Retention of water in the stratum corneum of skin epidermis plays an important role in regulation of skin function. Loss of water may decline skin appearance gradually and lead to irregular skin disorders. The root extract of Lithospermum erythrorhizon (LES) is known to help in increasing skin humidity.
Lithospermum is a genus of plants belonging to the family Boraginaceae. The genus is distributed nearly worldwide, but most are native to the Americas and the center of diversity is in the southwestern United States and Mexico. Species are known generally as gromwells or stoneseeds. The dried root of Lithospermum erythrorhizon is a Chinese herbal medicine with various antiviral and biological activities, including inhibition of human immunodeficiency virus type 1 (HIV-1). Lithospermum purpurocaeruleum is native to Japan, where it has been traditionally been used to make a purple dye.