Antioxidant properties of dried `kayamo-nori', a brown alga Scytosiphon lomentaria (Scytosiphonales, Phaeophyceae)

Dried Scytosiphon lomentaria, a brown alga, is a traditional food in the Noto area in Japan. To determine the antioxidant properties of the dried S. lomentaria, assays for antioxidant activities, including suppression of hemoglobin-induced linoleic acid peroxidation, reducing power, ferrous ion chelating, 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging and scavenging of a superoxide anion radical-generated non-enzymatic system were tested in this study. A water extract contained total phenols at about 5.5 mg catechin equivalents (CatE)/g dry sample (DS) and showed strong antioxidant activities in all five assays, especially in the linoleic acid peroxidation assay (about 22 mg CatE/g DS). On the other hand, the antioxidant activities of an ethanol extract were not detected or were very low compared with the water extract. The dietary fibres (crude fucoidan and alginate) showed antioxidant activity, not only in the ferrous chelating (binding) assay, but also in the superoxide anion radical scavenging assay. These results suggest that S. lomentaria is useful seafood and a healthy food having antioxidant activity.