Due to the chemical complexity of extracts (or syrups) of
plant sources, different methods are required to assess their
antioxidant activity. In the present study, therefore, seven
complementary methods were followed to evaluate the ability
to scavenge free radicals and the capacity to inhibit lipid peroxidation.
In addition, the correlation of total phenolic contents
and total flavonoids with antioxidant activity of palm
date syrups has been studied. The values of total antioxidant
activity of various palm date syrups on the oxidation of liver
homogenate as a rich source of lipid peroxides were expressed
as percentage inhibition of TBARS formation (Table 1). The
data showed that all palm date syrups had antioxidant activity
as they inhibited lipid peroxidation in a dose-dependent manmanner.
Thus, the results of TBARS obtained from the lowest and
the second levels of syrups have shown that Rotab syrup has
significantly higher activity in preventing lipid peroxidation
in comparison with other syrups. However, at higher levels
all syrups and the positive control showed almost the same
ability to prevent lipid peroxidation.