Int J Cosmet Sci. 2021 Aug 17. doi: 10.1111/ics.12730. Online ahead of print.
ABSTRACT
INTRODUCTION: We report on the in vitro and ex vivo effects of chiral (R)-10-hydroxystearic acid (10-HSA) compared with other mono-hydroxystearic acid regioisomers and stearic acid (SA) together with its benefit when combined with retinol.
METHODS: Following treatment with hydroxystearic acids Peroxisomal Proliferator Activated Receptor Alpha (PPARα) activity was determined in a luciferase reporter gene assay, Collagen type I was assessed in primary human dermal fibroblasts by immunohistochemistry, modification of the intracellular fibroblast collagen proteome was studied by mass-spectrometry-based proteomics and Collagen type III was assessed by immunohistochemistry on human ex vivo skin.
RESULTS: 10-HSA was the most effective PPARα agonist (15.7X induction; p<0.001), followed by 9-HSA (10.1X induction) and then 12-HSA (4.9X induction) with 17-HSA (1.7X induction) being similar to the effects of stearic acid (1.8X induction). Collagen type I levels were increased in primary human fibroblasts by 2.12X and 1.56X for 10-HSA & 9-HSA respectively in vitro with the10-HSA being significant (p<0.05): whereas 12-HSA and SA had no statistical effect over the untreated control. 10-HSA and 12-HSA modified the intracellular fibroblast collagen proteome slightly with significant increases in Collagen alpha-1 (VI) and alpha-3 (VI) proteins but only 10-HSA increased levels of Collagen alpha-2 (V), alpha-1 (III), alpha-1 (I) and alpha-2 (I) (all p<0.05) with the increases being significantly different between 10-HSA and 12-HSA for Collagen alpha-1 (I), Collagen-3 (VI) and Collagen alpha-2 (I) (p<0.01). Collagen type III in ex vivo skin was increased +47% (p<0.05) by 0.05% (1.7 mM) retinol, +70% (p<0.01) by 0.01% (0.33 mM) 10-HSA and the combination increased levels by +240% (p<0.01 for either ingredient).
CONCLUSION: Chiral (R)-10-HSA has been shown to be superior to 9, 12 & 17-HSA as a PPARα agonist. Moreover, 10-HSA stimulated collagen synthesis in monolayer fibroblast culture as assessed by proteomics and immunohistochemically. Furthermore, we also show the synergistic effects of 10-HSA with retinol on collagen III synthesis in skin explants. These results further highlight the efficacy of 10-HSA as a cosmetically-acceptable PPARα agonist and anti-aging ingredient.
PMID:34403541 | DOI:10.1111/ics.12730
