Antioxidant activity and components of Salvia plebeia R.Br. - a Chinese herb

The antioxidant properties of the extracts from Salvia plebeia R.Br. which was screened out of over 700 species of Chinese herbs, were tested in lard at 110 degreesC using the Oxidative Stability Instrument. The ethyl acetate extract of the herb was re-extracted by solvents (with increasing polarity ) into petroleum ether-, diethyl ether-, acetone-and-ethanol-soluble fracti ons. The fractions obtained were then separated according to their acidic p roperties. From the most active sub-fractions, namely the acidic sub-fracti on of the petroleum ether-soluble fraction and the weakly acidic sub-fracti on of the diethyl ether-soluble fraction, three antioxidant components were isolated and identified as royleanonic acid, hispidulin and eupatorin. The royleanonic acid was a novel compound and eupatorin was isolated for the f irst time from the herb. Though royleanonic acid and hispidulin prolonged t he induction period significantly, their antioxidant activities were much w eaker than the crude extracts, implying that synergistic effects might be r esponsible for the high activity of the crude extracts. (C) 2001 Elsevier S cience Ltd. All rights reserved.