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. 2023 Mar 25;13(4):876.
doi: 10.3390/life13040876.

Effect of an Emollient Emulsion Containing 15.0% of Caprylic/Capric Triglyceride on the Urocanic Acid of the Stratum Corneum

Alicio Vitorino de Souza Neto  1 , Débora Quintas Balla  1 , Thalita Marcilio Candido  2 , Catarina Rosado  3 , André Rolim Baby  2 , Fabiana Vieira Lima Solino Pessoa  1
Affiliations

Effect of an Emollient Emulsion Containing 15.0% of Caprylic/Capric Triglyceride on the Urocanic Acid of the Stratum Corneum

Alicio Vitorino de Souza Neto et al. Life (Basel). .

Abstract

Natural moisturizing factor (NMF) includes several compounds in the stratum corneum (SC), among them, urocanic acid (UCA). Ultraviolet (UV) exposure turns the trans-UCA of the SC into its cis isomer. We investigated the impact of a topical emollient emulsion treatment on the UCA isomers of the SC exposed to artificial UV stress. Aliquots of emollient emulsion were applied in healthy subjects for 2 h on delimited areas of the volar forearm, then, the SC was removed by tape stripping. Tapes were irradiated in a solar simulator chamber and a high performance liquid chromatograph was used to quantify UCA isomers from stripped SC extract. The amount of both UCA isomers were almost twice higher in the SC treated with the emollient emulsion. We also observed that the UV irradiation elevated the amount of the cis/trans UCA ratio on the SC (non-treated and treated), suggesting that the emollient sample was not able to avoid the UCA isomerization. The in vivo tests corroborated with the UCA data obtained ex vivo, since we found an increase in the superficial skin hydration with respective reduction of the TEWL, probably occurring by the occlusion performed by the emollient emulsion containing 15.0% w/w of caprylic/capric triglyceride.

Keywords: HPLC; TEWL; hydration; stratum corneum; urocanic acid.

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Conflict of interest statement

The authors declare no conflict of interest.

Figures

Figure 1
Figure 1
Amount of trans and cis UCA in SC versus SC + emollient emulsion. ** p = 0.00; *** p < 0.001, n = 12.
Figure 2
Figure 2
Total UCA quantification in the SC and SC + emollient emulsion. *** p < 0.001, n = 12.
Figure 3
Figure 3
Comparison for cis/trans UCA ratio in function after UV stress. p = 0.266 (no irradiated skin x cream); p = 0.910 (irradiated skin x cream); ** p = 0.004 (skin before and after UV); * p = 0.014 (cream before and after UV); n = 12.
Figure 4
Figure 4
Influence of the emollient emulsion in the skin barrier function: (a) TEWL (b) skin superficial hydration. ** p = 0.005 (a); *** p < 0.001 (b); n = 18.
See this image and copyright information in PMC

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