Safety Evaluation and Anti-wrinkle Effects of Retinoids on Skin

Innovative analytical methodology for skin anti-aging compounds discovery from plant extracts: Integration of High-Performance Thin-Layer Chromatography-in vitro spectrophotometry bioassays with multivariate modeling and molecular docking

Skin aging, characterized by reduced elasticity, wrinkles, and changes in pigmentation, presents significant challenges in the cosmetics industry. Identifying compounds that can help mitigate these effects is crucial to developing effective anti-aging treatments and improving skin health. An advanced analytical approach for identifying skin anti-aging compounds within complex natural mixtures must be developed to achieve this. This study introduces a state-of-the-art methodology that combines High-Performance Thin-Layer Chromatography (HPTLC) and in vitro skin anti-aging spectrophotometry bioassays with regression multivariate analysis and molecular docking. The proposed methodology integrates spectrophotometric assays for tyrosinase inhibition (anti-pigmentation), elastase inhibition (anti-wrinkle), and radical scavenging capacity (DPPH•/ ABTS• assays) with analytical signals obtained from HPTLC chromatograms using Partial Least Squares models (PLS). The PLS models for predicting elastase inhibition and antioxidative capacity showed high accuracy with minimal errors. This study introduces an innovative approach combining HPTLC profiling and PLS regression to identify single phenolic compounds/bands responsible for anti-aging effects. In addition, identified bioactives were submitted to molecular docking studies to elucidate the enzyme inhibition mechanisms of elastase and confirm our approach. This integrated, simple, cost-effective, and high-throughput approach represents a significant advancement in the discovery of anti-aging compounds, with promising implications for future skincare and therapeutic applications.

Decoding senescence of aging single cells at the nexus of biomaterials, microfluidics, and spatial omics

Aging has profound effects on the body, most notably an increase in the prevalence of several diseases. An important aging hallmark is the presence of senescent cells that no longer multiply nor die off properly. Another characteristic is an altered immune system that fails to properly self-surveil. In this multi-player aging process, cellular senescence induces a change in the secretory phenotype, known as senescence-associated secretory phenotype (SASP), of many cells with the intention of recruiting immune cells to accelerate the clearance of these damaged senescent cells. However, the SASP phenotype results in inducing secondary senescence of nearby cells, resulting in those cells becoming senescent, and improper immune activation resulting in a state of chronic inflammation, called inflammaging, in many diseases. Senescence in immune cells, termed immunosenescence, results in further dysregulation of the immune system. An interdisciplinary approach is needed to physiologically assess aging changes of the immune system at the cellular and tissue level. Thus, the intersection of biomaterials, microfluidics, and spatial omics has great potential to collectively model aging and immunosenescence. Each of these approaches mimics unique aspects of the body undergoes as a part of aging. This perspective highlights the key aspects of how biomaterials provide non-cellular cues to cell aging, microfluidics recapitulate flow-induced and multi-cellular dynamics, and spatial omics analyses dissect the coordination of several biomarkers of senescence as a function of cell interactions in distinct tissue environments. An overview of how senescence and immune dysregulation play a role in organ aging, cancer, wound healing, Alzheimer's, and osteoporosis is included. To illuminate the societal impact of aging, an increasing trend in anti-senescence and anti-aging interventions, including pharmacological interventions, medical procedures, and lifestyle changes is discussed, including further context of senescence.

A Comprehensive Review of the Strategies to Reduce Retinoid-Induced Skin Irritation in Topical Formulation

Currently, retinoids are known for their abundant benefits to skin health, ranging from reducing signs of aging and decreasing hyperpigmentation to treating acne. However, it cannot be denied that there are various side effects associated with the use of retinoids on the skin, one of which is irritation. Several approaches can be employed to minimize the irritation caused by retinoids. This review article discusses topical retinoid formulation technology strategies to reduce skin irritation effects. The methodology used in this study is a literature review of 21 reference journals. The sources used in compiling this review are from PubMed, Scopus, ScienceDirect, and MEDLINE. The findings obtained indicate that the following methods can be used to lessen retinoid-induced irritation in topical formulations: developing drug delivery systems in the formulation, such as encapsulating retinoids, transforming retinoids into nanoparticles, forming complexes (e.g., with cyclodextrin), and binding retinoids with carriers (e.g., polymers, NLC, SLN), adding ingredients with anti-irritation activity, skin barrier improvement, and increased skin hydration to retinoid formulations (e.g., combinations of glucosamine, trehalose, ectoine, sucralfate, omega-9, and 4-t-butylcyclohexanol, addition of ethanolic bark extract of Alstonia scholaris R. Br).

Use of Retinoids in Topical Antiaging Treatments: A Focused Review of Clinical Evidence for Conventional and Nanoformulations

Nowadays, numerous skincare routines are used to rejuvenate aging skin. Retinoids are one of the most popular ingredients used in antiaging treatments. Among the representatives of retinoids, tretinoin is considered the most effective agent with proven antiaging effects on the skin and can be found in formulations approved as medicines for topical treatment of acne, facial wrinkles, and hyperpigmentation. Other retinoids present in topical medicines are used for various indications, but only tazarotene is also approved as adjunctive agent for treatment of facial fine wrinkling and pigmentation. The most commonly used retinoids such as retinol, retinaldehyde, and retinyl palmitate are contained in cosmeceuticals regulated as cosmetics. Since clinical efficacy studies are not required for marketing cosmetic formulations, there are concerns about the efficacy of these retinoids. From a formulation perspective, retinoids pose a challenge to researchers as a result of their proven instability, low penetration, and potential for skin irritation. Therefore, novel delivery systems based on nanotechnology are being developed to overcome the limitations of conventional formulations and improve user compliance. In this review, the clinical evidence for retinoids in conventional and nanoformulations for topical antiaging treatments was evaluated. In addition, an overview of the comparison clinical trials between tretinoin and other retinoids is presented. In general, there is a lack of evidence from properly designed clinical trials to support the claimed efficacy of the most commonly used retinoids as antiaging agents in cosmeceuticals. Of the other retinoids contained in medicines, tazarotene and adapalene have clinically evaluated antiaging effects compared to tretinoin and may be considered as potential alternatives for antiaging treatments. The promising potential of retinoid nanoformulations requires a more comprehensive evaluation with additional studies to support the preliminary findings.

Keratinocyte Carcinoma and Photoprevention: The Protective Actions of Repurposed Pharmaceuticals, Phytochemicals and Vitamins

Simple Summary

Keratinocyte carcinoma is the most common type of cancer. Sun exposure and ultraviolet radiation are significant contributors to the development of carcinogenesis, mediated by DNA damage, increased oxidative stress, inflammation, immunosuppression and dysregulated signal transduction. Photoprevention involves using different compounds to delay or prevent ultraviolet radiation-induced skin cancer. In this review, we look at new avenues for systemic photoprevention that are based on pharmaceuticals, plant-derived phytochemicals and vitamins. We also investigate the mechanisms underlying these strategies for preventing the onset of carcinogenesis.

Abstract

Ultraviolet radiation (UVR) arising from sun exposure represents a major risk factor in the development of keratinocyte carcinomas (KCs). UVR exposure induces dysregulated signal transduction, oxidative stress, inflammation, immunosuppression and DNA damage, all of which promote the induction and development of photocarcinogenesis. Because the incidence of KCs is increasing, better prevention strategies are necessary. In the concept of photoprevention, protective compounds are administered either topically or systemically to prevent the effects of UVR and the development of skin cancer. In this review, we provide descriptions of the pathways underlying photocarcinogenesis and an overview of selected photoprotective compounds, such as repurposed pharmaceuticals, plant-derived phytochemicals and vitamins. We discuss the protective potential of these compounds and their effects in pre-clinical and human trials, summarising the mechanisms of action involved in preventing photocarcinogenesis.

Enhancement of the Anti-Skin Wrinkling Effects of Aloe arborescens Miller Extracts Associated with Lactic Acid Fermentation

This work clearly shows that Aloe arborescens but not gels from Aloe vera, a common juice-type product of Aloe, exerted anti-skin wrinkling effects, and these effects were greatly enhanced by lactic acid fermentation with Lactobacillus plantarum. Treatment with the extract from the fermentation process (FE) at a dose of 0.5% highly activated human fibroblast cells by up to 175%, whereas 140% activation and 105% activation were observed with the extract obtained using conventional water extraction (WE) and the gel from A. vera (GE), respectively. The treatment of human fibroblasts with FE at a dose of 0.5% increased collagen production by up to 170% and inhibited MMP-1 synthesis to 48%, which is likely due to its high antioxidant activity because the WE and GE showed markedly lower effects compared with those of the FE. Interestingly, the FE exhibited a profile dominated by relatively low-molecular-weight (MW) polysaccharides: 20% of the total polysaccharides in the FE were in the MW weight range of 600 to 900, whereas 95% of the total polysaccharides in the GE were in the MW range of 200,000 to 300,000. This result suggests that the larger polysaccharide molecules in the extract might be broken down during lactic acid fermentation, and the easy penetration of the small molecules in the extract into fibroblast cells thus results in improved anti-skin wrinkling effects. This conclusion is also supported by the finding that the FE and WE, but not the GE, contained similar amounts of barbaloin, a strong antioxidant eluted from A. arborescens through the fermentation process. Therefore, this study strongly indicates that the enhanced anti-skin wrinkling effects of the FE are most likely due to synergistic effects between the barbaloin and the low-MW polysaccharides retained after the fermentation process.

Topical Proretinal Nanoparticles: Biological Activities, Epidermal Proliferation and Differentiation, Follicular Penetration, and Skin Tolerability

Proretinal nanoparticles, the retinilidene-chitosan nanoparticles, have been developed to overcome the physicochemical instability of retinal and to lessen the dose-dependent cutaneous irritation, through sustaining the release of retinoid. Compared to conventional retinal at the same concentration, proretinal nanoparticles had no cytotoxicity and could induce a spontaneously immortalized human keratinocyte line to express more cellular retinoic acid binding protein-2. Compared to rats topically applied with conventional retinal which showed clear skin irritation and inflammation, daily topical application of proretinal nanoparticles to rats for 28 consecutive days produced neither irritation nor inflammation but significantly increased epidermal proliferation, epidermal thickness, cellular retinoic acid binding protein- 2 expression, and up-regulation of various differentiation markers including keratin 5, keratin 10, keratin 14, cellular retinoic acid binding protein-2, and proliferating cell nuclear antigen. Through the use of confocal laser scanning microscopy, we observed the in vivo follicular penetration of proretinal nanoparticles with the depth of penetration independent of postapplication time. Proretinal nanoparticles provide better biological activities of retinoids on epidermis and could eliminate the side effect of retinoid dermatitis.

The Impact of Herbal Products in the Prevention, Regeneration and Delay of Skin Aging

Skin aging is a complex process induced by intrinsic and extrinsic factors and causes alterations to the structural and functional aspects of the skin. Skin aging affects patients physically and physiologically. Understanding the process of skin aging can provide new knowledge on how to attenuate or reduce skin disorder symptoms. Herbs have been used for ages to prevent and treat skin aging, yet there are growing interests by researchers in this field globally. Various strategies have been developed for improving the quality and effectivity of herbal skin care products, both for topical and oral applications. This review will provide an overview of the relationship between herbal skin care products and the skin aging process.

The Protective Effect of Violaxanthin from Nannochloropsis oceanica against Ultraviolet B-Induced Damage in Normal Human Dermal Fibroblasts

Skin photoaging, which is mainly induced by ultraviolet B (UVB) radiation, is prevented by the application of UV-protective agents. The microalga Nannochloropsis oceanica (N. oceanica) has been primarily reported as a potential biofuel; however, in this study, we investigated whether N. oceanica extracts exerted photoprotective effects against UVB-irradiated human dermal fibroblasts (HDFs) and which single component was responsible for the protective effect of the extracts. Two extracts-pigment and nonpigment-were prepared from N. oceanica biomass. WST-1 assay and expression analysis of interleukin genes showed that the pigment extracts were not significantly cytotoxic to HDFs. Further experiments revealed that treatment with the pigment extract upregulated the expression of collagen genes and significantly blocked UVB-induced damage such as decreased cell viability and increased ROS production. Next, to investigate the pigment composition of the extracts, HPLC analysis was conducted and violaxanthin was identified as the major pigment. The UVB photoprotective effect of the pigment extracts was confirmed in violaxanthin-treated HDFs. In addition, violaxanthin significantly attenuated UVB-induced G1 phase arrest, senescence-associated β-galactosidase activation, p16 and p21 upregulation, ERK phosphorylation and the downregulation of ECM molecules in HDFs. Therefore, we concluded that violaxanthin was a potential antiphotoaging agent.