phytochemicals Phytochemicals

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Astaxanthin as antioxidant

The carotenoid astaxanthin is a powerful antioxidant and may protect against oxidative damage to body tissues. The presence of hydroxyl and keto endings on astaxtanthin explains its higher anti-oxidant activity than the more popular carotenoid beta-carotene. The free radical scavenging activity of astaxanthin protects lipids from peroxidation and reduces oxidative damage of LDL-cholesterol (thereby reducing arterial plaque formation), DNA, proteins, cell membranes, mitochondrial membranes. Its antioxidant activity has been demonstrated in many studies.

Astaxanthin is very effective in protecting membranous lipids against oxidation. A study conducted by Naguib showed that astaxathin showed the strongest activities among the tested antioxidants (alpha-carotene, alpha-tocopherol, astaxanthin, beta-carotene, lycopene, lutein and Trolox) by using a newly developed fluorometric assay (1). Kappi and co-workers at University of Kuopio, Finland, found that astaxanthin supplementation may decrease in vivo oxidation of fatty acids (2). They investigated the effect of three-month astaxanthin supplementation on lipid peroxidation in healthy non-smoking Finnish men in a randomized double-blind study. The men received two 4 mg astaxanthin capsules daily. They found that the phytochemical was well absorbed and resulted in significantly reduced plasma levels of oxidized fatty acids.

Astaxanthin not only exerts direct anti-oxidant action but it also regulates antioxidant enzymes. Jang and co-workers at the Kangwon National University, Korea, explored the effect of astaxanthin against nitric oxide-induced oxidative stress on cell viability (3). The researchers found that that astaxanthin has a antioxidative effect on cell viability and lipid peroxidation of bovine oviduct epithelial cell, due to the induction of antioxidant genes and suppression of apoptosis genes.

Under conditions of oxidative stress, astaxanthin seems to protect mitochondria. A study conducted at the Nippon Medical School, Japan, Nippon Medical School, suggests that astaxanthin is effective in improving mitochondrial function through retaining mitochondria in the reduced state (4). The team of Japanese researchers, lead by Wolf, found that the carotenoid reduced oxidative stress and protected cells against oxidative stress induced with a respiratory inhibitor. Liu and co-workers at Nagoya University, Japan, also found this protective effect in mitochondria (5). They investigated the effect and the mechanism of astaxanthin on reactive oxygen species-mediated apoptosis in neuroblastomas cells. They demonstrated that astaxanthin pre-treatment of these cells with improved their viability when exposed to the neurotoxins DHA hydroperoxide or 6-hydroxydopamine. The authors concluded that astaxanthin may be an effective treatment for oxidative stress-associated neurodegeneration.

(1) Antioxidant activities of astaxanthin and related carotenoids. J Agric Food Chem. 2000 Apr;48(4):1150-4.
(2) Effects of astaxanthin supplementation on lipid peroxidation. Int J Vitam Nutr Res. 2007 Jan;77(1):3-11.
(3) Antioxidative effects of astaxanthin against nitric oxide-induced oxidative stress on cell viability and gene expression in bovine oviduct epithelial cell and the developmental competence of bovine IVM/IVF embryos. Reprod Domest Anim. 2010 Dec;45(6):967-74.
(4) Astaxanthin protects mitochondrial redox state and functional integrity against oxidative stress. J Nutr Biochem. 2010 May;21(5):381-9.
(5) Astaxanthin inhibits reactive oxygen species-mediated cellular toxicity in dopaminergic SH-SY5Y cells via mitochondria-targeted protective mechanism. Brain Res. 2009 Feb 13;1254:18-27.

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