The quantification data of individual antioxidants and contents of
the investigated compounds in tea were presented in Table 4 and
Table 5 respectively, which showed that the Trolox equivalent concentration
and the contents of the investigated compounds varied
greatly in different tea samples and revealed significant differences
(p b 0.05) among green tea (S1–S6), oolong tea (S7–S12) and white
tea (S13–S16). The relative contribution of individual active constituents
to the overall scavenging activity was evaluated, which can be
estimated by Trolox equivalent concentration of individual antioxidants.
Table 4 showed clearly that EGCG was the major contributor
to the free radical scavenging activity in tea, which was responsible
from 67.56 to 79.18% of the total antioxidant activity. It was probably
because EGCG not only had the highest TEAC value of 5.822, but also
possessed the highest concentration from 46.58 to 56.43% of the total
amount of the tested ten components which were presented in
Table 5. Nanjo, Mori, Goto, and Hara (1999) also found EGCG to be
the most effective scavenger among tea catechins for the superoxide
anion, hydroxyl radical and DPPH radical. In previous study, it was
proved that intensity of antioxidant peaks depend on both types
and amounts of the antioxidant compounds present in the sample
(Nuengchamnong et al., 2005). EGC, procyanidin dimer and ECG
also contributed greatly to the overall antioxidant capacity of the
tea extracts (from 4.000 to 24.84%, 3.967 to 7.219% and 2.009 to
7.489%, respectively), since both TEAC values and concentrations of
them were relatively high among the tested components except
EGCG.
The quantification data of individual antioxidants and contents ofthe investigated compounds in tea were presented in Table 4 andTable 5 respectively, which showed that the Trolox equivalent concentrationand the contents of the investigated compounds variedgreatly in different tea samples and revealed significant differences(p b 0.05) among green tea (S1–S6), oolong tea (S7–S12) and whitetea (S13–S16). The relative contribution of individual active constituentsto the overall scavenging activity was evaluated, which can beestimated by Trolox equivalent concentration of individual antioxidants.Table 4 showed clearly that EGCG was the major contributorto the free radical scavenging activity in tea, which was responsiblefrom 67.56 to 79.18% of the total antioxidant activity. It was probablybecause EGCG not only had the highest TEAC value of 5.822, but alsopossessed the highest concentration from 46.58 to 56.43% of the totalamount of the tested ten components which were presented inTable 5. Nanjo, Mori, Goto, and Hara (1999) also found EGCG to bethe most effective scavenger among tea catechins for the superoxideanion, hydroxyl radical and DPPH radical. In previous study, it wasproved that intensity of antioxidant peaks depend on both typesand amounts of the antioxidant compounds present in the sample(Nuengchamnong et al., 2005). EGC, procyanidin dimer and ECGalso contributed greatly to the overall antioxidant capacity of thetea extracts (from 4.000 to 24.84%, 3.967 to 7.219% and 2.009 to
7.489%, respectively), since both TEAC values and concentrations of
them were relatively high among the tested components except
EGCG.
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