University of Guilan Aquatic Animals Nutrition 2980-8499 11 3 2026 08 11 Assessment of antioxidant activity in microalgae and macroalgae using various analytical assays and extraction solvents Assessment of antioxidant activity in microalgae and macroalgae using various analytical assays and extraction solvents 17 30 9755 10.22124/janb.2026.33027.1303 FA Hasti Beigzadeh Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran, 8415683111 Omidvar Farhadian Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran, 8415683111 Eisa Ebrahimi Dorcheh Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran, 8415683111 Farideh Balali Department of Natural Resources, Isfahan University of Technology, Isfahan, Iran, 8415683111 Journal Article 2025 05 21 Introduction: Algae are rich in bioactive compounds and can grow in harsh environments, producing secondary metabolites with high biological value. They are considered natural sources of antioxidants, offering safer alternatives to synthetic compounds like Butylated hydroxyanisole (BHA) and Butylated hydroxytoluene (BHT). Brown algae generally exhibit higher antioxidant activity than green or red algae. Green algae, such as the genus Ulva, are rich in proteins, minerals, fatty acids, and antimicrobial compounds. Materials and Methods: Microalgae (Tetraselmis tetrathele and Scenedesmus quadricauda) and macroalgae (Sargassum ilicifolium and Ulva lactuca) were collected, cleaned, dried, and powdered. Ethanolic and acetone extracts were prepared using maceration. Antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH), Ferric Reducing Ability of Plasma (FRAP), and 3-ethylbenzothiazoline-6-sulfonate)2/2- azinobis (ABTS) assays. All experiments were performed in triplicate, and data were analyzed using t-tests in SPSS. Results: Antioxidant activity varied significantly with algae species, solvent, and assay type. For macroalgae, S. ilicifolium showed higher antioxidant activity than U. lactuca, with acetone extracts more effective in DPPH, while ethanol extracts were stronger in ABTS. For microalgae, ethanol extracts of T. tetrathele and S. quadricauda showed higher DPPH and FRAP activity, while ABTS results showed high antioxidant capacity for both solvents. Solvent type influenced the extraction of different antioxidant compounds. Discussion: The results confirm that antioxidant capacity depends on species, extraction solvent, and assay method. Brown algae like S. ilicifolium contain diverse phlorotannins, enhancing free radical scavenging. Microalgae contain polar compounds like carotenoids and chlorophylls, which are better extracted with ethanol. Differences among assays reflect distinct mechanisms of antioxidant action. Conclusion: All algae studied are valuable natural sources of antioxidants. S. ilicifolium and T. tetrathele are particularly potent, highlighting the importance of species selection and extraction methods. Algae can be sustainably used in food, pharmaceutical, cosmetic, and biotechnological applications. Introduction: Algae are rich in bioactive compounds and can grow in harsh environments, producing secondary metabolites with high biological value. They are considered natural sources of antioxidants, offering safer alternatives to synthetic compounds like Butylated hydroxyanisole (BHA) and Butylated hydroxytoluene (BHT). Brown algae generally exhibit higher antioxidant activity than green or red algae. Green algae, such as the genus Ulva, are rich in proteins, minerals, fatty acids, and antimicrobial compounds. Materials and Methods: Microalgae (Tetraselmis tetrathele and Scenedesmus quadricauda) and macroalgae (Sargassum ilicifolium and Ulva lactuca) were collected, cleaned, dried, and powdered. Ethanolic and acetone extracts were prepared using maceration. Antioxidant activity was evaluated using 2,2-diphenyl-1-picrylhydrazyl (DPPH), Ferric Reducing Ability of Plasma (FRAP), and 3-ethylbenzothiazoline-6-sulfonate)2/2- azinobis (ABTS) assays. All experiments were performed in triplicate, and data were analyzed using t-tests in SPSS. Results: Antioxidant activity varied significantly with algae species, solvent, and assay type. For macroalgae, S. ilicifolium showed higher antioxidant activity than U. lactuca, with acetone extracts more effective in DPPH, while ethanol extracts were stronger in ABTS. For microalgae, ethanol extracts of T. tetrathele and S. quadricauda showed higher DPPH and FRAP activity, while ABTS results showed high antioxidant capacity for both solvents. Solvent type influenced the extraction of different antioxidant compounds. Discussion: The results confirm that antioxidant capacity depends on species, extraction solvent, and assay method. Brown algae like S. ilicifolium contain diverse phlorotannins, enhancing free radical scavenging. Microalgae contain polar compounds like carotenoids and chlorophylls, which are better extracted with ethanol. Differences among assays reflect distinct mechanisms of antioxidant action. Conclusion: All algae studied are valuable natural sources of antioxidants. S. ilicifolium and T. tetrathele are particularly potent, highlighting the importance of species selection and extraction methods. Algae can be sustainably used in food, pharmaceutical, cosmetic, and biotechnological applications.

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