Dietary Antioxidant Capacity and Skin Photoaging: A 15-Year Longitudinal Study

Natural autophagy activators: A promising strategy for combating photoaging

BACKGROUND

Photodamage to the skin stands out as one of the most widespread epidermal challenges globally. Prolonged exposure to sunlight containing ultraviolet radiation (UVR) instigates stress, thereby compromising the skin's functionality and culminating in photoaging. Recent investigations have shed light on the importance of autophagy in shielding the skin from photodamage. Despite the acknowledgment of numerous phytochemicals possessing photoprotective attributes, their potential to induce autophagy remains relatively unexplored.

PURPOSE

Diminished autophagy activity in photoaged skin underscores the potential benefits of restoring autophagy through natural compounds to enhance photoprotection. Consequently, this study aims to highlight the role of natural compounds in safeguarding against photodamage and to assess their potential to induce autophagy via an in-silico approach.

METHODS

A thorough search of the literature was done using several databases, including PUBMED, Science Direct, and Google Scholar, to gather relevant studies. Several keywords such as Phytochemical, Photoprotection, mTOR, Ultraviolet Radiation, Reactive oxygen species, Photoaging, and Autophagy were utilized to ensure thorough exploration. To assess the autophagy potential of phytochemicals through virtual screening, computational methodologies such as molecular docking were employed, utilizing tools like AutoDock Vina. Receptor preparation for docking was facilitated using MGLTools.

RESULTS

The initiation of structural and functional deterioration in the skin due to ultraviolet radiation (UVR) or sunlight-induced reactive oxygen species/reactive nitrogen species (ROS/RNS) involves the modulation of various pathways. Natural compounds like phenolics, flavonoids, flavones, and anthocyanins, among others, possess chromophores capable of absorbing light, thereby offering photoprotection by modulating these pathways. In our molecular docking study, these phytochemicals have shown binding affinity with mTOR, a negative regulator of autophagy, indicating their potential as autophagy modulators.

CONCLUSION

This integrated review underscores the photoprotective characteristics of natural compounds, while the in-silico analysis reveals their potential to modulate autophagy, which could significantly contribute to their anti-photoaging properties. The findings of this study hold promise for the advancement of cosmeceuticals and therapeutics containing natural compounds aimed at addressing photoaging and various skin-related diseases. By leveraging their dual benefits of photoprotection and autophagy modulation, these natural compounds offer a multifaceted approach to combatting skin aging and related conditions.

Omnivore and vegetarians show similar body composition and skin physiology across body regions-A comparative analysis

BACKGROUND

Skin physiology seems to be influenced by dietary choices and body composition, although links between these factors remain poorly characterised. In the present manuscript, we elaborate on the potential relationships among food groups, body composition and skin physiology in omnivores and vegetarians.

MATERIAL AND METHODS

This cross-sectional observational study involved 181 participants, 129 omnivores and 52 vegetarians. The main functions of the skin measured in our laboratory were transepidermal water loss, deep and superficial epidermal hydration, skin elasticity, and carotenoid content. Skin variables obtained from different body regions were made comparable by a new Proportional Skin Index calculated to respect their relative representativity.

RESULTS

No statistical differences were found when comparing both groups' body composition and skin variables from different body regions, with the exception of the skin carotenoid content significantly higher in the vegetarian group (p < 0.001).

CONCLUSION

Although dietary patterns significantly differed between groups, with vegetarians consuming fewer animal-derived products and more plant-based foods, multiple linear regression analysis revealed no differences or association between the dietary pattern and the skin physiology. These findings highlight the need for further research to elucidate the specific impact of diet and food groups and body composition on skin physiology.

Comparison of five retinoids for anti-photoaging therapy: Evaluation of anti-inflammatory and anti-oxidative activities in vitro and therapeutic efficacy in vivo

Over the past decades, increasing evidences have demonstrated that five retinoids, including retinol (ROL), retinol acetate (RAc), retinol propionate (RP), retinol palmitate (RPalm), and hydroxypinacolone retinoate (HPR), can be potential therapeutic agents for skin photoaging. However, therapeutic efficacies and biosafety have never been compared to these compounds. This study aimed to determine the optimal retinoid type(s) for anti-photoaging therapy both in vitro and in vivo. Our data demonstrated that four retinoids (RPalm, RP, HPR and ROL) but not RAc were effective for anti-photoaging treatment at 5 μg/mL in vitro, with action mechanisms associated with antioxidative, anti-inflammatory and anti-skin ECM degradation activities. Notably, both RPalm and RP appeared superior to HPR and ROL for those activities. Importantly, both RPalm and RP were shown to be optimal for anti-photoaging therapy when topically applied at 5 mg/kg in a UVB-induced mice model of photoaging, which is consistent with their high anti-photoaging activities in vitro. Additionally, topical application of these five retinoids showed satisfactory biosafety without causing significant apoptosis in animal organs, although RP application led to a slight decline in animal body weights. Collectively, these data have laid a good foundation for the next development of the clinical application of these retinoids for skin healthcare.

Antioxidants in Photoaging: From Molecular Insights to Clinical Applications

Photoaging (PA) is considered a silent disease affecting millions of people globally and is defined as skin damage due to prolonged exposure to ultraviolet radiation (UVR) from the sun. Physiologically, the skin is in a state of renewal and synthesis of components of the extracellular matrix (ECM). However, exposure to UVR affects the production of the ECM, and the functioning and response of skin cells to UVR begins to change, thus expressing clinical and phenotypic characteristics of PA. The primary mechanisms involved in PA are direct damage to the DNA of skin cells, increases in oxidative stress, the activation of cell signaling pathways responsible for the loss of skin integrity, and cytotoxicity. The medical and scientific community has been researching new therapeutic tools that counteract PA, considering that the damage caused by UVR exceeds the antioxidant defense mechanisms of the skin. Thus, in recent years, certain nutraceuticals and phytochemicals have been found to exhibit potential antioxidant and photoprotective effects. Therefore, the main objective of this review is to elucidate the molecular bases of PA and the latest pharmaceutical industry findings on antioxidant treatment against the progression of PA.

Screening of novel bovine-elastin-derived peptides with elastase inhibition and photoprotective potential: a combined in silico and in vitro study

BACKGROUND

The demand for food-based anti-photoaging products is surging because of the rising recognition of health and beauty, as well as enhanced comprehension of the detrimental impact of ultraviolet (UV) radiation. This study aimed to investigate the potential of bioactive peptides derived from bovine elastin, specifically focusing on identifying novel elastase inhibitory peptides and assessing their photoprotective properties using bioinformatics techniques.

RESULTS

A total of 48 bioactive peptides were screened in bovine elastin hydrolysate (EH) utilizing Peptide Ranker analysis. Three novel elastase inhibitory peptides, GAGQPFPI, FFPGAG and FPGIG (in descending order of activity), exhibited potent inhibitory effects on elastase in vitro, surpassing the inhibitory effect of EH by a factor of 1-2 and reaching significantly lower concentrations (8-15 times lower) than EH. The cumulative inhibitory effect of GAGQPFPI, FFPGAG, and FPGIG reached 91.5%. Further analysis revealed that FFPGAG and FPGIG exhibited mixed inhibition, whereas GAGQPFPI displayed non-competitive inhibition. Molecular simulations showed that these peptides interacted effectively with the elastase active site through hydrogen bonding and hydrophobic interactions. Furthermore, GAGQPFPI, FFPGAG, and FPGIG demonstrated high stability in gastrointestinal digestion, demonstrated transcellular permeability across Caco-2 cell monolayers, and exhibited remarkable photoprotective properties against UVB-irradiated HaCaT cells.

CONCLUSION

GAGQPFPI showed the most promising potential as a functional food with photoprotective effects against UVB damage and inhibitory properties against elastase. © 2023 Society of Chemical Industry.

Catechol chitosan coated dual-loaded liposomes based on oxidation and saccharification mechanisms for enhancing skin anti-aging effects

Skin aging has become a major urgent problem to be solved. Evidence reveals that oxidation and glycosylation are two dominant inducements of aging. Resveratrol (RES) with outstanding anti-oxidant effect and carnosine (CAR) with superb anti-glycation property were selected as two model drugs to evaluate the feasibility of their synergistic anti-aging effect. RES and CAR at the most desired mass ratio, supplying the most superior synergistic anti-aging effects were further encapsulated in liposomes (LP), which were separately coated with chitosan (CS) and catechol chitosan (Cat-CS) to increase the transdermal penetration. Their anti-aging efficacy was explored in human skin fibroblast (HSF) and human immortalized keratinocytes (HaCaT) cells, as well as the back skin of guinea pigs. Herein, RES and CAR at the mass ratio of 2:1 exhibited the most ideal synergistic anti-aging effect. The constructed liposomes have been shown to possess excellent fundamental properties and sustained-release properties. The aging-related indicator levels in the two cells and guinea pigs were obviously improved for the RES + CAR@Cat-CS-LP group. Additionally, skin appearance, tissue morphology, and collagen content were visibly improved, indicating its perfect anti-aging effect. In conclusion, RES + CAR@Cat-CS-LP is expected to be exploited as a potential anti-aging drug delivery system.

Exploring the potential of the nano-based sunscreens and antioxidants for preventing and treating skin photoaging

Excessive exposure to sunlight, especially UV irradiation, causes skin photodamage. Sunscreens, such as TiO2 and ZnO, can potentially prevent UV via scattering, reflection, and absorption. Topical antioxidants are another means of skin photoprotection. Developing nanoparticles for sunscreens and antioxidants is recommended for photoaging prevention and treatment as it can improve uncomfortable skin appearance, stability, penetration, and safety. This study reviewed the effects of nano-sized sunscreens and antioxidants on skin photoprevention by examining published studies and articles from PubMed, Scopus, and Google Scholar, which explore the topics of skin photoaging, skin senescence, UV radiation, keratinocyte, dermal fibroblast, sunscreen, antioxidant, and nanoparticle. The researchers of this study also summarized the nano-based UV filters and therapeutics for mitigating skin photoaging. The skin photodamage mechanisms are presented, followed by the introduction of current skin photoaging treatment. The different nanoparticle types used for topical delivery were also explored in this study. This is followed by the mechanisms of how nanoparticles improve the UV filters and antioxidant performance. Lastly, recent investigations were reviewed on nanoparticulate sunscreens and antioxidants in skin photoaging management. Sunscreens and antioxidants for topical application have different concepts. Topical antioxidants are ideal for permeating into the skin to exhibit free radical scavenging activity, while UV filters are prescribed to remain on the skin surface without absorption to exert the UV-blocking effect without causing toxicity. The nanoparticle design strategy for meeting the different needs of sunscreens and antioxidants is also explored in this study. Although the benefits of using nanoparticles for alleviating photodamage are well-established, more animal-based and clinical studies are necessary.

Melatonin Exerts Prominent, Differential Epidermal and Dermal Anti-Aging Properties in Aged Human Eyelid Skin Ex Vivo

Human skin aging is associated with functional deterioration on multiple levels of physiology, necessitating the development of effective skin senotherapeutics. The well-tolerated neurohormone melatonin unfolds anti-aging properties in vitro and in vivo, but it remains unclear whether these effects translate to aged human skin ex vivo. We tested this in organ-cultured, full-thickness human eyelid skin (5-6 donors; 49-77 years) by adding melatonin to the culture medium, followed by the assessment of core aging biomarkers via quantitative immunohistochemistry. Over 6 days, 200 µM melatonin significantly downregulated the intraepidermal activity of the aging-promoting mTORC1 pathway (as visualized by reduced S6 phosphorylation) and MMP-1 protein expression in the epidermis compared to vehicle-treated control skin. Conversely, the transmembrane collagen 17A1, a key stem cell niche matrix molecule that declines with aging, and mitochondrial markers (e.g., TFAM, MTCO-1, and VDAC/porin) were significantly upregulated. Interestingly, 100 µM melatonin also significantly increased the epidermal expression of VEGF-A protein, which is required and sufficient for inducing human skin rejuvenation. In aged human dermis, melatonin significantly increased fibrillin-1 protein expression and improved fibrillin structural organization, indicating an improved collagen and elastic fiber network. In contrast, other key aging biomarkers (SIRT-1, lamin-B1, p16INK4, collagen I) remained unchanged. This ex vivo study provides proof of principle that melatonin indeed exerts long-suspected but never conclusively demonstrated and surprisingly differential anti-aging effects in aged human epidermis and dermis.

Smart nanostructures for targeted oxygen-producing photodynamic therapy of skin photoaging and potential mechanism

Background: Photodynamic therapy increases collagen and decreases solar fibrosis in photoaged skin; however, the efficacy of photodynamic therapy is limited in tissues with a hypoxic microenvironment. Methods: A novel autogenous oxygen-targeted nanoparticle, named MCZT, was synthesized based on the zeolitic imidazole framework material ZIF-8, methyl aminolevulinate, catalase and an anti-TRPV1 monoclonal antibody, and its effects on skin photoaging were investigated. Results: MCZT was successfully synthesized and showed uniform particle size, good dispersion, and excellent biocompatibility and safety. Moreover, MCZT effectively alleviated UV-induced inflammation, cellular senescence and apoptosis in HFF-1 cells. In in vivo models, MCZT ameliorated UV-evoked erythema and wrinkling, inflammation and oxidative stress, as well as the loss of collagen fibers and water, in the skin of mice. Conclusion: These findings suggest that MCZT holds promising potential for the treatment of skin photoaging.

On the Potential Role of the Antioxidant Couple Vitamin E/Selenium Taken by the Oral Route in Skin and Hair Health

The relationship between oxidative stress and skin aging/disorders is well established. Many topical and oral antioxidants (vitamins C and E, carotenoids, polyphenols) have been proposed to protect the skin against the deleterious effect induced by increased reactive oxygen species production, particularly in the context of sun exposure. In this review, we focused on the combination of vitamin E and selenium taken in supplements since both molecules act in synergy either by non-enzymatic and enzymatic pathways to eliminate skin lipids peroxides, which are strongly implicated in skin and hair disorders.

Urolithin A protects human dermal fibroblasts from UVA-induced photoaging through NRF2 activation and mitophagy

Photoaging, caused by exposure to sunlight and especially UVA, has been identified as one of the culprits for age-related skin deterioration. Here, we initially demonstrated that urolithin A (UroA), a metabolite derived from intestine microflora, possessed sufficient photoprotective capacity and attenuated UVA-induced senescent phenotypes in human fibroblasts, such as growth inhibition, senescence-associated β-galactosidase activity, breakdown of extracellular matrix, synthesis of senescence-associated secretory phenotypes and cell cycle arrest. Furthermore, UroA lessened the accumulation of intracellular reactive oxygen species, which promoted the phosphorylation and afterwards nuclear translocation of NRF2, subsequently driving the activation of downstream antioxidative enzymes. In parallel, we proved that UroA restored mitochondrial function by induction of mitophagy, which was regulated by the SIRT3-FOXO3-PINK1-PARKIN network. Taken together, our results showed that UroA protected dermal fibroblast from UVA damage through NRF2/ARE activation and mitophagy process, thus supporting UroA as a potential therapeutic agent for photoaging.

Mechanism of Ba Zhen Tang Delaying Skin Photoaging Based on Network Pharmacology and Molecular Docking

Purpose

To study the efficacy of Ba Zhen Tang in delaying skin photoaging and its potential mechanism based on network pharmacology and molecular docking.

Methods

First, we screened the active components and targets of Ba Zhen Tang by Traditional Chinese Medicine Database and Analysis Platform (TCMSP) and The Universal Protein Resource (UniProt). The target genes of skin photoaging were obtained from GeneCards and GeneMap database. Then, we analyzed the protein–protein interaction (PPI) by STRING database. The network map was constructed by Cytoscape. Finally, we performed Gene Ontology (GO) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis by Metascape database. The molecular docking via Autodock Vina and Pymol. Furthermore, skin photoaging cellular models were established, and the effects of Ba Zhen Tang on ameliorating skin photoaging were investigated.

Results

A total of 160 active ingredients in Ba Zhen Tang and 60 targets of Ba Zhen Tang for delaying skin photoaging were identified. By GO enrichment analysis, 1153 biological process entries, 45 cellular component entries and 89 molecular functional entries were obtained. A total of 155 signal pathways were obtained by KEGG analysis. Ba Zhen Tang is related to MAPK signaling pathway, TNF signaling pathway and AGE-RAGE signaling pathway in diabetic complications, etc., which directly affect the key nodes of photoaging. The molecular docking results showed that there was a certain affinity between the main compounds (kaempferol, quercetin, β-sitosterol, naringenin) and core target genes (PTGS2, CASP3, MAPK1, MAPK3, TP53). Ba Zhen Tang-treated mouse serum inhibited the senescence and p16^INK4a expression of human immortalized keratinocyte (HaCaT) cells irradiated by ultraviolet-B (UVB).

Conclusion

Our study elucidated the potential pharmacological mechanism of Ba Zhen Tang in the treatment of photoaging through multiple targets and pathways. The therapeutic effects of Ba Zhen Tang on skin photoaging were validated in cellular models.

Reframing aging in dermatology: The role of the dermatologist in healthy aging

Dermatology is often tasked with balancing the clinical appearance of aging skin with the reality of what healthy aging means. In this article, we review some of the core principles of healthy aging and explore common misconceptions, both from patients and physicians, regarding aging. Recognition of the basics of healthy aging and awareness of these aging myths can empower providers to advise patients accurately and productively regarding their aging goals.

Attenuation of UV-induced skin photoaging in rats by walnut protein hydrolysates is linked to the modulation of MAPK/AP-1 and TGF-β/Smad signaling pathways

There is growing evidence that prevention of skin photoaging by oral administration of food-derived proteins hydrolysates is intricately linked to its alleviation against oxidative stress through modulation of the signaling pathway. Previously, walnut protein hydrolysates (WPHs) were prepared by enzymatic hydrolysis by our group and exhibited excellent anti-photoaging effect through regulation of extracellular matrix metabolism and the NF-κB signaling pathway. However, its response to oxidative stress and cascade mechanism remain unknown. In the present study, Sprague-Dawley rats were exposed periodically to UV irradiation and orally administered with WPHs to further examine the effects of WPHs on the redox state, MAPK/AP-1 and TGF-β/Smad signaling pathways, type I procollagen synthesis, and histopathological impairments in photoaging skin. Intervention with WPHs for 18 weeks significantly alleviated the photoaging morphology, enhanced the antioxidant components, and downregulated the phosphorylation levels of extracellular signal-regulated kinase (ERK) and C-Jun N-terminal kinase (JNK and p38 proteins) in photoaging tissues, while significant alterations on the gene expression levels of ERK, JNK and p38 were not observed. Meanwhile, WPHs significantly activated the TGF-β/Smad signaling pathway and type I procollagen production. Furthermore, histopathological analysis illustrated that WPHs predominately attenuated epidermal hyperplasia, reduced inflammatory filtration, and promoted the deposition of collagen fibers in photoaging skin. Altogether, the underlying mechanism of WPHs attenuating skin photoaging might lie in the synergistic modulation by increasing the antioxidant capacity, modulating the MAPK/AP-1/MMP-1 and TGF-β/Smad signaling pathways, stimulating the synthesis of type I procollagen, and restoring the impaired architecture structure. Our findings suggest that WPHs are promising agents for preventing skin photoaging.

Core-Shell Iron-Nickel Hexacyanoferrate Nanoparticle-Based Sensors for Hydrogen Peroxide Scavenging Activity

To access hydrogen peroxide scavenging activity, we propose a sensor based on core-shell iron-nickel hexacyanoferrate nanoparticles. On the one hand, the sensor preparation procedure is simple: syringing the nanoparticles suspension with subsequent annealing. On the other hand, the sensor demonstrates a stable response to 0.05 mM of H2O2 within one hour, which is sufficient for the evaluation of antioxidant activity (AO). The analytical performance characteristics of the sensor (0.5–0.6 A M−1 cm−2, detection limit 1.5 × 10−7 M and linear dynamic range 1–1000 µM) are leads to advantages over the sensor based on Prussian Blue films. The pseudo-first-order constant of hydrogen peroxide scavenging was chosen as a characteristic value of AO. The latter for trolox (standard antioxidant) was found to be linearly dependent on its concentration, thus allowing for the evaluation of antioxidant activity in trolox equivalents. The approach was validated by analyzing real beverage samples. Both the simplicity of sensor preparation and an expressiveness of analytical procedure would obviously provide a wide use of the proposed approach in the evaluation of antioxidant activity.

UVA Exposure Combined with Glycation of the Dermis Are Two Catalysts for Skin Aging and Promotes a Favorable Environment to the Appearance of Elastosis

Skin aging is the result of superimposed intrinsic (individual) and extrinsic (e.g., UV exposure or nutrition) aging. Previous works have reported a relationship between UV irradiation and glycation in the aging process, leading, for example, to modified radical species production and the appearance of AGEs (advanced glycosylation end products) in increasing quantities, particularly glycoxidation products like pentosidine. In addition, the colocalization of AGEs and elastosis has also been observed. We first investigated the combination of the glycation reaction and UVA effects on a reconstructed skin model to explain their cumulative biological effect. We found that UVA exposure combined with glycation had the ability to intensify the response for specific markers: for example, MMP1 or MMP3 mRNA, proteases involved in extracellular matrix degradation, or proinflammatory cytokine, IL1α, protein expression. Moreover, the association of glycation and UVA irradiation is believed to promote an environment that favors the onset of an elastotic-like phenomenon: mRNA coding for elastin, elastase, and tropoelastin expression is increased. Secondly, because the damaging effects of UV radiation in vivo might be more detrimental in aged skin than in young skin due to increased accumulation of pentosidine and the exacerbation of alterations related to chronological aging, we studied the biological effect of soluble pentosidine in fibroblasts grown in monolayers. We found that pentosidine induced upregulation of CXCL2, IL8, and MMP12 mRNA expression (inflammatory and elastotic markers, respectively). Tropoelastin protein expression (elastin precursor) was also increased. In conclusion, fibroblasts in monolayers cultured with soluble pentosidine and tridimensional in vitro skin constructs exposed to the combination of AGEs and UVA promote an inflammatory state and an alteration of the dermal compartment in relation to an elastosis-like environment.

Study of Carnosine's effect on nude mice skin to prevent UV-A damage

The skin is an important barrier against external attacks from bacteria, radicals, or radiations. UV-A radiations cause significant impairment of this barrier, inducing inflammation, oxidative stress, and wrinkle formation, thereby promoting photoaging. Previous studies reported that carnosine, a potent antioxidant, and carbonyl scavenger agent, may prevent photoaging features in the skin of hairless mice exposed to UV-A radiations. In the present study, we used a quantitative proteomic approach to analyze the changes evoked by carnosine in the skin proteome of hairless mice exposed to UV-A. This approach allowed to quantify more than 2480 proteins, among them consistent differences were observed for 89 proteins in UV-A exposed vs control unexposed skins, and 252 proteins in UV-A-exposed skin preventively treated by carnosine (UVAC) vs UV-A. Several functional pathways were altered in the skins of UV-A exposed hairless mice, including the integrin-linked kinase, calcium signaling, fibrogenesis, cell migration and filament formation. An impairment of mitochondrial function and metabolism was observed, with an up-regulation of cytochrome C oxidase 6B1 and NADH: ubiquinone oxidoreductase S8. Skins pre-treated by carnosine were prevented from UV-A induced proteome alterations. In conclusion, our study emphasizes the potency of a proteomic approach to identify the consequences of UV radiations in the skins, and points out the capacity of carnosine to prevent the alterations of skin proteome evoked by UV-A.