LC-ESI-QTOF-MS/MS characterization of phenolic compounds from Victorian shorebound red seaweeds and their antioxidant capacity

Seaweeds are considered a promising source of phytochemical compounds, including polyphenols. The Australian shoreline hosts a diverse array of seaweeds; however, the phenolic profile and the antioxidant potential of most species remain unclear, necessitating further exploration. To this end, ten red seaweeds were collected, identified using molecular testing, and their phenolic compounds were extracted using acidified ethanol and subjected to ten in vitro assays. The Relative Antioxidant Capacity Index (RACI) was calculated for each sample to compare the overall results. The results indicated that Phacelocarpus peperocarpos exhibited the highest overall phenolic and antioxidant potential, followed by Callophyllis sp. and Rhodophyllis sp.. A total of 365 phenolic compounds were screened, comprising 85 phenolic acids, 164 flavonoids, and 118 other polyphenols. Correlation analysis displayed a positive correlation between phenolic content, antioxidant activity, and the identified phenolic compounds. Overall, this study sheds light on the polyphenol content and antioxidant potential of ten red seaweed species from Queenscliff, Victoria, through various in vitro assays and LC-ESI-QTOF-MS/MS characterization. The findings indicate that Australian red seaweeds are a promising source of polyphenols and exhibit considerable antioxidant properties, underscoring their potential in providing substantial health benefits and functional food products.