Antioxidants astaxanthin

Kiso (3) observed that the liposoluble antioxidant astaxanthin, (III), significantly enhanced the circadian rhythm normalizing action of melatonin. 

Bennedsen, M. et al.. Treatment of//, pylori infected mice with antioxidant astaxanthin reduces gastric inflammation, bacterial load and modulates cytokine release by splenocytes, Immunol. Lett, 70, 185,1999. 

Odeberg, J.M. et al.. Oral bioavaUability of the antioxidant astaxanthin in humans is enhanced by incorporation of lipid based formulations, Eur. J. Pharm. Set, 19, 299, 2003. 

This work demonstrated that an airlift system was suitable for the cultivation of Haematococcus pluvialis, one of the most effective microorganisms that could produce high potential antioxidant carotenoid, astaxanthin. Aeration was shown to be crucial for a proper growth of the alga in the airlift bioreactor, but it must be maintained at low level, and the most appropriate superficial velocity was found to be at the lower limit of the pump, i.e. 0.4 cm s". ... 

It has been established that carotenoid structure has a great influence in its antioxidant activity for example, canthaxanthin and astaxanthin show better antioxidant activities than 3-carotene or zeaxanthin. 3- 3 3-Carotene also showed prooxidant activity in oil-in-water emulsions evaluated by the formation of lipid hydroperoxides, hexanal, or 2-heptenal the activity was reverted with a- and y-tocopherol. Carotenoid antioxidant activity against radicals has been established. In order of decreasing activity, the results are lycopene > 3-cryptoxanthin > lutein = zeaxanthin > a-carotene > echineone > canthaxanthin = astaxanthin. ... 

Some of the advantages of astaxanthin over other carotenoids include (1) better stability compared to other carotenoids, (2) high antioxidant potential (10 times... 

Astaxanthin is a powerful bioactive antioxidant and has demonstrated efficacy in animal and human models of macular degeneration, a cause of blindness in a large population. It is also helpful in treating Alzheimer s and Parkinson s diseases and is known to offer protection against cancer. 

One possible mechanism responsible for cooperative action of antioxidants is reduction of a semi-oxidized carotenoid by another antioxidant. Carotenoid cation radicals can be reduced, and therefore recycled to the parent molecule, by a-tocopherol, ascorbate, and melanins (Edge et al., 2000b El-Agamey et al., 2004b) (Figure 15.5). Interestingly, lycopene can reduce radical cations of other carotenoids, such as astaxanthin, (3-carotene, lutein, and zeaxanthin (Edge et al., 1998). 

Since increased 02 generation appeared to correlate with increased carotenoid biosynthesis, we examined the effect of DQ exposure on carotenoid levels and composition. Exposure of cultures to DQ increased the levels of carotenoid produced by about 40%, and also increased the relative proportion of xanthophylls and diminished the levels of carotene precursors (31). In addition to producing more carotenoids, the increased proportion of xanthophylls would provide greater resistance to oxidative stress since xanthophylls are generally more effective antioxidants than carotenes (2). This pattern of increased levels of carotenoids and a higher proportion of xanthophylls also takes place as cultures age. The astaxanthin pathway may function in part to prevent aging of yeast and possibly to supply antioxidant capacity to their progeny. Microscopic examination of autofluorescence supported that carotenoids are... 

Our results support the hypothesis that IO2 may trigger astaxanthin biosynthesis, and that carotenoids serve an antioxidant role in the yeast by reacting with peroxyl radicals. Generation of IO2 may explain the increase in carotenoid formation mediated by O2 and blue light in P. rhodozyma (44,45). Short light pulses of 15 minutes resulted in transient increases in astaxanthin levels in P. rhodozyma, but the highest carotenoid yields were obtained by continuous illumination. 

Strong antioxidants with no prooxidant properties canthaxanthin (16) astaxanthin (17) > actinioerythrol (26). 

Carotenoids represent one of the broadest groups of natural antioxidants (over 600 characterized structurally) with significant biological effects and numerous industrial applications. Lycopene is a typical acyclic carotene that serves as a starting metabolite for formation of carotenoid derivatives via specific routes (p-carotene, torulene, etc.). Xanthophylls include hydroxy-, methoxy- oxo-, epoxy-, carboxy-, and aldehydic groups (torularhodin, zeaxanthin, astaxanthin, etc.), which results in a broad structural variety of carotenoid compounds. 

Several other naturally occurring carotenoids that are not considered significant in the human diet have shown potential as cancer chemopreventive agents. These inclnde neoxanthin, fucoxanthin, phytoflnene, ( -carotene, phytoene, crocetin, capsanthin, peridinin, and astaxanthin. The xanthophyll astaxanthin is a powerful antioxidant and has great potential for reducing human disease processes related to oxidative damage." Therefore, it warrants a more detailed discussion as follows. 

Astaxanthin has demonstrated strong antioxidant behavior in a variety of in vitro studies. In organic solutions, astaxanthin is a potent quencher of singlet oxygen, an effective inhibitor of peroxyl radical-dependent lipid peroxidation, and an efficient peroxyl... 

The antioxidant behavior of astaxanthin has been demonstrated in vivo as well. In Haematococcus algae, astaxanthin is accumulated as part of a stress response, and it is believed to protect cellular DNA from photodynamic damage. This carotenoid also protects lipids from peroxidation in trout and salmon. In chicks, astaxanthin supplementation suppressed the formation of lipid peroxides in the plasma. Significant biological antioxidant effects have been observed in vitamin E-deficient rats fed an astaxanthin-rich diet these include protection of mitochondrial function and inhibition of peroxidation of erythrocyte membranes. In two independent studies, lipid peroxidation in the seram and liver of astaxanthin-fed rats treated with carbon tetrachloride was... 

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