Skin-Whitening and Anti-Photoaging Activities of Limosilactobacillus reuteri DS0333 Culture Supernatant Produced in Unripe Rubus occidentalis L. Extract-Supplemented Medium.

This study investigated the skin-whitening and anti-photoaging activities of a culture supernatant obtained by cultivating Limosilactobacillus reuteri DS0333 in chemically defined medium (CDM) supplemented with unripe Rubus occidentalis L. extract (UROE). DS0333 was cultured in UROE-supplemented medium, and the resulting DS0333/(CDM+UROE) group was evaluated alongside all control and comparison groups. The DS0333/(CDM+UROE) culture supernatant showed enhanced DPPH and ABTS radical scavenging activities compared with all other experimental groups. In α-MSH-stimulated B16F10 cells, the culture supernatant reduced melanin content and intracellular tyrosinase activity and downregulated MITF, TRP-1, and TRP-2 expression. In UVB-irradiated human dermal fibroblasts, the culture supernatant increased type I procollagen production, reduced MMP-1 levels, and suppressed MMP-1/MMP-3 expression through attenuation of the MAPK/AP-1 signaling pathway. These results suggest that culturing DS0333 in UROE-supplemented medium enhances skin-whitening and anti-photoaging activities, potentially through cultivation-associated modification of extracellular metabolites in the culture matrix. Therefore, the DS0333/(CDM+UROE) culture supernatant may serve as a promising multifunctional cosmetic ingredient for skin applications.