Photochemical & Photobiological Sciences最新文献

Dispersion interactions are ubiquitous weak interactions that can play a role in many chemical events. Tailor-made catalysts and additives can lead to more selective reactions by properly exploiting dispersion interactions. Although radical-π dispersion interactions are known to have an important stabilizing role, this concept has been so far overlooked in synthetic photochemistry. We recently proved that similar dispersion interactions can play a profound impact on several reactions involving an energy transfer step. We present herein a study on the co-catalytic effect of tethered bi-naphthyl derivatives on the visible-light-promoted alkene-alkene [2 + 2] cycloaddition. A library of tethered bi-naphthyl derivatives was prepared in order to evaluate the impact of the tether on the efficiency of the prototypical [2 + 2] cycloaddition. The best performing additives showed a dramatic effect on the efficiency of the cyclization, and a rationalization of their relative efficiency was carried out through DFT modeling. The best co-catalyst allowed one to isolate desired products in good to excellent yields even employing several challenging substrates. These results offer new tools to devise optimized [2 + 2] photocycloaddition methods and provide valuable information for the design of organic co-catalyst that can boost photochemical reactions by exploiting dispersion interactions.

Sunscreens are used for the protection of human skin against the harmful effects of solar UV radiation. Due to the low thickness of sunscreen films typically applied to the skin, it can be challenging to achieve the strong absorbance needed for good UV-protection, and most efficient sunscreen compositions are desirable. The presence of scattering particles can increase the efficacy of dissolved UV-absorbers in the oil or water phases of the formulation. As many sunscreens contain UV-absorbing particles, it is of interest how much the scattering effect of such materials contribute to the protection of the respective sunscreen. The currently available software programs for simulating sunscreen performance are based on a Beer-Lambert law approach and do not take into account such scattering effects of particles. However, Monte Carlo simulations of the UV-light transport through sunscreen films are capable to take scattering from particles into consideration. Using Monte Carlo simulations, this work shows that the efficacy of absorbance is indeed increased in the presence of scattering particles. However, this is of limited significance when the particles are UV-absorbers themselves.

Background: Neurodevelopmental disorders (NDDs) such as autism spectrum disorder (ASD), attention-deficit/hyperactivity disorder (ADHD), and Down syndrome (DS) significantly impact social, communicative, and behavioral functioning. Transcranial photobiomodulation (t-PBM) with near-infrared light is a promising non-invasive neurostimulation technique for neuropsychiatric disorders, including NDDs. This narrative review aimed to examine the preclinical and clinical evidence of photobiomodulation (PBM) in treating NDDs.

Methods: A comprehensive search across six databases was conducted, using a combination of MeSH terms and title/abstract keywords: "photobiomodulation", "PBM", "neurodevelopmental disorders", "NDD", and others. Studies applying PBM to diagnosed NDD cases or animal models replicating NDDs were included. Protocols, reviews, studies published in languages other than English, and studies not evaluating clinical or cognitive outcomes were excluded.

Results: Nine studies were identified, including one preclinical and eight clinical studies (five on ASD, two on ADHD, and one on DS). The reviewed studies encompassed various t-PBM parameters (wavelengths: 635-905 nm) and targeted primarily frontal cortex areas. t-PBM showed efficacy in improving disruptive behavior, social communication, cognitive rigidity, sleep quality, and attention in ASD; in enhancing attention in ADHD; and in improving motor skills and verbal fluency in DS. Minimal adverse effects were reported. Proposed mechanisms involve enhanced mitochondrial function, modulated oxidative stress, and reduced neuroinflammation.

Conclusions: t-PBM emerges as a promising intervention for NDDs, with potential therapeutic effects across ASD, ADHD, and DS. These findings underscore the need for further research, including larger-scale, randomized sham-controlled clinical trials with comprehensive biomarker analyses, to optimize treatment parameters and understand the underlying mechanisms associated with the effects of t-PBM.

The giant-fruiting body, sporangiophore, of the fungus Phycomyces blakesleeanus grows toward near-UV/blue-light (phototropism). The blue-light photoreceptor, MadA, should contain FAD bound to the LOV domain, and forms a complex with MadB. Both proteins are homologs of white collar proteins WC-1 and WC-2 from the fungus Neurospora crassa and should be localized in nuclei, where they function as a light-sensitive transcription factor complex. The photoreceptor properties of two further Wc proteins, WcoA and WcoB, remain unclear because of lack of mutants. We propose that WcoA and/or WcoB play essential roles in photoreception by enlarging the dynamic range that help explain complex stimulus-response relationships. Even though red light does not elicit photo-movement or -differentiation in Phycomyces, it affects the effectiveness of blue light which indicates an underlying photochromic receptor. Protein sequence searches show that other fungal red-light receptors are absent in Phycomyces. The solution to the red-light riddle is thus sought in the ability of Wc complexes to generate after blue-light irradiation a neutral flavosemiquinone radical that absorbs red light and functions as primary photochemical signal. Phototropism requires Ras-GAP (MadC) as part of the signal transduction cascade and, we propose, to allocate photoreceptors in the plasmalemma of the growing zone, which allows for receptor dichroism, range adjustment and contrast recognition for spatial orientation. Phototropic signal chains must entail transduction networks between Wc receptors and small G-proteins and their associated Ras-GAP and Ras-GEF proteins. The interactions among these proteins should occur in trans-Golgi vesicles and the plasmalemma of the growing zone.

The present study aimed to evaluate the effect of photobiomodulation therapy (PBM) on different stages of osteogenesis in vitro. For this, osteoblastic-like cells (Saos-2 cell lineage) were irradiated in two different periods: during the Proliferation phase (PP; from the second to the fourth day) and during the Differentiation phase (DP; from the seventh to the ninth day). The energy density used in the study was 1.5 J/ cm². The following parameters were evaluated: 1) quantification of collagen type 1 (COL 1), osteopontin (OPN), and bone morphogenetic protein 2 (BMP-2); 2) quantification of alkaline phosphatase (ALP) activity; and 3) quantification of  extracellular matrix (ECM) mineralization. Non-irradiated cultures were used as controls. The data were analyzed using the Student's t-test or one-way ANOVA, considering a significance level of 5%. The results indicated that COL 1 and BMP-2 quantification was higher in Saos-2 irradiated during the DP in relation to the control group at day 10 (p < 0.05). No differences were observed for other comparisons at this time point (p > 0.05). OPN expression was greater in PP compared with the other experimental groups at day 10 (p < 0.05). Irradiation did not affect ALP activity in Saos-2 regardless of the exposure phase and the time point evaluated (p > 0.05). At day 14, ECM mineralization was higher in Saos-2 cultures irradiated during the DP in relation to the PP (p < 0.05). In conclusion, the results suggested that the effects of PBM on osteoblastic cells may be influenced by the stage of cell differentiation.

In this work the influence of o-fluorine substituents on the photo-dehydro-Diels-Alder (PDDA) reaction was investigated and the findings of this study were applied to the total synthesis of natural products. The reactant molecules consisted of two alkyl arylpropiolates, connected by a suberic acid tether and bearing fluorine substituents in each of the o-positions. While quantum chemical calculations suggested that a fluorine substituent prevents an attack of the adjacent carbon atom in the second C-C bond forming step of the PDDA reaction, this attack took place nevertheless. The subsequent fluoride elimination, assisted by protic solvents or trialkylsilanes, resulted in an "Umpolung" of the 4-position of the cycloallene intermediate enabling the introduction of nucleophiles at this position. The nucleophilic replacement of the second fluorine substituent could also be triggered photochemically. After removal of the tether, the two arene moieties stand nearly perpendicular to each other and a selective excitation of the naphthalene moiety was possible. This led to an intramolecular photoinduced electron transfer (PET) followed by a nucleophilic replacement of the fluoride according to a S_R+N1Ar* mechanism. The formed phenolic hydroxyl group underwent spontaneous lactonization with the adjacent ester group. Based on these results, the first total synthesis of the lignan Comfreyn A and some structural analogues were developed.

[3₂](1,4)Naphthalenophanes, bearing carbon-bridge chains (syn- and anti-NPs) and nitrogen-bridge chains (syn- and anti-ANPs), were synthesized, and their X-ray structures and photoreactions were investigated. The intramolecular separation distance between the naphthalene cores for ANPs was shorter than that for NPs, suggesting that intramolecular interactions between the naphthalene rings  were more efficient for ANPs compared to NPs. Upon photoirradiation at 300 nm, anti-NP, syn-ANP and anti-ANP produced the corresponding intramolecular [π4s + π4s] cycloadducts, whereas syn-NP gave an unidentified complex product mixture. Quantum yields for the photo-consumption (Φ_PC) of NPs and ANPs were evaluated to quantitatively compare their photoreactivity. The Φ_PC values of ANPs were approximately two-fold higher than those of ANPs.Noteworthily, the Φ_PC value of syn-ANP was estimated to be unity. Based on these results we discuss the effects of the alignments of the naphthalene cores (anti vs. syn) and the bridging elements (C-bridge vs. N-bridge) on the photoreaction efficiencies of [3₂](1,4)naphthalenophanes.

Bismuth-doped metal oxides exhibit favourable photocatalytic features when exposed to both sunlight and UV light. In this approach, Bi⁰/TiO₂ and Bi⁺³/TiO₂ photocatalysts were prepared and their structural and optical properties are analysed using various characterization techniques. These developed photocatalysts were further tested for the photocatalytic elimination of Nitrobenzene in UV light and sunlight and compared with the performance of bare TiO₂. The catalyst Bi⁺³/TiO₂ performed better in UV light with 72.31% degradation, and 4.74 × 10^-6 mol.litre^-1.min^-1 initial rate of reaction. However, when exposed to sunlight, Bi⁰/TiO₂ outperformed with 73.85% degradation, and 4.63 × 10^-6 mol.min^-1 initial rate of reaction. This significant increase in photocatalytic activity of Bi⁰/TiO₂ under sunlight could be accredited to increased light harvesting and enhanced efficiency in charge carrier separation, both of which were made possible by bismuth-induced surface plasmon resonance.

Since the molecular mechanisms behind adaptation and the bacterial stress response toward antimicrobial photodynamic therapy (aPDT) are not entirely clear yet, the aim of the present study was to investigate the transcriptomic stress response in Escherichia coli after sublethal treatment with aPDT using RNA sequencing (RNA-Seq). Planktonic cultures of stationary phase E. coli were treated with aPDT using a sublethal dose of the photosensitizer SAPYR. After treatment, RNA was extracted, and RNA-Seq was performed on the Illumina NextSeq 500. Differentially expressed genes were analyzed and validated by qRT-PCR. Furthermore, expression of specific stress response proteins was investigated using Western blot analysis.The analysis of the differential gene expression following pathway enrichment analysis revealed a considerable number of genes and pathways significantly up- or down-regulated in E. coli after sublethal treatment with aPDT. Expression of 1018 genes was up-regulated and of 648 genes was down-regulated after sublethal treatment with aPDT as compared to irradiated controls. Analysis of differentially expressed genes and significantly de-regulated pathways showed regulation of genes involved in oxidative stress response and bacterial membrane damage. In conclusion, the results show a transcriptomic stress response in E. coli upon exposure to aPDT using SAPYR and give an insight into potential molecular mechanisms that may result in development of adaptation.

Blue light exposure of the ocular apparatus is currently rising. This has motivated a growing concern about potential deleterious effects on different eye structures. To address this, ARPE-19 cells were used as a model of the retinal pigment epithelium and subjected to cumulative expositions of blue light. The most relevant cellular events previously associated with blue-light-induced damage were assessed, including alterations in cell morphology, viability, cell proliferation, oxidative stress, inflammation, and the induction of DNA repair cellular mechanisms. Consistent with previous reports, our results provide evidence of cellular alterations resulting from repeated exposure to blue light irradiation. In this context, we explored the potential protective properties of the vegetal extract from Polypodium leucotomos, Fernblock® (FB), using the widely known treatment with lutein as a reference for comparison. The only changes observed as a result of the sole treatment with either FB or lutein were a slight but significant increase in γH2AX⁺ cells and the raise in the nuclear levels of NRF2. Overall, our findings indicate that the treatment with FB (similarly to lutein) prior to blue light irradiation can alleviate blue-light-induced deleterious effects in RPE cells, specifically preventing the drop in both cell viability and percentage of EdU⁺ cells, as well as the increase in ROS generation, percentage of γH2AX⁺ nuclei (more efficiently with FB), and TNF-α secretion (the latter restored only by FB to similar levels to those of the control). On the contrary, the induction in the P21 expression upon blue light irradiation was not prevented neither by FB nor by lutein. Notably, the nuclear translocation of NRF2 induced by blue light was similar to that observed in cells pre-treated with FB, while lutein pre-treatment resulted in nuclear NRF2 levels similar to control cells, suggesting key differences in the mechanism of cellular protection exerted by these compounds. These results may represent the foundation ground for the use of FB as a new ingredient in the development of alternative prophylactic strategies for blue-light-associated diseases, a currently rising medical interest.