In vivo determination of the Infrared-A protection factor on human skin.

BACKGROUND: Chronic exposure to infrared A (IR-A) irradiation causes photoaging. However, daily or acute exposure to IR-A rarely induces erythema or pigmentation. Thus, evaluation of the physiological changes taking place on the skin surface is insufficient for clinical investigations. MATERIALS AND METHODS: We fabricated a novel device to obtain the IR-A protection factor (IPF) on human skin. This device consists of an artificial light source that mimics the actual IR-A intensity of sunlight, and a spectrophotometer to measure the spectral reflectance on the skin surface. The IPF can be determined by measuring the difference in spectral reflectance on the skin before and after the use of products and can be verified by the statistical criterion. A validation study was performed using different light intensities and two experimenters. Finally, we monitored the IPF on 12 commercial cosmetics. RESULTS: After considering the IPF and L*-values, we selected the optimal sample and performed a validation study. Neither the intensity of IR-A irradiation or the experimenters significantly affected the IPF. 12 commercial products exhibited their own IPF values and were verified by statistical criteria, with one exception. CONCLUSION: The present IPF evaluation method was concluded to be robust and reliable. This method is simple and safe for the subjects, and could be helpful for the development of IR-A protection products and the confirmation of product performances.

Synthesis of Kisspeptin-Mimicking Fragments and Investigation of their Skin Anti-Aging Effects.

In recent years, a number of active materials have been developed to provide anti-aging benefits for skin and, among them, peptides have been considered the most promising candidate due to their remarkable and long-lasting anti-wrinkle activity. Recent studies have begun to elucidate the relationship between the secretion of emotion-related hormones and skin aging. Kisspeptin, a neuropeptide encoded by the KISS1 gene, has gained attention in reproductive endocrinology since it stimulates the reproductive axis in the hypothalamus; however, the effects of Kisspeptin on skin have not been studied yet. In this study, we synthesized Kisspeptin-10 and Kisspeptin-E, which are biologically active fragments, to mimic the action of Kisspeptin. Next, we demonstrated the anti-aging effects of the Kisspeptin-mimicking fragments using UV-induced skin aging models, such as UV-induced human dermal fibroblasts (Hs68) and human skin explants. Kisspeptin-E suppressed UV-induced 11 beta-hydroxysteroid dehydrogenase type 1 (11ß-HSD1) stimulation leading to a regulation of skin aging related genes, including type I procollagen, matrix metalloproteinases-1 (MMP-1), interleukin-6 (IL-6), and IL-8, and rescued the skin integrity. Taken together, these results suggest that Kisspeptin-E could be useful to improve UV-induced skin aging by modulating expression of stress related genes, such as 11ß-HSD1.

A novel in vivo test method for evaluating the infrared radiation protection provided by sunscreen products.

BACKGROUND: Infrared radiation (IR) exposure generates reactive oxygen species and induces matrix metalloproteinase-1 expression in human skin. Moreover, while not as acute as ultraviolet radiation, repeated infrared irradiation can result in the photoaging of skin. Broad-spectrum sunscreens can protect skin from IR, but no human in vivo test methods for the evaluation of sunscreens' IR protection effect have been developed. We aimed to develop such a method. MATERIALS AND METHODS: We included 155 Korean subjects in our three-part clinical study. The IR reflectance of subjects' skin was measured using a benchtop model of an IR light source and a reflectance measuring probe. We measured the IR reflectance in relation to skin color and hydration level to set up our experimental conditions. We then calculated the infrared protection factors (IPFs) of cosmetic emulsions as the IR reflectance ratio between cosmetic sunscreen-applied skin and non-sunscreen-applied skin and assessed the relationship between IPFs and the amount of sunscreen ingredients. Finally, this method was validated using several commercial sunscreen cosmetics. RESULTS: Skin color and hydration level did not influence the IR reflectance of subjects' skin. The IPFs of cosmetic sunscreens showed a positive correlation with the amount of inorganic sunscreen ingredients. CONCLUSION: In this study, we developed a simple, fast, and ethically acceptable human in vivo test method for evaluating the IPFs of cosmetic sunscreens.

Depth profiling of epidermal hydration inducing improvement of skin roughness and elasticity: in vivo study by confocal Raman spectroscopy.

INTRODUCTION: Skin hydration in the stratum corneum plays an important role in skin condition, and skin efficacy properties are influenced by its hydration level. However, few studies have identified the correlation between changes in skin hydration content and skin characteristics by skin depth level. AIMS: This study aims to determine how changes in skin hydration at specific depth levels affect skin condition by long-term tracking changes in hydration of stratum corneum and viable epidermis after usage of moisturizer. METHODS: Ten volunteers were recruited and subjected to in vivo confocal Raman spectroscopy to perform water content profiling at skin depths of up to 52 µm. Mechanical properties of skin were measured using Cutometer and Antera 3D. Skin-elasticity and roughness values observed before and after 15 days of moisturizing emulsion use were compared to demonstrate the correlation between observed changes in skin efficacy parameters and skin water content at specific depths. RESULTS: Significant increase in relative water content at specific depths was observed in this study. Among mechanical properties of skin, only R4, R6, and R8 parameters demonstrated significant changes. Additionally, rates of change in values of the R6 and R8 parameters revealed a high correlation with water content changes at viable epidermis depths below the stratum corneum. On the other hand, skin roughness parameter showed a correlation with water content changes at the outermost layer of stratum corneum. CONCLUSION: Results of this study indicate that skin elasticity is influenced by its hydration level at viable epidermis depths and skin roughness at stratum corneum each. This suggests that monitoring depth profiles of water content using in vivo confocal Raman spectroscopy provides a breakthrough in tracking the skin efficacy effect of topically applied substances.

Solid-State Fermentation With Aspergillus cristatus Enhances the Protopanaxadiol- and Protopanaxatriol-Associated Skin Anti-aging Activity of Panax notoginseng.

A metabolomics approach was used to profile metabolites of Panax notoginseng fermented with Aspergillus cristatus in two ways, liquid-state fermentation (LF-P) and solid-state fermentation (SSF-P) and examine metabolite markers representing antioxidant activity and skin anti-aging. Protopanaxadiol (PPD) and protopanaxatriol (PPT) contents were higher in SSF-P than in LF-P and showed a multiplicative increase over the fermentation period of four days. PPD and PPT levels also correlated with antioxidant and anti-aging effects in skin, based on the mRNA expression of dermal extracellular matrix components. In the bioactivity validation assays, PPD and PPT significantly improved the expression of type-I collagen, fibrillin-1, and elastin in human dermal fibroblasts from both young and old subjects; these were comparable with the effects of the SSF-P extracts. Overall, our results suggest that changes in the metabolites of P. notoginseng fermented with A. cristatus enhance the quality and availability of bioactive compounds associated with skin anti-aging.