3.3. DPPH radical-scavenging activity and inhibition of deoxyribose
degradation
The antioxidant properties of phenolic substances vary significantly
depending on their functional groups (Rice-Evans, Miller,& Paganga, 1996). Therefore, when the antioxidant activity of a
mixture of phenolic substances is evaluated it is important to compare
the effect of concentration as well as the quality of phenolic
substances on the antioxidant activity. The antioxidant activity of
the phenolic extracts of CECO and HECO was determined by DPPH
radical-scavenging activity assay and deoxyribose assay. The DPPH
radical-scavenging activity and the inhibition of deoxyribose degradation
are shown in Figs. 3 and 4, respectively. Both concentration
effect and the quality of phenolic substances on the
antioxidant activity are illustrated in Figs. 3 and 4. To determine
the direct dependence of antioxidant activity on the phenolic contents,
the colorimetrically determined total phenolic contents of
CECO and HECO were adjusted to the known concentrations by
suitable dilutions. BHT was used as the control to compare the
antioxidant activity.