Effects of solvent extraction on phenolic concentration and antioxidant capacity of the Oedogonium sp. (Chlorophyta) using a simplex-centroid mixture design

Among the freshwater benthic macroalgae found in Brazilian rivers and streams, species of Oedogonium (Chlorophyta) have shown great ability to produce high biomass in several environmental conditions. Their resilience to eutrophic habitats provides an opportunity to assess the use of Oedogonium biomass for applications in different fields, especially those related to the extraction of biologically active compounds of interest for health, food, and cosmetic applications. Thus, this study assessed the effects of different organic solvents (acetone, ethanol, and methanol) and their mixtures when combined with water (20% v/v), on the extraction efficiency of total phenolic compounds (TPC), and their antioxidant capacity (AC), from Oedogonium sp. biomass, using simplex-centroid mixture design. TPC ranged from 90 to 150 mg of gallic acid equivalent per 100 g dry weight (DW), while AC ranged from 1 to 8 µM of Trolox equivalent per gram (DW). The highest TPC and AC were found for extracts using an ethanol/acetone (50:50) binary aqueous solvent mixture, while the lowest values for both TPC and AC were found for the methanolic aqueous solvent. Considering the relatively low-cost and less adverse environmental impacts of the ethanol and acetone aqueous mixture, our results suggest that the use of this specific mixture of organic solvents may have significant advantages in an eventual industrial process for the extraction of phenolic compounds from Oedogonium species.