Biological activities and utilizations of red pigments in Lithospermum erythrorhizon

Abstract

The root of Lithospermum erythrorhizon has been used as a traditional folk remedy for treatment of blood circulation, injuries and burns in Korea. Especially its red pigments suggested to be main biological constituents in the root were used in Korean traditional liquor. Six kinds of shikonin derivative were isolated as red pigments from the ethanol extract of the root and investigated their biological activities. The isolated compounds showed strong biological activities such as antioxidant, antimicrobial and cytotoxicity. Although shikonin derivatives have potent biological activities, they were used in the limited food application because of the hydrophobic property. In the derivatives, shikonin is relatively bright red color and has low hydrophobicity and cytotoxicity. However, shikonin was a minor compound to be consisted in below 5% among its derivatives. So, the enzymatic method to liberate their derivatives was investigated to produce shikonin from the extracts for increasing the utilization. Enzymatic properties of commercial enzymes that are related to the hydrolysis of an acyl group in triglyceride were investigated. We found esterase originated from pig liver showed very strong activity for producing shikonin (up to 90%) from the crude extract including its derivatives. The application of bioactive red pigments as an antioxidant and antimicrobial agents were also investigated in this study.