Acta Scientiarum http://periodicos.uem.br/ojs ISSN on-line: 1807-8664 Doi: 10.4025/actascitechnol.v45i1.61471 SCIENCE, FOOD TECHNOLOGY AND FOOD ENGINEERING Acta Scientiarum. Technology, v. 45, e61471, 2023 Effects of solvent extraction on phenolic concentration and antioxidant capacity of the Oedogonium sp. (Chlorophyta) using a simplex-centroid mixture design Rodolfo José Tófoli 1 , Adriana Luiza Ferreira 1 , Eutimio Gustavo Fernández Núñez 2 , Charles Windson Isidoro Haminiuk 3 , Ciro Cesar Zanini Branco 1 and Ivanise Guilherme Branco 1* 1 Departamento de Ciências Biológicas, Faculdade de Ciências e Letras, Universidade Estadual Paulista, Av. Dom Antônio, 2100, 19806-900, Assis, São Paulo, Brazil. 2 Escola de Artes, Ciências e Humanidades, Universidade de São Paulo, São Paulo, São Paulo, Brazil. 3 Departamento Acadêmico de Química e Biologia, Universidade Tecnológica Federal do Paraná, Curitiba, Paraná, Brazil. *Author for correspondence. E-mail: ivanise.branco@unesp.br ABSTRACT. 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. Keywords: stream macroalgae; phenolic compounds; antioxidant; solvent extractor; mixture design method. Received on November 8, 2021. Accepted on May 30, 2022. Introduction Green algae can produce a vast array of biologically active compounds, including phenolic chemicals (Seal, Halder, Chaudhuri, & Sinha, 2014), photosynthetic and photoprotective pigments (Fabrowska, Ibañez, Łęska, & Herrero, 2016), as well as alkaloids, ketones, terpenes, hydrocarbons, esters, and sterols (Abdel-Aal, Haroon, & Mofeed, 2015). Chemical compounds produced by algae exhibit diverse biological properties, such as antimicrobial, antiviral, and anti-inflammatory activities (Shalaby, 2011), which has facilitated their application as ingredients in the cosmetic, food, and pharmaceutical industries (Fabrowska et al., 2016). Among the freshwater green algal species, those belonging to the genus Oedogonium have recurrently been reported as essential components of the macroscopic primary producer assemblages in lotic and lentic habitats worldwide (Lawton, Cole, Roberts, Paul, & Nys, 2017). In Brazil, these filamentous green algae comprise approximately 65 species and have been classified as one of the most species-rich genera of Chlorophyta (Menezes et al., 2015). Species of the genus Oedogonium can be found in diverse freshwater habitats in different Brazilian ecoregions/biomes, and, commonly, they can produce huge amounts of algal biomass in these environments (Branco, Peres, Krupek, & Bertusso, 2009). Some authors have suggested that species of Oedogonium may be a promising and relevant source of bioactive compounds, as observed for other freshwater green algae (e.g., Scenedesmus sp. in Bulut et al., 2019). Wang, Manabe, Sugawara, Paul, and Zhao (2018), for instance, identified seven major carotenoids from Oedogonium intermedium, including loroxanthin, which is a kind of carotenoid that is lacking in land plants. An additional reason to investigate Oedogonium species as potential sources of bioactive compounds is that