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Molecules (Basel, Switzerland) Mar 2022Significant efforts have been made in recent years to identify more environmentally benign and safe alternatives to side-chain protection and deprotection in solid-phase...
Significant efforts have been made in recent years to identify more environmentally benign and safe alternatives to side-chain protection and deprotection in solid-phase peptide synthesis (SPPS). Several protecting groups have been endorsed as suitable candidates, but finding a greener protecting group in SPPS has been challenging. Here, based on the 2-(-nitrophenyl) propan-1-ol (Npp-OH) photolabile protecting group, a structural modification was carried out to synthesize a series of derivatives. Through experimental verification, we found that 3-(-Nitrophenyl) butan-2-ol (Npb-OH) had a high photo-release rate, high tolerance to the key conditions of Fmoc-SPPS (20% piperidine DMF alkaline solution, and pure TFA acidic solution), and applicability as a carboxyl-protective group in aliphatic and aromatic carboxyl groups. Finally, Npb-OH was successfully applied to the synthesis of head-tail cyclic peptides and side-chain-tail cyclic peptides. Moreover, we found that Npb-OH could effectively resist diketopiperazines (DKP). The α-H of Npb-OH was found to be necessary for its photosensitivity in comparison to 3-(-Nitrophenyl)but-3-en-2-ol (Npbe-OH) during photolysis-rate verification.
Topics: Peptides, Cyclic; Photolysis; Solid-Phase Synthesis Techniques
PubMed: 35408630
DOI: 10.3390/molecules27072231 -
Environmental Research Mar 2021Nicotine is an important emerging contaminant widely detected in water resources. The main nicotine sources are human excretions from users and leaching from discarded...
Nicotine is an important emerging contaminant widely detected in water resources. The main nicotine sources are human excretions from users and leaching from discarded tobacco product waste, which represents the most commonly littered item in urban areas and coasts. In this study, the UV photolytical fate of nicotine in natural water and leachates produced from conventional cigarettes (CCs) and the new generation heat-not-burn (HnBs) tobacco products is examined for the first time. The effect of UV irradiation on nicotine depletion in ultrapure water was initially studied. The reaction was pseudo first-order with respect to nicotine concentration at low concentrations and shifted to lower order at higher concentrations, an effect associated to absorption saturation. Although nicotine removal was fast, only 9.5% of the total organic carbon was removed after irradiation due to the formation of by-products. The chemical structures of six photo-products were derived by means of liquid and gas chromatography coupled to mass spectrometry. The photodegradation kinetics was found to depend on pH and faster kinetics were recorded when the monoprotonated form of nicotine was dominant (pH = 5-8). The presence of humic acids was found to slightly delay kinetics as they competed with nicotine for lamp irradiance, whereas the presence of salt had no effect on the direct photolysis of nicotine. Direct photolysis studies were also performed using natural waters. Compared to ultra-pure water, photodegradation was found to proceed slightly slower in river water, in similar kinetics in seawater, and relatively faster in rain water. The later was assumed to be due to the lower pH compared to the rest of the natural water tested. Leachates from used HnBs and smoked CCs were also submitted to UV irradiation and direct photolysis was found to proceed fast despite the high complexity of these matrices. Nonetheless, the total organic carbon in the system remained the same after irradiation due to the abundance of organics and photo-products formed. We take advantage of the present investigations and report the leaching behavior of nicotine from HnBs and CCs. Among others, we found that in HnBs ~70% of the total and bioavailable nicotine content remains in the tobacco sticks after operation and this percentage drops to 15% in CCs due to the reduction in mass after smoking. This finding demonstrated the importance of properly disposing tobacco product waste to prevent nicotine leaching in water bodies.
Topics: Gas Chromatography-Mass Spectrometry; Hot Temperature; Humans; Kinetics; Nicotine; Photolysis; Tobacco Products; Water Pollutants, Chemical
PubMed: 33400945
DOI: 10.1016/j.envres.2020.110695 -
Photochemical & Photobiological... Dec 2015Spatio-temporal release of biologically relevant small molecules provides exquisite control over the activation of receptors and signaling pathways. This can be...
Spatio-temporal release of biologically relevant small molecules provides exquisite control over the activation of receptors and signaling pathways. This can be accomplished via a photochemical reaction that releases the desired small molecule in response to irradiation with light. A series of biologically-relevant signaling molecules (serotonin, octopamine, capsaicin, N-vanillyl-nonanoylamide, estradiol, and tyrosine) that contain a phenol moiety were conjugated to the 8-bromo-7-hydroxyquinolinyl (BHQ) or 8-cyano-7-hydroxyquinolinyl (CyHQ) photoremovable protecting groups (PPGs). The CyHQ caged compounds proved sensitive toward 1PE and 2PE processes with quantum efficiencies of 0.2-0.4 upon irradiation at 365 nm and two-photon action cross sections of 0.15-0.31 GM when irradiated at 740 nm. All but one BHQ caged compound, BHQ-estradiol, were found to be sensitive to photolysis through 1PE and 2PE with quantum efficiencies of 0.30-0.40 and two photon cross sections of 0.40-0.60 GM. Instead of releasing estradiol, BHQ-estradiol underwent debromination.
Topics: Hydroxyquinolines; Light; Nitriles; Phenols; Photolysis; Photons
PubMed: 26467796
DOI: 10.1039/c5pp00334b -
Biochimica Et Biophysica Acta. General... Feb 2020The invention of the X-ray free-electron laser (XFEL) has provided unprecedented new opportunities for structural biology. The advantage of XFEL is an intense pulse of...
BACKGROUND
The invention of the X-ray free-electron laser (XFEL) has provided unprecedented new opportunities for structural biology. The advantage of XFEL is an intense pulse of X-rays and a very short pulse duration (<10 fs) promising a damage-free and time-resolved crystallography approach.
SCOPE OF REVIEW
Recent time-resolved crystallographic analyses in XFEL facility SACLA are reviewed. Specifically, metalloproteins involved in the essential reactions of bioenergy conversion including photosystem II, cytochrome c oxidase and nitric oxide reductase are described.
MAJOR CONCLUSIONS
XFEL with pump-probe techniques successfully visualized the process of the reaction and the dynamics of a protein. Since the active center of metalloproteins is very sensitive to the X-ray radiation, damage-free structures obtained by XFEL are essential to draw mechanistic conclusions. Methods and tools for sample delivery and reaction initiation are key for successful measurement of the time-resolved data.
GENERAL SIGNIFICANCE
XFEL is at the center of approaches to gain insight into complex mechanism of structural dynamics and the reactions catalyzed by biological macromolecules. Further development has been carried out to expand the application of time-resolved X-ray crystallography. This article is part of a Special Issue entitled Novel measurement techniques for visualizing 'live' protein molecules.
Topics: Animals; Carbohydrates; Cattle; Crystallography, X-Ray; Cyanobacteria; Dimerization; Electron Transport Complex IV; Lasers; Ligands; Macromolecular Substances; Metalloproteins; Molecular Conformation; Oxidoreductases; Photolysis; Photosystem II Protein Complex; Plants; Thermosynechococcus; X-Rays
PubMed: 31678142
DOI: 10.1016/j.bbagen.2019.129466 -
The Science of the Total Environment Feb 2021In the present study, the photoinduced degradation of the antidepressant drug sertraline under artificial solar radiation was examined. Photolysis was studied under...
In the present study, the photoinduced degradation of the antidepressant drug sertraline under artificial solar radiation was examined. Photolysis was studied under different experimental conditions to explore its photolytic fate in the aqueous environment. Photolytic degradation kinetics were carried out in ultrapure water, wastewater effluent, as well as in the presence of dissolved organic matter (humic acids), bicarbonate and nitrate ions which enabled their assessment on sertraline photo-transformation. The reaction of sertraline with photoactive compounds accelerated sertraline transformation in comparison with direct photolysis. Moreover, TiO-mediated photocatalytic degradation of sertraline was investigated, and focus was placed on the identification of by-products. As expected, photocatalysis was extremely effective for sertraline degradation. Photocatalytic degradation proceeded through the formation of forty-four transformation products identified by HPLC-HRMS and after 240 min of irradiation total mineralization was achieved. Microtox bioassay (Vibrio fischeri) was employed to assess the ecotoxicity of the photocatalysis-treated solutions and results have indicated that sertraline photo-transformation proceeds through the formation of toxic compounds.
Topics: Aliivibrio fischeri; Kinetics; Photolysis; Sertraline; Titanium; Water; Water Pollutants, Chemical
PubMed: 33310221
DOI: 10.1016/j.scitotenv.2020.143805 -
Environmental Science and Pollution... Aug 2022Antifungal azoles are the most frequently used fungicides worldwide and occur as active ingredients in many antifungal pharmaceuticals, biocides, and pesticides. Azole...
Antifungal azoles are the most frequently used fungicides worldwide and occur as active ingredients in many antifungal pharmaceuticals, biocides, and pesticides. Azole fungicides are frequent environmental contaminants and can affect the quality of surface waters, groundwater, and drinking water. This study examined the potential of combined vacuum UV (185 nm) and UVC (254 nm) irradiation (VUV/UVC) of the azole fungicide tebuconazole and the transformation product 1,2,4-trizole on degradation and changes in ecotoxicity. In vivo ecotoxicity was examined before and after UV treatment using bioassays with test organisms from different trophic levels to integrate changes in biological effect of the parent compound and the degradation products. The test battery included the luminescent bacterium Aliivibrio fischeri, the Gram-positive bacterium Bacillus subtilis, the fungus Fusarium graminearum, the green microalga Raphidocelis subcapitata, and the crustacean Daphnia magna. The combined VUV/UVC treatment of tebuconazole in drinking water efficiently degraded the parent compound at the µg/L-mg/L level and resulted in transformation products with lower toxicity than the parent compound. A direct positive correlation was observed between the applied UV dose (fluence, J/cm), the disappearance of tebuconazole, and the decrease in ecotoxicity. The combined VUV/UVC process does not require addition of supplementary oxidants or catalysts and our study suggests that VUV/UVC-mediated photolysis of azole fungicides in water can decrease the overall toxicity and represent a potentially environmentally friendly treatment method.
Topics: Antifungal Agents; Drinking Water; Fungicides, Industrial; Photolysis; Triazoles; Ultraviolet Rays; Vacuum; Water Pollutants, Chemical
PubMed: 35364793
DOI: 10.1007/s11356-022-19691-0 -
Molecules (Basel, Switzerland) Jul 2022Different advanced oxidation processes (AOPs) (ultraviolet radiation, hydrogen peroxide photolysis and photo-Fenton) were applied to test the degradation of...
Different advanced oxidation processes (AOPs) (ultraviolet radiation, hydrogen peroxide photolysis and photo-Fenton) were applied to test the degradation of terbuthylazine in three types of water: (a) ultrapure water, (b) surface water from the Gaditana area (Los Hurones reservoir, Cádiz, Spain) and (c) groundwater from the Tempul spring in Jerez de la Frontera (Cádiz, Spain). The experiments were carried out on a laboratory scale, using two different types of reactors, batch and semi-continuous. In batch reactors, the most efficient process for the experiments carried out with both ultrapure water and underground groundwater was ultraviolet radiation, whereas for surface water from the Gaditana area, the process that obtained the best results was the photolysis of hydrogen peroxide with 2.5 mg L of HO. In semi-continuous reactors, the most efficient process was the photolysis of hydrogen peroxide with 2.5 mg L of HO for all the matrices studied. In both types of reactors, terbuthylazine degradation percentages higher than 90% were achieved; the main difference was in the reaction time, which varied from minutes in the batch reactor to seconds in the semi-continuous reactor. In all the applied AOPs, N-terbutyl-6-hydroxy-N'ethyl-1,3,5-triazine-2,4-diamine (TBA-212) was generated as a reaction intermediate.
Topics: Hydrogen Peroxide; Oxidation-Reduction; Photolysis; Triazines; Ultraviolet Rays; Water; Water Pollutants, Chemical; Water Purification
PubMed: 35889384
DOI: 10.3390/molecules27144507 -
Environmental Pollution (Barking, Essex... Jan 2020Irinotecan (CPT-11) is a water-soluble anticancer drug widely used to treat several types of cancer. Even if the metabolites of CPT-11 are well-known and investigated,...
Irinotecan (CPT-11) is a water-soluble anticancer drug widely used to treat several types of cancer. Even if the metabolites of CPT-11 are well-known and investigated, only limited information is available in the literature about the formation of photo-degradation products that can naturally originate from sunlight irradiation when the drug is released in aqueous systems. CTP-11 solutions at 10.0 mg L were irradiated by simulated sunlight. The intensity of the drug decreased by 90% after 7.5 days of irradiation and no significant reduction of absorbance values was observed after 13 days. A sensitive UHPLC-MS/MS method was developed employing a hybrid triple quadrupole/linear ion trap mass spectrometer, that is able to work in data-dependent acquisition mode and to obtain information about the compounds formed during the photoirradiation. Moreover, a selected reaction monitoring method was built using the MS/MS fragmentation pattern of the compounds previously investigated. The method was validated considering LOD, LOQ, linearity, precision, selectivity, recovery and matrix effect. LOD and LOQ values were 0.02 and 0.05 ng mL, respectively, whereas MDL and MQL values in real water samples (river water, groundwater, well water, and wastewater) were lower than 0.05 and 0.2 ng mL, respectively. Eight photodegradation products were identified, among which five for the first time. Based on the MS and MS/MS fragmentation, the chemical structures of the degradation products were proposed. Hydrolysis experiments were carried out on the same solutions preserved in the dark, but no formation of other species was highlighted. The method was applied to several real samples: CPT-11 was detected and quantified only in a hospital effluent sample at the concentration of 0.41 ± 0.2 ng mL together with the occurrence of PDP3. The outcomes of this study may be useful for updating the pollutant screening in water samples.
Topics: Chromatography, High Pressure Liquid; Irinotecan; Limit of Detection; Photolysis; Reproducibility of Results; Sunlight; Tandem Mass Spectrometry; Wastewater; Water Pollutants, Chemical
PubMed: 31662244
DOI: 10.1016/j.envpol.2019.113370 -
Molecules (Basel, Switzerland) Nov 2022The mechanism of photolytic degradation of 2-4-6-trinitrotoluene (TNT) by UVA−visible light (>320 nm) in ethanolic, aqueous-ethanolic, and aqueous solutions was...
Photolysis by UVA-Visible Light of TNT in Ethanolic, Aqueous-Ethanolic, and Aqueous Solutions According to Electrospray and Aerodynamic Thermal Breakup Droplet Ionization Mass Spectrometry.
The mechanism of photolytic degradation of 2-4-6-trinitrotoluene (TNT) by UVA−visible light (>320 nm) in ethanolic, aqueous-ethanolic, and aqueous solutions was investigated by electrospray and aerodynamic thermal breakup droplet ionization mass-spectrometric analyses. For the photolysis, a DRK-120 mercury-quartz lamp was used. Products of the photolysis reaction were compared with known products of TNT transformation in the environment. Because the photochemistry of some compounds in alcohols (in contrast to aqueous solutions) features a transfer of electrons from the solvent to the light-excited compound, we believe that the efficiency of photolysis (polymerization) of TNT in ethanol and aqueous-ethanolic solutions is based on this mechanism.
Topics: Photolysis; Trinitrotoluene; Light; Mass Spectrometry; Water; Ethanol
PubMed: 36432093
DOI: 10.3390/molecules27227992 -
Molecules (Basel, Switzerland) Dec 2019This work systematically compares both structural features and photocatalytic performance of a series of graphitic and amorphous carbon dots (CDs) prepared in a...
This work systematically compares both structural features and photocatalytic performance of a series of graphitic and amorphous carbon dots (CDs) prepared in a bottom-up manner from fructose, glucose, and citric acid. We demonstrate that the carbon source and synthetic procedures diversely affect the structural and optical properties of the CDs, which in turn unpredictably influence their photo electron transfer ability. The latter was evaluated by studying the photo-reduction of methyl viologen. Overall, citric acid-CDs were found to provide the best photocatalytic performance followed by fructose- and glucose-CDs. However, while the graphitization of glucose- and citric acid-CDs favored the photo-reaction, a reverse structure-activity dependence was observed for fructose-CDs due to the formation of a large graphitic-like supramolecular assembly. This study highlights the complexity to design in advance photo-active bio-based carbon nanomaterials.
Topics: Carbon; Catalysis; Citric Acid; Fructose; Glucose; Molecular Structure; Photolysis; Quantum Dots
PubMed: 31888094
DOI: 10.3390/molecules25010101