Effects of trans-2-nonenal and olfactory masking odorants on proliferation of human keratinocytes

YMalodorous compounds induce stress responses, mood changes, an increase of skin conductance, activation of the sympathetic nervous system and other physiological changes, and it has been suggested that sensing malodors could provide warning of danger to health. Furthermore, the human body secretes various malodorous compounds as waste products of metabolism, including trans-2-nonenal ((E)-2-nonenal), the amount of which increases with aging. In the present study, we examined the effects of some endogenous malodorous compounds ((E)-2-nonenal, nonanal, pentanal, hexanal, hexanoic acid, hexylamine and isovaleric acid) on cultured human keratinocytes. (E)-2-Nonenal decreased the viability and promoted apoptosis of cultured keratinocytes. It also reduced the thickness and the number of proliferative cells in a three-dimensional epidermal equivalent model. Co-application of masking odorants (dihydromycenol, benzaldehyde, linalool, phenethyl alcohol, benzyl acetate and anisaldehyde), but not non-masking odorants (1,8-cineol, beta-damascone, and o-t-butylcyclohexyl acetate), reduced the effect of (E)-2-nonenal on keratinocyte proliferation, and restored the thickness and number of proliferative cells in a three-dimensional epidermal equivalent model. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

Malodorous compounds can induce stress responses and physiological changes in the body, with certain endogenous malodorous compounds like (E)-2-nonenal affecting the viability and proliferation of human keratinocytes negatively. However, the negative effects of (E)-2-nonenal can be reduced by co-application of masking odorants, leading to restoration of cell proliferation and thickness in a three-dimensional epidermal equivalent model.