonas gingivalis and Fusobacterium nucleatum in different exposure periods.Materials and Methods:In this in vitro prospective study, strains of P. gingivalis and F. nucleatum. were exposed to visible light at wavelengths of 440 nm and diode laser light, Gallium-Arsenide, at wavelength of 830 nm in the presence of a photosensitizer (erythrosine, curcuma, or hydrogen peroxide). They were exposed 1-5 min to each light. Each experiment was repeated 3 times for each strain of bacteria. Data were analyzed by two-ways ANOVA and least significant difference post-hoc tests. P < 0.05 was considered as significant. After 4 days the colonies were counted.Results:Viability of P. gingivalis was reduced 10% and 20% subsequent to exposure to visible light and diode laser, respectively. The values were 65% and 75% for F. nucleatum in a period of 5-min, respectively. Exposure to visible light or laser beam in conjugation with the photosensitizers suspension caused significant reduction in the number of P. gingivalis in duration of 5-min, suggesting a synergic phototoxic effect. However, the survival rate of F. nucleatum following the exposure to laser with hydrogen peroxide, erythrosine and rhizome of Curcuma longa (curcumin) after 5-min was 10%, 20% and 90% respectively.Conclusion:Within the limitations of this study, the synergic phototoxic effect of visible light in combination with each of the photosensitizers on P. gingivalis and F. nucleatum. However, the synergic phototoxic effect of laser exposure and hydrogen peroxide and curcumin as photosensitizers on F. nucleatum was not shown.

Red light-controlled polymerase chain reaction.

A 23-mer DNA "caged" at its 3'-terminus with a 9-anthracenyl moiety was prepared. It can be uncaged in the presence of photosensitizer (In(pyropheophorbide-a)chloride)-containing DNAs (9-12 mers) and upon irradiation with red light. This mixture of DNAs was used to design red-light controlled polymerase chain reaction.

Oxidation of bisphenol A from simulated and real urban wastewater effluents by UV, O3 and UV/O3

Increased concentration of micropollutants in the aquatic environment triggers the necessity to develop more effective methods for their elimination. A variety of research has been devoted to similar subject matters regarding the efficiency of different advanced oxidation processes to eliminate micropollutants. On the basis of them, this study was undertaken so as to assess the efficiency of bisphenol A (BPA) elimination from both stimulated and real urban wastewater effluents by photolysis (UV), ozonation (O3) and UV/O3 processes. The obtained results were juxtaposed in terms of the efficiency of BPA elimination for deionised water. The physical and chemical composition of the solution differentiated BPA elimination efficiency in the investigated processes. BPA decomposition degree was higher for real wastewater effluents than for deionised water and stimulated effluents. It is probably connected with the presence of photosensitisers in the real effluent. It was established that the combination of photolysis and ozonation led to the highest level of compound decomposition (for real effluent >90%). In this research, a first-order reaction model was used to establish the reaction rate constant for BPA decomposition in a combined UV/O3 process. The half-life of the investigated compound was also identified.

Decreased SOCS1 mRNA expression levels in peripheral blood mononuclear cells from patients with systemic lupus erythematosus in a Chinese population.

The aim of this study was to investigate the mRNA expression levels of suppressor of cytokine signaling 1 (SOCS1) in patients with systemic lupus erythematosus (SLE) compared with healthy controls. The associations of systemic lupus erythematosus disease activity index scores and clinical features of SLE with the expression levels of SOCS1 mRNA were also evaluated. Real-time quantitative reverse transcription-polymerase chain reaction was applied to detect the mRNA expression levels of SOCS1 in peripheral blood mononuclear cells from 34 patients with SLE and 34 healthy controls. The mRNA expression level of SOCS1 was significantly decreased in SLE patients in comparison with healthy controls (Z=-4.207, P<0.001). Lower SOCS1 mRNA expression was detected in active SLE patients when compared with inactive ones (Z=-2.428, P=0.015). There was no significant difference found for the SOCS1 mRNA levels between SLE patients with nephritis and those without (Z=-0.642, P=0.521). The presence of photosensitivity, proteinuria, positive antinuclear antibody, and C4 decline were associated with SOCS1 mRNA levels in SLE patients (all P<0.05). Furthermore, the SOCS1 mRNA expression was negatively correlated with disease activity (r s =-0.372, P=0.030). Our results suggest that the dysregulation of SOCS1 might be associated with the pathogenesis of SLE.

Photolysis of Naproxen under UV Light: Effect of Natural Organic Matter and Nitrate to Transformation Product Formation

Naproxen is one of the most commonly used pharmaceuticals in the world. It was measured at different concentration levels in environmental water. Since naproxen can be exposed to UV light during water and wastewater treatment, an investigation was conducted to identify photolysis rate and transformation product formation during photolysis in the presence of photosensitizers. Different experiments were carried out to identify the effect of dissolved organic matter and NO3− to photolysis reactions of naproxen. Naproxen was measured and transformation products were detected using liquid chromatograph coupled with triple quadrupole tandem mass spectrometer. MassBank libraries were used to propose transformation product molecular structures. During direct photolysis experiments pseudo first order degradation kinetic constant kobs was found as 0.121 min−1. kobs decreased to 0.068 min−1 during indirect photolysis experiments. While presence of dissolved organic matter decreases photolysis rate, NO3− accelerates the degradation of naproxen. Benzyl succinic acid and caffeic acid were proposed as potential transformation products of naproxen along with an unidentified transformation product having 177 m/z. All potential transformation products of naproxen proposed in this study were identified for the first time in the literature.

Antiradical and photoprotective activity of oxibiol, a novel water-soluble heteroaromatic antioxidant

5-Hydroxybenzo[d]thiazol-2-ylammonium N-acetyl-l-cysteinate (oxibiol) was synthesized and studied. This novel water-soluble azaheterocyclic antioxidant is a white crystalline solid (m.p. 148–150 °C) soluble in ethanol and water. The UV spectrum of oxibiol shows two absorption bands at 220±1 and 265±1 nm. Its antiradical activity was examined using a homogeneous hydrophilic chemiluminescent system. The emission quenching constant of oxibiol is (2.4±0.4)·105 L mol−1, which is nearly seven times that of the antioxidant mexidol widely used in current medical practice. Oxibiol efficiently inhibits the free radical oxidation of photoreceptor cells that is induced by iron(II) ions and UV and visible light in the presence of photosensitizers. Oxibiol is especially effective in suppressing the photoinduced lipid peroxidation sensitized by lipofuscin granules from human retinal pigment epithelial cells. Oxibiol is highly resistant when exposed to UV light. Being a novel, more efficient and photoresistant antioxidant, oxibiol can also find other medical applications and replace the widely used agent mexidol.

Photo‐Induced Water Oxidation Based on a Mononuclear Cobalt(II) Complex

AbstractPhoto‐induced water oxidation based on first row transition metal complexes has drawn much attention recently as a part of the efforts to design systems for solar fuel production. Here, the classic tetradentate ligand TPA (tris(2‐pyridylmethyl)amine) is used together with cobalt(II) in CH3CN to form a mononuclear cobalt complex [Co(TPA)Cl]Cl. Single crystal X‐ray diffraction shows that [Co(TPA)Cl]Cl is composed of discrete cationic units with a penta‐coordinate cobalt center, along with chloride counter ions. In borate buffer, the Co complex acts as a water oxidation catalyst, as shown by the presence of a catalytic wave in electrochemistry. Under visible light irradiation, in the presence of photosensitizer and electron acceptor, the Co complex catalyzes O2 evolution with a turnover frequency (TOF) of 1.0 mol(O2)·mol(Co)−1·s−1 and a turnover number (TON) of 55 mol(O2)·mol(Co)−1 in pH 8 borate buffer.