Photochemistry and Photobiology最新文献

We aimed to compare the anticandidal effect among different preirradiation times, measure singlet oxygen levels, and investigate the correlation between candidal reduction and singlet oxygen formation in erythrosine + KI photodynamic therapy. Candida albicans (ATCC10231) biofilms were treated with 100/200 μM erythrosine + 100 mM KI for 1, 3, or 5 min before light-emitting diode (520 ± 10 nm, 250 mW/cm², 20 J/cm²) irradiation. Phosphate-buffered saline, and nystatin were negative and positive controls, respectively. Candidal cells were quantified using a drop plate assay. Singlet oxygen was measured using a 9,10-dimethylanthacene probe at 375/436 nm emission/excitation wavelengths. Median candidal counts and singlet oxygen formation were compared using Kruskal-Wallis with Dunn test. A p-value <0.05 was considered significant. Spearman's correlation was used to correlate candidal reduction and singlet oxygen formation. All preirradiation times for 200 μM erythrosine + 100 mM KI decreased candidal cells by 7.59 (IQR = 0.33) log₁₀CFU/mL. At a 1-min preirradiation, this group significantly generated higher singlet oxygen than the positive control (p < 0.001). Singlet oxygen levels correlated mildly with candidal reduction in the lower erythrosine group but not the higher group, likely due to singlet oxygen saturation. A 1-min preirradiation with 200 μM erythrosine + 100 mM KI generates singlet oxygen to inhibit C. albicans biofilms and shows potential for clinical oral candidiasis treatment.

This study investigated the synergistic effects of resveratrol and antimicrobial photodynamic therapy (aPDT) on peri-implant bone repair in a type 2 diabetes model. Forty-eight rats were allocated into four groups: normoglycemic, normoglycemic + resveratrol, type 2 diabetes (T2D), and T2D + resveratrol. Diabetes was induced using a cafeteria diet and streptozotocin (35 mg/kg). Resveratrol (100 mg/kg) was administered systemically beginning 7 days later. After 14 days, maxillary molars were extracted, and surgical drilling was performed. Half of the animals in each group received aPDT (methylene blue and 660 nm diode laser) before immediate implant placement. Animals were euthanized 28 days post-surgery for biomechanical, RT-PCR, and confocal microscopy analyses. Resveratrol improved glycemic control and body weight. In T2D animals, aPDT significantly enhanced implant removal torque. Gene expression analyses revealed downregulation of bone resorption markers and upregulation of bone mineralization genes in T2D and T2D + resveratrol groups treated with aPDT. Confocal microscopy demonstrated increased mineral apposition rates in animals treated with resveratrol and/or aPDT. These findings suggest that the combination of systemic resveratrol and local aPDT enhances peri-implant bone healing under diabetic conditions, highlighting a potential therapeutic approach to improve implant osseointegration in compromised metabolic states.

Exposure to UVR is well understood to accelerate symptoms of photoaging such as wrinkling and loss of skin elasticity. Sunscreen formulations containing titanium dioxide (TiO₂) and zinc oxide (ZnO) UV filters can therefore be used as an effective photoprotective measure to prevent the induction of signaling pathways in skin that contribute to photoaging. The aim of this study is to provide a broad investigation on the photoprotective impact of TiO₂, ZnO, and inorganic-only (ZnO + TiO₂) sunscreen formulations in human dermal fibroblasts at a gene and protein level. The study focused on genes involved in UV-only and complete solar light-induced MMP production, prostanoid biosynthesis for inflammation, and cell cycle arrest, as previously identified through RNA-seq analysis. Three inorganic formulations were prepared at commercially applicable active levels and varying particle sizes: (1) F(TiO₂ ^179nm), (2) F(ZnO^57nm), and (3) an inorganic-only (ZnO + TiO₂) formulation F(ZnO^57nm/TiO₂ ^47nm). The three formulations significantly alleviated the irradiation-induced expression of MMP1, MMP3, PTGS1, PTGES, MDM2, CDKN1A, and CCNE2, with the latter most alleviated by up to 77% (p ≤ 0.05). The inorganic-only (ZnO + TiO₂) formulation, containing both inorganic UV filters, exhibited the greatest mean or maximum alleviation in 75% of the genes investigated. Protein analyses of MMP1, PTGES, and p21, by immunocytochemistry and Western blot, also showed positive translation of alleviation at a protein level. The study provides further academic and commercial insights on the photoprotective impact of inorganic particles in sunscreens, based on relevant signaling pathways, genes, and proteins that are induced by UV to accelerate photoaging.

Exposure to the ultraviolet (UV) spectrum of sunlight poses a threat to terrestrial species. Nearly all species possess the nucleotide excision repair (NER) machinery, which can repair the helix-distorting DNA lesions induced by UV light. However, many species also have photolyase enzymes, which use near-UV and visible wavelengths of sunlight to directly reverse major classes of UV photoproducts. In eukaryotic cells, both of these repair pathways must efficiently locate and repair UV photoproducts present in chromatin. While genome-wide damage mapping methods have been used to extensively characterize how chromatin and ongoing transcription impact NER, much less is known about how photolyase enzymes navigate these obstacles to repair UV damage. Here, we highlight a recent article from our laboratory that used genome-wide sequencing methods to characterize how yeast photolyase repairs UV damage, both in NER-proficient and -deficient cells, and prevents UV-induced mutations.

The SKH-1 mouse model is commonly used to assess the effects of ultraviolet light exposure on skin using visual and biological endpoints. Although skin bi-fold thickness is a well-established quantitative measure of edema, evidence characterizing its use to evaluate skin responses in the UVC range remains limited. This study evaluated skin bi-fold thickness measurements made using a digital caliper. Hairless SKH-1 mice were exposed using the narrow bandwidth output from a monochromator with wavelengths from 200 to 270 nm. Post-exposure thickness measurements were normalized against pre-exposure thickness measurements to determine the fold change. These findings were compared with qualitative visual assessments of changes to the skin. The results indicate that quantitative measures of increases in skin thickness are correlated with subjective visual scoring measures. The observed magnitude of the bi-fold change following UVC exposures was limited in this study because exposures were at doses close to the threshold dose for causing a visually observed change to the skin. The results support using skin bi-fold measurements for quantifying skin responses to ultraviolet light exposure.

Phototherapy approaches include photodynamic therapy (PDT), which utilizes chemically stable photocatalysts to sensitize the conversion of endogenous molecules such as oxygen (O₂) to form transient reactive species such as ¹O₂, and photopharmacology, a complementary approach that relies on molecules that undergo self-modifying photochemistry, such as bond cleavage reactions or isomerization, for the creation of biologically active products. While Ru(II) polypyridyl systems have demonstrated utility for both approaches, related organometallic systems are relatively less explored. Here, the photochemistry and photobiological responses were compared for five Ru(II) arene compounds containing photolabile monodentate azine ligands and the π-expansive bidentate ligands dipyrido[3,2-a:2',3'-c]phenazine (dppz), 4,5,9,16-tetraaza-dibenzo[a,c]naphthacene (dppn), and α-terthienyl-appended imidazo[4,5-f][1,10]phenanthroline (IP-3T). The compounds demonstrated significant light-mediated photocytotoxicity in lung cancer and melanoma cell lines, with up to 6000-fold increases in cytotoxicity upon irradiation. The arene systems were capable of partitioning between different excited state relaxation pathways, both releasing the monodentate ligand and generating ¹O₂, but with notably low yields that did not correlate with the photocytotoxicity of the systems. The organometallic compounds exhibit less mixing of the metal-associated and ligand-centered excited states than analogous polypyridyl coordination compounds, providing a structurally, photochemically, and photobiologically distinct class of compounds that can support both metal- and ligand-centered reactivity.

Light pollution from widespread artificial illumination affects photosensitive organisms, including humans. Prolonged exposure to artificial light at night (ALAN), particularly blue light, is associated with melatonin suppression and circadian disruption, both implicated in carcinogenesis. This systematic review investigated the relationship between extended ALAN exposure and malignant neoplasms, identifying associated cancer types and biological mechanisms. A search was conducted in PubMed/Medline and Scopus using PRISMA guidelines. Original studies evaluating associations between ALAN, light pollution, or blue light and cancer in humans were included. Eighteen studies demonstrated a positive link between ALAN and breast cancer, with mechanisms involving interference in the cell cycle, DNA repair, oxidative stress, and activation of oncogenic pathways. Night-shift work correlated with increased breast cancer risk, reduced melatonin levels, and hormonal dysregulation. Exogenous melatonin showed oncostatic potential, reversing epigenetic changes induced by ALAN and reducing tumor burden. Melatonin suppression may promote tumor progression through circadian gene disruption and hormonal imbalance. While findings support a consistent link between ALAN exposure and oncogenesis-especially breast and prostate cancers-methodological variability and confounding factors, such as genetic predisposition and lifestyle, limit generalization. Further studies are needed to clarify mechanisms and explore preventive strategies, including light pollution control and melatonin-based interventions.

The search for natural alternatives to synthetic sunscreens has driven interest in marine compounds with antioxidant and UV-protective properties. The present study expands our understanding of the potential of gadusol by evaluating the photochemoprotective and antioxidant effects of extracts from an underexploited marine by-product: the roes of yellowtail amberjack fish (Seriola lalandi). UVB-mediated responses were studied in vitro and in vivo using HaCaT keratinocytes and Caenorhabditis elegans worms, respectively. Additionally, several antioxidant assays were conducted to evaluate the antioxidant capacity and thermal stability over time. We also tested the docking binding of gadusol to the Nrf2-binding domain of Keap1 to better understand its potential chemoprotective role. Overall, the gadusol-containing extracts exhibited remarkable stability over time, offering effective protection against UVB radiation in both in vitro and in vivo models. This information contributes to a better characterization of the functional role of gadusol in crude extracts and its relevance for the design of innovative applications in various pharmaceutical and cosmetic industries.

Vascular smooth muscle cell (VSMC) migration is a crucial factor contributing to the development and progression of atherosclerosis and in-stent restenosis. Although far-infrared (FIR) rays have been suggested to alleviate atherosclerosis, their effects on VSMC migration remain unclear. To investigate the underlying mechanisms, we performed wound healing migration assays, cell viability assays, transfection with wild-type (WT)-Akt gene, western blot analyses, and ex vivo studies using isolated rat aortas. FIR irradiation inhibited basal and platelet-derived growth factor (PDGF)-stimulated VSMC migration without affecting cell viability, and decreased the phosphorylation of Akt at Ser473 (p-Akt-Ser⁴⁷³) in a time-dependent manner. Transfection with WT-Akt gene restored FIR-suppressed VSMC migration. Co-treatment with okadaic acid, an inhibitor of protein phosphatase 2A (PP2A), reversed the FIR irradiation reduction in p-Akt-Ser⁴⁷³. FIR irradiation for 30 min enhanced the physical interaction between Akt and PP2Ac. A series of effects was not observed with the hyperthermal stimulus (39°C). Lastly, ex vivo sprouting assays showed that FIR irradiation markedly reduced VSMC sprouting. Furthermore, FIR irradiation decreased p-Akt-Ser⁴⁷³ levels in PDGF-stimulated rat aortas. These results indicate that FIR irradiation inhibits PDGF-induced VSMC migration through PP2A-dependent suppression of p-Akt-Ser⁴⁷³, suggesting its potential use in treating arterial occlusive disorders such as atherosclerosis and in-stent restenosis.