Enhancement of skin defense against UVB damage by fermentation of Leonurus japonicus with Saccharomyces cerevisiae

Background Leonurus japonicus (Chinese motherwort) is a medicinal plant that is widely used in Asia. The fermentation of plant materials can produce bioactive compounds through a series of biochemical reactions that alter the substrate's chemical composition. However, research on the effective components of l. japonicus after probiotic fermentation by fungi is still limited. Purpose This study aimed to explore the effect of products of l. japonicus fermentation supernatant (LF) by various fungi against UVB-induced skin injury. Methods Herein, l. japonicus was fermented using 11 fungal strains, including yeasts and filamentous fungi. Based on the bioactive compounds change in the fermentation products, Saccharomyces cerevisiae was ultimately selected for the fermentation of l. japonicus , and the resulting LF was collected for further research. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to determine the levels of zonula occludens-1, desmoplakin, claudin-7, and loricrin to observe the repair effect of LF on skin barrier damage in HaCaT cells. The expression of interleukin (IL)-1β, IL-6, matrix metalloproteinases (MMP)-8, MMP-3, MMP-13, MMP-9, COL1α1, COL1α2, and COL5α1 was investigated to study the effect of LF on inflammation and anti-aging by using RT-qPCR and ELISA assays in HaCaT or HSF cells. The levels of transient receptor potential vanilloid type 1 (TRPV1) were analyzed to investigate the regulatory effect of LF on Ca 2+ in HaCaT cells. To evaluate LF's protective effects against skin photoaging in vivo, we established a UVB-induced photoaging model on mouse dorsal skin. The expression of PI3K/AKT and ROCK/Frizzled-7/wingless/integrated (WNT) pathway was detected by western blotting in vivo. Results Fermentation of l. japonicus with S. cerevisiae resulted in elevated levels of total alkaloids, phenolic compounds, and flavonoid content. The increase in these bioactive compounds is beneficial for enhancing the antioxidant activity of LF compared to l. japonicus water extracts (LW). Meanwhile, treatment with LF improved skin barrier damage through the WNT-11 signal pathway and the TRPV1 signal pathway. LF can increase skin permeability by promoting Ca 2+ concentration regulation. Collagen degradation was mediated by MMPs and IL-1β. Notably, LF significantly alleviates the levels of inflammatory factors and MMPs, as well as leading to up-regulation of the expression of collagen. Conclusion In summary, our results demonstrate a connection between LF and collagen production, implying that LF plays a role in shielding dermal fibroblasts from UVB-induced aging. These findings support the potential use of LF as an anti-aging supplement in skincare formulations.