Evaluation of antioxidant activity and the fatty acid profile of the leaves of Vernonia amygdalina growing in South Africa

The leaves of Vernonia amygdalina were examined for antioxidant activity and analysed for their fatty acids content. Using transesterification and GC-MS analysis, 12 fatty acids were identified, which accounted for 74.1% of the lipid content. Two essential fatty acids (EFA), linoleic and cy-linolenic acid were found in abundance in the oil. Using DPPH and a ABTS radical scavenging experiments, acetone, methanol and water extracts were screened for their antioxidant activity. The methanol extract exhibited high activity, by scavenging 75-99.3% of the DPPH radicals and 96.2-100% of the ABTS(-+)radicals. These values are higher than those of butylated hydroxytoluene and were less than or equal to those of catechin. The water extract was the least active; its activity ranged from 29% to 88% for DPPH radicals and 76.8-98.3% for ABTS(-+). The presence of EFA and the high antioxidant activity of the leaf extracts have validated the importance of V. amygdalina in the diet. (C) 2006 Elsevier Ltd. All rights reserved.