Canthaxanthin (β, β-carotene-4,4'-dione) is a dicyclic xanthophyll with two carbonyl groups at the 4 and 4' positions of the terminal ring, extending the conjugated double bond system to 13 double bonds. Xanthophylls are the oxygenated derivatives of carotene (known as hydrocarbon carotenoids). Common oxygen substituents are hydroxyl, keto, epoxy, and aldehyde groups, and these functional groups determine the polarity and solubility of the xanthophylls. Because of its nonpolar polyene chain, canthaxanthin is insoluble in polar solvents, such as water and ethanol, but it is soluble in tetrahydrofuran. Canthaxanthin is a precursor of astaxanthin and is therefore present in very low amounts in animal-based foods where astaxanthin is the major pigment. Canthaxanthin is naturally occurring and can be obtained via total synthesis or biosynthesis by microorganisms.
Canthaxanthin
| Chemical structure |
 |
| IUPAC name |
β,β-Carotene-4,4′-dione |
| CAS number |
514-78-3 |
| Chemical formula |
C40H52O2 |
| Molar mass |
564.82 g/mol |
| Appearance |
Violet crystals |
In contrast to other carotenoids, canthaxanthin is not used as a nutraceutical. Apart from its function as a pigment, canthaxanthin also has potential benefits including free radical scavenging, antioxidant, and gene regulatory properties. Several in vitro studies suggest that cantharidin may affect gap junction communication and immune function. Unlike other carotenoids such as β-carotene, lycopene, and astaxanthin, the biological functions of canthaxanthin are less studied.
Products
Amerigo Scientific provides highly purified canthaxanthin analytical standards for research.
Biosynthesis of Red-orange Canthaxanthin
Canthaxanthin can be biosynthesized from precursor β-carotene through β-carotene keto enzymes encoded by the gene bkt in algae and crtW in bacteria. This enzyme oxidize the allyl 4-position in the β ring to a carbonyl group, producing the intermediate echinenone. Subsequently, the same enzyme converts the 4' -carbon atom in the second β ring to a carbonyl group. Canthaxanthin is found in red-feathered birds such as flamingos, crested ibis, and cardinals, as well as in fish such as carp, golden mullet, and seabream. Animals and humans cannot biosynthesize canthaxanthin or other carotenoids. In many animals, a redorange color comes from the diet. Birds can consume diets rich in carotenoids, such as corn, algae, shrimp, mollusks, and insect larvae. Food sources for wild fish are often composed of plankton and small crustaceans, which may contain carotenoids. The red to pink color of salmonids is mediated by the ability to combine canthaxanthin with actomyosinic acid complexes in muscle.
Canthaxanthin and other carotenoids are added to animal feed to color foods such as egg yolks, broilers, salmon, and trout to meet consumer expectations. As a lipophilic compound, canthaxanthin accumulates in food, mainly in adipose tissues such as broilers skin, egg yolks, and fish filets, and in the cuticle of crustaceans. Dietary canthaxanthin supplementation in diet may significantly increase the antioxidative status of egg yolk and the hatching rate of eggs. In addition, carotenoids including canthaxanthin have a positive effect on animal health and product quality.
Safety of Canthaxanthin
Canthaxanthin has been evaluated for safety as food and feed additives by the European Food Safety Authority (EFSA) and the US Food and Drug Administration (FDA). The Joint Expert FAO/WHO Committee on Food Additives (JECFA) and Scientific Committee for Food (SCF) have defined an acceptable daily intake of canthaxanthin of 0.03 mg/kg body weight based on the level of absence of adverse effects.
The potential toxic effects of canthaxanthin in humans are ocular lesions mediated by macular crystal formation and retinopathy. Hydrogen bonds between canthaxanthin keto groups and lipid C=O groups of the lipid or hydrogen bonds between the polyene chain and water may lead to the formation of canthaxanthin aggregates. The dose of canthaxanthin that causes ocular toxicity is much higher than the dietary intake of canthaxanthin form eggs, poultry, and fish. In addition, canthaxanthin is not genotoxic. Therefore, dietary canthaxanthin is considered safe for humans.
Antioxidant Activity of Canthaxanthin
Reactive oxygen species (ROS) and reactive nitrogen species (RNS) can cause oxidative and nitrifying damage to DNA, lipids, and proteins. Canthaxanthin has the properties of scavenging free radicals. Canthaxanthin, being a ketocarotenoid, exhibits higher antioxidant and free radical scavenging properties than other carotenoids such as lycopene and β-carotene. The ketone group in conjugation with the polyene backbone is responsible for stabilizing the carbon-centered radicals more effectively than the polyene backbone alone. Geometrical isomerization appears to have an impact on the free radical scavenging activity of canthaxanthin. (9Z)-canthaxanthin is more effective than all-E-canthaxanthin in scavenging superoxide radicals, which may be related to its higher potential energy. In addition, canthaxanthin is a potent lipophilic antioxidant that can quench singlet oxygen. The antioxidant activity may have a positive impact on the product quality of animal-derived food and the health status of humans and animals.
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