ANTIOXIDANT PROPERTIES OF BUTEIN ISOLATED FROM DALBERGIA-ODORIFERA

The antioxidant properties of butein, isolated from Dalbergia odorifer a T. Chen, were investigated in this study. Butein inhibited iron-indu ced lipid peroxidation in rat brain homogenate in a concentration-depe ndent manner with an IC50, 3.3 +/- 0.4 mu M. It was as potent as alpha -tocopherol in reducing the stable free radical diphenyl-2-picrylhydra zyl (DPPH) with an IC0.200, 9 2 +/- 1.8 mu M. It also inhibited the ac tivity of xanthine oxidase with an IC50, 5.9 +/- 0.3 mu M. Besides, bu tein scavenged the peroxyl radical derived from 2,2-azobis(2-amidinopr opane) dihydrochloride (AAPH) in aqueous phase, but not that from 2,2- azobis(2,4-dimethylvaleronitrile) (AMVN) in hexane. Furthermore, butei n inhibited copper-catalyzed oxidation of human low-density lipoprotei n (LDL), as measured by conjugated dienes and thiobarbituric acid-reac tive substance (TBARS) formations, and electrophoretic mobility in a c oncentration-dependent manner. Spectral analysis revealed that butein was a chelator of ferrous and copper ions. It is proposed that butein serves as a powerful antioxidant against lipid and LDL peroxidation by its versatile free radical scavenging actions and metal ion chelation . (C) 1998 Elsevier Science B.V.