The Effect of Solvent Choice on Antioxidant Potential and Chemical Composition of Extracts from Microalgae Chaetocerus costatus

This study aim to compare the extraction yield, antioxidant potential, and chemical composition of Chaetoceros costatus extracted with acetone, ethanol, and hexane. The freeze-dried diatom biomass was extracted by ultrasonication for 1 h at 40 °C. The antioxidant capacity was determined using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging and oxygen radical absorbance capacity (ORAC), while the chemical profiles of the extracts were analyzed using high-performance liquid chromatography with high-resolution mass spectrometry with electrospray ionization (UHPLC-ESI-HRMS). The ORAC assay showed a 27% higher activity of the acetone extract, while the DPPH assay showed almost 3-fold higher DPPH inhibition. Pigments, fatty acids, sterols, and their derivatives were identified in all extracts. The chemical composition of ethanolic and acetonic extracts did not differ significantly, and hexane yielded the fewest compounds. The results of this study will contribute to extraction challenges that limit biotechnological application and exploitation of diatoms.