STUDIES ON FREE-RADICAL SCAVENGING ABILITIES OF FOUR CATECHINS AND THEIR BLENDED COMPOSITE

The objectives of this paper were to study the free-radical scavenging abilities of four catechins and their blended composite toward superoxide radical anion （O2·-） and hydroxyl radical （OH·）, and to make a comparison with each other using a chemiluminescence technique. The results showed that EGCG, ECG, EGC and EC could scavenge O2·- at SC50 values of 4.2, 4.9, 5.2 and 6.2 μmol/L respectively, and scavenge OH· at SC50 values of 0.22, 0.25, 0.26 and 0.30 μmol/L respectively. The scavenging rates at the same total concentration of four catechins were as follows: EGCG > ECG > EGC > EC. In addition, orthogonal experimental was used to obtain the optimal ratio of four catechins. The optimal blended composite of scavenging rate toward O2·- and OH· were found to be EGCG:ECG:EGC:EC 3:3:1:1. EGCG was the most important factor and was of the most significance. The scavenging rate of four-catechin composite was higher than those of corresponding individual catechins while EGCG in the composite was high in proportion.