Search Results (81)

Dermal drug delivery is a promising alternate route of drug administration, offering localized therapeutic effects, reduced systemic effects, and improved patient compliance. However, the skin’s intricate configuration, especially the stratum corneum (SC), presents formidable barriers, restricting drug permeation. This review summarizes biological, synthetic, and methodological models employed to study dermal absorption and permeability. Ex vivo human skin is a reference point, but limited availability and ethical constraints necessitate reliance on animal models, including porcine, rodent, rabbit, monkey, and even snake skin, each with unique advantages and drawbacks. Synthetic substitutes, e.g., reconstructed human epidermis and Strat-M^® membranes, provide reproducibility and economic practicality, though none fully mimic the barrier functions of human skin. Innovative analytical methods, including diffusion cells, skin-PAMPA, tape stripping, and advanced imaging techniques, enable quantitative, semi-quantitative, and qualitative insights into drug transport. Collectively, these tools support formulation optimization and aid regulatory bioequivalence assessments. However, challenges remain in correlating in vitro, ex vivo, and in vivo outcomes and in replicating the skin’s dynamic physiology. This review highlights current opportunities and limitations, emphasizing the need for more physiologically relevant models to advance safe, effective, and innovative dermal drug delivery systems. Full article

The abnormal barrier function of the stratum corneum is a significant characteristic of surface-active agent-induced inflammatory skin diseases, and its cause is closely related to the abnormal lipid components of the stratum corneum. Total saponins of Panax notoginseng (TSPN) have significant potential in improving inflammatory skin barrier function. This study aims to investigate the barrier repair efficacy of TSPN using the EpiKutis^® skin model and to explore the potential mechanisms through multi-omics analysis based on transcriptomics, proteomics, and lipid metabolomics. We found that TSPN could ameliorate Sodium dodecyl sulfate (SDS)-induced barrier impairment in the EpiKutis^® model, alleviating stratum corneum thickening and upregulating the expression of barrier-related proteins, e.g., Filaggrin, Involucrin, and Loricrin. Through an integrated multi-omics network, we identified seven key target proteins and screened six lipid metabolites, which are involved in lipid metabolism and exert barrier-repairing effects through five pathways. The result indicated that TSPN might repair the epidermal barrier by regulating the phosphatidylinositol 3 kinase (PI3K)-protein kinase B (AKT)-mediated proliferation pathway, Mitogen-activated protein kinase (MAPK)-mediated apoptotic pathways, sphingolipid synthesis, Calcium/calmodulin-dependent protein kinase II beta (CAMK2B)-mediated actin cytoskeleton regulation, and Inositol-trisphosphate 3-kinase B (ITPKB)-mediated phosphatidylinositol signaling system. Further study is needed to explore the mechanism of the molecular link between lipid abnormalities and skin barrier function. Full article

Background: Acorus calamus (sweet flag) is widely used in traditional medicine, yet its dermal safety profile remains insufficiently defined under modern regulatory standards. Objective: To comprehensively evaluate the skin irritation, corrosion, and sensitisation potential of A. calamus rhizome oil using new approach methodologies’ (NAMs) test batteries under GLP conditions. Results: The A. calamus rhizome oil was predicted as a Category 2 skin irritant, non-corrosive and GHS Category 1B skin sensitiser. Chemical analysis revealed β-asarone as the major constituent (~40.75%). The reconstructed human epidermis models established reversible irritation without corrosion. Mechanistic concordance across the Direct Peptide Reactivity Assay, KeratinoSens™, and Human Cell Line Activation Test showed activation of the three key events of the skin sensitisation adverse outcome pathway. Using the “2-out-of-3” Defined Approach with the KE 3/1 sequential strategy allowed for hazard classification into GHS Category 1B. Quantitative risk modelling using SARA-ICE models and SCCS parameters yielded conservative safe-use concentrations ranging from 0.13 to 0.78% (w/w) for leave-on products and up to 7.46% (w/w) for rinse-off formulations. Conclusions: The combined evidence from the NAM-based assays showed that A. calamus rhizome oil is a moderate sensitiser and irritant but not corrosive, providing critical data for risk assessment and regulatory decision-making, which was previously unknown. The SARA-ICE PoD-derived safe-use concentrations provide guidance for cosmetic formulators to ensure consumer safety, particularly in leave-on applications such as face and hand creams, where sensitisation risk is highest. This study demonstrates the utility of NAMs for botanical safety assessment and regulatory decision-making. Full article

Benefit/risk management of skin exposure to sunlight, especially ultraviolet (UV) rays, is mainly driven by photoaging, cancer incidence, and the requirement for vitamin D3 synthesis. Antioxidant phytocompounds are considered to be a valuable source of molecules to protect skin from UV-induced damage, but their impact on other UV-related metabolic pathways is rarely described. In this study, an indigoid-rich Persicaria tinctoria extract (PTE) was evaluated on three consequences of UV exposure: DNA damage and inflammation, vitamin D3 content, and melanogenesis. A moderate UV exposure was applied on skin models, corresponding to approximately 1 h exposure in the spring in western Europe. UV-induced DNA damage and inflammation were measured through the quantification of cyclobutane pyrimidine dimers (CPDs) and cytokines. Response to heat stress was quantified through the release of prostaglandin. Then, the impact of PTE on vitamin D3 and melanin synthesis was observed. PTE decreased by −56% in the number of cells presenting CPDs. PTE decreased the production of pro-inflammatory cytokine IL-6 (−59%) and stimulated the release of the protective cytokine IL-1Ra (+49%). It decreased PGE₂ release by −27%. In skin explants, PTE boosted the vitamin D3 concentration (+345%). Several genes involved in melanogenesis were up-regulated by PTE (MC1R × 2.46, MITF × 1.69, TYR × 2.06, MLPH × 1.53). It promoted melanin content by +126% and by +86% when associated with SPF 30. The extract decreased the amount of protective eumelanin, leading to visible skin tanning of reconstructed human epidermis (L*-15%, ITA −125%). As a new finding, PTE minimized DNA damage and inflammation caused by a daily dose of UV, and surprisingly, promoted vitamin D3 and eumelanin synthesis, suggesting that it represents an opportunity to reconcile skin protection and the physiological need for sunlight. Full article

Postbiotics are bioactive microbial metabolites recognized for their potential to support skin health and balance the microbiota. In this study, nonwoven fabrics and adult diaper prototypes, with and without postbiotic incorporation, were evaluated for their effects on skin microbiota, epidermal integrity, and cytotoxicity. In vitro assays using reconstructed human epidermis and keratinocyte cell lines demonstrated that postbiotic-containing samples maintained high tissue and cell viability. Microbiota diversity analyses confirmed that postbiotic formulations maintained a favorable ratio of Staphylococcus epidermidis to Staphylococcus aureus. Collectively, these findings indicate that ATA-coded postbiotic-embedded nonwoven and adult diaper prototypes are skin microbiota-friendly, safe for epidermal contact, and stable in their bioactive compound content. These results underscore the potential of postbiotics as functional agents in personal hygiene products to promote skin health. Full article

Ultrafine particles (UFPs) containing polycyclic aromatic hydrocarbons (PAHs) benzo[a]pyrene (BaP), are linked to pollution-induced health concerns, with skin being highly susceptible to contamination. Understanding the metabolic fate of these environmental pollutants in the skin is crucial. Moreover, traditional in vitro models often lack metabolic competency, while animal testing raises ethical concerns. This study introduces a novel approach combining stable isotope labeling (SIL) and liquid chromatography–high-resolution mass spectrometry (LC-HRMS) to investigate BaP metabolism. The physiologically relevant 3D reconstructed human epidermis (RHE) model was used. RHE models were exposed to BaP and deuterium-labeled BaP (BaP-d12). These analyses, followed by data analysis incorporating stable isotope filtering, revealed the presence of five distinct BaP phase I metabolites, including mono-hydroxylated, dihydroxylated, and quinone derivatives. This study demonstrates the power of coupling stable isotope labeling with LC-HRMS for the comprehensive characterization of BaP metabolic pathways in human skin. The identification of specific metabolites enhances our understanding of BaP detoxification mechanisms and their potential adverse effects. This analytical approach holds promise for investigating the metabolic fate of various other environmental pollutants. Full article

Twenty natural products used in traditional medicine to treat dermatophytosis were evaluated for their efficacy against Trichophyton rubrum, the most frequent dermatophyte infecting humans. For this purpose, aqueous and methanolic extracts were prepared from ash, honey, and plant organs as pure (100%) or diluted (75%, 50%, 25%, 12.5%, 6.25%, 3.125%, and 1.56%) preparations. The extracts were then evaluated by incorporating them into a Sabouraud medium and seeding them with T. rubrum as a fungal culture. The results identify fourteen extracts as being able to completely inhibit T. rubrum growth through either fungistatic or fungicidal activity. The five extracts with the highest efficacy to inhibit T. rubrum growth were further analyzed for their potential to alter in vitro reconstructed human epidermis (RHE). An aqueous extract from Allium sativum produced no tissue alteration in RHE, unlike the extracts from Conyza sumatrensis, Rumex abyssinicus, or Pentas longiflora. The data suggest that preparations used in traditional medicine by rural population in South-Kivu (DR-Congo) might represent valid alternatives to fight dermatophytosis. However, they also illustrate that several preparations remain inefficient and that others may be detrimental to the epidermis. This work reveals that traditional preparations, although affordable and easily available, require an evaluation of their efficacy and safety. Full article

Photosafety assessments are a key requirement for the safe development of pharmaceuticals, cosmetics, and agrochemicals. Although in vitro methods are widely used for phototoxicity and photoallergy testing, their limited applicability and predictive power often necessitate supplemental in vivo studies. To address this, we developed the PhotoChem Reference Chemical Database, comprising 251 reference compounds with curated data from in vitro, in vivo, and human studies. Using this database, we evaluated the predictive capacity of three OECD in vitro test guidelines—TG 432 (3T3 NRU), TG 495 (ROS assay), and TG 498 (reconstructed human epidermis)—by comparing the results against human and animal data. Against human reference data, all three test methods showed high sensitivity (≥82.6%) and strong overall accuracy: TG 432 (accuracy: 94.2% (49/52)), TG 495 (100% (27/27)), and TG 498 (86.7% (26/30)). In comparison with animal data, sensitivity remained high for all tests (≥92.0%), while specificity varied: TG 432 (54.3% (19/35)), TG 495 (63.6% (7/11)), and TG 498 (90.5% (19/21)). TG 498 demonstrated the most balanced performance in both sensitivity and specificity across datasets. We also analyzed 106 drug approvals from major regulatory agencies to assess real-world application of photosafety testing. Since the mid-2000s, the use of in vitro phototoxicity assays has steadily increased in Korea, particularly following the 2021 revision of the MFDS regulations. Test method preferences varied by region, with 3T3 NRU and ROS assays most widely used to evaluate phototoxicity, while photo-LLNA and guinea pig tests were frequently employed for photoallergy assay. Collectively, this study provides a valuable reference for optimizing test method selection and supports the broader adoption of validated, human-relevant non-animal photosafety assessment strategies. Full article

Modern dermocosmetics combine the effectiveness of active substances with the benefits of percutaneous penetration enhancers to address skin issues such as hyperpigmentation. In this study, three bioactive tripeptides (with amino acid sequences CSF, CVL, and CSN) with previously confirmed tyrosinase inhibition activity were synthesized using the solid-phase synthesis method. The structures of the obtained peptides were determined. In addition, elastase in silico and in vitro inhibition assays were carried out. The tripeptides were subsequently encapsulated into liposomes, for which key physicochemical parameters were determined, including size, zeta potential, and encapsulation efficiency. The average diameter of the prepared liposomes was approximately 100 nm across all samples. The prepared carriers were found to be stable and exhibited no cytotoxicity toward reconstructed human epidermis cells. The peptides achieved an encapsulation efficiency of approximately 20–30%, with no significant differences observed between the cationic and anionic vesicles. Liposomes containing the CSF tripeptide, which showed the strongest tyrosinase-inhibiting effect, did not transport the peptide through the human skin in an ex vivo assay to permit quantification in the receptor solution, but facilitated penetration and retention of the tripeptide within the epidermis (4.65 ± 1.81 μg/cm²). These findings suggest that the prepared liposomes may serve as valuable carriers of bioactive tripeptides in anti-aging cosmetics. Full article

Hydrogels (HDs) offer a promising platform for localized and sustained drug delivery. In this study, carboxymethyl chitosan (CMC)—based hydrogels were crosslinked with genipin and evaluated for the controlled release and tissue retention of suramin, a polyanionic drug with anti-inflammatory and antifibrotic properties. The influence of crosslinking density (1%, 3%, and 5%) on drug release, permeation kinetics, and retention was investigated using in vitro synthetic membranes and reconstructed human epithelial tissue models. The 1% genipin HD exhibited the highest cumulative release and drug retention (48.8 ± 6.8 μg/cm² in synthetic membranes; 24.06 ± 7.33 μg/cm² in epithelial models), along with a sustained release profile governed by first-order and Fickian diffusion kinetics. Notably, the 1% crosslinked formulation also demonstrated enhanced transmembrane flux (>140 μg/cm²/h after six hours), suggesting that lower crosslinking density favors both diffusional mobility and depot functionality. In contrast, free suramin solution displayed limited tissue interaction and minimal permeation, highlighting the role of the hydrogel matrix in regulating local bioavailability. These findings demonstrate that CMC–genipin HD can closely modulate drug delivery kinetics through crosslinking density, offering a biocompatible strategy for localized treatment of ulcerated epithelial conditions such as oral mucositis or chronic wounds. Diffusion models included a synthetic multilayer membrane (Strat-M^®) and a reconstructed human epidermis (EpiDerm™) to simulate skin-like barrier properties. Full article

An in vitro 3D model using fungus colonized Reconstructed Human Epidermis (RHE) represents an effective preclinical model to simulate the pathological conditions of onychomycosis. We evaluated the suitability of this 3D onychomycosis model and use it to assess the effects of topical products on fungus growth and nail structure. Five sets of differentiated RHE were colonized with Trichophyton rubrum and covered with bovine nails. Colonized RHE with no product application (CNA) served as the control. Four different products classified as medical devices were applied once daily on the nails: Urgo Damaged Nails (UDN), Excilor (EXlor), Poderm Purifying (PDermP), Poderm Booster (PDermB). After 5 days, T. rubrum presence was visualized by the Grott Methenamine Silver staining method and quantified as the sum signal intensity of processed acquisitions. Fungal hyphae and the nail structure were analyzed by SEM. A semi-quantitative evaluation of fungal presence showed a reduction after UDN (−34%, p < 0.001) and EXlor (−28%, p < 0.020) applications compared to CNA. No significant difference was observed after PDermP applications (−2%). The nail structure appeared preserved after UDN applications and severely damaged after EXlor and PDermP applications. These findings demonstrate significant effects of different products on fungal growth and nail structure, suggesting that this 3D model might be a valuable tool for predicting the effects of antimycotic treatment in humans. Full article

Tyrosinase is a key enzyme responsible for the formation of melanin (a natural skin pigment with ultraviolet-protection properties). However, some people experience melanin overproduction, so new, safe, and biocompatible enzyme inhibitors are sought. New tripeptide tyrosinase inhibitors were developed using molecular modeling. A combinatorial library of tripeptides was prepared and docked to the mushroom tyrosinase crystal structure and investigated with molecular dynamics. Based on the results of calculations and expert knowledge, the three potentially most active peptides (CSF, CSN, CVL) were selected. Their in vitro properties were examined, and they achieved half-maximal inhibitory concentration (IC₅₀) values of 136.04, 177.74, and 261.79 µM, respectively. These compounds attach to the binding pocket of tyrosinase mainly through hydrogen bonds and salt bridges. Molecular dynamics simulations demonstrated the stability of the peptid–tyrosinase complexes and highlighted the persistence of key interactions throughout the simulation period. The ability of these peptides to complex copper ions was also confirmed. The CSF peptide showed the highest chelating activity with copper. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay confirmed that none of the test tripeptides showed cytotoxicity toward the reconstructed human epidermis. Our results indicated that the developed tripeptides were non-toxic and effective tyrosinase inhibitors. They could be applied as raw materials in skin-brightening or anti-aging cosmetic products. Full article

Background/Objectives: Skin hyperpigmentation is a biological process that results in an excessive production of melanin and is highly regulated by several mechanisms, tyrosinase being one of the key enzymes involved. Current reported inhibitors lack clinical efficacy, show toxic side effects, have poor bioavailability, or low formulation compatibility. The aim of this study was to design a new effective tyrosinase inhibitor for topical hyperpigmentation and anti-aging treatments. Methods: Homology modeling was used to build the tridimensional structure of human tyrosinase, and virtual docking was used to predict molecule–enzyme binding modes. The tyrosinase activity of the designed and synthesized compounds was assessed and water solubility was determined by HPLC. Cell assays were performed to determine melanin content, cytotoxicity, wound healing, anti-glycation, antioxidation, and autophagy efficacy. Gene expression and miRNA levels were quantified by qPCR and chromatin accessibility by ATAC-Seq. Human reconstructed epidermis was used to test the depigmenting efficacy as well as the skin irritation potential. Results: The 3D structure of human tyrosinase was designed and validated. The new molecule could effectively inhibit human tyrosinase and melanin synthesis in 2D monocultures and a 3D epidermis model. Two melanogenesis-related miRNAs were increased in treated cells. Anti-glycation, antioxidant, mitochondria protection, autophagy activation, and wound healing properties were also observed, with special emphasis on epigenetics. Conclusions: The designed molecule is a potential candidate to be used as a depigmenting and anti-aging agent, with suitable properties to be introduced in final product formulations for dermatology or cosmetics treatments. Full article

The integrity of the reconstructed human epidermis generated in vitro can be assessed using histological analyses combined with immunohistochemical staining of keratinocyte differentiation markers. Technical differences during the preparation and capture of stained images may influence the outcome of computational methods. Due to the specific nature of the analyzed material, no annotated datasets or dedicated methods are publicly available. Using a dataset with 598 unannotated images showing cross-sections of in vitro reconstructed human epidermis stained with DAB-based immunohistochemistry reaction to visualize four different keratinocyte differentiation marker proteins (filaggrin, keratin 10, Ki67, HSPA2) and counterstained with hematoxylin, we developed an unsupervised method for the detection and quantification of immunohistochemical staining. The pipeline consists of the following steps: (i) color normalization; (ii) color deconvolution; (iii) morphological operations; (iv) automatic image rotation; and (v) clustering. The most effective combination of methods includes (i) Reinhard’s normalization; (ii) Ruifrok and Johnston color-deconvolution method; (iii) proposed image-rotation method based on boundary distribution of image intensity; and (iv) k-means clustering. The results of the work should enhance the performance of quantitative analyses of protein markers in reconstructed human epidermis samples and enable the comparison of their spatial distribution between different experimental conditions. Full article

Skin barrier dysfunction and thin epidermis are hallmarks of sensitive skin and contribute to premature aging. Avenanthramides are the primary bioactive components of colloidal oatmeal, a commonly used treatment to enhance skin barrier function. This study investigated the relationship between skin barrier function and epidermal characteristics and explored the potential of dihydroavenanthramide D (dhAvD), a synthetic avenanthramide, to improve the skin barrier. We observed a significant correlation between impaired skin barrier function and decreased epidermal thickness, suggesting that a weakened barrier contributes to increased sensitivity. Our in vitro results in HaCaT cells demonstrated that dhAvD enhances keratinocyte proliferation, migration, and tight junction protein expression, thereby strengthening the skin barrier. To mimic skin barrier dysfunction, we treated keratinocytes and full-thickness skin equivalents with IL-4 and IL-13, cytokines that are implicated in atopic dermatitis, and confirmed the downregulation of tight junction and differentiation markers. Furthermore, dhAvD treatment restored the barrier function and normalized the expression of key epidermal components, such as tight junction proteins and natural moisturizing factors, in keratinocytes treated with inflammatory cytokines. In the reconstructed human skin model, dhAvD promoted both epidermal and dermal restoration. These findings suggest that dhAvD has the potential to alleviate skin sensitivity and improve skin barrier function. Full article