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Molecules (Basel, Switzerland) Feb 2024The 3',5'-dimethoxybenzoin (DMB) system has been widely investigated as a photoremovable protecting group (PRPG) for the elimination of various functional groups and has...
The 3',5'-dimethoxybenzoin (DMB) system has been widely investigated as a photoremovable protecting group (PRPG) for the elimination of various functional groups and has been applied in many fields. The photolysis of DMB fluoride leads to a highly efficient photocyclization-deprotection reaction, resulting in a high yield of 3',5'-dimethoxybenzofuran (DMBF) in a MeCN solution, while there is a competitive reaction that produces DMB in an aqueous solution. The yield of DMB increased as the volume ratio of water increased. To understand the solvent effect of the photolysis of selected DMB-based compounds, a combination of femtosecond to nanosecond transient absorption spectroscopies (fs-TA and ns-TA), nanosecond time-resolved resonance Raman spectroscopy (ns-TR) and quantum chemical calculation was employed to study the photophysical and photochemical reaction mechanisms of DMB fluoride in different solutions. Facilitated by the bichromophoric nature of DMB fluoride with electron-donating and -withdrawing chromophores, the cyclized intermediates could be found in a pure MeCN solution. The deprotection of a cyclic biradical intermediate results in the simultaneous formation of DMBF and a cyclic cation species. On the other hand, in aqueous solution, fs-TA experiments revealed that α-keto cations could be observed after excitation directly, which could easily produce the DMB through the addition of a hydroxyl within 8.7 ps. This work provides comprehensive photo-deactivation mechanisms of DMB fluoride in MeCN and aqueous conditions and provides critical insights regarding the biomedical application of DMB-based PRPG compounds.
PubMed: 38398594
DOI: 10.3390/molecules29040842 -
Toxics Feb 2024Florfenicol (FLO) is a widely used antibacterial drug, which is often detected in the environment. In this paper, the photolysis mechanism of FLO in water was...
Study on the Direct and Indirect Photolysis of Antibacterial Florfenicol in Water Using DFT/TDDFT Method and Comparison of Its Reactivity with Hydroxyl Radical under the Effect of Metal Ions.
Florfenicol (FLO) is a widely used antibacterial drug, which is often detected in the environment. In this paper, the photolysis mechanism of FLO in water was investigated using density functional theory (DFT) and time-dependent density functional theory (TDDFT). The focus of the study is to elucidate the direct photolysis mechanism of FLO in the water environment and the indirect photolysis of free radicals (·OH, ·NO, and ·SO) as active species. The effect of metal ions Ca/Mg/Zn on the indirect photolysis was also investigated. The results show that the direct photolysis of FLO involves C-C/C-N/C-S bond cleavage, the C5-S7 bond cleavage is most likely to occur, and the C17-C18 cleavage reaction is not easy to occur during the direct photodegradation of FLO. The indirect photolysis of FLO is more likely to occur in the environment than direct photolysis. The main indirect photolysis involves OH-addition, NO-addition, and SO-addition on benzene ring. The order of difficulty in the indirect photolysis with ·OH is C2 > C3 > C4 > C5 > C6 > C1, Ca can promote the indirect photolysis with ·OH, and Mg/Zn has a dual effect on the indirect photolysis with ·OH. In other words, Mg and Zn can inhibit or promote the indirect photolysis with ·OH. These studies provide important information for theoretical research on the environmental behavior and degradation mechanism of drug molecules.
PubMed: 38393222
DOI: 10.3390/toxics12020127 -
Nature Communications Feb 2024Hydroxyl radicals (OH) determine the tropospheric self-cleansing capacity, thus regulating air quality and climate. However, the state-of-the-art mechanisms still...
Hydroxyl radicals (OH) determine the tropospheric self-cleansing capacity, thus regulating air quality and climate. However, the state-of-the-art mechanisms still underestimate OH at low nitrogen oxide and high volatile organic compound regimes even considering the latest isoprene chemistry. Here we propose that the reactive aldehyde chemistry, especially the autoxidation of carbonyl organic peroxy radicals (R(CO)O) derived from higher aldehydes, is a noteworthy OH regeneration mechanism that overwhelms the contribution of the isoprene autoxidation, the latter has been proved to largely contribute to the missing OH source under high isoprene condition. As diagnosed by the quantum chemical calculations, the R(CO)O radicals undergo fast H-migration to produce unsaturated hydroperoxyl-carbonyls that generate OH through rapid photolysis. This chemistry could explain almost all unknown OH sources in areas rich in both natural and anthropogenic emissions in the warm seasons, and may increasingly impact the global self-cleansing capacity in a future low nitrogen oxide society under carbon neutrality scenarios.
PubMed: 38388476
DOI: 10.1038/s41467-024-45885-w -
Environmental Research Jun 2024The literature rarely compiles studies devoted to the removal of pollutants in aqueous media comparing adsorption and photocatalytic degradation, and does not pay enough... (Comparative Study)
Comparative Study
Removal of malachite green from water: Comparison of adsorption in a residue-derived AC versus photocatalytic oxidation with TiO and study of the adsorption-photocatalysis synergy.
The literature rarely compiles studies devoted to the removal of pollutants in aqueous media comparing adsorption and photocatalytic degradation, and does not pay enough attention to the analysis of combined adsorption-photocatalytic oxidation processes. In the present manuscript, the removal of malachite green (MG) from aqueous solutions has been investigated in three different sustainable scenarios: i) adsorption on activated carbon (AC) derived from a residue, luffa cylindrica, ii) photocatalytic oxidation under simulated solar light using titanium dioxide (TP) and iii) combined adsorption-photocatalytic oxidation using TP-AC (70/30 wt./wt.) under simulated solar light. The study has revealed that in the three scenarios and studied conditions, the total removal of this endocrine-disrupting dye from the solution takes place in the assayed time, 2 h, in some cases just in a few minutes. MG adsorption in the AC is a very fast and efficient removal method. MG photocatalytic oxidation with TP also occurs efficiently, although the oxidized MG is not totally mineralized. MG removal using the TP-AC composite under simulated solar light occurs only slightly faster to the MG adsorption in the AC, being adsorption the dominating MG removal mechanism for TP-AC. Thus, more than 90% of the removed MG with TP-AC under simulated solar light is adsorbed in this carbon-containing composite. The obtained results highlight the interest in adsorption, being the selection of the most suitable removal method dependent on several factors (i.e., the cost of the AC regeneration, for adsorption, or the toxicity of the intermediate oxidation species, for photooxidation). Paying attention to MG photooxidation with TiO, comparison of two working photodegradation schemes shows that the direct photodegradation of MG from solution, avoiding any initial dark equilibrium period, is more efficient from a time perspective. The use of scavengers has proved that MG photodegradation occurs via an oxidation mechanism dominated by superoxide anion radicals.
Topics: Rosaniline Dyes; Titanium; Adsorption; Water Pollutants, Chemical; Oxidation-Reduction; Catalysis; Charcoal; Water Purification; Photolysis; Photochemical Processes
PubMed: 38387495
DOI: 10.1016/j.envres.2024.118510 -
The Science of the Total Environment Apr 2024Sulfonamide antibiotics (SUAs) released into the environment can affect environmental und human health, e.g., by accelerating the development and selection of...
Sulfonamide antibiotics (SUAs) released into the environment can affect environmental und human health, e.g., by accelerating the development and selection of antimicrobial resistant bacteria. Benign by Design (BbD) of SUAs is an effective risk prevention approach. BbD principles aim for fast and complete mineralization or at least deactivation of the SUA after release into the aquatic environment. Main objective was to test if mixtures of transformation products (TPs) generated via photolysis of SUAs can be used as an efficient way to screen for similarly effective but better biodegradable SUA alternatives. Six SUAs were photolyzed (Hg ultraviolet (UV) light), and generated UV-mixtures analysed by high performance liquid chromatography coupled to an UV and tandem mass spectrometry detector. UV-mixtures were screened for antibiotic activity (luminescence bacteria test, LBT, on luminescence and growth inhibition of Aliivibrio Fischeri) and environmental biodegradability (manometric respirometry test, MRT, OECD 301F) using untreated parent SUAs in comparison. Additionally, ready environmental biodegradability of three commercially available hydroxylated sulfanilamide derivatives was investigated. SUA-TPs contributed to acute and chronic bacterial luminescence inhibition by UV-mixtures. LBT's third endpoint, growth inhibition, was not significant for UV-mixtures. However, it cannot be excluded for tested TPs as concentrations were lower than parents' concentrations and inhibition by most parental concentrations tested was also not significant. HPLC analysis of MRT samples revealed that one third of SUA-TPs was reduced during incubation. Three of these TPs, likely OH-SIX, OH-SMX and OH-STZ, were of interest for BbD because the sulfonamide moiety is still present. However, hydroxylated sulfanilamide derivatives, tested to investigate the effect of hydroxylation on biodegradability, were not readily biodegraded. Thus, improving mineralization through hydroxylation as a general rule couldn't be confirmed, and no BbD candidate could be identified. This study fills data gaps on bioactivity and environmental biodegradability of SUAs' TP-mixtures. Findings may support new redesign approaches.
Topics: Humans; Sulfonamides; Biodegradation, Environmental; Sulfanilamide; Anti-Bacterial Agents; Photolysis; Water Pollutants, Chemical; Ultraviolet Rays
PubMed: 38378053
DOI: 10.1016/j.scitotenv.2024.171027 -
ACS Omega Feb 2024Self-assembling peptides are attractive alternatives in the field of biomaterial science due to their variability and biocompatibility. Unfortunately, such peptides have...
Self-assembling peptides are attractive alternatives in the field of biomaterial science due to their variability and biocompatibility. Unfortunately, such peptides have poor solubility, and their purification, synthesis, and overall handling are challenging. Our main objective was to develop a cage peptide design with full control over self-assembly. Theoretically, aggregation can be suppressed by temporally masking the amino acid side chains at critical positions. Taking into account several biological and synthetic requirements, a photosensitive protecting group, -hydroxy-phenacyl (pHP), was chosen as the "masking" moiety. To test our theory, EAK16-II was chosen as a model self-assembling peptide, and a caged derivative containing photosensitive pHP groups was synthesized. Both spectroscopic and in vitro experiments on A2058 melanoma cells confirmed our hypothesis that the caged-EAK16-II peptide has good solubility and that the hydrogel formed after photolysis results in similar viability and cell aggregate formation of melanoma cells as the native EAK16-II-based hydrogel.
PubMed: 38371799
DOI: 10.1021/acsomega.3c08289 -
Biophysics and Physicobiology Mar 2023Microbial rhodopsins are photoreceptive transmembrane proteins that transport ions or regulate other intracellular biological processes. Recent genomic and metagenomic...
Microbial rhodopsins are photoreceptive transmembrane proteins that transport ions or regulate other intracellular biological processes. Recent genomic and metagenomic analyses found many microbial rhodopsins with unique sequences distinct from known ones. Functional characterization of these new types of microbial rhodopsins is expected to expand our understanding of their physiological roles. Here, we found microbial rhodopsins having a DSE motif in the third transmembrane helix from members of the Actinobacteria. Although the expressed proteins exhibited blue-green light absorption, either no or extremely small outward H pump activity was observed. The turnover rate of the photocycle reaction of the purified proteins was extremely slow compared to typical H pumps, suggesting these rhodopsins would work as photosensors or H pumps whose activities are enhanced by an unknown regulatory system in the hosts. The discovery of this rhodopsin group with the unique motif and functionality expands our understanding of the biological role of microbial rhodopsins.
PubMed: 38362324
DOI: 10.2142/biophysico.bppb-v20.s023 -
Molecules (Basel, Switzerland) Jan 2024In total, three related substances (RS) associated with sotalol hydrochloride (STHCl) were herein identified with a novel gradient high-performance liquid chromatography...
In total, three related substances (RS) associated with sotalol hydrochloride (STHCl) were herein identified with a novel gradient high-performance liquid chromatography (HPLC) protocol. Further characterization of these substances was then performed via liquid chromatography-mass spectroscopy (LC-MS/MS) and nuclear magnetic resonance (NMR) approaches. For these analyses, commercial STHCl samples were used for quantitative HPLC studies and the degradation of STHCl under acidic (1M HCl), alkaline (1M NaOH), oxidative (30% HO), photolytic (4500 Lx), and thermal stress conditions (100 °C) was assessed. This approach revealed this drug to be resistant to acidic, alkaline, and high-temperature conditions, whereas it was susceptible to light and oxidation as confirmed through long-term experiments. The putative mechanisms governing RS formation were also explored, revealing that RS3 was derived from the manufacturing process, whereas RS2 was generated via oxidation and RS1 was generated in response to light exposure. The cytotoxicity of these RS compounds was then assessed using MTT assays and acute toxicity test. Overall, this study provides details regarding the characterization, isolation, quantification, and toxicological evaluation of STHCl and associated RS compounds together with details regarding the precise, specific, and reliable novel HPLC technique, thus providing the requisite information necessary to ensure STHCl purity and safety.
Topics: Chromatography, High Pressure Liquid; Chromatography, Liquid; Sotalol; Tandem Mass Spectrometry; Hydrogen Peroxide; Liquid Chromatography-Mass Spectrometry; Drug Stability; Hydrolysis; Oxidation-Reduction; Photolysis
PubMed: 38338332
DOI: 10.3390/molecules29030588 -
Molecules (Basel, Switzerland) Jan 2024Solar irradiation of 2-butenedial in the lower troposphere mainly produces isomeric ketene-enol (a key intermediate product), furanones, and maleic anhydride, the...
Tropospheric Photochemistry of 2-Butenedial: Role of the Triplet States, CO and Acrolein Formation, and the Experimentally Unidentified Carbonyl Compound-Theoretical Study.
Solar irradiation of 2-butenedial in the lower troposphere mainly produces isomeric ketene-enol (a key intermediate product), furanones, and maleic anhydride, the formation pathways of which were investigated in a previous study. The other main products were carbon monoxide and an experimentally unidentified carbonyl compound. This was the subject of the present study. The oxidative reaction mechanisms were studied using DFT calculations. Water intervention is found essential. Its addition and subsequent water-assisted isomerizations (an ene--diol/enol and a carboxylic acid/enol form), followed by cyclization, lead to an interesting cyclic carbonyl compound, but this pathway appears to be rather energy demanding. An alternative implies water cooperation in a ketene-enol + carboxylic acid/enol addition that gives the relevant anhydride. The anhydride is proposed as a candidate for the experimentally unidentified carbonyl product. Regarding CO and acrolein formation, the role of the triplet states, as defined by the probability of intersystem crossing from the excited singlet state S to T and T, is discussed. The T photolysis pathway connecting butenedial to propenal + CO was then defined.
PubMed: 38338321
DOI: 10.3390/molecules29030575 -
Chemical Science Feb 2024Photocleavable protecting groups (PPGs) enable the precise spatiotemporal control over the release of a payload of interest, in particular a bioactive substance, through...
Photocleavable protecting groups (PPGs) enable the precise spatiotemporal control over the release of a payload of interest, in particular a bioactive substance, through light irradiation. A crucial parameter that determines the practical applicability of PPGs is the efficiency of payload release, largely governed by the quantum yield of photolysis (QY). Understanding which parameters determine the QY will prove crucial for engineering improved PPGs and their effective future applications, especially in the emerging field of photopharmacology. The Contact Ion Pair (CIP) has been recognized as an important intermediate in the uncaging process, but the key influence of on the quantum yield has not been explored yet, limiting our ability to design improved PPGs. Here, we demonstrate that the CIP escape mechanism of PPGs is crucial for determining their payload- and solvent-dependent photolysis QY, and illustrate that an intramolecular type of CIP escape is superior over diffusion-dependent CIP escape. Furthermore, we report a strong correlation of the photolysis QY of a range of coumarin PPGs with the DFT-calculated height of all three energy barriers involved in the photolysis reaction, despite the vastly different mechanisms of CIP escape that these PPGs exhibit. Using the insights obtained through our analysis, we were able to predict the photolysis QY of a newly designed PPG with particularly high accuracy. The level of understanding of the factors determining the QY of PPGs presented here will move the ever-expanding field of PPG applications forward and provides a blueprint for the development of PPGs with QYs that are independent of payload-topology and solvent polarity.
PubMed: 38332822
DOI: 10.1039/d3sc05725a