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56-439: Astaxanthin / æ s t ə ˈ z æ n θ ɪ n / is a keto- carotenoid within a group of chemical compounds known as carotenones or terpenes . Astaxanthin is a metabolite of zeaxanthin and canthaxanthin , containing both hydroxyl and ketone functional groups. It is a lipid -soluble pigment with red coloring properties, which result from the extended chain of conjugated (alternating double and single) double bonds at

112-666: A Wittig reaction . Two equivalents of the proper ylide combined with the proper dialdehyde in a solvent of methanol, ethanol, or a mixture of the two, yields astaxanthin in up to 88% yields. The cost of astaxanthin extraction, high market price, and lack of efficient fermentation production systems, combined with the intricacies of chemical synthesis, discourage its commercial development. The metabolic engineering of bacteria ( Escherichia coli ) enables efficient astaxanthin production from beta-carotene via either zeaxanthin or canthaxanthin . In addition to structural isomeric configurations, astaxanthin also contains two chiral centers at

168-468: A food coloring (or color additive) for specific uses in animal and fish foods. The European Commission considers it as a food dye with E number E161j. The European Food Safety Authority has set an Acceptable Daily Intake of 0.2 mg per kg body weight, as of 2019. As a food color additive, astaxanthin and astaxanthin dimethyldisuccinate are restricted for use in Salmonid fish feed only. Astaxanthin

224-526: A Seattle judge dismissed the case, ruling that enforcement of the applicable food laws was up to government and not individuals. The primary human application for astaxanthin is as a dietary supplement , and it remains under preliminary research. In 2020, the European Food Safety Authority reported that an intake of 8 mg astaxanthin per day from food supplements is safe for adults. Lobsters, shrimp, and some crabs turn red when cooked because

280-427: A number of different steps within the carotenoid biosynthetic pathway. Glyceraldehyde 3-phosphate and pyruvate , intermediates of photosynthesis , are converted to deoxy-D-xylulose 5-phosphate (DXP) catalyzed by DXP synthase (DXS). DXP reductoisomerase catalyzes the reduction by NADPH and subsequent rearrangement. The resulting MEP is converted to 4-(cytidine 5’-diphospho)-2-C-methyl-D-erythritol (CDP-ME) in

336-458: A scientific opinion on a similar xanthophyll carotenoid, lutein, stating that "following passage through the gastrointestinal tract and/or uptake lutein esters are hydrolyzed to form free lutein again". While it can be assumed that non-esterified astaxanthin would be more bioavailable than esterified astaxanthin due to the extra enzymatic steps in the intestine needed to hydrolyse the fatty acid components, several studies suggest that bioavailability

392-461: A single enzyme, the bacterial phytoene desaturase (CRTI) for the catalysis. Plants and cyanobacteria however utilize four enzymes for this process. The first of these enzymes is a plant-type phytoene desaturase which introduces two additional double bonds into 15-cis-phytoene by dehydrogenation and isomerizes two of its existing double bonds from trans to cis producing 9,15,9’-tri-cis-ζ-carotene. The central double bond of this tri-cis-ζ-carotene

448-407: Is a higher energy state and is essential in photoprotection. Light produces damaging species during photosynthesis, with the most damaging being reactive oxygen species (ROS). As these high energy ROS are produced in the chlorophyll the energy is transferred to the carotenoid’s polyene tail and undergoes a series of reactions in which electrons are moved between the carotenoid bonds in order to find

504-468: Is a virulence factor with an antioxidant action that helps the microbe evade death by reactive oxygen species used by the host immune system. The basic building blocks of carotenoids are isopentenyl diphosphate (IPP) and dimethylallyl diphosphate (DMAPP). These two isoprene isomers are used to create various compounds depending on the biological pathway used to synthesize the isomers. Plants are known to use two different pathways for IPP production:

560-441: Is cyclized; cyclization gives rise to carotenoid diversity, which can be distinguished based on the end groups. There can be either a beta ring or an epsilon ring, each generated by a different enzyme ( lycopene beta-cyclase [beta-LCY] or lycopene epsilon-cyclase [epsilon-LCY]). α-Carotene is produced when the all-trans lycopene first undergoes reaction with epsilon-LCY then a second reaction with beta-LCY; whereas β-carotene

616-509: Is derived from herbicides applied to soil and binds to DXP synthase. This inhibits DXP synthase, preventing synthesis of DXP and halting the MEP pathway. The use of this toxin leads to lower levels of carotenoids in plants grown in the contaminated soil. Fosmidomycin , an antibiotic , is a competitive inhibitor of DXP reductoisomerase due to its similar structure to the enzyme. Application of said antibiotic prevents reduction of DXP, again halting

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672-437: Is directly related to their structure, especially the length of the conjugation. Xanthophylls are often yellow, giving their class name. Carotenoids also participate in different types of cell signaling. They are able to signal the production of abscisic acid , which regulates plant growth, seed dormancy , embryo maturation and germination , cell division and elongation, floral growth, and stress responses. The length of

728-455: Is eliminated from the CDP-ME2P molecule. MECDP is then converted to (e)-4-hydroxy-3-methylbut-2-en-1-yl diphosphate (HMBDP) via HMBDP synthase in the presence of flavodoxin and NADPH. HMBDP is reduced to IPP in the presence of ferredoxin and NADPH by the enzyme HMBDP reductase . The last two steps involving HMBPD synthase and reductase can only occur in completely anaerobic environments. IPP

784-457: Is favored over HT photodimers with increasing polarity of the medium. Isophorone occurs naturally in cranberries . Isophorone is produced on a multi-thousand ton scale by the aldol condensation of acetone using KOH. Diacetone alcohol , mesityl oxide , and 3-hydroxy-3,5,5-trimethylcyclohexan-1-one are intermediates. A side product is beta-isophorone , where the C=C group is not conjugated with

840-554: Is imperative that female birds carefully select high quality mates. Current literature supports the theory that vibrant carotenoid coloration is correlated with male quality—either though direct effects on immune function and oxidative stress, or through a connection between carotenoid metabolizing pathways and pathways for cellular respiration. It is generally considered that sexually selected traits, such as carotenoid-based coloration, evolve because they are honest signals of phenotypic and genetic quality. For instance, among males of

896-446: Is influenced by the source organism as well as growth conditions. The astaxanthin fed to salmon to enhance flesh coloration is in the non-esterified form The predominance of evidence supports a de-esterification of fatty acids from the astaxanthin molecule in the intestine prior to or concomitant with absorption resulting in the circulation and tissue deposition of non-esterified astaxanthin. European Food Safety Authority (EFSA) published

952-400: Is isomerized by the zeta-carotene isomerase Z-ISO and the resulting 9,9'-di-cis-ζ-carotene is dehydrogenated again via a ζ-carotene desaturase (ZDS) . This again introduces two double bonds, resulting in 7,9,7’,9’-tetra-cis-lycopene. CRTISO , a carotenoid isomerase, is needed to convert the cis -lycopene into an all-trans lycopene in the presence of reduced FAD . This all-trans lycopene

1008-436: Is more dependent on formulation than configuration. Astaxanthin is used as a dietary supplement and feed supplement as food colorant for salmon, crabs, shrimp, chickens and egg production. The primary use of synthetic astaxanthin today is as an animal feed additive to impart coloration, including farm-raised salmon and chicken egg yolks. Synthetic carotenoid pigments colored yellow, red or orange represent about 15–25% of

1064-403: Is no correlation between consumption of foods high in carotenoids and vitamin A and the risk of Parkinson's disease . Humans and other animals are mostly incapable of synthesizing carotenoids, and must obtain them through their diet. Carotenoids are a common and often ornamental feature in animals. For example, the pink color of salmon , and the red coloring of cooked lobsters and scales of

1120-450: Is present in most red-coloured aquatic organisms. The content varies from species to species, but also from individual to individual as it is highly dependent on diet and living conditions. Astaxanthin and other chemically related asta-carotenoids have also been found in a number of lichen species of the Arctic zone. The primary natural sources for industrial production of astaxanthin comprise

1176-513: Is produced by two reactions with beta-LCY. α- and β-Carotene are the most common carotenoids in the plant photosystems but they can still be further converted into xanthophylls by using beta-hydrolase and epsilon-hydrolase, leading to a variety of xanthophylls. It is believed that both DXS and DXR are rate-determining enzymes, allowing them to regulate carotenoid levels. This was discovered in an experiment where DXS and DXR were genetically overexpressed, leading to increased carotenoid expression in

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1232-988: Is recognised as a food component in the EU diet. Carotenoid All are derivatives of tetraterpenes , meaning that they are produced from 8 isoprene units and contain 40 carbon atoms. In general, carotenoids absorb wavelengths ranging from 400 to 550 nanometers (violet to green light). This causes the compounds to be deeply colored yellow, orange, or red. Carotenoids are the dominant pigment in autumn leaf coloration of about 15-30% of tree species, but many plant colors, especially reds and purples, are due to polyphenols . Carotenoids serve two key roles in plants and algae: they absorb light energy for use in photosynthesis , and they provide photoprotection via non-photochemical quenching . Carotenoids that contain unsubstituted beta-ionone rings (including β-carotene , α-carotene , β-cryptoxanthin , and γ-carotene ) have vitamin A activity (meaning that they can be converted to retinol ). In

1288-414: Is then able to isomerize to DMAPP via IPP isomerase. Two GGPP molecules condense via phytoene synthase (PSY), forming the 15-cis isomer of phytoene . PSY belongs to the squalene/phytoene synthase family and is homologous to squalene synthase that takes part in steroid biosynthesis. The subsequent conversion of phytoene into all-trans- lycopene depends on the organism. Bacteria and fungi employ

1344-621: The European Union , astaxanthin-containing food supplements derived from sources that have no history of use as a source of food in Europe, fall under the remit of the Novel Food legislation, EC (No.) 258/97. Since 1997, there have been five novel food applications concerning products that contain astaxanthin extracted from these novel sources. In each case, these applications have been simplified or substantial equivalence applications, because astaxanthin

1400-502: The 3- and 3 ′ -positions, resulting in three unique stereoisomers (3R,3 ′ R and 3R,3'S meso and 3S,3'S). While all three stereoisomers are present in nature, relative distribution varies considerably from one organism to another. Synthetic astaxanthin contains a mixture of all three stereoisomers, in approximately 1:2:1 proportions. Astaxanthin exists in two predominant forms, non-esterified (yeast, synthetic) or esterified (algal) with various length fatty acid moieties whose composition

1456-415: The MEP pathway.  Isophorone Isophorone is an α,β-unsaturated cyclic ketone . It is a colorless liquid with a characteristic peppermint-like odor, although commercial samples can appear yellowish. Used as a solvent and as a precursor to polymers, it is produced on a large scale industrially. Isophorone undergoes reactions characteristic of an α,β-unsaturated ketone. Hydrogenation gives

1512-549: The ability to utilize these pigments for external coloration has evolved independently many times throughout avian evolutionary history. Carotenoid coloration exhibits high levels of sexual dimorphism , with adult male birds generally displaying more vibrant coloration than females of the same species. These differences arise due to the selection of yellow and red coloration in males by female preference . In many species of birds, females invest greater time and resources into raising offspring than their male partners. Therefore, it

1568-529: The algae, such as salmon , red trout, red sea bream , flamingos , and crustaceans (shrimp, krill, crab, lobster, and crayfish), subsequently reflect the red-orange astaxanthin pigmentation. Astaxanthin is used as a dietary supplement for human, animal, and aquaculture consumption. Astaxanthin from algae, synthetic and bacterial sources is generally recognized as safe in the United States. The US Food and Drug Administration has approved astaxanthin as

1624-895: The astaxanthin, which was bound to the protein in the shell, becomes free as the protein denatures and unwinds. The freed pigment is thus available to absorb light and produce the red color. In April 2009, the United States Food and Drug Administration approved astaxanthin as an additive for fish feed only as a component of a stabilized color additive mixture. Color additive mixtures for fish feed made with astaxanthin may contain only those diluents that are suitable. The color additives astaxanthin, ultramarine blue , canthaxanthin , synthetic iron oxide , dried algae meal, Tagetes meal and extract, and corn endosperm oil are approved for specific uses in animal foods. Haematococcus algae meal (21 CFR 73.185) and Phaffia yeast (21 CFR 73.355) for use in fish feed to color salmonoids were added in 2000. In

1680-669: The bird species Parus major , the more colorfully ornamented males produce sperm that is better protected against oxidative stress due to increased presence of carotenoid antioxidants . However, there is also evidence that attractive male coloration may be a faulty signal of male quality. Among stickleback fish, males that are more attractive to females due to carotenoid colorants appear to under-allocate carotenoids to their germline cells. Since carotinoids are beneficial antioxidants, their under-allocation to germline cells can lead to increased oxidative DNA damage to these cells. Therefore, female sticklebacks may risk fertility and

1736-513: The center of the compound. The presence of the hydroxyl functional groups and the hydrophobic hydrocarbons render the molecule amphiphilic. Astaxanthin is produced naturally in the freshwater microalgae Haematococcus pluvialis , the yeast fungus Xanthophyllomyces dendrorhous (also known as Phaffia rhodozyma ) and the bacteria Paracoccus carotinifaciens . When the algae are stressed by lack of nutrients, increased salinity, or excessive sunshine, they create astaxanthin. Animals who feed on

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1792-419: The cost of production of commercial salmon feed. In the 21st century, most commercial astaxanthin for aquaculture is produced synthetically. Class action lawsuits were filed against some major grocery store chains for not clearly labeling the astaxanthin-treated salmon as "color added". The chains followed up quickly by labeling all such salmon as "color added". Litigation persisted with the suit for damages, but

1848-419: The cyclohexanone derivative. Epoxidation with basic hydrogen peroxide affords the oxide. Isophorone is degraded by attack of hydroxyl radicals . When exposed to sunlight in aqueous solutions, isophorone undergoes 2+2 photocycloaddition to give three isomeric photodimers (Figure). These "diketomers" are cis-syn-cis, head to tail (HT), cys-anti-cys (HT), and head-head (HH). The formation of HH photodimers

1904-555: The cytosolic mevalonic acid pathway (MVA) and the plastidic methylerythritol 4-phosphate (MEP). In animals, the production of cholesterol starts by creating IPP and DMAPP using the MVA. For carotenoid production plants use MEP to generate IPP and DMAPP. The MEP pathway results in a 5:1 mixture of IPP:DMAPP. IPP and DMAPP undergo several reactions, resulting in the major carotenoid precursor, geranylgeranyl diphosphate (GGPP). GGPP can be converted into carotenes or xanthophylls by undergoing

1960-468: The development of monoclonal antibodies to trans- lycopene it was possible to localise this carotenoid in different animal and human cells. Beta-carotene , found in pumpkins , sweet potato , carrots and winter squash , is responsible for their orange-yellow colors. Dried carrots have the highest amount of carotene of any food per 100-gram serving, measured in retinol activity equivalents (provitamin A equivalents). Vietnamese gac fruit contains

2016-432: The disappearance of chlorophyll. Carotenoids are responsible for the brilliant yellows and oranges that tint deciduous foliage (such as dying autumn leaves ) of certain hardwood species as hickories , ash , maple , yellow poplar , aspen , birch , black cherry , sycamore , cottonwood , sassafras , and alder . Carotenoids are the dominant pigment in autumn leaf coloration of about 15-30% of tree species. However,

2072-482: The eye, lutein , meso -zeaxanthin , and zeaxanthin are present as macular pigments whose importance in visual function, as of 2016, remains under clinical research . Carotenoids are produced by all photosynthetic organisms and are primarily used as accessory pigments to chlorophyll in the light-harvesting part of photosynthesis. They are highly unsaturated with conjugated double bonds , which enables carotenoids to absorb light of various wavelengths . At

2128-421: The fatty tissues of animals, and exclusively carnivorous animals obtain the compounds from animal fat. In the human diet, absorption of carotenoids is improved when consumed with fat in a meal. Cooking carotenoid-containing vegetables in oil and shredding the vegetable both increase carotenoid bioavailability . The most common carotenoids include lycopene and the vitamin A precursor β-carotene. In plants,

2184-494: The final molecule, astaxanthin, is obtained. The structure of astaxanthin by synthesis was described in 1975. Nearly all commercially available astaxanthin for aquaculture is produced synthetically, with an annual market of about $ 1 billion in 2019. An efficient synthesis from isophorone , cis -3-methyl-2-penten-4-yn-1-ol and a symmetrical C 10 -dialdehyde has been discovered and is used in industrial production. It combines these chemicals together with an ethynylation and then

2240-634: The flesh itself, and most of it only becomes visible during cooking as the pigment separates from the denatured proteins that otherwise bind it. Astaxanthin is extracted from Euphausia superba (Antarctic krill) and from shrimp processing waste. Astaxanthin biosynthesis starts with three molecules of isopentenyl pyrophosphate (IPP) and one molecule of dimethylallyl pyrophosphate (DMAPP) that are combined by IPP isomerase and converted to geranylgeranyl pyrophosphate (GGPP) by GGPP synthase. Two molecules of GGPP are then coupled by phytoene synthase to form phytoene. Next, phytoene desaturase creates four double bonds in

2296-424: The following: Astaxanthin concentrations in nature are approximately: Algae are the primary natural source of astaxanthin in the aquatic food chain . The microalgae Haematococcus pluvialis contains high levels of astaxanthin (about 3.8% of dry weight), and is the primary industrial source of natural astaxanthin. In shellfish, astaxanthin is almost exclusively concentrated in the shells, with only low amounts in

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2352-446: The highest known concentration of the carotenoid lycopene . Although green, kale , spinach , collard greens , and turnip greens contain substantial amounts of beta-carotene. The diet of flamingos is rich in carotenoids, imparting the orange-colored feathers of these birds. Reviews of preliminary research in 2015 indicated that foods high in carotenoids may reduce the risk of head and neck cancers and prostate cancer . There

2408-491: The ketone. The partly hydrogenated derivative trimethylcyclohexanone is used in production of polycarbonates . It condenses with phenol to give an analogue of bisphenol A . Polycarbonates produced by phosgenation of these two diols produces a polymer with improved thermal stability. Trimethyl adipic acid and 2,2,4-trimethylhexamethylenediamine are produced from trimethylcyclohexanone and trimethylcyclohexanol. They are used to make specialty polyamides . Hydrocyanation gives

2464-571: The most balanced (lowest energy) state for the carotenoid. Carotenoids defend plants against singlet oxygen , by both energy transfer and by chemical reactions. They also protect plants by quenching triplet chlorophyll. By protecting lipids from free-radical damage, which generate charged lipid peroxides and other oxidised derivatives, carotenoids support crystalline architecture and hydrophobicity of lipoproteins and cellular lipid structures, hence oxygen solubility and its diffusion therein. Like some fatty acids , carotenoids are lipophilic due to

2520-424: The multiple conjugated double bonds determines their color and photophysics. After absorbing a photon, the carotenoid transfers its excited electron to chlorophyll for use in photosynthesis. Upon absorption of light, carotenoids transfer excitation energy to and from chlorophyll . The singlet-singlet energy transfer is a lower energy state transfer and is used during photosynthesis. The triplet-triplet transfer

2576-475: The nitrile followed by reductive amination gives isophorone diamine . This diamine is used to produce isophorone diisocyanate which has certain niche applications. Full hydrogenation gives 3,3,5-Trimethylcyclohexanol , a precursor to both sunscreens and chemical weapons. The LD 50 value of isophorone in rats and rabbits by oral exposure is around 2.00 g/kg. The safety aspects of isophorone have been subject to several studies. The use of isophorone as

2632-426: The phytoene molecule to form lycopene. After desaturation, lycopene cyclase first forms γ-carotene by converting one of the ψ acyclic ends of the lycopene as a β-ring, then subsequently converts the other to form β-carotene. From β-carotene, hydrolases (blue) are responsible for the inclusion of two 3-hydroxy groups, and ketolases (green) for the addition of two 4-keto groups, forming multiple intermediate molecules until

2688-406: The presence of CTP using the enzyme MEP cytidylyltransferase. CDP-ME is then converted, in the presence of ATP , to 2-phospho-4-(cytidine 5’-diphospho)-2-C-methyl-D-erythritol (CDP-ME2P). The conversion to CDP-ME2P is catalyzed by CDP-ME kinase . Next, CDP-ME2P is converted to 2-C-methyl-D-erythritol 2,4-cyclodiphosphate (MECDP). This reaction occurs when MECDP synthase catalyzes the reaction and CMP

2744-399: The presence of long unsaturated aliphatic chains. As a consequence, carotenoids are typically present in plasma lipoproteins and cellular lipid structures. Carotenoids are located primarily outside the cell nucleus in different cytoplasm organelles, lipid droplets , cytosomes and granules. They have been visualised and quantified by raman spectroscopy in an algal cell. With

2800-524: The reds, the purples, and their blended combinations that decorate autumn foliage usually come from another group of pigments in the cells called anthocyanins . Unlike the carotenoids, these pigments are not present in the leaf throughout the growing season, but are actively produced towards the end of summer. Dietary carotenoids and their metabolic derivatives are responsible for bright yellow to red coloration in birds. Studies estimate that around 2956 modern bird species display carotenoid coloration and that

2856-417: The resulting seedlings. Also, J-protein (J20) and heat shock protein 70 (Hsp70) chaperones are thought to be involved in post-transcriptional regulation of DXS activity, such that mutants with defective J20 activity exhibit reduced DXS enzyme activity while accumulating inactive DXS protein. Regulation may also be caused by external toxins that affect enzymes and proteins required for synthesis. Ketoclomazone

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2912-759: The same time, the terminal groups regulate the polarity and properties within lipid membranes . Most carotenoids are tetraterpenoids , regular C 40 {\displaystyle {\ce {C40}}} isoprenoids . Several modifications to these structures exist: including cyclization , varying degrees of saturation or unsaturation, and other functional groups . Carotenes typically contain only carbon and hydrogen, i.e., they are hydrocarbons . Prominent members include α-carotene , β-carotene , and lycopene , are known as carotenes . Carotenoids containing oxygen include lutein and zeaxanthin . They are known as xanthophylls . Their color, ranging from pale yellow through bright orange to deep red,

2968-409: The sweet floral smells present in black tea , aged tobacco , grape , and many fruits are due to the aromatic compounds resulting from carotenoid breakdown. Some carotenoids are produced by bacteria to protect themselves from oxidative immune attack. The aureus (golden) pigment that gives some strains of Staphylococcus aureus their name is a carotenoid called staphyloxanthin . This carotenoid

3024-453: The viability of their offspring by choosing redder, but more deteriorated partners with reduced sperm quality. Products of carotenoid degradation such as ionones , damascones and damascenones are also important fragrance chemicals that are used extensively in the perfumes and fragrance industry. Both β-damascenone and β-ionone although low in concentration in rose distillates are the key odor-contributing compounds in flowers. In fact,

3080-488: The xanthophyll lutein is the most abundant carotenoid and its role in preventing age-related eye disease is currently under investigation. Lutein and the other carotenoid pigments found in mature leaves are often not obvious because of the masking presence of chlorophyll . When chlorophyll is not present, as in autumn foliage, the yellows and oranges of the carotenoids are predominant. For the same reason, carotenoid colors often predominate in ripe fruit after being unmasked by

3136-403: The yellow morph of common wall lizards are due to carotenoids. It has been proposed that carotenoids are used in ornamental traits (for extreme examples see puffin birds) because, given their physiological and chemical properties, they can be used as visible indicators of individual health, and hence are used by animals when selecting potential mates. Carotenoids from the diet are stored in

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