The results (Fig. 2) indicate that the scavenging activity
of seaweed extracts were concentration dependent. However,
the positive control (a-tocopherol) did not show dose
dependency and had a DPPH and hydroxyl radical scavenging
activities about 95% and 78%, respectively. The
scavenging activity was found to increase with increasing
concentration of extract in both the DPPH and deoxyribose
assay and corroborated well with earlier reports
(Ismail and Hong, 2002; Kuda et al., 2005). However, themethanol extracts showed a relatively low DPPH scavenging
activity (Fig. 2) as compared to standard antioxidant
(a-tocopherol). This present finding corroborates well with
earlier reports in other higher plants including brown/red
seaweeds (Kuda et al., 2005; Kumaran and Karunakaran,
2007). Further, methanol extracts of all the three brown
seaweeds showed higher hydroxyl radical scavenging activity
compared to standard antioxidant (Fig. 2).