The purpose of this study is to evaluate the potential photoprotective effects of a cranberry extract containing proanthocyanins, phenolic acids, and anthocyanins in a full thickness reconstructed human skin model (FTSK). The effects of a cranberry extract (20 μg/mL) on the release and expression of procollagen I, a precursor to collagen I (main protein structure of human skin) were assessed in FTSK treated with repetitive UV-irradiation (four consecutive days with UVA[+UVB] - 6 J/cm2 [+307 mJ/cm2]). The skin model corresponds to the two main human skin components (epidermis and dermis). These effects were also tested on cranberry (poly)phenol metabolites generated during invitro hepatocyte incubation. Multiple irradiations of the FTSK induced a strong inhibition of procollagen I release in reconstructed tissue. When the reconstructed tissue was incubated with the cranberry extract, the effects of UV-irradiation were mitigated with a significant stimulation of procollagen I release (p < 0.05). This effect was also observed after digestion of this extract by hepatocytes (p < 0.05), suggesting that its metabolites could also have photoprotective effect, without a clear link with reactive oxygen species induced by photoaging, even if digested extract showed antioxidative species and properties. The cranberry extract and the cranberry (poly)phenol metabolites had no effect on procollagen I expression. Cranberries may have a photoprotective effect through its ability to stimulate collagen synthesis via procollagen I release.

Blue light has been implicated in oxidative stress and pigmentary changes, yet no standardized method exists to quantify cosmetic protection in this spectral range. To develop a single session invivo method that quantifies the protection of topical products against blue light-induced immediate pigmentation darkening (IPD) and to compare its outcomes with a multi-day protocol from the literature. IPD was assessed using the Individual Typology Angle (ITA°) measured before (ITA0) and after exposure (ITAimm) to a 420 nm LED source delivering 80 J cm-2. Twenty-two cosmetic formulations (mineral and organic filters, nano and non-nano, with or without additional blue light actives) were applied at 2 mg cm-2 to the backs of volunteers spanning ITA0 -5 to 45°. For each product, 24 paired (ITA0, ITAimm) values were modelled by linear regression and compared with a fixed no product control. Protective efficacy was summarized as a Blue Light Protection Index (BLPI), defined as the mean percentage reduction in immediate darkening relative to the control over ITA0 = 10-40°, where immediate darkening corresponds to the difference between ITA0 andITAimm. BLPI values ranged from 14.6 to 79.2 (median 34.0), demonstrating a wide dynamic range. Mineral filter formulations predominantly occupied the upper BLPI range, whereas organic-only products were mainly in the lower to intermediate range. Non-nano mineral filters generally outperformed their nano equivalents, and mixed TiO2 + ZnO systems yielded the highest BLPI values within mineral products. A flat increase in BLPI was observed for formulations containing 2%, 4% and 6% benzotriazole, consistent with a concentration effect, although pairwise differences did not reach statistical significance. For four products, rankings obtained with BLPI were concordant with those obtained using a multi-day Blue Light Protection Factor method from the literature. The proposed single session IPD-based method provides a rapid, reproducible, and biologically relevant assessment of blue light protection. It discriminates effectively between formulations, reflects expected optical behaviour and shows good agreement with a multi-day protocol. This approach is well-suited for formulation screening and could contribute to future methodological harmonization in the visible light domain.

The combination of chemist techniques is a powerful tool on hair's structure observation and its behaviour when submitted to different process, like chemical damages as bleaching and ultraviolet (UV) radiation exposition, or physical damages, like successive brushing. This study mimicked solar radiation damage suffered by hair fibres during Brazilian summer (3 months of intense sun), and compared this kind of damage with the ones caused by bleaching process using different techniques. Natural hair after radiation exposition showed cuticular damages compared to the effects caused by bleaching. The increase of cystic components oxidation and hydrophobicity decrease were observed when natural hair was exposed to 96 and 192 h of UV radiation. Additionally, keratin's degradation enthalpy of damaged hair showed a decrease of mean values in comparison to natural healthy hair. These changes can be explained due to the protein and lipidic oxidative damages caused by UV radiation, causing alterations on cuticular level. Regarding cortical damage, natural hair tresses exposed to UV radiation for 192 h exhibited a significant decrease in mechanical parameters-specifically, force at 20% elongation and elongation at break-when compared with the initial condition of both bleached and double-bleached hair. This suggests that UV exposure exerts a more pronounced impact on these mechanical properties than chemical oxidation alone. In contrast, the enthalpy measurements show that the chemical degradation caused by bleaching is comparable to the structural alterations observed after 192 h of UV exposure. Moreover, double bleaching results in substantially more severe degradation of structural proteins than that induced by UV radiation.

This study aimed to assess and compare the permeation of catechin, epicatechin, chlorogenic acid (CGA), neochlorogenic acid (NCGA) and their mixture using a 3D full-thickness skin model and exvivo human skin explants. The 3D full-thickness model was independently prepared using dermal (HDF) and epidermal (HaCaT) cell lines cultured under air-liquid interface conditions. Separately, exvivo human skin explants were mounted on Franz diffusion cells. 3D full-thickness model barrier formation was monitored by transepithelial electrical resistance (TEER), while permeation was quantified by liquid chromatography coupled with diode array detection and mass spectrometry (LC-DAD-MS) in both models. Cytocompatibility was evaluated using the MTT assay. The 3D co-culture model exhibited a progressive increase in TEER, reaching stable values above 200 Ω.cm2, indicating a functional skin barrier formation. Invitro permeation studies enabled the detection of all tested compounds and revealed compound-specific permeation profiles strongly influenced by the structural characteristics of flavan-3-ols and hydroxycinnamic acids. In contrast, exvivo human skin explants exhibited a more restrictive barrier, with only CGA and NCGA being quantifiable, achieving 44%-50% permeation after 24 h and displaying high skin retention rates (63%-70%). None of the tested compounds induced cytotoxic effects. This work demonstrates that full-thickness 3D skin models represent a robust and ethically advantageous screening platform for cosmetic ingredients, bridging the gap between conventional 2D monocultures and exvivo human skin explants, and contributing to the reduction of human tissue use in dermal absorption studies.

ObjectiveOzone has recently been marketed as a hair‐revitalizing treatment claimed to enhance shine, softness and overall fibre quality. However, given its strongly oxidative nature, rigorous evaluation is required to determine its true effects on hair structure. This study investigates the impact of repeated exposure to ozonated water on a variety of hair‐fibre properties.MethodsMultiple analytical techniques were used: Fourier transform infrared spectroscopy (FTIR) to detect chemical changes; scanning electron microscopy (SEM) and fluorescence microscopy to assess surface and internal morphological alterations; differential scanning calorimetry (DSC) to analyse keratin and matrix thermal behaviour; tensile testing to determine mechanical responses; and combability, shine and colour measurements to evaluate consumer‐relevant attributes.ResultsOzonated water induced distinct oxidative modifications across structural, chemical and functional domains. FTIR revealed progressive increases in cysteic acid–related bands and carbonyl groups, confirming protein and lipid oxidation. SEM and fluorescence imaging showed cuticle fusion and increased cortical fluorescence, consistent with elevated carbonyl content. Morphological cuticle changes, together with increased cysteic acid content, aligned with the rise in combing force. DSC demonstrated an increased denaturation temperature accompanied by a slight reduction in enthalpy, indicating altered crosslink density and partial disruption of keratin order; these changes were further supported by increased post‐yield stiffness in tensile tests and modifications observed in the Amide I and II regions. Changes in shine and colour were minimal.ConclusionsProlonged exposure to ozonated water induced cumulative oxidative modifications of hair proteins, lipids and pigments, resulting in alterations to various hair properties. Ozone appears to induce a unique damage signature that extends beyond the cuticle into the cortex. Future studies will explore lipidomic and biochemical changes in greater depth and evaluate how ozone‐treated hair responds to subsequent cosmetic and environmental stressors.

Chemical and thermal stress disrupts the intramolecular and intermolecular interactions that stabilize hair keratin, leading to structural degradation and reduced mechanical strength. This study evaluates a plant-derived amino acid complex (Avena strigosa seed extract) for its ability to reinforce keratin intra-bonding and restore hair fibre integrity. Chemically damaged human hair was treated with formulations containing A. strigosa complex. Structural and surface changes were assessed by scanning electron microscopy (SEM), inverse gas chromatography (IGC) and glossmetry. Mechanical performance was quantified via tensile testing. Molecular interaction with keratin was examined using nano-differential scanning fluorimetry (nano-DSF) and thiol-binding fluorescence assays. A split-head invivo study (n = 20) evaluated sensory and visual attributes after a single shampoo application. Treatment with A. strigosa complex significantly improved hair properties. SEM revealed cuticle resealing and reduced porosity; Brunauer-Emmett-Teller-specific surface area decreased by 23% compared to bleached control. Gloss increased by 105% after five wash cycles, and tensile strength improved by up to 30% in leave-on treatments (p < 0.001). Nano-DSF indicated direct interaction with keratin (thermal shift: -3.18°C), and thiol-binding assays showed a 9.2% reduction in free sulfhydryl groups, confirming protection of disulphide bonds. Invivo, hair treated with A. strigosa complex scored higher for shine and smoothness versus placebo (mean difference + 1 point; p < 0.05). A. strigosa complex reinforces keratin intra-bonding by stabilizing hydrogen and ionic interactions and preserving disulphide integrity, resulting in measurable improvements in strength, gloss and surface quality. This targeted approach offers a validated strategy for repairing chemically damaged hair.

Determination of sun protection factors (SPFs) using the ‘gold standard’ in vivo method (ISO 24444) is known to be associated with appreciable uncertainty because of experimental variability. Consequently, several in vitro methods have been evaluated, that show promising accuracy, reproducibility and correlation with the in vivo ISO 24444 method. As a way of eliminating the uncertainties associated with both in vivo and in vitro methods, a proposal is made here to dispense with the concept of the SPF and instead to introduce a binary system for labelling the protection afforded by topical sunscreens. Phototesting can be either in vivo or in vitro, with in vivo phototesting requiring only a single area of sunscreen‐protected skin to be irradiated. Alternatively, a validated in vitro method could be employed to determine the threshold protection required for assigning products to the appropriate binary category.

Hair loss is a common issue that affects a large proportion of the population, leading to lower self-confidence and quality of life. Microbial dysbiosis of the scalp has been shown to be associated with several different disorders leading to hair loss. Though several 'microbiome friendly cosmetic treatments are currently on the market, there is no agreement on the best technique for assessing dysbiosis, leading to a lack of scientific rigour for quantifying the effective treatments. To help address this, the association between self-perceived hair loss and the scalp microbiome in an African-American cohort (n = 36) was investigated. Using a self-controlled design, swabs were collected from both 'sparse' and 'normal' scalp sites. The scalp microbiome was characterized via 16S rRNA gene sequencing and a dysbiosis score was calculated based on the proportion of all taxa within the samples. Further, we identified the taxa that contributed most to abnormal or dysbiotic hair sites using a machine learning random forest classifier and a negative binomial mixed-effects model. The dysbiosis index is sensitive to participants' self-assessment of hair loss and interindividual variation. We found a core set of operational taxonomic units (OTUs) assigned to 7 genera that significantly contributed to increased scalp dysbiosis. This study demonstrates that self-perceived hair loss is associated with significant and measurable alterations in the scalp microbiome, making the reported dysbiosis index a practical tool that may be used to assess microbiome changes following cosmetic or medical interventions for hair loss and other microbiome-associated disorders.