Antioxidant potential of methanolic and aqueous extracts of Chnoospora minima, Padina gymnospora and Sargassum cymosum (Ochrophyta, Phaeophyceae)

Abstract

Brown seaweeds are reported to have high antioxidant activity, due to the rich composition in phenolic compounds. In this way, they present potential as functional ingredients and additives for food, feed, cosmeceutical and pharmaceutical industries. The objective of this study was to evaluate the antioxidant potential of methanolic and aqueous extracts of three species of brown algae by five in vitro assays, in order to contribute to screening of functional foods ingredients, and to the search for natural antioxidants from marine alga biomass matrix. The ABTS, DPPH, FRAP and iron-chelating assays were used for analysis of antioxidant activity, and the Folin-Ciocalteu assay for the quantification of total phenolic compounds. The methanolic and aqueous extracts of Padina gymnospora and Sargassum cymosum showed up to 50% of antioxidant potential for the five assays, and Chnoospora minima presented antioxidant potential up to 50% only for ABTS assay. Comparing the extracts, aqueous extracts of C. minima and S. cymosum presented higher antioxidant activities and phenolic compounds than methanolic extracts, whereas for P. gymnospora the methanolic extracts presented greater activities. To integrate the results of antioxidant potential, a total antioxidant capacity index was calculated, classifying the extract potential in reactivity order. It was verified that the methanolic extract of P. gymnospora had the highest antioxidant activity and content of phenolic compounds, indicating the potential of this species in the search for natural antioxidant substances and suitable candidate for further studies as food and functional ingredients.