Topical dexpanthenol effects on physiological parameters of the stratum corneum by Confocal Raman Microspectroscopy

Abstract

Background: Topical use of dexpanthenol presents well-established moisturizing properties and maintenance and repair of the skin barrier function, however, its exact action mechanisms are not completely elucidated. In this context, Confocal Raman Microspectroscopy is an optical method that enables non-invasive and non-destructive in vivo analysis with the sensitive acquisition of molecular changes in different skin layers. Herein, the aim was to evaluate the effects of topical dexpanthenol on the components and physiological parameters of the stratum corneum (SC).

Materials and methods: Ten healthy female subjects underwent skin evaluation by means of a Confocal Raman Spectrometer Skin Analyzer 3510. Spectral data were obtained from the skin of the anterior forearm region, before and 2 h after applying a cosmetic formulation containing or not containing 5% dexpanthenol.

Results: Semiquantitative analysis of the natural moisturizing factor showed a significant decrease in content after 2 h of topical dexpanthenol application, while the analysis of the lamellar organization of intercellular lipids and the secondary structure of keratin showed a significant increase in hexagonal organization of lipids at the first half of the SC and a significant increase in β-pleated sheet conformation of keratin.

Conclusion: Effects of topical dexpanthenol on SC suggest a contribution in increasing fluidity of both lipidic and protein components of the SC and are compatible with dexpanthenol activity in maintaining adequate physiological conditions and preventing transepidermal water loss. This study also contributes to the elucidation of action mechanisms and other concurrent biochemical processes.

Keywords: dexpanthenol; intercellular lipids; natural moisturizing factor; skin barrier function.

FIGURE 1

On the left, the dendrogram obtained from the background corrected spectra of the skin before the application of F1 and F2 (T0) highlighting the spectral range of 1000–1700 cm⁻¹ employed for the HCA analysis and, on the right, the depth profile of keratin in relative amounts highlighting the data points obtained from each respective spectrum and averaged over all individual depth profiles (n = 10).

FIGURE 2

Normalized and background corrected spectra of dexpanthenol, formulation F1 (vehicle), formulation F2 (containing dexpanthenol), and the mean SC at baseline condition (T0) measured at 12.3 μm depth (frame 7). Highlighted in blue are spectral regions of interest 574, 808, 854, 883, 1060, 1080, 1130, and 1650 cm⁻¹.

FIGURE 3

Mean natural moisturizing factor (NMF) profile (n = 5) in relative amounts (a.u.) before (T0) and after 2 h (T2) of application of F1 and F2. *Significantly different (p = 0.0176), paired sample t‐test.

FIGURE 4

Mean profile (n = 9, Grubbs (α = 0.2)) of keratin conformation (β‐sheet and random turns and coils)/α‐helix in relative amounts (a.u.) (A) and mean area under the curve (AUC) (a.u) (B) and, mean profile (n = 10) of buried/exposed tyrosine configuration (a.u.) (C) and mean AUC (a.u) (D), before (T0) and after 2 h (T2) of application of F1 and F2. * Significantly different (p = 0.0646), paired sample t‐test.

FIGURE 5

Mean profile (n = 9, Rout (Q = 1%)) relating the gauche‐trans conformation of ICLs determined with respect to intensities I₁₀₈₀/(I₁₁₃₀ + I₁₀₆₀) (A) in relative amounts (a.u.) (A) and mean area under the curve (AUC) (a.u) (B) before (T0) and after 2 h (T2) of application of F1 and F2. ** Significantly different (p = 0.0399), paired sample t‐test. * Significantly different (p = 0.0850), paired sample t‐test.

FIGURE 6

Mean profile (n = 10) of ceramides and fatty acids (A) in relative amounts (a.u.) and mean AUC (a.u) (B) and, mean profile (n = 10) of cholesterol (a.u.) (C) and mean area under the curve (AUC) (a.u) (D) before (T0) and after 2 h (T2) of application of F1 and F2.