Background: Skin dryness is an omnipresent symptom in various types of skin disorders. Thereby, a large panel of skin care products is developed for therapeutic purposes. However, there is still a lack of non-invasive methods to determine the mechanisms of action of moisturizers at the molecular level.
Methods: In the present study, confocal Raman spectroscopy coupled to classical least square analyses and ATR-FTIR were used to investigate the effect of different molecules on the stratum corneum (SC) hydration degree and barrier state. First, hygroscopic property was determined by analyzing samples at 90% RH; secondly, the water barrier function was evaluated after the dehydration process (4% RH). The molecules penetration kinetics across SC were also studied for 2 h.
Results: Using the present approach, glycerin and propylene glycol were found to be humectants; lanoline showed occlusive action, lactic acid has both humectant and barrier enhancer properties, and ethylhexyl palmitate and caprylic/capric acid triglyceride seemed to be emollients. These observations are in accordance with literature.
Conclusion: The present method non-invasively characterizes the mechanism of action of tested molecules. This may improve knowledge of new molecules' structure-activity relationship and help make an effective therapeutic concept dealing with the various skin dysfunctions.
Keywords: ATR-FTIR; Raman spectroscopy; classical least square analysis; skin moisturizers; stratum corneum barrier function.
© 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.