Data published in Cosmetics indicated that a lotion formulated with 0.1% AOH led to statistically significant larger decrease in trans-epidermal water loss (TEWL) after eight weeks compared to placebo.
In addition, larger increases in the moisture content in the stratum corneum were reported for the AOH formulation, wrote scientists from Vitamin C60 BioResearch Corp in collaboration with researchers from Shizuoka University.
“This study is the first report to show that AOH has the effect of decreasing TEWL,” they wrote.
Building the science
The Japan-based scientists note that this study expands on earlier DNA microarray research, which found that AOH “increased the expression levels of genes involved in skin barrier functions such as intercellular adhesion, stratum corneum exfoliation, and differentiation induction in a concentration-dependent manner”.
“The expression level of HAS3, a type of hyaluronic acid synthase, also increased in a concentration-dependent manner with the addition of AOH, suggesting its moisturizing effect,” they said.
To test an AOH formulation in human subjects, the researchers recruited 20 Japanese adults with an average age of 48 to participate in their a double-blind, placebo-controlled, split-face comparative trial. Skin moisture content was assessed at the start and end of the eight-week study.
The results showed that the AOH lotion led to statistically significant decrease in TEWL, compared to the placebo. While the water content of the stratum corneum was found to increase after AOH application, the difference with the placebo did not reach statistical significance.
“These results indicate that the lotion containing 0.1% AOH had a moisturizing function, as well as a barrier-function-improving or strengthening effect, compared to the placebo lotion,” they wrote.
Importantly, the researchers did not find any adverse events to be causally linked to AOH during the study.
“Based on the results of clinical trials and DNA microarrays, AOH may be a promising cosmetic ingredient for maintaining homeostasis of the skin barrier function. However, the mechanism by which AOH increases the expression levels of barrier function-related gene groups remains to be elucidated,” wrote the researchers.
2021, 8(3), 83; doi: 10.3390/cosmetics8030083
“Clinical Evaluation of Topical Lotion Containing 2-Aza-8-Oxohypoxanthine on Skin Barrier Function against Water Loss”
Authors: H. Aoshima et al.