Antioxidant activity and phenolic compounds of Swiss chard (Beta vulgaris subspecies cycla) extracts

The antioxidant activity (radical scavenging and thiocyanate method), total phenolic contents (gallic acid equivalents) and phenolic composition (coulometric array detection) in methanol extracts of different parts and tissue types of hydroponically grown Swiss chard (Beta vulgaris subspecies cycla) were determined. Significant differences (P <0.01) in the antioxidant activity were found between leaves and stems. Phenolic content and composition of the leaves and the stems also were found to be different. A positive linear correlation (R=0.943) was demonstrated between radical scavenging activity and total phenolic content of each extract. The major phenolic acid and flavonoid in leaves of Swiss chard were syringic acid and kaempferol. Coulometric array detection showed good reproducibility (CV, 0.06-1.05%) and sensitivity (1 ng/ml, detection limit) for simultaneous detection of 13 phenolics. Our data indicates that Swiss chard has potential as a good dietary source of phenolic antioxidants. (C) 2003 Elsevier Ltd. All rights reserved.