Antioxidant activity of the ascidian marine invertebrates, Didemnum SP.

Objective: This study aimed to determine the antioxidant activity of samples of the ascidian Didemnum sp. collected from Seribu Islands, Jakarta. Methods: Antioxidant activity was tested using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) method. Didemnum sp. was extracted into methanol and then fractionated using n-hexane, ethyl acetate, and water. Fractions with the highest antioxidant activity were further fractionated using accelerated column chromatography. Results: The concentration of sample that reduced the DPPH radical by 50% (IC₅₀) in a methanol extract of Didemnum sp. was 105.10 µg/mL. The ethyl acetate fraction had the highest antioxidant activity (IC₅₀ of 90.804 µg/mL). The most active fraction obtained from accelerated column chromatography fraction had an IC₅₀ of 86.35 µg/mL. The compounds contained in the most active fractions were alkaloids, saponins, steroids/triterpenoids, and glycosides. Conclusion: The methanol extract of the ascidian Didemnum sp. exhibited antioxidant activity. Fractionation of the Didemnum sp. extract showed that the ethyl acetate fraction had the highest antioxidant activity. Further, fractionation of the ethyl acetate fraction by accelerated column chromatography showed that fraction VI had the highest antioxidant activity. The most active fraction contained alkaloids, steroids/triterpenoids, saponins, and glycosides.