Astaxanthin is a kind of red natural carotenoid that is widely found in squid, shrimp, and crab, as well as in leaves, flowers, and fruits. Most of the marine crustaceans and fishes contain astaxanthin, which are all derived from microalgae, phytoplankton and zooplankton through food chain. Studies in recent years have confirmed that natural astaxanthin has a strong antioxidant activity and has been praised as “Super Vitamin E. It is widely used for human food additives, pharmaceuticals, aquatic animals and poultry.

1 Super antioxidant activity of natural astaxanthin
Photooxidation, physiological stress, and normal immune system function in organisms produce several kinds of harmful reactive oxygen compounds, such as singlet oxygen and oxygen radicals. These molecules contain unpaired electrons and are highly unstable, leading to oxidation of amino acids, protein degradation and DNA damage and another cell damage. Oxygen radicals also attack unsaturated fatty acids on cell membranes. Over-oxidized fatty acids can generate more fatty acid radicals through chain reactions. The presence of free radicals breaks the balance between free radicals and antioxidants in organisms and causes rheumatism, arthritis, heart disease, Parkinson’s syndrome, Alzheimer’s syndrome, multiple cancers, and shock.

Natural astaxanthin has a special molecular structure. It has been found in vitro to be a powerful quencher of singlet oxygen and has a powerful ability to remove oxygen free radicals. It is an extremely effective antioxidant. In Haematococcus pluvialis cell, astaxanthin acts as a photoprotective agent and a strong antioxidant and can quench a variety of reactive oxygen compounds generated by strong light and excessive oxidation and preventing active oxygen from damaging cells.
Natural astaxanthin is more effective than canthaxanthin, carotene and zeaxanthin to prevent excessive oxidation of unsaturated fatty acid methyl esters. Its antioxidant activity is 550 times that of vitamin E. It is 10 times the carotenoids such as carotene, zeaxanthin, lutein and canthaxanthin, and is known as “Super Vitamin E” and “Super Antioxidant”.

The main biological activity of natural astaxanthin:
1.1 Protecting skin from light-induced injury
Ultraviolet radiation is an important cause of epidermal photoaging and skin cancer. Studies have shown that astaxanthin has a special effect on transglutaminase and can deplete putrescine when exposed to light. Oral astaxanthin has a stronger inhibitory effect on putrescine accumulation than oral vitamin A, indicating that astaxanthin can be used as a potential photoprotective agent to prevent photoaging of the skin.

1.2 Prevention of venous sclerosis and related diseases
Clinical studies have shown that the oxidation of low-density lipoprotein (LDL) is an important cause of arteriosclerosis. Astaxanthin can significantly increase high-density lipoprotein (HDL) and decrease LDL efficacy in vivo. Carotene and canthaxanthin do not have this effect, so it has been speculated that astaxanthin can reduce the oxidation of apolipoprotein and can be used as a preparation for preventing arteriosclerosis, coronary heart disease and ischemic brain injury.

1.3 Anti-cancer
Immunological studies have shown that oral carotenoids have anti-cancer effects and can act directly on the immune system, leading to tumor shrinkage. Administration of astaxanthin to experimental rats and mice obviously inhibits chemically induced primary carcinogenesis and has antiproliferative and immune-enhancing effects on epithelial cells exposed to carcinogens with dose-effect relationship. Therefore, it is speculated that astaxanthin has significant anti-cancer properties. Astaxanthin can also induce enzymes in liver, significantly inhibiting mouse bladder cancer, rat oral cancer, colon cancer and gastric cancer, and is more effective than carotene. Oral astaxanthin can also inhibit the growth of breast cancer. Its dose effect is absent in carotenes and canthaxanthin. Astaxanthin can also reduce the carcinogenicity of aflatoxin and reduce the aflatoxin-induced liver tumor cells.

1.4 Enhancing immune system function
Singlet oxygen has a cytotoxic effect on the animal’s immune system. It catalyzes the production of free radicals that accelerate the degradation of macrophage cell membranes, resulting in decreased phagocytic efficiency and dysfunction. Astaxanthin can significantly influence the immune function of animals, significantly promote the ability of spleen cells to produce antibodies in the presence of antigens, enhance the production of immunoglobulin in blood cells stimulated by T cells, and can also partially restore the humoral immunity of old mice. The system shows that astaxanthin can enhance the specific humoral immune response in the early stage of antigen invasion, and astaxanthin can also enhance the release of interleukin and tumor necrosis factor in mice, which is much stronger than carotene and canthaxanthin. Thus, it is considered that astaxanthin has the best activity of inducing cell division and has an important immunomodulatory effect and can be used as an immunopotentiator.

1.5 Protecting the Health of the Eye and Central Nervous System
The polyunsaturated fatty acids and high concentrations of oxygen in human retina are higher than in any other tissue. When high-energy blue light acts on the retina, the singlet oxygen and oxygen radicals produced by photooxidation can cause superoxide damage to the retina. For humans and other animals, dietary carotenoids are essential for maintaining eye health. They can quench these damaging reactive oxygen compounds and help protect the retina against oxidative damage. They are clinically useful for the treatment of age-related macular diseases. Recent studies have shown that astaxanthin can effectively prevent retinal oxidation and photoreceptor cell damage through the blood-brain barrier, indicating that astaxanthin is good at preventing and treating “age-related macular degeneration” and improving retinal function.

The central nervous system (including the brain, spinal cord, and peripheral nerves) is rich in unsaturated fatty acids and iron, is highly metabolically active, and is highly vulnerable to oxidative damage, leading to a variety of diseases of the nervous system. Astaxanthin can protect the central nervous system. Especially the brain and spine can effectively treat ischemic reperfusion injury, spinal cord injury, Parkinson’s syndrome, Azheimer’s syndrome and other central nervous system damage.

1.6 Strengthening the body’s energy metabolism
Oral astaxanthin enhances aerobic metabolism and can significantly increase muscle strength and tolerance in humans. Feeding astaxanthin also increased the survival rate of shrimp in stress environment. The study found that for farmed Atlantic salmon fry, if the content of astaxanthin in the feed is below 5.1 ug·g, the fry will stop growing. Below 1 ug·g, the fry’s survival rate is below 50%. It is possible that astaxanthin acts as a storage material for intracellular oxygen, allowing fish and crustaceans to survive under anoxic conditions.

1.7 Anti-infection
The latest study showed that when mice were fed haematococcus pluvialis algae powder rich in astaxanthin, it can significantly reduce the helicobacter pylori on the attachment and infection of the stomach, for which scientists have developed oral preparations as anti-infective preparations, astaxanthin diester also has the role of anti-infective drug compounding agent, and aspirin can be taken at the same time to strengthen its efficacy.

2 Application of natural astaxanthin
At present, natural astaxanthin is used to develop advanced human nutrition and health foods and medicines, its products are mainly used in strengthening the immune system function, anti-cancer, protecting the retina from ultraviolet radiation and photooxidation, anti-inflammatory, prevention of blood LDL-cholesterol in terms of oxidative damage. Japanese scientists have developed skin external preparations, as well as anti-inflammatory preparations and beverages containing astaxanthin, which can be used to protect the skin from damage caused by ultraviolet radiation.