ISOLATION AND IDENTIFICATION OF A NEW HOMOISOFLAVAN WITH POTENT ANTIOXIDANT ACTIVITY FROM COMMELINA ELEGANS

Potent antioxidative compounds have been isolated from the ethyl acetate extract of Commelina elegans, Commelinaceae, using a repeated column chromatography. On the basis of spectral analyses, the compounds were identified as brazilin, brazilein and the new homoisoflavan-3, 7, 9, 3 ,4 -ol (4-4) dimer with X- and Y-conformers. The compounds inhibited both enzymatic lipid peroxidation using rat liver microsomes and mitochondria and non-enzymatic reactions. The compounds completely protected the activities of the mitochondrial enzymes NADH- and succinate-cytochrome c reductase. Furthermore, the radical scavenging activity on enzymatically and non-enzymatically generated superoxide anion was investigated. Electron spin resonance using the spin trapping method suggested that the compounds have potent superoxide anion scavenging activities.