Search Results (172)

Breast cancer treatments, such as chemotherapy, radiation, and surgery, often face significant limitations, highlighting the need for more effective and targeted therapies. Here, we investigate the potential of 266 nm laser irradiation of chlorpromazine as a novel approach to develop new antitumoral compounds. We identify six chlorpromazine photocompounds with masses in the range of 178–334 u, along with several dimeric compounds with masses between 566 and 600 u, using an HPLC-MS. In silico approaches assess their pharmacokinetic and pharmacodynamic properties while comparing their toxicity with the parent compound. Molecular docking simulations indicate that some photoproducts have a low estimated free energy of binding to cancer-related targets, suggesting enhanced therapeutic potential compared to chlorpromazine. Additionally, ADME-Tox predictions indicate that these photoproducts may have pharmacokinetic and toxicity profiles similar to chlorpromazine. Overall, this study highlights that laser-generated chlorpromazine photoproducts exhibit enhanced biological activity to breast cancer-related targets compared to chlorpromazine while maintaining a similar ADME-Tox profile. Full article

In this paper, we analyze the application of an analytical gluon distribution based on double-asymptotic scaling to the photoproduction of vector mesons in coherent $pp$, $pA$, and $AA$ collisions at LHC energies, using the color dipole formalism. Predictions for the rapidity distribution are presented for ${\rho }^0$, $J/\psi$, $\psi \left(2S\right)$, and $\mathrm{{\rm Y}}\left(1S\right)$ mesons photoproduction. An analysis of the uncertainties associated with different implementations of the dipole–proton amplitude is performed. The vector meson photoproduction accompanied by electromagnetic dissociation is also analyzed. Full article

Levofloxacin is an antibiotic classified as an emerging contaminant. Its presence in aquatic environments represents potential risks to ecosystems and human health, making its removal during wastewater treatment of relevant importance. Here, we present a comprehensive kinetic analysis of levofloxacin photodegradation under UVB solar irradiation, with emphasis on the influence of pH and dissolved oxygen, two conditions that can vary widely in wastewater and impact treatment efficiency. We also investigated the formation and role of reactive oxygen species in the degradation mechanism, as well as the cytotoxicity and antibacterial activity of photoproducts. Our findings reveal that the efficiency of levofloxacin photodegradation is highly dependent on environmental conditions; it requires neutral or slightly alkaline pH and a high concentration of dissolved oxygen, a situation not always observed in contaminated waters. Several reactive oxygen species are generated, with singlet oxygen being the most reactive with the antibiotic. We report for the first time the singlet oxygen quantum yield from levofloxacin. Bioassays demonstrated that photoproducts neither exhibit antibacterial activity nor induce significant cytotoxicity. Our study suggests that UVB treatment of contaminated effluent containing levofloxacin could be an effective and environmentally safe strategy for the antibiotic degradation under certain conditions of pH and dissolved oxygen. Full article

Co-trimoxazole is an antibacterial drug, a mixture of sulfamethoxazole (SMX) and trimethoprim (TMP) in a ratio of 5:1. Due to the different susceptibility of both components to decomposition under the influence of sunlight, the aim of the study was to assess the change in bacteriostatic activity during irradiation of the mixture of these antibiotics in a sunlight simulator. The bacteriostatic activity was assessed using a Microbial Assay for Risk Assessment (MARA), monitoring drug concentrations as well as the formation of photodegradation products using liquid chromatography (LC). The toxicity analysis of the SMX and TMP mixture showed synergistic bacteriostatic activity for six bacterial strains. This activity was maintained even during sample irradiation when 80–90% of SMX was degraded. This may indicate the bacteriostatic effect of SMX photoproducts and/or the lack of necessity to maintain a 5:1 ratio between SMX and TMP to maintain a strong effect of the mixture of these antibiotics. Analysis using LC with a high-resolution mass spectrometry detector revealed the presence of 11 SMX degradation products, including two with preserved sulfonamide structure, which may exhibit bacteriostatic activity. Full article

Porphyrins play important roles in biological systems including oxygen transport and catalysis. Due to their tetrapyrrole core structure, they exhibit exceptional photophysical and electrochemical properties and find many applications in both technical and life science fields, including photodynamic therapy and neurosurgery. The irradiation of porphyrins may cause modifications to their molecular structure or their degradation. Such photobleaching processes potentially affect the success and sensitivity of photosensitizer applications. While there have been many studies using fluorescence spectroscopy to investigate this phenomenon, reports about analytically validated structures of photoproducts are scarce. It is, however, necessary to know the individual contributions of different molecules to the fluorescence signal in order to evaluate it correctly. This review provides a summary of the current state of knowledge in this respect, discussing especially the validated hydroxyaldehyde and formyl photo-oxidation products of protoporphyrin IX. Full article

Ofloxacin is one of the most commonly used antibacterial substances in the world. Like most medicines, it ends up in the environment through municipal sewage and undergoes various transformations, e.g., photodegradation. The aim of this study was an extensive analysis of ofloxacin photodegradation in both pure antibiotic and a commercial eye drop forms. In this study, a sunlight simulator, chromatographic methods of quantitative and qualitative determination, and biological methods for the evaluation of toxicity (Microbial Assay for Risk Assessment (MARA), Microtox^® and Spirotox) were used. The results showed that ofloxacin decomposed almost completely over 2 h of irradiation. Based on the high resolution mass spectrometry, 22 photoproducts were identified. The most sensitive strain of bacteria in the MARA test (Delftia acidovorans) responded at a concentration of 7.6 µg L⁻¹ of ofloxacin. The antibacterial activity of the irradiated samples was higher than that predicted based on the ofloxacin concentration. This suggests that the resulting photoproducts may have a bacteriostatic effect. The results of additional acute toxicity tests indicate the formation of toxic photoproducts, so it is reasonable to use other organisms that are not focused on a specific target. Such actions may allow for the capture of other, unexpected effects of formed photoproducts. Full article

The extraction of the Generalized Parton Distributions of the nucleons from phenomenological analyses of experimental data presents a challenging problem which is being actively studied in the literature. Due to theoretical limitations of some of the well-known channels, currently many new processes are being analyzed in the literature as potential novel probes. In this proceeding we propose to use the exclusive photoproduction of ${\eta }_c\gamma$ pairs as a new channel for study of the GPDs. Our analysis shows that this process is primarily sensitive to the unpolarized gluon GPDs $H_g$ in the Efremov-Radyushkin-Brodsky-Lepage (ERBL) kinematics. The numerical estimates of the cross-section and the expected counting rates for middle-energy photoproduction experiments show that expected counting rates are sufficiently large for a dedicated experimental study at the future Electron-Ion Collider (EIC) or in ultraperipheral collisions at the LHC. The total (integrated) photoproduction cross-section ${\sigma }_{\mathrm{tot}}^{\gamma p\to \gamma {\eta }_{c}p}$ in this kinematics scales with energy W as ${\sigma }_{\mathrm{tot}}^{\gamma p\to \gamma {\eta }_{c}p}\left(W,M_{\gamma {\eta }_c}\ge 3.5\mathrm{GeV}\right)\approx 0.48\mathrm{pb}{\left({\displaystyle \frac{W}{100\mathrm{GeV}}}\right)}^{0.75},$ and yields a few thousands of events per $100{\mathrm{fb}}^{-1}$ of the integrated luminosity. Full article

Singlet oxygen quantum yield (Φ_Δ) is a critical parameter in photodynamic studies, particularly for evaluating photosensitizers’ efficiency in diverse applications such as photodynamic therapy and environmental remediation. Standard photosensitizers, including Rose Bengal, Methylene Blue, and porphyrins, are widely employed as benchmarks for determining Φ_Δ. However, accurate determination of Φ_Δ relies not only on the intrinsic properties of these photosensitizers but also on their experimental conditions, such as concentration. This study investigated the influence of photosensitizer concentration on singlet oxygen quantum yield using several standard photosensitizers. Our findings revealed a significant decrease in Φ_Δ with increasing photosensitizer concentrations across all tested compounds. This decline was attributed to self-quenching effects and molecular aggregation, which reduced the efficiency of energy transfer from the excited triplet state of the photosensitizer to molecular oxygen. The results emphasize the importance of optimizing photosensitizer concentration to ensure reliable Φ_Δ measurements and avoid underestimations. This work underscores the need to consider concentration-dependent effects in future studies to ensure accurate and reproducible outcomes. Full article

A series of photoacylations of 1,4-naphthoquinone with various aldehydes and using Pyrex-filtered UVB light was conducted under continuous-flow conditions. Acetone served as a triplet photosensitizer and convenient solvent that kept all materials in solution and could be easily removed. The corresponding acylated 1,4-naphthohydroquinone photoproducts were obtained in acceptable to excellent yields of 30–90% with residence times of just 70 min. The photoacylation process was successfully coupled with in-line oxidation to obtain acylated 1,4-naphthoquinones. Full article

Earlier, it has been shown that carotenoid-dependent singlet oxygen photogeneration in LH2 of Ectothiorhodospira haloalkaliphila leads to damage to pigments and protein. Present work continues this investigation using LH2 complexes with altered carotenoid composition: carotenoid-less LH2, and LH2 complexes with incorporated neurosporene, spheroidene, or rhodopin (LH2-Neu, LH2-Sph, or LH2-Rho, respectively). This work provides the first data on the products (hydroperoxides of organic molecules, most likely components of the protein matrix of the complexes) of the interaction of singlet oxygen with LH2 components with a modified carotenoid composition; the ability of various carotenoids to both influence the stability of LH2 and participate in oxidative damage to the complexes is assessed. It was shown that inhibition of carotenoid synthesis led to a decrease in LH2 thermal stability and reduced the light-induced oxidative damage to bacteriochlorophyll and protein. Re-incorporation of exogenous carotenoids did not return stability of the complexes but reduced the tendency of complexes to aggregate, and (in the case of LH2-Rho) reactivated both photooxidation of bacteriochlorophyll and photoproduction of organic hydroperoxides. It was concluded that carotenoids play an important role in comple x stability and are capable of inducing oxidative damage to LH2 components through singlet oxygen photogeneration. Full article

Sunlight exposure plays an important role in human health, impacting processes such as mood, blood pressure regulation, and vitamin D₃ production. Solar ultraviolet B radiation initiates vitamin D₃ synthesis in the skin, which is subsequently metabolized into its biologically active form. UVB exposure plays a key role in enabling vitamin D₃ synthesis, but it can also contribute to skin carcinogenesis, creating a complex interplay between its beneficial and harmful effects. Vitamin D deficiency, affecting over half the global population, is linked to a range of chronic diseases, including cancers, cardiovascular conditions, and autoimmune disorders. Simultaneously, excessive solar UVB exposure increases the risk of non-melanoma and melanoma skin cancers through mechanisms involving DNA damage and oxidative stress. This review examines the dual role of UVB radiation in health and disease, focusing on the mechanisms of cutaneous vitamin D₃ synthesis, the epidemiology of skin cancer, and the protective roles of vitamin D₃’s photoproducts and its active metabolite, 1,25-dihydroxyvitamin D₃. Understanding these interconnections is critical for developing strategies that balance adequate sun-induced vitamin D₃ production with skin cancer prevention. Full article

In a search for dyes photoactivatable with visible light, fluorenes with substituents at positions 2 and 7 were prepared, and their absorption and emission spectra were studied. In particular, the synthesis route to 9-diazofluorenes with 2-(N,N-dialkylamino) and N-modified 7-(4-pyridyl) substituents was established. These compounds are initially non-fluorescent, undergo photolysis with UV or blue light, and—in non-polar media—provide orange- to red-emitting products with a large separation between absorption and emission bands. Irradiation of non-fluorescent 9-diazoderivative 20 in dioxane with the light of 365 nm or 470 nm was accompanied by strong fluorescence gain (10 to 20 times), orange–red emission, and a large Stokes shift of photoproducts, which structurally relate to fluorescent betaine 13 (model compound without diazo group). Photolysis of 20 in protic solvents (ROH = MeOH, H₂O) provided clean transformation to C⁹-OR derivatives, though the emission gain in protic solvents was low. Full article

The photolysis kinetics of propaquizafop in water under ultraviolet light was investigated in this study, and the effects of different influencing factors (pH, ${\mathrm{N}\mathrm{O}}_3^{-}$, metal ions) on the photolysis of propaquizafop were clarified. Propaquizafop residues in water were determined by a HPLC-UV detector. The results showed that the pH of the aqueous solution had no significant effect on the photolysis of propaquizafop (p < 0.05). The low ${\mathrm{N}\mathrm{O}}_3^{-}$, concentration (0.5~2 mmol/L) had a weak inhibitory effect on the photolysis of the propaquizafop; when the concentration of ${\mathrm{N}\mathrm{O}}_3^{-}$ was 4 mmol/L, the degradation half-life of the propaquizafop was significantly higher than with other treatments (p < 0.05); Different concentrations of Fe³⁺ had varying degrees of inhibitory effects on the photolysis of propaquizafop. The inhibitory effect was stronger at low concentrations (0.5 mmol/L and 1 mmol/L) and weaker at high concentrations (2 mmol/L and 4 mmol/L). As the concentrations of Cu²⁺, Cd²⁺, Mn²⁺, Zn²⁺, and Ni²⁺ increased, their inhibitory effect on the photolysis of propaquizafop in an aqueous solution became stronger. In addition, LC–QTOF-MS was used to identify the photoproducts of propaquizafop in aqueous solution in this study. Five types of photoproducts were identified, and several propaquizafop degradation pathways and mechanisms were proposed, mainly including rearrangement, cracking reactions, dechlorination reactions, and light-induced redox reactions. The results of this study will help us to better understand the photodegradation law of propaquizafop in aqueous solution and provide data support for its safety evaluation in water. Full article

Applying an extended Peierls–Hubbard model to $\pi$ electrons in a coronene isomer, we investigate their ground-state properties and photoinduced dynamics with particular interest in possible loop current states. Once we switch on a static magnetic field perpendicular to the coronene disk, diamagnetic (diatropic) and paramagnetic (paratropic) loop currents appear on the rim circuit and inner hub, respectively. Besides this well-known homocentric two-loop current state, heterocentric multiloop current states can be stabilized by virtue of possible electron–lattice coupling. These multiloop current states generally have a larger diamagnetic moment than the conventional two-loop one, and hence it follows that coronene, or possibly polycyclic conjugated hydrocarbons in general, may become more aromatic than otherwise with their $\pi$ electrons being coupled to phonons. When we photoirradiate a ground-state coronene isomer without applying a static magnetic field, loop currents are induced in keeping with the incident light polarization. Linearly and circularly polarized lights induce heterocentric two-loop and multiloop currents, respectively, without and together with two homocentric loop currents of the conventional type, respectively. The heterocentric two-loop currents occur in a mirror-symmetric manner, which reads as the emergence of a pair of antiparallel magnetic moments, whereas the heterocentric multiloop ones appear at random in both space and time, which reads as the emergence of disordered local magnetic moments. Full article

Monomers of N-hydroxypyridine-2(1H)-thione were isolated in low-temperature matrices of solid normal hydrogen (n-H₂). The matrix-isolated compound was irradiated with UV-B (λ = 305 nm) or UV-A (λ > 360 nm) light. Upon such irradiation, the initial form of N-hydroxypyridine-2(1H)-thione was completely consumed and converted into photoproducts. 2-Mercaptopyridine and water were identified as the main products of these photochemical transformations. Identification of photoproduced 2-mercaptopyridine is unquestionable. It is based on the identity of two sets of IR bands: (i) the bands observed in the IR spectrum recorded (in a separate experiment) for monomers of 2-mercaptopyridine trapped in an n-H₂ matrix and (ii) a set of IR bands observed in the spectrum recorded after UV irradiation of N-hydroxypyridine-2(1H)-thione. It should be emphasized that the UV-induced processes, occurring for N-hydroxypyridine-2(1H)-thione isolated in an n-H₂ matrix, lead to products that are significantly different from those generated from the compound trapped in solid Ar or in solid N₂. Full article