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 techniques. They were identified as luteolin, luteolin 7-O-beta-glucuronoside, and luteolin 7-O-beta-glucoside. The most abundant compound was luteolin 7-O-beta-glucuronoside. The antioxidant activity of the three flavones was determined by measuring the coupled oxidation of beta-carotene and linoleic acid. It was shown that luteolin was a significantly more potent antioxidant than the synthetic antioxidant butylated hydroxytoluene (BHT) at the same concentration (15 mg/L). The two glycosides showed similar activities but significantly lower activities than luteolin or BHT.