Antioxidant activity of compounds isolated from Salvia plebeia

Six compounds, hispidulin-glucuronide (1), hispidulin-7-O-D-glucoside (2), 6-methoxy-luteolin-7-glucoside (3), p-sitosterol (4), 2'-hydroxy-5'-methoxybiochanin A (5) and coniferyl aldehyde (6), were isolated from Salvia plebeia and identified by UV, IR, Mass, H-1 and (CNMR)-C-13 spectra. Their antioxidant activities were investigated individually and compared with butylatedhydroxytoluene (BHT) (8) and alpha-tocopherol (7) by the oxidative stability instrument (OSI) at 100 degrees C. Compounds 3, 4 and 5 had strong antioxidant activities, but compounds 1, 2 and 6 had low antioxidant activities at 0.02 and 0.04% levels. (C) 2000 Elsevier Science Ltd. All rights reserved.