Antioxidant capacity of microalgae and cyanobacteria of interest as food source

Oxidative stress can damage cell components (mainly proteins, lipids, and DNA), which contributes to cell aging. Microalgae are still a scarcely exploited source of natural oxidative stress inhibitors. The aim of this study was to investigate the total phenolic content and profile using the Folin-Ciocalteu assay and HPLC, the in vitro antioxidant capacity by the DPPH radical scavenging assay, and intracellular oxidation using Saccharomyces cerevisiae as in vivo model, of microalgae of interest as a food source (Arthrospira platensis, Aphanizomenon flos-aquae, Nostoc sphaeroides, Porphyridium purpureum, Chlorella vulgaris, Chlorella sorokiniana, Tetraselmis suecica, Phaeodactylum tricornutum, Tisochrysis lutea, Nannochloropsis oceanica). A high correlation between in vitro and in vivo antioxidant activity was found. The cyanobacteria showed the highest antioxidant activity and high phenolic content measured by the Folin-Ciocalteu assay. All the Chlorophyceae (except T. suecica) showed low values by the Folin-Ciocalteu assay and the lowest antioxidant activities. The rest of the microalgae showed an intermediate behavior. The total phenolic content quantified via HPLC did not fully confirm the data obtained by the Folin-Ciocalteu assay. Among the cyanobacteria, only Aphanizomenon flos-aquae showed high phenolic content quantified by HPLC. In almost all microalgae (especially Chlorophyceae), catechin derivatives were the major contributors to the total phenolic content, while in cyanobacteria flavonoids were the major class.