Antioxidant properties of edible sea weed from the Northern Coast of the Sea of Japan

Introduction. New natural antioxidants remain a relevant research task of food science. Natural antioxidants neutralize free radicals in food systems, as well as in human body. The antioxidant properties of seaweed have attracted scientific attention for many years. However, most experiments featured non-polar extracts while aqueous extracts still remain understudied. The present research objective was to evaluate the antioxidant properties of hydrothermal extracts of edible seaweed from the Northern Coast of the Sea of Japan. Study objects and methods. The study featured hot-water and autoclave (30 and 60 min) extracts of three edible seaweed species from Russia’s Far East. The research focused on dry matter yield, total phenol content, phenolic profile, antiradical properties, hydroxylion (OH•) scavenging activity, and superoxide radical (O2•−) scavenging activity. Results and discussion. The hot-water extracts appeared to have a higher yield than the autoclave extracts. The hot-water extract of red-purple seaweed Gracilaria verrucosa had the highest yield – 15.90%. The extract of brown seaweed Sargassum miyabei demonstrated the highest total phenol content. The phenolic profile of the extracts revealed 10 compounds, syringic acid and epicatechin being the major ones. The radical scavenging activity of the extracts varied from 48.2 to 88.9%, the highest value was observed in the hot-water extract of S. miyabei. The autoclave S. miyabei extracts also had a high radical scavenging activity, which exceeded other samples by 5.0–13.3%. The hot-water (30 min) extract of G. verrucosa had the lowest antiradical activity. Hot-water and autoclave extracts of S. miyabei showed the best OH• scavenging activity. Only the samples of G. verrucosa demonstrated signs of superoxide radical scavenging. Conclusion. The extracts of brown seaweed S. miyabei proved to be the most active. The hot-water and autoclave extracts had the highest total phenol content and the strongest DPPH and OH• inhibitory activity.