Complex nanoemulsion for vitamin delivery: droplet organization and interaction with skin membranes.

Lipid nanoemulsions are promising nanomaterials for drug delivery applications in food, pharmaceutical and cosmetic industries. Despite the noteworthy commercial interest, little is known about their supramolecular organization, especially about how such multicomponent formulations interact with cell membranes. In the present work, coarse-grained molecular dynamics simulations have been employed to study the self-assembly of a 15-component lipid nanoemulsion droplet containing vitamins A and E for skin delivery. Our results display aspects of the unique "onion-like" agglomeration between the chemical constituents in the different layers of the lipid nanodroplet. Vitamin E molecules are more concentrated in the center of the droplet together with other hydrophobic constituents such as the triglycerides with long tails. On the other hand, vitamin A occupies an intermediate layer between the core and the co-emulsifier surface of the nanodroplet, together with lecithin phospholipids. Coarse-grained molecular dynamics simulations were also performed to provide insight into the first steps involved in absorption and penetration of the nanodroplet through skin membrane models, representing an intracellular (hair follicle infundibulum) and intercellular pathway (stratum corneum) through the skin. Our data provide a first view on the complex organization of commercial nanoemulsion and its interaction with skin membranes. We expect our results to open the way towards the rational design of such nanomaterials.

Sterol-standardized phytopharmaceutical from ground cherry: Corticoid-like properties on human keratinocytes and fibroblasts and its effects in a randomized double-blind placebo-controlled clinical trial.

BACKGROUND: Topical corticosteroids have been the most commonly prescribed drugs to treat skin inflammation, but their uses can lead to several adverse effects. Nowadays, new pharmacological strategies have been evaluated to improve dermatologic efficacy and reduce adverse effects, including natural products. OBJECTIVES: The aim of this study was to evaluate and compare the effects of a plant sterol standardized supercritical CO2 phytopharmaceutical of Physalis angulata L. with hydrocortisone on the immune and inflammatory mediators, and skin repair components production. Moreover, we studied effects of both products on the skin microcirculation and temperature in a double-blind placebo-controlled clinical trial. METHODS: Both products were evaluated on the immune (IL-6, IL-10, INF-γ, TNF-α, and IL-1α), inflammatory (COX-2, LOX, PLA2 , PGE2 , LTB4 , histamine, and NF-κB), and repair components (TGF-ß, GM-CSF, collagen, and GAG) production on human keratinocytes and fibroblast in non-stimulated and LPS-stimulated conditions. Indeed, in a randomized double-blind placebo-controlled clinical trial, we evaluated the effects of the both creams on the skin microcirculation and temperature using laser Doppler and infrared thermometer, respectively. RESULTS: Physalis angulata acted on the skin, modulating immune status and inflammatory response producing corticoid-like effects, but different of hydrocortisone, increased skin repair factors. The effects of phytopharmaceutical cream in the clinical trial promoted a better reduction in skin microcirculation and temperature than hydrocortisone. CONCLUSIONS: Taken together, the results indicate that sterol standardized CO2 supercritical preparation of P angulata is a new and innovative phytopharmaceutical with multiple pharmacological effects potentially useful as human skin protective product, particularly against cutaneous inflammatory disorders.

Antiageing Mechanisms of a Standardized Supercritical CO 2 Preparation of Black Jack (Bidens pilosa L.) in Human Fibroblasts and Skin Fragments.

The use of topical retinoids to treat skin disorders and ageing can induce local reactions, while oral retinoids are potent teratogens and produce several unwanted effects. This way, efforts to explore complementary care resources should be supported. Based on this, we evaluate the antiageing effects of a supercritical CO2 extract from Bidens pilosa L. (BPE-CO2A) containing a standardized multicomponent mixture of phytol, linolenic, palmitic, linoleic, and oleic acids. BPE-CO2A was assessed for its effects on human dermal fibroblasts (TGF-ß1 and FGF levels using ELISA; collagen, elastin, and glycosaminoglycan by colorimetric assays, and mRNA expression of RXR, RAR, and EGFr by qRT-PCR) and human skin fragments (RAR, RXR, collagen, elastin, and glycosaminoglycan by immunohistochemical analysis). Levels of extracellular matrix elements, TGF-ß1 and FGF, and EGFr gene expression were significantly increased by BPE-CO2A. The modulation of RXR and RAR was positively demonstrated after the treatment with BPE-CO2A or phytol, a component of BPE-CO2A. The effects produced by BPE-CO2A were similar to or better than those produced by retinol and retinoic acid. The ability to stimulate extracellular matrix elements, increase growth factors, and modulate retinoid and rexinoid receptors provides a basis for the development of preparation containing BPE-CO2A as an antiageing/skin-repair agent.

Active ingredients against human epidermal aging.

The decisive role of the epidermis in maintaining body homeostasis prompted studies to evaluate the changes in epidermal structure and functionality over the lifetime. This development, along with the identification of molecular mechanisms of epidermal signaling, maintenance, and differentiation, points to a need for new therapeutic alternatives to treat and prevent skin aging. In addition to recovering age- and sun-compromised functions, proper treatment of the epidermis has important esthetic implications. This study reviews active ingredients capable of counteracting symptoms of epidermal aging, organized according to the regulation of specific age-affected epidermal functions: (1) several compounds, other than retinoids and derivatives, act on the proliferation and differentiation of keratinocytes, supporting the protective barrier against mechanical and chemical insults; (2) natural lipidic compounds, as well as glycerol and urea, are described as agents for maintaining water-ion balance; (3) regulation of immunological pathogen defense can be reinforced by natural extracts and compounds, such as resveratrol; and (4) antioxidant exogenous sources enriched with flavonoids and vitamin C, for example, improve solar radiation protection and epidermal antioxidant activity. The main objective is to provide a functional classification of active ingredients as regulatory elements of epidermal homeostasis, with potential cosmetic and/or dermatological applications.

Triple nanoemulsion potentiates the effects of topical treatments with microencapsulated retinol and modulates biological processes related to skin aging / Tripla nanoemulsao potencializa os efeitos do tratamento topico com retinol microencapsulado e modula processos biologicos relacionados ao envelhecimento da pele

BACKGROUND: The sum of environmental and genetic factors affects the appearance and function of the skin as it ages. The identification of molecular changes that take place during skin aging provides biomarkers and possible targets for therapeutic intervention. Retinoic acid in different formulations has emerged as an alternative to prevent and repair age-related skin damage. OBJECTIVES: To understand the effects of different retinoid formulations on the expression of genes associated with biological processes that undergo changes during skin aging. METHODS: Ex-vivo skin samples were treated topically with different retinoid formulations. The modulation of biological processes associated with skin aging was measured by Reverse Transcription quantitative PCR (RT-qPCR). RESULTS: A formulation containing microencapsulated retinol and a blend of active ingredients prepared as a triple nanoemulsion provided the best results for the modulation of biological, process-related genes that are usually affected during skin aging. CONCLUSION: This association proved to be therapeutically more effective than tretinoin or microencapsulated retinol used singly. .

FUNDAMENTOS: A soma de fatores genéticos e ambientais afeta a aparência e a funcionalidade da pele ao longo do envelhecimento. O conhecimento a respeito das mudanças moleculares durante o envelhecimento fornece biomarcadores e possíveis alvos para intervenções terapêuticas. O ácido retinoico em diferentes formulações surgiu como uma alternativa para prevenir e reparar os danos da pele associados ao envelhecimento. OBJETIVOS: Avaliar comparativamente os efeitos de diferentes formulações contendo retinoides na expressão de genes associados a processos biológicos que são alterados com o envelhecimento da pele. MÉTODOS: Peles ex vivo foram topicamente tratadas com diferentes retinoides, micro e nanoencapsulados. A modulação dos processos biológicos associados ao envelhecimento da pele foi medida por PCR quantitativa, precedida de transcrição reversa (RT-qPCR). RESULTADOS: A formulação contendo uma mistura de princípios ativos incorporados em uma tripla nanoemulsão e retinol microencapsulado apresentou os melhores resultados de modulação de genes relacionados a processos biológicos que são normalmente alterados durante o envelhecimento da pele. CONCLUSÃO: Essa associação demonstrou uma maior eficácia terapêutica quando comparada ao uso isolado de tretinoína ou retinol microencapsulado. .

Photoprotective and antioxidant effects of Rhubarb: inhibitory action on tyrosinase and tyrosine kinase activities and TNF-α, IL-1α and α-MSH production in human melanocytes.

BACKGROUND: Exposure to ultraviolet (UV) radiation causes various forms of acute and chronic skin damage, including immunosuppression, inflammation, premature aging and photodamage. Furthermore, it induces the generation of reactive oxygen species, produces proinflammatory cytokines and melanocyte-stimulating hormone (MSH) and increases tyrosinase activity. The aim of this study was to evaluate the potential photoprotective effects of Rheum rhaponticum L. rhizome extract on human UV-stimulated melanocytes. METHODS: The effects of Rheum rhaponticum rhizome extract on tyrosine kinase activity, and on interleukin-1α (IL-1α), tumour necrosis factor α (TNF-α), and α-MSH production in human epidermal melanocytes were evaluated under UV-stimulated and non-stimulated conditions. Antioxidant activity was evaluated by lipid peroxidation and 1,1-dyphenyl-2-picryl-hydrazyl (DPPH) assays, while anti-tyrosinase activity was evaluated by the mushroom tyrosinase method. RESULTS: Rheum rhaponticum L. rhizome extract showed in vitro antioxidant properties against lipid peroxidation, free radical scavenging and anti-tyrosinase activities, and inhibited the production of IL-1α, TNF-α, α-MSH, and tyrosine kinase activity in melanocytes subjected to UV radiation. CONCLUSIONS: These results support the inclusion of Rheum rhaponticum L. rhizome extract into cosmetic, sunscreen and skin care products for the prevention or reduction of photodamage.

Triple nanoemulsion potentiates the effects of topical treatments with microencapsulated retinol and modulates biological processes related to skin aging.

BACKGROUND: The sum of environmental and genetic factors affects the appearance and function of the skin as it ages. The identification of molecular changes that take place during skin aging provides biomarkers and possible targets for therapeutic intervention. Retinoic acid in different formulations has emerged as an alternative to prevent and repair age-related skin damage. OBJECTIVES: To understand the effects of different retinoid formulations on the expression of genes associated with biological processes that undergo changes during skin aging. METHODS: Ex-vivo skin samples were treated topically with different retinoid formulations. The modulation of biological processes associated with skin aging was measured by Reverse Transcription quantitative PCR (RT-qPCR). RESULTS: A formulation containing microencapsulated retinol and a blend of active ingredients prepared as a triple nanoemulsion provided the best results for the modulation of biological, process-related genes that are usually affected during skin aging. CONCLUSION: This association proved to be therapeutically more effective than tretinoin or microencapsulated retinol used singly.

Avaliação in vitro do perfil de segurança de cosmecêuticos contendo fatores de crescimento e seus análogos / In vitro evaluation of the safety profile of cosmeceuticals containing growth factors and their analogues

Introdução: Envelhecimento cutâneo é afecção que atinge ou atingirá todas as pessoas, e seu tratamento representa desafio clínico. Os fatores de crescimento e seus análogos surgem como promissora opção terapêutica. Objetivos: avaliar o perfil de segurança de alguns produtos dermocosméticos à base de fatores de crescimento ou seus análogos destinados a esse fim, utilizando modelos in vitro de cultura de células da pele humana. Métodos: foram estudados dois tipos de culturas celulares, com a avaliação dos efeitos dos produtos teste sobre a proliferação de células tumorais (células de melanoma) e sobre a proliferação de fibroblastos humanos normais. Resultados: não foram encontradas alterações morfológicas significativas nas culturas de melanoma humano e não houve alterações significativas no número de células saudáveis, pelo menos na cultura de fibroblastos normais, tendo mesmo havido em alguns deles a proliferação dessas células. Conclusões: Esses dados preliminares demonstram que os produtos cosmecêuticos que contêm fatores de crescimento como ativos principais podem ser considerados seguros para aplicação tópica.

Introduction: Aging skin is a condition that affects (or will affect) all people, and its treatment is considered a clinical challenge. Growth factors and their analogues are emerging as a promising therapeutic option. Objectives: To evaluate the safety profile of some dermocosmetic products with formulations based on growth factors ­ or their analogs intended for that purpose ­ using in vitro human skin cell culture models. Methods: Two types of cell cultures were studied, and the effects of the study products on the proliferation of melanoma cells and normal human fibroblasts were evaluated. Results: No significant morphological alterations were found in the cultured human melanoma, and no significant decrease in the number of healthy cells was verified in the normal fibroblasts culture. In some cases there was even a proliferation of those cells. Conclusions: These preliminary data demonstrate that cosmeceutical products containing growth factors as an active principle can be considered safe for topical application.

Eficácia in vitro e clínica do uso cosmético tópico de fitoestrógenos em pele fotoenvelhecida / In vitro and clinical efficacy of the use of phytoestrogens-based topical cosmetic use in photoaged skin

Introdução: O tratamento do envelhecimento cutâneo representa um desafio clínico. Objetivos: Avaliar a eficácia in vitro e in vivo, e a segurança clínica de cosmético com fitoestrógenos na abordagem do fotoenvelhecimento. Métodos: A etapa in vitro foi realizada pela análise da expressão gênica de fibronectina e pró-colágeno, avaliação da atividade imunomoduladora e análise histoquímica e por imunofluorescência da pele e da junção dermoepidérmica com o produto analisado. No estudo clínico in vivo foi 76 mulheres, foram randomizadas em dois grupos: o Grupo A usou creme contendo complexo de fitoestrógenos e FPS 20 duas vezes ao dia, enquanto o Grupo B usou este mesmo creme associado a outro com função de antienvelhecimento aplicado à noite. O estudo durou 120 dias tendo sido realizadas mensalmente avaliações médicas, da voluntária, ultrassonografia (20MHz), fotografias e biópsias pré e pós-tratamento. Resultados: No estudo in vitro houve aumento na expressão de fibronectina e procolágeno, potencial imunomodulador, representado pelo aumento de IL-1α diminuição de IL-10; melhora da integridade da JDE, aumento da viabilidade e espessura da epiderme, e da síntese de colágeno. in vivo: melhora global subjetiva da aparênciada pele da face; redução de manchas, eritema, poros e porfirina cutânea. O ultrassom e a biópsia revelaram aumento da densidade dérmica (52,7%) e de fibras dérmicas (22,25%), respectivamente. Conclusões: Fitoestrógenos tópicos melhoram a condição geral da pele, avaliada clínicamente, histológicamente e por ultrassonografia; acrescentam-se resultados in vitro de aumento da síntese de fibronectina, prócolágeno e colágeno, melhoria da integridade da junção dermoepidérmica e restauração da resposta imunológica da pele.

Introdução: Introduction: Skin aging is a challenge to treat. Objectives: To evaluate the in vitro and in vivo efficacy and clinical safety of a phytoestrogens-based cosmetic in the management of photoaging. Methods: The in vitro investigation was performed using the analysis of the genic expression of fibronectin and procollagen, evaluation of the immunomodulatory activity (proinflammatory and anti-inflammatory cytokines synthesis) and histochemistry and immunofluorescence analyses of the skin and the dermoepidermal junction. The in vivo investigation ­ performed in 76 women randomized into Group A (phytoestrogens complex cream and SPF 20 twice daily) or Group B (the same product plus a commercially available anti-aging cream applied overnight). The study lasted for 120 days, with physician- and patient-led evaluations, in addition to monthly ultrasound (20 MHz) and photographic analysis. Skin biopsies of the face were performed before and after treatment. Results: The study showed In vitro: increase in the expression of fibronectin, in procollagen, immunomodulator potential, represented by an increase in IL-1α and a decrease in IL-10; improvement in the integrity of the dermoepidermal junction; increase in the viability and thickness of the epidermis; increase in collagen synthesis .In vivo: subjective global improvement of the skin's appearance; reduction in the count and intensity of spots, erythema, skin pores, and cutaneous porphyrin. The ultrasound and biopsy revealed increased dermal density (52.7%) and dermal fibers (22.3%), respectively. Conclusions: The topical use of phytoestrogens-based cosmetics improves the overall condition of the skin.

Expression of differential genes involved in the maintenance of water balance in human skin by Piptadenia colubrina extract.

BACKGROUND: Hydration and integrity of the stratum corneum (SC) is an important determinant of skin appearance, metabolism, mechanical properties, and barrier function. The presence of aquaglyceroporins and envelope proteins are crucial to provide greater corneocyte cohesion to keep water and other moisturizers in the skin. AIMS: In this study, we evaluated the ability of Piptadenia colubrina, a plant native of South American rain forests, in the expression of genes involved in skin capacitance and SC integrity. METHODS: The expression of genes for aquaporin-3 (AQP3), loricrin, involucrin (INV), and filaggrin (FLG) was measured by real-time PCR, using an in vitro model of human keratinocytes incubated with concentrations of 2.5, 5, 10, and 20 mg/mL of a hydroglycolic extract of P. colubrina (HEPC). The amount of AQP3 protein was also tested by immunohistochemistry in human skin explants. Clinical trials were conducted to evaluate the effects of a gel-cream containing HEPC on the glycerol index and skin capacitance. RESULTS: Hydroglycolic extract of P. colubrina increased both the expression and immunoreactivity of AQP3 in cultured keratinocytes and human skin explants. The gene induction to envelope proteins FLG and INV was also observed after cell incubation with HEPC. Skin capacitance was significantly improved in human volunteers under treatment with HEPC-containing cream. CONCLUSIONS: The extract of P. colubrina promotes cellular hydration and induces gene expression of envelope proteins providing greater corneocyte cohesion to keep water and other moisturizers in the skin and an appropriate epidermal adhesion. The in vitro findings were clinically confirmed and encourage the clinical use of this compound in skin care products.

Effects of a Brazilian herbal compound as a cosmetic eyecare for periorbital hyperchromia ("dark circles").

BACKGROUND: Evidence suggests that periorbital hyperchromia (dark circles) occurs mainly as a consequence of postinflammatory hemodynamic congestion producing a typical bruising aspect on the lower eyelids. AIMS: To evaluate the clinical effects of Pfaffia paniculata/Ptychopetalum olacoides B./Lilium candidum L.-associated compound (PPLAC) on periorbital hyperchromia and to study in vitro its underlying anti-inflammatory and antioxidant mechanisms. METHODS: Twenty-one volunteers presenting with periorbital hyperchromia received a serum sample containing 5.0% PPLAC, which was applied topically in the periorbital area twice a day for 28 days. Skin color was measured using variations in the individual typological angle (DeltaITA(0)) and skin luminance (DeltaL*) calculated in the area around the eyes and in the adjacent area. Colorimetric readings were taken at the onset and end of the 28-day treatment. Volunteers were also asked to fill out a questionnaire concerning the improvement in "dark circles." The anti-inflammatory and antioxidant effects of PPLAC were measured by quantification of prostaglandin E(2), leukotriene B(4), histamine, and superoxide dismutase levels using an in vitro model of human skin culture. RESULTS: Topical application of PPLAC led to a significant improvement in skin luminance and tone in the periorbital area, which was demonstrated by increased values of ITA(0) and L* in about 90% of volunteers. In addition, subjects reported reduced intensity and improved appearance of "dark circles." A dose-dependent decreased production of inflammatory mediators, concomitant to increased antioxidant enzyme levels, was observed in our in vitro studies, under basal and lipopolysaccharide-stimulated conditions. CONCLUSIONS: Although the precise mechanisms related to PPLAC remain to be clarified, our results indicate that the reduction in the inflammatory process as well as the antioxidant protection against deleterious elements may be considered as an integral approach to preserve the integrity of vascular endothelium, preventing the hemodynamic congestion that culminates in the formation of "dark circles" around the eyes.

Effect of green Coffea arabica L. seed oil on extracellular matrix components and water-channel expression in in vitro and ex vivo human skin models.

BACKGROUND: Green Coffea arabica L. seed oil is being widely used in cosmetic formulations, although its effects on human skin cells are not clear and most observations are unpublished. AIMS: In this study, we evaluated the in vitro effects of green coffee (C. arabica L.) oil (GCO) on the synthesis of collagen, elastin, and glycosaminoglycans (GAG) and in the release of transforming growth factor-beta1 (TGF-beta1) and granulocyte-macrophage colony-stimulating factor (GM-CSF) by human skin fibroblasts. We also investigated the ability of GCO to increase aquaglycerolporins-3 (AQP-3) mRNA expression in cultured keratinocytes and human skin explants. METHODS: Human fibroblasts were incubated for 48 h with several GCO concentrations (3.12, 6.25, 12.5, 25.0 and 50.0 mg/mL). The levels of growth factors and extracellular matrix compounds in the culture supernatant were measured using commercial kits. To evaluate AQP-3 relative expression, using real-time reverse transcription polymerase chain reaction, keratinocytes were incubated for 3-6 h with the GCO optimal concentration of 25.0 mg/mL. Histological sections of human skin were also incubated with GCO (25.0 mg/mL) and immunostained by antiserum against AQP-3. RESULTS: Our results demonstrated that incubation with GCO produces a dose-dependent stimulation in the synthesis of collagen, elastin, and GAG, in addition to increasing the release of the growth factors TGF-beta1 and GM-CSF. GCO also induced the expression of AQP-3 mRNA, which reached levels up to 6.5-fold higher than those of the control cultures. CONCLUSION: The findings presented herein suggest that GCO might improve physiological balance in the skin, thus allowing the formation of new connective tissue, and preventing epidermis dryness by increasing AQP-3 levels. Taking into account the limitations of in vitro studies, it is encouraging in this context to consider CGO as an adjuvant to be used in dermocosmetic formulations. Clinical studies are in progress in our laboratory aiming to further investigate the protective effects of CGO in the skin.

Effects of Coccoloba uvifera L. on UV-stimulated melanocytes.

BACKGROUND: Exposure to ultraviolet (UV) radiation induces generation of reactive oxygen species, production of proinflammatory cytokines and melanocyte-stimulating hormone (MSH) as well as increase in tyrosinase activity. The potential photoprotective effects of Coccoloba uvifera extract (CUE) were evaluated in UV-stimulated melanocytes. METHODS: Human epidermal melanocytes were used as an in vitro model to evaluate the effects of CUE on the production interleukin-1alpha (IL-1alpha), tumor necrosis factor alpha (TNF-alpha), and alpha-MSH under basal and UV-stimulated conditions. Antioxidant and anti-tyrosinase activities were also evaluated in membrane lipid peroxidation and mushroom tyrosinase assay, respectively. RESULTS: Coccoloba uvifera L. showed antioxidant and anti-tyrosinase activities and also inhibited the production of IL-1alpha, TNF-alpha and alpha-MSH in melanocytes subjected to UV radiation (P<0.01). Moreover, CUE inhibited the activity of tyrosine kinase in cell culture under basal and UV radiation conditions (P<0.001), corroborating the findings of the mushroom tyrosinase assay. CONCLUSION: This study supports the photoprotective potential of CUE.

Relievene® SK: neuroimunomodulação para o tratamento dermocosmético da pele sensível / Relievene® SK: neuroimunomodulation for dermocosmetic treatment of sensitive skin

Pele sensível (PS) é definida como uma condição de tolerância reduzida ao uso freqüente ou prolongado de cosméticos e produtos de higiene pessoal, que apresenta desde sinais clínicos visíveis, como eritema, edema e descamação, até sinais neurossensoriais subjetivos de desconforto, como pinicamento, queimação, prurido, ressecamento e dor. A fisiopatologia da PS consiste em reação inflamatória decorrente de uma disfunção da barreira cutânea associada ao desequilíbrio da resposta neuroimunoendocrinológica da pele. Neste trabalho demonstramos os efeitos do produto Relievene® SK sobre a proteção do metabolismo celular, considerando as atividades adaptógena e neuroendócrina deste composto, bem como a melhora da função da barreira cutânea e da hiper-reatividade da pele em indivíduos com PS.

Neuroimmunomodulatory compound for sensitive skin care: in vitro and clinical assessment.

BACKGROUND: The pathophysiology of sensitive skin consists of an inflammatory reaction resulting from the abnormal penetration in the skin of potentially irritating substances, which occurs due to skin barrier dysfunction and changes in the production of local neuromediators. AIMS: The therapeutic potential of L-carnosine and Rhodiola rosea, as antioxidant and neuromodulatory, respectively, leads us to investigate the effects of the R. rosea extract/L-carnosine-associated compound (RCAC) on sensitive skin alterations. METHODS: A double-blind comparative study was conducted on 124 volunteers with sensitive skin, who were selected by their reactivity to stinging test. Two randomized groups of 62 each received either a formulation containing 1% of RCAC or placebo, which was applied twice a day for 28 consecutive days. One perceptibility questionnaire was applied at the onset and at the end of the treatment to evaluate the subjective response to test product. Additionally, in vitro studies were performed to investigate RCAC neuroimmunomodulatory mechanisms. RESULTS: RCAC treatment produced in vivo protective effects in skin barrier function and a positive subjective response of sensitive skin volunteers. In vitro treatment promoted the release of proopiomelanocortin peptides and restored to normal the increased levels of neuropeptides and cytokines produced by keratinocytes exposed to ultraviolet radiation. Clinical effectiveness was measured by reduction of transepidermal water loss, positive perceptions of improvements in skin dryness and skin comfort sensation, and reduction of discomfort sensation after stinging test. CONCLUSIONS: The protective effect of RCAC in skin barrier function and the positive response produced in human subjects with sensitive skin could be partially explained by our in vitro results showing a significant increase in opioid peptides release, an inhibitory effect on neuropeptides production, and modulation of cytokines production by keratinocytes under ultraviolet stress.