Detection of highly abundant small molecules in the stratum corneum of healthy young women using desorption electrospray ionization-mass spectrometry imaging

[Abstract] Aging reflects skin appearance drastically, which reduces skin juvenescence. However, the small molecules underlying skin juvenescence have not been well studied. We aimed to explore the molecules potentially responsible for young-looking skin. Eleven healthy women aged 24-59 years were recruited and divided into young and middle-aged groups. Multiple layers of the stratum corneum from the cheek area were taken by tape-stripping, followed by desorption electrospray ionization mass spectrometry imaging (DESI-MSI). Overall, five molecules (m/z 284.33, 340.39, 488.39, 628.37, and 863.65) were highly abundant in young subjects. Among them, m/z 284.33 and 340.39 were dominantly detected in each layer of all young subjects. Interestingly, m/z 488.39 and 628.37 were prominent in young subject 4. All of these molecules were gradually decreased in the successive layers of the stratum corneum in subjects 3 and 4 of the young group. These molecules could be endogenous, co-related with youthful skin, or retained from topical cosmetics. Extensive research is indispensable to characterize them and find the relationship between these molecule's retention capacity in the stratum corneum with different skin parameters. Our findings provide a novel perspective on young skin that could be advantageous in future cosmetic formulations to improve skin juvenescence.