Antioxidant Activity of Natural Astaxanthin Extracted from Shell of Arabian Red Shrimp Aristeus alcocki (Ramadan, 1938)

Shrimp processing waste is one of the important natural sources of carotenoid. The major component of carotenoids of shrimp and crab shell were mono and diesters of astaxanthin, a very potent antioxidant with some unique properties. Astaxanthin is a powerful quencher of singlet oxygen activity and a strong scavenger of oxygen free radicals. Antioxidant activity of shrimp shell astaxanthin was evaluated. The in vitro antioxidant activity of astaxanthin extract showed significant hydroxyl radical scavenging activity, superoxide anion scavenging activity and inhibition of lipid peroxidation. The IC50 values obtained were 56.43 +/- 1.06, 27.91 +/- 0.54 and 26.54 +/- 0.42 ng ml(-1), respectively. Antioxidant activity of astaxanthin from Aristeus alcocki was obtained at nanogram levels. This powerful antioxidant function may be due to the unique molecular structure of astaxanthin and synergistic effect of astaxanthin and PUFAs present in the astaxanthin monoester and diester fractions.