Evaluating In Vivo Penetration of Yeast Rice Ferment Filtrate Into Skin Using Confocal Raman Microspectroscopy: A...

Investigating the skin penetration behavior of pharmaceuticals and cosmetics is crucial. Due to the Raman-active properties of many active ingredients, Confocal Raman microspectroscopy (CRM) emerges as a promising, non-invasive technique for penetration studies.

To evaluate the in vivo penetration behavior of yeast rice ferment filtrate (RFF) into the skin using CRM.

Raman spectra of RFF were acquired at 0.5, 1, 2, and 4 h post-application using CRM. The penetration of RFF at various skin depths (10-40 µm) and different time points was analyzed. Multivariate analysis was applied to generate Raman spectral maps that can show RFF depth penetration and spatial distribution across different skin layers.

RFF surpassed the stratum corneum barrier within 30 min and penetrated into the dermis layer after 4 h of application, indicating rapid permeation kinetics. Quantitative analysis, based on Raman spectra, showed increasing RFF penetration over time, reaching 1.02%, 3.17%, 5.29%, and 8.75% after 0.5, 1, 2, and 4 h, respectively. The heat map visualized depth penetration and spatial distribution, indicating a significant increase in penetration with extended application durations.

CRM proves to be a powerful tool for studying the in vivo penetration of RFF into the skin, offering valuable insights into the complex dynamics underlying its permeation behavior.