Antioxidant properties of components extracted from puccoon (Lithospermum erythrorhizon Sieb. et Zucc.)

The petroleum ether extract of puccoon has been separated with thin-layer chromatography (TLC) and three compounds have been isolated. The structures of the compounds have been identified by spectroscopic methods as β,β-dimethyl-acrylshikonin, acetylshikonin and shikonin. Their antioxidant properties in lard have been tested with the oxidative stability instrument (OSI). The raw extracts and pure compounds all have obvious antioxidant activity, and all have some synergistic effects with d,l-α-tocopherol (Ve) and butylatedhydroxytoluene (BHT). They all show antioxidant properties in lard containing Fe3+, and all show synergistic effects with Ve and citric acid (CA) with different degrees. In the concentration range of 0.01–0.06%, antioxidant activity of Ve and BHT, on OSI at 100°C, increases with increase of concentration, but much less than acetylshikonin, shikonin and β,β-dimethyl-acrylshikonin.