Red pigment from Lithospermum erythrorhizon by supercritical CO2 extraction.

In this study, a stable red pigment was prepared from Lithospermum erythrorhizon via supercritical carbon dioxide extraction. The optimal extraction conditions were 400 bar and 60 degrees C. The patch tests indicated that up to 10% of the red pigment was acceptable from a skin irritation standpoint. According to the results of the CIE LAB chromaticity test, the color difference was acceptable when compared to commercial synthetic red pigments. The light-illuminated color stability test indicated that the pigment was more stable than the red pigment extracted with ethanol. The higher stability was also demonstrated in the DPPH antioxidant activity test. The supercritical red pigment harbored elevated amounts of shikonin and derivatives, and appears to be usable as a stable red pigment for cosmetic color products.