Kaempferol (11) exhibited the most potent antioxidant
activity among the five compounds, with TROLOX equivalent
(TE) values of 2.36 in the FRAP assay and 2.4 in the DPPH
assay (Figure 6). Due to the presence of a catechol moiety,
quercetin-3-O-β-D-glucopyranoside (6) displayed good antioxidant
activity with a TE value of 0.56 in both the FRAP and
DPPH assays, comparable to that of catechin (4), which had
TE values of 0.56 in the FRAP assay and 0.44 in the DPPH
assay. The presence of a catechol moiety also imparts
dihydrochalcone-type structures such as 3′-hydroxyphloretin
(10) and its rhamnoside glycyphyllin B (1) antioxidant
activities with TE values of 0.64 and 0.88 for 10 and 0.72
and 0.48 for 1 in the FRAP and DPPH assays, respectively. In
contrast to 1 and 10, glycyphyllin A (3) and its aglycone.