Abstract

• The major carotenoids present in prawn waste include astaxanthin complexes. Astaxanthin is a lipid-soluble, and orange-reddish carotenoid pigment. Two astaxanthin compounds, AS-I (astaxanthin diester, an orange oil, 1.84%) and AS-III (astaxanthin monoester, a yellow oil, 1.13%), were isolated from the ethanol crude astaxanthin extract of freshwater prawn waste using silica gel column chromatography with n-hexane-acetone eluents. The chemical structures of these isolated compounds were confirmed by UV-Vis spectroscopy, FT-IR spectroscopy, GC MS spectrometry, and visualization reagents, as well as solubility and Rf values. The antioxidant activity of the isolated astaxanthin compounds was evaluated using IC50 values. AS-III (astaxanthin monoester, IC50: 36.84 µg/mL) exhibited greater antioxidant activity than standard ascorbic acid (IC50: 47.48 µg/mL) and AS-I (astaxanthin diester, IC50: 263.53 µg/mL) as determined by