FLAVONOIDS FROM VERNONIA-AMYGDALINA AND THEIR ANTIOXIDANT ACTIVITIES

Flavonoids occurring in Vernonia amygdalina leaves have been studied. Three flavones were identified with chemical and spectroscopic techniq ues. They were identified as luteolin, luteolin 7-O-beta-glucuronoside , and luteolin 7-O-beta-glucoside. The most abundant compound was lute olin 7-O-beta-glucuronoside. The antioxidant activity of the three fla vones was determined by measuring the coupled oxidation of beta-carote ne and linoleic acid. It was shown that luteolin was a significantly m ore potent antioxidant than the synthetic antioxidant butylated hydrox ytoluene (BHT) at the same concentration (15 mg/L). The two glycosides showed similar activities but significantly lower activities than lut eolin or BHT.