Evaluation of antioxidant properties of some naturally isolated microalgae: Identification and characterization of the most efficient strain

Antioxidant capacity and polyphenol content of both intra- and extracellular constituents were investigated in five naturally isolated microalgal strains using DPPH and Folin-Ciocalteu assays respectively. Three distinct solvents with different polarities including water, ethyl acetate and hexane were employed for extracting the bioactive compounds. Obtained data from DPPH assay suggest that the studied microalgal cells show significant levels of antioxidants and polyphenol compounds ranging from 14.68 +/- 1.36 (Oocystis pusilla) to 68.68 +/- 5.95 (Scenedesmus rubescens) mu mol Trolox g(-1) and 9.62 +/- 1.37 (O. pusilla) to 48.57 +/- 3.99 (S. rubescens) mg gallic acid equivalent (GAE) g(-1) respectively. Considerable connection (R-2=0.9316) between two investigated factors prove that a great part of antioxidant activity in the studied microalgae are due to its phenolic compounds. Besides, the results of growth kinetic studies and composition analysis in the most efficient strain (S. rubescens) showed a great potential for antioxidant and polyphenolic compounds production in large scales.