The role and safety of UVA and UVB in UV-induced skin erythema

Utilizing Extracellular Vesicles from Phaeodactylum tricornutum as a Novel Approach for Protecting the Skin from Oxidative Damage

Oxidative stress is a principal factor contributing to skin damage induced by deleterious stimuli, including ultraviolet (UV) radiation. Microalgae-derived extracellular vesicles (EVs), particularly those from Phaeodactylum tricornutum (PTEV), are gaining recognition as a potential therapeutic avenue for restoring skin homeostasis, owing to their scalable production and multifaceted biological activities. This study evaluates the therapeutic effects of PTEV on oxidative damage in H2O2-stimulated HaCaT cells and UV-exposed KM mouse models, based on the extraction and characterization of PTEV. Subsequently, the oxidative stress injury model of HaCaT cells induced by H2O2 and the acute photodamage model of KM mice skin induced by UV were established. The results show that HaCaT cells exhibit a time-dependent uptake of PTEV, confirming that PTEV is nontoxic and has the potential for intercellular cross-boundary regulation. Treatment with PTEV can enhance the vitality of H2O2-stimulated HaCaT cells, reduce intracellular ROS levels, and increase antioxidant enzyme activity in the cells. Further evaluation revealed that PTEV can inhibit UV-induced thickening of the epidermis and degradation of collagen fibers in mice by suppressing the overexpression of matrix metalloproteinase (MMP-3) induced by UV. It enhances the expression of type I collagen (COL1A1) and increases the activity of antioxidant enzymes, as well as the overall antioxidant capacity of tissues. Additionally, PTEV reduces the increase in malondialdehyde levels and lowers the expression levels of inflammatory factors TNF-α and IL-6, thereby protecting the skin barrier and function in mice with acute photodamage. Continuous production of PTEV offers promising applications in therapeutic strategies.

Protective Effect of Red Light-Emitting Diode against UV-B Radiation-Induced Skin Damage in SKH:HR-2 Hairless Mice

In this in vivo study on hairless mice, we examined the effects of light-emitting diode (LED) treatment applied prior to ultraviolet B (UVB) irradiation. We found that pre-treating with LED improved skin morphological and histopathological conditions compared to those only exposed to UVB irradiation. In our study, histological evaluation of collagen and elastic fibers after LED treatment prior to UVB irradiation showed that this pretreatment significantly enhanced the quality of fibers, which were otherwise poor in density and irregularly arranged due to UV exposure alone. This suggests that LED treatment promotes collagen and elastin production, leading to improved skin properties. Additionally, we observed an increase in Claudin-1 expression and a reduction in nuclear factor-erythroid 2-related factor 2 (Nrf-2) and heme-oxygenase 1 (HO-1) expression within the LED-treated skin tissues, suggesting that LED therapy may modulate key skin barrier proteins and oxidative stress markers. These results demonstrate that pretreatment with LED light can enhance the skin's resistance to UVB-induced damage by modulating gene regulation associated with skin protection. Further investigations are needed to explore the broader biological effects of LED therapy on other tissues such as blood vessels. This study underscores the potential of LED therapy as a non-invasive approach to enhance skin repair and counteract the effects of photoaging caused by UV exposure.

Conjugated Network Supporting Highly Surface-Exposed Ru Site-Based Artificial Antioxidase for Efficiently Modulating Microenvironment and Alleviating Solar Dermatitis

Solar dermatitis, a form of acute radiation burn that affects the skin, results from overexposure to ultraviolet B (UVB) radiation in strong sunlight. Cell damage caused by the accumulation of reactive oxygen species (ROS) produced by UVB radiation plays an important role in UVB-induced inflammation in the skin. Here, for efficiently scavenging excess ROS, modulating the microenvironment, and alleviating solar dermatitis, a π-conjugated network polyphthalocyanine supporting a highly surface-exposed Ru active site-based artificial antioxidase (HSE-PPcRu) is designed and fabricated with excellent ROS-scavenging, antioxidant, and anti-inflammatory capabilities. In photodamaged human keratinocyte cells, HSE-PPcRu could modulate mitogen-activated protein kinase (MAPK) and nuclear factor kappa-B signaling pathways, prevent DNA damage, suppress apoptosis, inhibit pro-inflammatory cytokine secretion, and alleviate cell damage. In vivo animal experiments reveal the higher antioxidant and anti-inflammatory efficacies of HSE-PPcRu by reversing the activation of p38 and c-Jun N-terminal kinase, inhibiting expression of cyclooxygenase-2, interleukin-6, interleukin-8, and tumor necrosis factor-α. This work not only provides an idea for alleviating solar dermatitis via catalytically scavenging ROS and modulating the microenvironment but also offers a strategy to design an intelligent conjugated network-based artificial antioxidase with a highly surface-exposed active site.

Evaluating β-cryptoxanthin antioxidant properties against ROS-induced macromolecular damages and determining its photo-stability and in-vitro SPF

Natural antioxidants have become vital to minimize macromolecular damage caused by Reactive Oxygen Species (ROS). This study investigated the antioxidant property of β-cryptoxanthin (β-CRX) extracted from Kocuria marina DAGII and its protective effect against macromolecular damages by generating ROS via two models: UV radiation and the Fenton reaction. β-cryptoxanthin exhibited the highest scavenging activity towards hydrogen peroxide radicals with an IC50 value of 38.30 ± 1.13 μg/ml, favoring the hydrogen atom transfer mechanism. The total antioxidant capacity value of 872.0101 ± 1.84 μg BHT/mg β-CRX indicated the cumulative ROS scavenging ability of β-cryptoxanthin. β-cryptoxanthin could protect against ROS-induced lipid peroxidation, protein oxidation, and DNA damage. The highest lipid peroxidation and protein oxidation inhibition values of β-cryptoxanthin against ROS were 99.371 ± 0.51% and 78.19 ± 0.15%, respectively. β-cryptoxanthin also showed a protective effect in maintaining DNA intactness against ROS-mediated DNA damage. Allium cepa test showed the non-genotoxic nature of β-cryptoxanthin and its protective effect against ROS genotoxic effects. A photo-stability study of β-cryptoxanthin toward UVA and UVB radiation showed a rapid bleaching result of UVB obeying pseudo-zero order kinetics with an average R2 value of 0.9897 and a higher k value (-6.3 × 10-11 ± 0.2 M/s) than UVA (k value -3.1 × 10-11 ± 0.17 M/s), signifying that UVB is more potent toward photo-degradation. The good SPF value of 23.1737 ± 0.15 showed the UV protection capability of β-cryptoxanthin. Thus, the present study suggests that β-cryptoxanthin could be a valuable antioxidant to protect against ROS-induced various macromolecular damages and act as a good UV protectant.