(roots of Burea plant). Even at the 10 μg/mL level, all extracts
showed slight antioxidant activity ranging from 20.05 ± 0.73%
(stems of Burea plant) to 5.05 ± 0.49% (roots of Bureau plant).
Figure 2 shows the antioxidant activity of the extracts from
the same plant samples tested by the MA/GC assay. Values are
mean ± SD (n = 3). This assay involves analysis of a secondary
lipid peroxidation product, MA, which is formed at the last
stage of lipid peroxidation.3 In addition, this assay can monitor
how much antioxidant inhibits the formation of genotoxic MA.
All extracts exhibited antioxidant activity with a clear dose
response. Antioxidant activity at 160 μg/mL (the highest
concentration tested) ranged from 76.17 ± 0.27% (roots of
Burea plant) to 59.32 ± 0.27% (stems of Mulberry tea). Even at
the level of 20 μg/mL, extract from the Mulberry teas made
from stems (47.29 ± 1.59%) and leaves (36.18 ± 7.50%)
showed moderate antioxidant activity. Previous reports also
indicated the presence of antioxidants in extracts from
Mulberry,23 Camellia sinensis,13 and Cudrania tricuspidata.14
These reports and the results from the present study suggest
that some antioxidant constituents were present in these
extracts.