Boosting Antioxidant Activity and Phenolic Content in Scenedesmus dimorphus

¹ Department of Biology Education, Faculty of Teacher Training and Education, Raja Ali Haji Maritime University, Indonesia, Dompak, Tanjungpinang 29100, Indonesia
² Department of Chemistry, Faculty of Engineering and Maritime Technology, Raja Ali Haji Maritime University, Senggarang, Tanjungpinang 29100, Indonesia
³ Academy of Scientific & Innovative Research (AcSIR), CSIR – Central Salt and Marine Chemicals Research Institute, Bhavnagar 364002, Gujarat, India

^* Corresponding author: triwidyaedelwis@gmail.com

Abstract

Scenedesmus dimorphus, a microalgae from the Chlorophyceae class, possesses compounds with antioxidant potential. This study focuses on determining the antioxidant activity of the methanol extract of *Scenedesmus dimorphus* cultured in Bold Basal Medium (BBM) with NaCl concentrations of 10 g/L, 12.5 g/L, and 15 g/L. NaCl was added after 3, 6, and 9 days of cultivation to evaluate the impact on antioxidant activity. The antioxidant activity was assessed using the DPPH (1,1-diphenyl-2- picrylhydrazyl) assay. The results showed that the highest antioxidant activity occurred in cultures with 15 g/L NaCl, with DPPH inhibition of 13.71% and a biomass yield of 0.1914 g in 500 mL of medium. The microalgae demonstrated the ability to withstand NaCl stress, showing improved antioxidant activity over time. On day 9, with the addition of 15 g/L NaCl, the antioxidant activity increased to 26.82%, the IC50 value was 183.63 mg/L, and the biomass weight reached 0.2568 g in 500 mL of medium. Additionally, the total phenolic content increased to 70.10 mg GAE/g extract on day 9. These findings suggest that NaCl stress at specific intervals enhances both antioxidant activity and phenolic content in Scenedesmus dimorphus.