The results obtained in the present study demonstrate the
wide range of antioxidant activities of the plant extracts.
However, it is difficult to pinpoint which constituents give
antioxidative activities to the extracts from these plants because
over 1000 components are present in plant extracts either as
high concentration major components or as minor trace
components.1 Although the activities of these constituents are
not as strong as the known natural antioxidants such as α-
tocopherol, the total activity of these compounds combined
might be comparable to those of known antioxidants. Also,
synergism and antagonism phenomena are important in
evaluating the antioxidant activities of plant extracts. There
are of course many factors involved in the antioxidant activity of
plant extracts. Therefore, more investigations of plant extracts
with the ultimate goal of maximizing their use as pharmacological
products are in order. Determination of the antioxidant
activity of medicinal plants’ components is one avenue through
which we can learn more about their biological activities and
increase the range of alternative natural medicines.