Stimulatory effect of dietary red ginseng on epidermal levels of hydration and ceramides in ultraviolet radiated hairless mice

Ultraviolet (UV) radiation induces skin dryness, which largely depends upon disruption of epidermal barrier. As searching dietary and plant sources of protecting from skin dryness, hairless mice were fed diets of either 0.5% or 1.0% red ginseng extract (groups H0.5 and H1.0) for 5 wks in parallel with UV radiation. As controls, two groups were fed a control diet with (group C) or without UV radiation (group UV) for 5 wks. With no differences in food intake and weight gains among all groups, epidermal levels of hydration and ceramides, the major lipid maintaining epidermal barrier, in group H0.5 were similar to those in the non‐UV radiated, normal control group (group C). In addition, protein expression of serine palmitoyl transferase (SPT), an enzyme of de novo ceramide synthesis, was increased. However, epidermal levels of hydration and ceramides in group H1.0 did not differ from in the UV radiated control group (group UV), in which ceramidase, an enzyme of ceramide degradation, is highly expressed. Together, we demonstrate that dietary supplementation of 0.5% red ginseng protects skin from UV induced dryness with the accumulation of ceramides coupled with a high expression of SPT protein.