Antioxidant activity of fresh and processed edible seaweeds

The antioxidant activity of aqueous/organic extracts of processed and raw edible seaweeds was determined using three methods, namely (a) free radical (DPPH.) scavenging, (b) ferric-reducing antioxidant power (FRAP) and (c) inhibition of copper-catalysed in vitro human low-density Lipoprotein (LDL) oxidation. Scavenging activity correlated well (r =0.73) with the corresponding total. polyphenolic content measured by the Folin-Ciocalteu procedure and expressed as phloroglucinol equivalents (PGE). Of the seaweeds tested, Fucus showed the highest antioxidant activity in two of the test methods used (1g (dry matter) had a DPPH. activity and a FRAP value equivalent to those 0.18 and 0.07 mmol of Trolox respectively) and the highest total polyphenolic content (41.4gPGEkg(-1) dry matter). The antioxidant activity and the content of phenolic compounds decreased with processing and storage in the seaweeds tested. In addition, Fucus showed good efficiency in the in vitro inhibition of LDL oxidation. (C) 2001 Society of Chemical Industry.