Background:

Seaweeds must survive in highly competitive environments and thus develop defense strategies that may produce highly diversified antioxidant compounds.

Goals:

The main objective of this work was to assess the antioxidant activity of green seaweeds.

Methods:

Six species of ulvophycean chlorophytes were collected during spring/summer, between the Antarctic (Monostroma hariotii, Protomonostroma rosulatum and Ulva hookeriana - formerly as U. bulbosa) and the southwestern Atlantic Ocean (Gayralia brasiliensis, Protomonostroma undulatum and Ulva fasciata). They were then tested for their antioxidant activities using the 2.2-diphenyl-picrylhydrazyl (DPPH) radical scavenging method and by quantification of their phenolic (expressed as gallic acid equivalent - GAE - and carotenoid contents.

Results:

Among the evaluated species, P. rosulatum and U. hookeriana showed high antioxidant potential (77.9±2.8 and 53.1±15.0%, respectively) and high phenolic content (176±6.0 and 144.7±8.9 µg GAE g-1, respectively). These species were collected on King George Island (South Shetland archipelago, around the Antarctic Peninsula) and their higher antioxidant potential may be associated with adaptation to the high incidence of UV rays in this region during summer. In general, tested seaweeds, mainly the samples collected in the Antarctic and Chilean Patagonia, showed higher values of phenolic (from 58.3±2.0 to 144.7±8.9 µg GAE g-1) and carote noid contents (from 23.4±0.2 to 51.5±0.1 µg β-carotene g-1).

Conclusions:

The presence and levels of these compounds suggest that the target seaweeds may have high antioxidant potential. Also the antioxidant activity could be associated with the occurrence area of the species instead of the order or taxonomic group to which they belong.