Astaxanthin, the chemical name is 3,3'-dihydroxy-4,4'-diketo-β, β'-carotene, the molecular formula is C40H52O4, the relative molecular mass is 596.86, also known as astaxanthin , astaxanthin, or lobster shell pigment, is a keto carotenoid. The color is pink, fat-soluble, insoluble in water, soluble in organic solvents such as chloroform, acetone, benzene and carbon disulfide. The chemical structure of ASTA astaxanthin is composed of 4 isoprene units connected by a conjugated double bond, and there are 2 isoprene units at both ends to form a six-membered ring structure. Its chemical structure is shown in Figure 1. Because the chemical structure of astaxanthin contains a long conjugated unsaturated double bond system, its structure is easily damaged by light, heat, oxides, etc.
1 Biological functions and applications of astaxanthin
ASTA astaxanthin was isolated from shrimp and crab shells as early as the 1930s, but its biological functions were not extensively studied until the mid-1980s. Studies have shown that astaxanthin has many important biological functions and broad application prospects.
1.1 Application of astaxanthin in aquatic animals
ASTA astaxanthin is widely present in the biological world, especially in the feathers of shrimp, crab, fish and birds of aquatic animals, and plays a color role. Astaxanthin has a bright red color, and when it is added to the feed of aquatic animals, it can make the body color of aquatic animals bright. Usually, astaxanthin is added to aquatic animal feed to supplement the pigment, which can greatly improve the market value of the product. Astaxanthin can not only be used as a colorant for aquaculture animals, but more and more evidences have confirmed that astaxanthin also plays an extremely important role in the normal growth, healthy breeding, survival rate and reproduction rate of aquatic animals. In addition, the addition of astaxanthin to aquaculture feeds can also prevent the deterioration of processed aquatic products such as rainbow trout due to lipid oxidation, and provide a rich source of astaxanthin for human food.
1.2 As an antioxidant
ASTA astaxanthin is a non-vitamin A source carotenoid that cannot be converted into vitamin A in animals. However, in the astaxanthin molecule, there are very long conjugated double bonds, and there are hydroxyl groups and unsaturated ketones at the end of the conjugated double bond chain, wherein the hydroxyl groups and ketone groups form α-hydroxy ketones. The more active electronic effect can provide electrons to free radicals or attract unpaired electrons of free radicals, making it easy to react with free radicals to scavenge free radicals, thereby playing an antioxidant role. Animal experiments show that astaxanthin can remove NO, sulfide, disulfide, etc. In terms of scavenging free radicals, astaxanthin has more than 10 times the ability of beta carotene and more than 100 times that of vitamin E. At the same time, astaxanthin has the effect of inhibiting or reducing lipid peroxidation and can protect phosphatidylcholine lipids from oxidation. Therefore, astaxanthin can be used in pharmaceutical products as anti-aging medicines and food health products.
1.3 As a sunscreen
ASTA astaxanthin can effectively remove free radicals generated by ultraviolet radiation in the body and reduce the damage caused by photochemistry. Therefore, it has a good preventive and therapeutic effect on skin cancer caused by ultraviolet rays. In addition, by compounding astaxanthin with cosmetics, new daily cosmetics with sunscreen function can be formed.
1.4 As an immunological agent
Research in recent years has shown that astaxanthin has important physiological functions in promoting the production of antibodies and enhancing the immune function of the host. Singlet oxygen has a cytotoxic effect on the immune system of animals, and the free radicals it catalyzes can accelerate the degradation of macrophage cell membranes, resulting in reduced phagocytic efficiency and dysfunction. Since astaxanthin has the function of scavenging singlet oxygen, it can significantly affect the immune function of animals. Experiments have shown that in the presence of antigens, astaxanthin can significantly promote the production of antibodies in spleen cells, thereby enhancing the production of immune globulin in human blood cells stimulated by T cells. Through experimental observation, Jyonouchi et al. found that astaxanthin can significantly promote the production of antibodies when stimulated by thymus-dependent antigen (TD-Ag), and increase the number of cells secreting IgG and IgG. Astaxanthin supplementation was also able to partially restore the humoral immune system in aged mice. Therefore, astaxanthin has an important immunomodulatory effect and can be used as an immune enhancer.
1.5 As an anticancer agent
Many experts have studied the physiological and biochemical functions of natural carotenoids and found that astaxanthin has a strong anti-cancer effect. It can inhibit by aflatoxin BI (AFB1), α-phenylpyrene (BaP), diethyl nitrite (DEN), α-nitropropane, N-butyl-N (4-hydroxybutyl) sulfite Mutagenic effects caused by nitramine and cyclophosphamide. Therefore, astaxanthin can effectively prevent liver cancer, oral cancer, colorectal cancer, bladder cancer and breast cancer. The use of astaxanthin can develop drugs for the treatment and prevention of tumors.
1.6 Other applications
In addition to the above-mentioned uses of ASTA astaxanthin, it can also be used to prevent atherosclerosis and related diseases, which is also due to the antioxidant properties of astaxanthin. Astaxanthin can reduce or inhibit the oxidation of low-density lipoprotein (LDL) in the blood, so that the deposits on the blood vessel wall are reduced, thereby reducing the occurrence of atherosclerosis. In addition, astaxanthin can also be used to prevent and treat eye diseases, similar to the properties of vitamin A. In particular, it has the effect of significantly reducing the incidence of diabetic eye disease, and can be used as an adjuvant drug for the treatment of diabetes.
2 Application of astaxanthin derivatives
ASTA astaxanthin can be divided into various types according to the stereoisomer, geometric isomer and degree of esterification. For example, the main stereoisomers of astaxanthin in Antarctic krill are 3R and 3R' and are esterified; astaxanthin in red yeast is mainly in the form of esterified 3R and 3R'; Haematococcus pluvialis ), the stereoisomers of astaxanthin are mainly esterified 3S and 3S' forms, monoesters account for about 80%, diesters account for about 15%, and the main fatty acids are oleic acid, elaidic acid, ricinoleic acid and arachidic acid, etc.
The chemically synthesized astaxanthin is free astaxanthin. Because free astaxanthin is unstable, natural astaxanthin rarely exists free. In addition to forming esters with fatty acids, natural astaxanthin tends to form complexes with proteins, resulting in different colors (such as blue, green, and yellow in lobsters); it is also soluble in oils, such as in snow algae (Chlamyclomonas nivalis) The red color is the result of the accumulation of astaxanthin in its cytoplasmic lipids.
In addition to the naturally occurring astaxanthin esters, esterification of astaxanthin has also been reported. Hawaii Biotech.Inc.(HBI) has successfully synthesized astaxanthin disuccinate disodium salt, which not only improves the solubility of astaxanthin in water (the solubility of this salt in water can reach 8.6 g/ L), and the derivative showed a stronger ability to scavenge superoxide radicals than astaxanthin. The good solubility of this salt in water helps to scavenge free radicals in the water phase. Therefore, this compound may play an important role in reducing the occurrence of atherosclerosis and cancer in humans. In addition, Jackson et al. used astaxanthin and lysine as raw materials to synthesize the tetrahydrochloride of dilysine ester of astaxanthin. The new compound is the most soluble astaxanthin derivative in water found so far. Its solubility in water at room temperature can reach 181.6g/L, and the compound also has strong free radical scavenging ability. Therefore, these astaxanthin derivatives can be applied to biologically and chemically scavenging free radicals in the water phase by taking advantage of the high solubility of these astaxanthin derivatives in water.
Astaxanthin's special molecular structure determines that it is easily destroyed by light, heat, oxides, etc.
Chen et al. studied the β-cyclodextrin inclusion complex of astaxanthin. The results showed that when astaxanthin and β-cyclodextrin formed an inclusion complex, the water solubility, light and heat stability of astaxanthin were improved, laying a scientific foundation for the further application of astaxanthin.
3 There is a problem
Because astaxanthin has many important physiological and biological functions such as anti-oxidation, anti-tumor and immunity enhancement, it has broad application prospects in food additives, aquaculture, cosmetics, health products and pharmaceutical industries. At present, the US Food and Drug Administration has approved the synthetic trans structure of astaxanthin as an additive in aquaculture. However, the price of astaxanthin on the market is very high now, and the unit price of its synthetic product reaches 2000~2500 US dollars/kg. Therefore, research and development of astaxanthin has important commercial and economic value.
With the development of industries such as aquaculture, food and medicine, the demand for astaxanthin at home and abroad has been increasing in recent years. However, the extraction of astaxanthin from aquatic product wastes generally has low astaxanthin content and high extraction costs. The disadvantage is that it cannot meet the needs of large-scale commercial production. Therefore, establishing practical technical solutions is the key, and at the same time, finding and developing new resources and methods, such as breeding high-yielding yeasts, fermenting and culturing Haematococcus, etc., will also be problems to be solved in the future.
Although there are many reports on the biological functions of astaxanthin, there are few studies on the residual problem of astaxanthin in animals and the toxicity caused by excessive use. Therefore, the research on the safety of long-term use of astaxanthin is also a subject to be explored.
With the continuous discovery of biological sources of astaxanthin and the further development of extraction, separation and purification technology, ASTA astaxanthin will surely have broader application prospects.
