Oxidative damage to the organism is mainly manifested in the destruction of lipids, proteins and nucleic acids. Lipid due to the destruction of the free radical chain reaction, resulting in biofilm structure and function change; protein oxidation is very sensitive, especially the sulfur amino acid; bases and pentose in DNA molecules are easily oxidized position, the oxidation can lead to DNA breaks, base degradation and protein cross-linking, making the genetic material to mutate or cause cell death.

Carotenoids by physical quenching Singlet oxygen, singlet-oxygen additional energy transfer to carotenoid, carotenoids accept energy into triplet (3Car3), then release the extra energy through exothermic go to the ground state (1Car), which is a physical process, the structure of the carotenoid is not changed, you can continue to quench singlet oxygen. The speed of chemical reaction can be used to describe the rate constant (k), the faster the reaction, the greater the rate constant. Carotenoid quencher of singlet oxygen, the speed can be described by the rate constant (kq) kq value of carotenoids reflect the size of the potential effectiveness of its antioxidant activity, kq, higher the value, the faster the reaction with singlet oxygen carotenoids to quench singlet oxygen, kq, higher the value, the more a certain amount of carotenoids per unit time, quenching singlet oxygen;, of course, values ​​of kq, and experimental conditions (such as temperature, solvent, photosensitizer types, determination methods) are closely related, so the size of the kq value of more carotenoids, the experimental conditions must be the same.

It can be seen from the data of carotenoids singlet oxygen quenching ability and its number of conjugated double bonds, and the end of the ionone ring is not obvious. 4, 4 'carbonyl (astaxanthin and angular zeaxanthin) can improve the ability to quench singlet oxygen the astaxanthin quenching singlet oxygen capacity of the strongest, 100 times that of the α2 tocopherol, and glutathione the reaction rate of 1/125 of α2 tocopherol, but in vivo environment and experimental conditions very different from the results of chemical experiments by astaxanthin supplier does not reflect the real situation in vivo; In order to simulate the biological environment, people with liposomes, cultured cells and animal experiments, the results due to the antioxidant capacity of oxidant species in biological environments, and the interaction between the different other substances such as carotenoids in the lipid environment (such as biofilms) than water-soluble antioxidants (alpha lipoic acid, glutathione), antioxidant capacity, while the latter antioxidant in the cytoplasm plays an important role.

Astaxanthin is a widely used carotenoid as cosmetic raw material, people have been extensively studied for its antioxidant and anti-oxidation efficiency. Several carotenoids quenching singlet oxygen, the efficiency of blood cells in vitro study found that lycopene is the most effective, astaxanthin, followed by, β2 carotene worst. Astaxanthin clear that the efficiency of free radicals and angular zeaxanthin, 50% higher than the β2-carotene and zeaxanthin, clear hydrogen peroxide free radicals and prevent lipid peroxidation was significantly better than zeaxanthin, canthaxanthin, and β2 carrots. Antioxidant, astaxanthin, each individual is not the strongest, but the highest antioxidant capacity. Astaxanthin similar to vitamin E, fat-soluble antioxidant in the performance of excellent oxidation resistance of biofilm and lipid-rich tissues. Feed with vitamin E deficiency, vitamin E rich feed and w (astaxanthin prime) = 1% of the feed fed to mice two to four months, and then liver mitochondria and red blood cells in vitro antioxidant experiments, found that astaxanthin significant antioxidant activity, more effective than vitamin E.

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