Introduction: Astaxanthin is a widely studied carotenoid due to its health-promoting properties. It has been reported to possess antibacterial, antimicrobial, anti-inflammatory, anticancer, and antioxidant properties, making it a valuable compound in the development of cosmetics, nutraceuticals and pharmaceuticals. In recent years, marine waste, such as shrimp shells, has been investigatedhas a source of astaxanthin. This study aimed to investigate the antioxidant capacity of astaxanthin extracts obtained from shrimp shells. Methods: Shrimp shells were collected, cleaned, dried, and subjected to ultrasound-assisted extraction to obtain astaxanthin-rich extracts. The antioxidant capacity of the extracts was evaluated using widely established radical scavenging assays, including DPPH and ABTS. The results were expressed as EC50 values and compared with ascorbic acid as a standard antioxidant.

Results: The shrimp shell extract showed potent antioxidant activity at low concentrations. In the DPPH assay, it achieved over 90% radical scavenging at 1.0 µg/mL, with an EC50 of 0.37 µg/mL. By comparison, ascorbic acid was far less potent (EC50 = 6.89 µg/mL) and reached only 60% scavenging at its highest tested concentration (7.5 µg/mL). Similar results were observed in the ABTS assay, where the shrimp shell extract achieved nearly complete inhibition at concentrations below 1 µg/mL (EC50 = 0.13 µg/mL), outperforming the positive control (EC50 = 1.74 µg/mL).
Conclusions: These findings demonstrate that astaxanthin extracts from shrimp shells exhibits strong antioxidant activity, making it highly suitable as a natural bioactive ingredient. Such extracts have clear potential for incorporation into nutraceuticals, functional foods, and cosmetic formulations, providing a sustainable route to natural antioxidant enrichment in commercial products.