Astaxanthin What Does It Do?

Astaxanthin is a keto-type carotenoid that is widely found in nature. Its chemical name is 3,3'-dihydroxy-4,4'-dione-beta,beta'-carotene, its molecular formula is C40H52O4, its relative molecular mass is 596.86, and its molecular structure is shown in Figure 1 [1]. Astaxanthin is insoluble in water, but soluble in organic solvents such as benzene, acetone and carbon disulfide, and appears reddish-orange [2]. Currently, the main natural sources of astaxanthin are Haematococcus pluvialis, Rhodopseudomonas palustris, salmon and krill [3].

The long carbon chain of the conjugated double bond in the molecular structure of astaxanthin and the α-hydroxyketone six-membered ring formed by the hydroxyl and ketone groups make astaxanthin more reactive with free radicals and reactive oxygen species than other carotenoids, and it can exert an antioxidant effect [4]. Astaxanthin has 50 times the antioxidant activity of beta-carotene and 500 times that of vitamin E. It is known as a “super antioxidant” and has a good effect on delaying skin aging caused by photochemistry, so it has a broad market in the cosmetics industry [3]. Recent studies have shown that astaxanthin can play an important role in preventing cardiovascular disease, fighting cancer and boosting the immune system, and is therefore used in the pharmaceutical and health product industries [6].

1. The main biological activities of astaxanthin

1.1 Antioxidant

Excess free radicals and reactive oxygen species in the body can cause protein and lipid oxidation and DNA damage through chain reactions, and induce cardiovascular disease, liver disease, cancer, etc. [5]. Yuan Lei et al. [6] showed that the ability of different carotenoids to scavenge hydroxyl radicals is in the following order: astaxanthin > lutein > β-carotene > lycopene. The conjugated double bond of astaxanthin can capture free radicals to the cell membrane, and the α-hydroxy ketone ring can remove free radicals and reactive oxygen species on the inside and outside of the membrane [5]. Liu [7] and others found that after feeding yellow catfish with astaxanthin added to the feed, the activities of both catalase and superoxide dismutase (SOD) in the fish liver were increased. Li et al. [8] found that astaxanthin can increase the activity of SOD and heme oxygenase-1 in the kidneys of mice by supplementing astaxanthin to mice with kidney damage induced by high-intensity exercise.

1.2 Anti-inflammatory

Astaxanthin helps repair damaged tissue and kill invading microorganisms, exhibiting strong anti-inflammatory properties [6]. Sun et al. [9] found that in a mouse model of chondrocyte apoptosis, astaxanthin can reduce chondrocyte apoptosis and extracellular matrix degradation by activating the Nrf2 signaling pathway, to some extent treating osteoarthritis. Zhang Tian et al. [10] also found that astaxanthin can be used to reduce bone and joint swelling in mice, and increase the content of type II collagen and SOD activity in articular cartilage. In addition, Kang et al. [11] showed that astaxanthin can directly inhibit the secretion and expression of pro-inflammatory factors such as interleukin-6, interleukin-1b and tumor necrosis factor-α.

2. Health benefits of astaxanthin

The antioxidant and anti-inflammatory properties of astaxanthin make it of great value in the prevention of cardiovascular disease [13-15], the treatment of cancer [16-19] and the strengthening of the body's immune system [20-22].

2.1 Prevention of cardiovascular disease

Oxidative stress and inflammation are the main pathological features of cardiovascular disease. The antioxidant and anti-inflammatory activities of astaxanthin make it a potential drug for the treatment of cardiovascular disease [12]. Shen et al. [13] found that astaxanthin can reduce the infiltration of inflammatory cells after myocardial ischemia in rats and maintain normal heart function. Chen et al. [14] reported that astaxanthin can inhibit the growth of vascular smooth muscle cells, increase the activity of antioxidant enzymes, and reduce mitochondrial autophagy to achieve vascular remodeling. Zou et al. [1 2] pointed out that astaxanthin supplementation can promote reverse cholesterol transport in mice and reduce the area of cholesterol plaques in the aorta. Xue et al. [15] found that feeding astaxanthin can significantly reduce myocardial cell apoptosis and dilate the coronary artery wall by studying a rat coronary artery microembolism model.

2.2 Anti-cancer

Astaxanthin can improve the gap junctions between cells, promote apoptosis of cancer cells, and prevent the proliferation and metastasis of cancer cells, exhibiting anti-cancer activity [4]. Tsuji et al. [16] found that astaxanthin can reduce the phosphorylation levels of Akt and ERK1/2 proteins and interfere with the proliferation and migration of glioblastoma cells. Rao et al. [17] reported that astaxanthin can be used to treat non-melanoma skin cancer. In addition, studies have shown that astaxanthin has a good effect on inhibiting the growth of breast cancer cells. Kim et al. [18] studied the effect of astaxanthin on apoptosis of human breast cancer cells, and the results showed that astaxanthin can down-regulate the expression of mutant p53 gene and induce apoptosis of cancer cells while enhancing the activity of SOD and anti-apoptotic factor pontin. Ahn et al. [19] further showed that astaxanthin has the conditions to be used as a clinical drug for the treatment of breast cancer.

2.3 Enhances immunity

Astaxanthin can protect the body from free radical damage and to a certain extent restore the immune system's defense mechanisms [5]. In terms of humoral immunity, Yin et al. [20] found that astaxanthin can downregulate the expression of CCR7 protein and alleviate the immune dysfunction of dendritic cells induced by lipopolysaccharide, which can be used as a potential drug for the treatment of sepsis. Zhang et al. [2 1] conducted a study on the effects of astaxanthin on a mouse intestinal mucosal damage model induced by cyclophosphamide. The results showed that astaxanthin can reduce intestinal oxidative stress levels, promote immunoglobulin A secretion, and maintain the barrier function of the intestinal mucosa. In terms of cellular immunity, Lin et al. [22] showed that astaxanthin can regulate the immune response of mouse lymphocytes by enhancing the ability of interferon-γ and interleukin-2.

2.4 Other

In addition to the therapeutic effects of astaxanthin supplementation on the above diseases, it also has a protective effect on the liver [23], improves glucose metabolism [24] and reduces skin damage [25]. Liu et al. [23] studied the effect of astaxanthin on ethanol-induced alcoholic fatty liver in mice and found that astaxanthin can alleviate liver lipid metabolism disorders, reduce lipid accumulation, and improve liver function. Mashhadi et al. [24] reported that astaxanthin can reduce the serum triglyceride and very low-density lipoprotein cholesterol concentrations in patients with type II diabetes and promote glucose metabolism in the body. In addition, Li Fumin et al. [25] pointed out that topical astaxanthin liposomes can absorb ultraviolet radiation, inhibit cell damage caused by free radicals in the skin after irradiation, and improve collagen damage in mouse skin.

3. Development and application of astaxanthin

Numerous studies at home and abroad have confirmed that astaxanthin plays an important role in the prevention and treatment of diseases, and it has broad market prospects in the pharmaceutical, food and health product industries. In the pharmaceutical and health product industries, relevant research has already been carried out abroad for a long time. For example, the American company Aquasearch has developed astaxanthin capsules with anti-thrombotic effects, and the Japanese company Fancl has produced nutritional supplements containing astaxanthin [26].

In the food industry, astaxanthin can be used as a coloring agent and additive to preserve freshness, color and shelf life. The European Union approved Haematococcus pluvialis astaxanthin as a novel food in 2008 and made a health claim on its efficacy. The Chinese Ministry of Health officially approved it in November 2010 [27].

Astaxanthin's strong antioxidant activity can significantly reduce the damage caused by ultraviolet rays to skin collagen and elastin, and therefore astaxanthin is also widely used in the cosmetics industry [28]. Many cosmetic brands around the world use it as an ingredient in products such as skin care products, sunscreens and lip balms, to promote anti-oxidation, anti-wrinkle and sun protection effects. International brands such as PROYA, Fancl and Mentholatum also use it [29].

4. Outlook

The results of good experiments in in vitro and in vivo models confirm that astaxanthin can be used to combat oxidative damage to diseased cells and has potential for a variety of diseases, including cardiovascular disease, liver disease and cancer. We need to conduct in-depth research on the metabolic pathways of astaxanthin to further evaluate the development prospects of astaxanthin in the pharmaceutical, health food and cosmetics industries.

References

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