Chiang Mai Journal of Science

The antioxidant activities and antimicrobial activities of dried Scytosiphon lomentaria, a brown alga, were studied in this research. Four isolation methods were adopted for the extraction of total phenols. The yield of total phenols was in the order of hot-water extract > ethanol extract > hot-water/ethanol extract > cold-water/ethanol extract. Antioxidant activities of extracts prepared by the above isolation methods were tested, including 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical-scavenging, ferrous ion chelating, reducing power, scavenging of hydroxyl radical, and anti-lipid peroxidation activities. A hot water extract showed strong antioxidant activities in assays including DPPH radical-scavenging, ferrous ion chelating, and reducing power. On the other hand, a cold water/ethanol extract displayed the highest hydroxyl radical scavenging activity and anti-lipid peroxidation effect, and higher than the control. The hot-water and ethanol extracts of S. lomentaria showed similar antimicrobial activity on Escherichia coli, the growth-free zone of inhibition was 11 mm, 9 mm respectively. The result indicated that S. lomentaria is an excellent resource with application potential as a healthy food.