Polyphenolic compounds previously quantified in brown seaweed include
caffeic acid, chlorogenic acid, coumaric acid and catechins
(Keyrouz et al., 2011). Phlorotannins, polyphenolics unique to marine
algae, are found at the highest levels (2–10%) in brown algal species
(Ragan & Glombitza, 1986). Due to the complexity and wide diversity
of compounds present in seaweeds, characterisation and quantification
of target compounds is difficult. In vitro antioxidant assays (e.g. total
phenol content (TPC), FRAP and DPPH radical scavenging activities)
are frequently used to assess the antioxidant activity and potency of
seaweed extracts (Zaragozá et al., 2008).