Topical application of retinyl propionate, 4 hexyl resorcinol, and niacinamide reverses molecular and clinical features of ageing.

OBJECTIVE: Topical tretinoin is the mainstay of treatment for photoageing, despite the risk of skin irritation. Cosmetic combination anti-ageing formulations may offer similar efficacy to tretinoin, while improving on tolerability. We aim to demonstrate facial appearance benefits of a novel triple-active cosmetic formulation containing 4-hexylresorcinol, retinyl propionate, and niacinamide and to identify transcriptomic biomarkers underpinning these benefits. METHODS: A cosmetic prototype formulation containing 4-hexylresorcinol, retinyl propionate, and niacinamide was evaluated ex vivo and in a clinical study. For ex vivo experiments, the cosmetic formulation was applied for 3 days to healthy surgical discard skin from female donors aged 31-51 years, with tissues harvested for gene expression and histologic analyses. In the clinical study, females aged 47-66 years with moderate-to-severe overall visual photodamage on the face applied either topical 0.02% tretinoin or the cosmetic formulation to the face for 16 weeks and to forearms for 1 week, with forearm biopsies taken for gene expression analyses. Visual grading for facial photodamage and VISIA-CR images was taken throughout the clinical study. Safety was visually assessed during site visits, and adverse event monitoring was conducted throughout. RESULTS: Gene expression analyses in both studies revealed modulation of pathways associated with skin rejuvenation, with several genes of interest identified due to being implicated in ageing and differentially expressed following the application of the cosmetic formulation. Reversal of a consensus skin ageing gene signature was observed with the cosmetic formulation and tretinoin in the ex vivo and clinical studies. Both the cosmetic formulation and tretinoin clinically improved the overall appearance of photoageing, crow's feet, lines, wrinkles, and pores. Adverse event reporting showed that the cosmetic formulation caused less skin irritation than tretinoin. CONCLUSION: In a double-blind clinical study, the novel triple-active cosmetic combination formulation improved the visual appearance of photoageing similarly to prescription tretinoin. The cosmetic formulation and tretinoin reversed a consensus gene signature associated with ageing. Together with adverse event reporting, these results suggest that the cosmetic formulation may be a well-tolerated and efficacious alternative to tretinoin for improving the visual features of photoageing.

OBJECTIF: Le trétinoine topique est le pilier du traitement du photovieillissement, malgré le risque d'irritation cutanée. Les formulations cosmétiques combinés anti­âge peuvent offrir une efficacité similaire à la trétinoine, tout en améliorant la tolérance. Notre objectif est de démontrer les avantages esthétiques pour l'apparence du visage d'une nouvelle formulation cosmétique triple active contenant du 4­hexylrésorcinol, du rétinyl propionate et de la niacinamide, et d'identifier les biomarqueurs transcriptomiques sous­jacents à ces avantages. MÉTHODES: Une formulation cosmétique prototype contenant du 4­hexylrésorcinol, du rétinyl propionate et de la niacinamide a été évaluée ex vivo et lors d'une étude clinique. Pour les expériences ex vivo, la formulation cosmétique a été appliquée pendant 3 jours sur des peaux saines issues de donatrices âgées de 31 à 51 ans, avec prélèvement de tissus pour l'analyse de l'expression génique et l'histologie. Dans l'étude clinique, des femmes âgées de 47 à 66 ans présentant un photovieillissement visuel global modéré a sévère sur le visage ont appliqué soit du trétinoine topique à 0.02%, soit la formulation cosmétique sur le visage pendant 16 semaines et sur les avant­bras pendant 1 semaine, avec des biopsies d'avant­bras prélevées pour l'analyse de l'expression génique. L'évaluation visuelle du photovieillissement facial et les images VISIA­CR ont été réalisées tout au long de l'étude clinique. La sécurité a été évaluée visuellement lors des visites sur site, et une surveillance des événements indésirables a été effectuée. RÉSULTATS: Les analyses de l'expression génique dans les deux études ont révélé une modulation des voies associées au rajeunissement cutané, avec plusieurs gènes d'intérêts identifiés en raison de leur implication dans le vieillissement et de leur expression différentielle suite à l'application de la formulation cosmétique. Une inversion de la signature génique du vieillissement cutané consensuelle a été observée avec la formulation cosmétique et la trétinoine dans les études ex vivo et cliniques. La formulation cosmétique et la trétinoine ont toutes deux amélioré cliniquement l'apparence globale du photovieillissement, des pattes d'oie, des ridules, des rides et des pores. Les rapports sur les événements indésirables ont montré que la formulation cosmétique provoquait moins d'irritation cutanée que la trétinoine. CONCLUSION: Dans une étude clinique en double aveugle, la nouvelle formulation cosmétique triple active a amélioré l'apparence visuelle du photovieillissement de manière similaire à la trétinoine sur ordonnance. La formulation cosmétique et la trétinoine ont inversé une signature génique consensuelle associée au vieillissement. En tenant compte des rapports sur les événements indésirables, ces résultats suggèrent que la formulation cosmétique pourrait constituer une alternative bien tolérée et efficace à la trétinoine pour améliorer les caractéristiques visuelles du photovieillissement.

Glutathione amino acid precursors protect skin from UVB-induced damage and improve skin tone.

BACKGROUND: UV radiation exposure causes skin irritation, erythema, darkening and barrier disruption by inducing oxidative stress and inflammation. Glutathione, a master antioxidant, plays an important role in the antioxidant defence network of the skin. OBJECTIVE: This study aimed to assess the in vitro protective effects of the glutathione amino acid precursors blend (GAP) on transcriptomic and phenotypic endpoints against UVB-induced challenges. METHODS: Normal human epidermal melanocytes (NHEMs) were exposed to GAP, ascorbic acid (AA) and its derivatives. Viability was assessed using the CCK8 method. Melakutis®, a pigmented living skin equivalent (pLSE) model, underwent repeated 50 mJ/cm2 UVB irradiation with or without GAP treatment. Images of the model were captured with consistent camera parameters, and the model's light intensity was measured using a spectrophotometer. Melanin content was determined by measuring absorbance at 405 nm. Confirmation of melanin deposition and distribution was achieved through Fontana-Masson staining. Transcriptomic analysis was conducted using RNA sequencing (RNA-Seq), and a machine learning approach was employed for transcriptomic aging clock analysis. RESULTS: In NHEMs, all tested compounds exhibited over 85% viability compared to the vehicle control, indicating no heightened risk of cytotoxicity. Notably, GAP demonstrated greater efficacy in inhibiting melanin production than AA derivatives at equivalent concentrations. In pLSE models, GAP notably enhanced model lightness, and reduced melanin content and deposition following the UVB challenge, whereas AA showed minimal impact. GAP effectively counteracted UVB-induced alterations in gene expression linked to pigmentation, inflammation and aging. Moreover, recurrent UVB exposure substantially elevated the biological age of pLSE models, a phenomenon mitigated by GAP treatment. CONCLUSIONS: In NHEMs, GAP exhibited enhanced effectiveness in inhibiting melanin production at identical tested doses in comparison to AA derivatives. Noteworthy protective effects of GAP against UVB irradiation were observed in the pLSE models, as evidenced by skin pigmentation measurements and transcriptomic changes.

Topical glutathione amino acid precursors protect skin against environmental and oxidative stress.

BACKGROUND: Although glutathione (GSH) has long been considered a master antioxidant, poor stability and bioavailability limit its application in skin protection. To overcome the challenges, Unilever R&D formulated a Glutathione Amino acid Precursors blend (named GAP) to boost GSH de novo synthesis. OBJECTIVE: Determine whether GAP can boost GSH levels and provide skin protection against stressors. METHODS: Normal human epidermal keratinocytes were treated with GAP, with or without stressors, namely, menadione, blue light or pollutants. Ascorbic acid was used as a benchmark. The levels of GSH, glutathione disulfide (GSSG), adenosine triphosphate (ATP) and reactive oxygen species (ROS) were quantified. A placebo-controlled clinical study was conducted on 21 female subjects who received product applications and subsequent UV radiation. Tape strip samples were collected from the subjects for GSH and GSSG quantification using ultra-performance liquid chromatography-mass spectrometry/mass spectrometry (UPLC-MS/MS). The UV-protective effect of GAP was investigated using ex vivo skin. Biomarkers related to DNA damage and the skin barrier were analysed using immunohistochemistry. RESULTS: Glutathione amino acid precursors significantly increased the GSH levels and GSH/GSSG ratio in normal human epidermal keratinocytes. Menadione treatment resulted in excessive ROS production and a decline in ATP levels, which were effectively abrogated by GAP. The protective effects of GAP against menadione-induced oxidative stress were superior to those of ascorbic acid. In addition, GAP effectively protected the cells against blue light-induced ROS production and pollutant-induced ATP depletion. Topical application of the GAP formulation significantly elevated the skin GSH/GSSG ratio in a clinical study. Ex vivo skin treated with the GAP formulation displayed a reduction in DNA damage and high levels of barrier proteins after UV exposure. CONCLUSIONS: Glutathione amino acid precursors effectively increases cellular GSH levels to protect the skin from oxidative and environmental stresses.