The term carotene (also carotin, from the Latin ''carota'', "carrot") is used for many related

unsaturated hydrocarbon 300px, Structure of an ethene molecule, the simplest unsaturated hydrocarbon Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms. The term "unsaturated" means more hydrogen atoms may ...

substances having the formula C₄₀H_x, which are synthesized by plants but in general cannot be made by animals (with the exception of some

aphid Aphids are small sap-sucking insects and members of the superfamily Aphidoidea. Common names include greenfly and blackfly, although individuals within a species can vary widely in color. The group includes the fluffy white woolly aphids. A t ...

s and spider mites which acquired the synthesizing genes from fungi). Carotenes are

photosynthetic pigment A photosynthetic pigment (accessory pigment; chloroplast pigment; antenna pigment) is a pigment that is present in chloroplasts or photosynthetic bacteria and captures the light energy necessary for photosynthesis. List of photosynthetic pigme ...

s important for

photosynthesis Photosynthesis is a process used by plants and other organisms to convert light energy into chemical energy that, through cellular respiration, can later be released to fuel the organism's activities. Some of this chemical energy is stored i ...

. Carotenes contain no oxygen atoms. They absorb ultraviolet, violet, and blue light and scatter orange or red light, and (in low concentrations) yellow light. Carotenes are responsible for the orange colour of the

carrot The carrot ('' Daucus carota'' subsp. ''sativus'') is a root vegetable, typically orange in color, though purple, black, red, white, and yellow cultivars exist, all of which are domesticated forms of the wild carrot, ''Daucus carota'', nat ...

, after which this class of chemicals is named, and for the colours of many other fruits, vegetables and fungi (for example,

sweet potato The sweet potato or sweetpotato (''Ipomoea batatas'') is a dicotyledonous plant that belongs to the Convolvulus, bindweed or morning glory family (biology), family, Convolvulaceae. Its large, starchy, sweet-tasting tuberous roots are used as a r ...

es,

chanterelle Chanterelle is the common name of several species of fungi in the genera '' Cantharellus'', '' Craterellus'', '' Gomphus'', and ''Polyozellus''. They are among the most popular of wild edible mushrooms. They are orange, yellow or white, meaty a ...

and orange

cantaloupe The cantaloupe, rockmelon (Australia and New Zealand, although cantaloupe is used in some states of Australia), sweet melon, or spanspek (Southern Africa) is a melon that is a variety of the muskmelon species (''Cucumis melo'') from the fami ...

melon). Carotenes are also responsible for the orange (but not all of the yellow) colours in dry foliage. They also (in lower concentrations) impart the yellow coloration to milk-fat and butter. Omnivorous animal species which are relatively poor converters of coloured dietary

carotenoids Carotenoids (), also called tetraterpenoids, are yellow, orange, and red organic pigments that are produced by plants and algae, as well as several bacteria, and fungi. Carotenoids give the characteristic color to pumpkins, carrots, parsnips, ...

to colourless retinoids, such as humans and

chicken The chicken (''Gallus gallus domesticus'') is a domesticated junglefowl species, with attributes of wild species such as the grey and the Ceylon junglefowl that are originally from Southeastern Asia. Rooster or cock is a term for an adult m ...

s, have yellow-coloured

body fat Adipose tissue, body fat, or simply fat is a loose connective tissue composed mostly of adipocytes. In addition to adipocytes, adipose tissue contains the stromal vascular fraction (SVF) of cells including preadipocytes, fibroblasts, vascular e ...

, as a result of the carotenoid retention from the vegetable portion of their diet. Carotenes contribute to photosynthesis by transmitting the light energy they absorb to

chlorophyll Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. Its name is derived from the Greek words , ("pale green") and , ("leaf"). Chlorophyll allow plants to a ...

. They also protect plant tissues by helping to absorb the energy from

singlet oxygen Singlet oxygen, systematically named dioxygen(singlet) and dioxidene, is a gaseous inorganic chemical with the formula O=O (also written as or ), which is in a quantum state where all electrons are spin paired. It is kinetically unstable at ambie ...

, an excited form of the oxygen molecule O₂ which is formed during photosynthesis.

β-Carotene β-Carotene is an organic, strongly coloured red-orange pigment abundant in fungi, plants, and fruits. It is a member of the carotenes, which are terpenoids (isoprenoids), synthesized biochemically from eight isoprene units and thus having 40 ...

is composed of two retinyl groups, and is broken down in the

mucosa A mucous membrane or mucosa is a membrane that lines various cavities in the body of an organism and covers the surface of internal organs. It consists of one or more layers of epithelial cells overlying a layer of loose connective tissue. It is ...

of the human

small intestine The small intestine or small bowel is an organ in the gastrointestinal tract where most of the absorption of nutrients from food takes place. It lies between the stomach and large intestine, and receives bile and pancreatic juice through the p ...

β-carotene 15,15'-monooxygenase In enzymology, beta-carotene 15,15'-dioxygenase, () is an enzyme with systematic name ''beta-carotene:oxygen 15,15'-dioxygenase (bond-cleaving)''. In human it is encoded by the BCDO2 gene. This enzyme catalyses the following chemical reaction ...

retinal Retinal (also known as retinaldehyde) is a polyene chromophore. Retinal, bound to proteins called opsins, is the chemical basis of visual phototransduction, the light-detection stage of visual perception (vision). Some microorganisms use retin ...

, a form of

vitamin A Vitamin A is a fat-soluble vitamin and an essential nutrient for humans. It is a group of organic compounds that includes retinol, retinal (also known as retinaldehyde), retinoic acid, and several provitamin A carotenoids (most notably bet ...

. β-Carotene can be stored in the

liver The liver is a major Organ (anatomy), organ only found in vertebrates which performs many essential biological functions such as detoxification of the organism, and the Protein biosynthesis, synthesis of proteins and biochemicals necessary for ...

and body fat and converted to retinal as needed, thus making it a form of vitamin A for humans and some other mammals. The carotenes α-carotene and

γ-carotene γ-Carotene is a carotenoid, and is a biosynthetic intermediate for cyclized carotenoid synthesis in plants. It is formed from cyclization of lycopene by lycopene cyclase epsilon.Rodriguez-Concepcion M, Stange C. Biosynthesis of carotenoids in ...

, due to their single retinyl group (β-

ionone The ionones are a series of closely related chemical substances that are part of a group of compounds known as rose ketones, which also includes damascones and damascenones. Ionones are aroma compounds found in a variety of essential oils, inclu ...

ring), also have some vitamin A activity (though less than β-carotene), as does the

xanthophyll Xanthophylls (originally phylloxanthins) are yellow pigments that occur widely in nature and form one of two major divisions of the carotenoid group; the other division is formed by the carotenes. The name is from Greek (, "yellow") and (, "l ...

carotenoid β- cryptoxanthin. All other carotenoids, including

lycopene Lycopene is an organic compound classified as a tetraterpene and a carotene. Lycopene (from the neo-Latin ''Lycopersicum'', the tomato species) is a bright red carotenoid hydrocarbon found in tomatoes and other red fruits and vegetables. Occu ...

, have no beta-ring and thus no vitamin A activity (although they may have antioxidant activity and thus biological activity in other ways). Animal species differ greatly in their ability to convert retinyl (beta-

) containing carotenoids to retinals. Carnivores in general are poor converters of dietary ionone-containing carotenoids. Pure carnivores such as

ferret The ferret (''Mustela furo'') is a small, Domestication, domesticated species belonging to the family Mustelidae. The ferret is most likely a domesticated form of the wild European polecat (''Mustela putorius''), evidenced by their Hybrid (biol ...

s lack β-carotene 15,15'-monooxygenase and cannot convert any carotenoids to retinals at all (resulting in carotenes not being a form of vitamin A for this species); while cats can convert a trace of β-carotene to retinol, although the amount is totally insufficient for meeting their daily retinol needs.

Molecular structure

Carotenes are polyunsaturated

hydrocarbon In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic, and their odors are usually weak or ex ...

s containing 40 carbon atoms per molecule, variable numbers of hydrogen atoms, and no other elements. Some carotenes are terminated by rings, on one or both ends of the molecule. All are coloured, due to the presence of

conjugated double bond In theoretical chemistry, a conjugated system is a system of connected p-orbitals with delocalized electrons in a molecule, which in general lowers the overall energy of the molecule and increases Chemical stability, stability. It is Resonance ...

s. Carotenes are

tetraterpene Tetraterpenes are terpenes consisting of eight isoprene units and have the molecular formula C40H64. Tetraterpenoids (including many carotenoids) are tetraterpenes that have been chemically modified, as indicated by the presence of oxygen-contain ...

s, meaning that they are derived from eight 5-carbon

isoprene Isoprene, or 2-methyl-1,3-butadiene, is a common volatile organic compound with the formula CH2=C(CH3)−CH=CH2. In its pure form it is a colorless volatile liquid. Isoprene is an unsaturated hydrocarbon. It is produced by many plants and animals ...

units (or four 10-carbon terpene units). Carotenes are found in plants in two primary forms designated by characters from the

Greek alphabet The Greek alphabet has been used to write the Greek language since the late 9th or early 8th century BCE. It is derived from the earlier Phoenician alphabet, and was the earliest known alphabetic script to have distinct letters for vowels as we ...

: alpha-carotene (α-carotene) and beta-carotene (β-carotene). Gamma-, delta-, epsilon-, and zeta-carotene (γ, δ, ε, and ζ-carotene) also exist. Since they are hydrocarbons, and therefore contain no oxygen, carotenes are fat-soluble and insoluble in water (in contrast with other carotenoids, the

s, which contain oxygen and thus are less chemically hydrophobic).

History

The discovery of carotene from carrot juice is credited to Heinrich Wilhelm Ferdinand Wackenroder, a finding made during a search for antihelminthics, which he published in 1831. He obtained it in small ruby-red flakes soluble in ether, which when dissolved in fats gave 'a beautiful yellow colour'.

William Christopher Zeise William Christopher Zeise (15 October 1789 – 12 November 1847) was a Danish organic chemist. He is best known for synthesising one of the first organometallic compounds, named Zeise's salt in his honour. He also performed pioneering studi ...

recognised its hydrocarbon nature in 1847, but his analyses gave him a composition of C₅H₈. It was Léon-Albert Arnaud in 1886 who confirmed its hydrocarbon nature and gave the formula C₂₆H₃₈, which is close to the theoretical composition of C₄₀H₅₆. Adolf Lieben in studies, also published in 1886, of the colouring matter in

corpora lutea The corpus luteum (Latin for "yellow body"; plural corpora lutea) is a temporary endocrine structure in female ovaries involved in the production of relatively high levels of progesterone, and moderate levels of estradiol, and inhibin A. It is th ...

, first came across carotenoids in animal tissue, but did not recognise the nature of the pigment.

Johann Ludwig Wilhelm Thudichum Johann Ludwig Wilhelm Thudichum, also known as John Louis William Thudichum (August 27, 1829, Büdingen – September 7, 1901) was a German-born physician and biochemist. From 1847 he studied medicine at the University of Giessen, where he ...

, in 1868–1869, after stereoscopic spectral examination, applied the term 'luteine'(

lutein Lutein (;"Lutein"

Richard Martin Willstätter, who gained the

Nobel Prize The Nobel Prizes ( ; sv, Nobelpriset ; no, Nobelprisen ) are five separate prizes that, according to Alfred Nobel's will of 1895, are awarded to "those who, during the preceding year, have conferred the greatest benefit to humankind." Alfr ...

Chemistry Chemistry is the science, scientific study of the properties and behavior of matter. It is a natural science that covers the Chemical element, elements that make up matter to the chemical compound, compounds made of atoms, molecules and ions ...

in 1915, mainly for his work on

, assigned the composition of C₄₀H₅₆, distinguishing it from the similar but oxygenated

, C₄₀H₅₆O₂. With

Heinrich Escher Heinrich Escher (26 July 1626 – 20 April 1710) was mayor of the City and Republic of Zürich at the turn of the 18th century. He is credited with introducing chocolate to Switzerland after learning about it in Brussels. At the beginning of his ...

, in 1910,

was isolated from tomatoes and shown to be an

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formulae – that is, same number of atoms of each element – but distinct arrangements of atoms in space. Isomerism is existence or possibility of isomers. Iso ...

of carotene. Later work by Escher also differentiated the ' luteal' pigments in egg yolk from that of the carotenes in cow corpus luteum.

Dietary sources

The following foods contain carotenes in notable amounts: *

s * wolfberries (goji) *

mango A mango is an edible stone fruit produced by the tropical tree ''Mangifera indica''. It is believed to have originated in the region between northwestern Myanmar, Bangladesh, and northeastern India. ''M. indica'' has been cultivated in South a ...

es *

red bell pepper The bell pepper (also known as paprika, sweet pepper, pepper, or capsicum ) is the fruit of plants in the Grossum Group of the species ''Capsicum annuum''. Cultivars of the plant produce fruits in different colors, including red, yellow, orange ...

papaya The papaya (, ), papaw, () or pawpaw () is the plant species ''Carica papaya'', one of the 21 accepted species in the genus ''Carica'' of the family Caricaceae. It was first domesticated in Mesoamerica, within modern-day southern Mexico and ...

spinach Spinach (''Spinacia oleracea'') is a leafy green flowering plant native to central and western Asia. It is of the order Caryophyllales, family Amaranthaceae, subfamily Chenopodioideae. Its leaves are a common edible vegetable consumed either f ...

kale Kale (), or leaf cabbage, belongs to a group of cabbage (''Brassica oleracea'') cultivars grown for their edible leaves, although some are used as ornamentals. Kale plants have green or purple leaves, and the central leaves do not form a head ...

tomato The tomato is the edible berry of the plant ''Solanum lycopersicum'', commonly known as the tomato plant. The species originated in western South America, Mexico, and Central America. The Mexican Nahuatl word gave rise to the Spanish word ...

* dandelion greens *

broccoli Broccoli (''Brassica oleracea'' var. ''italica'') is an edible green plant in the cabbage family (family Brassicaceae, genus ''Brassica'') whose large flowering head, stalk and small associated leaves are eaten as a vegetable. Broccoli is cl ...

collard greens Collard is a group of certain loose-leafed cultivars of ''Brassica oleracea'', the same species as many common vegetables including cabbage ( Capitata group) and broccoli ( Italica group). Collard is a member of the Viridis group of ''Brassica ...

winter squash Winter squash is an annual fruit representing several squash species within the genus ''Cucurbita''. Late-growing, less symmetrical, odd-shaped, rough or warty varieties, small to medium in size, but with long-keeping qualities and hard rinds, are ...

pumpkin A pumpkin is a vernacular term for mature winter squash of species and varieties in the genus ''Cucurbita'' that has culinary and cultural significance but no agreed upon botanical or scientific meaning. The term ''pumpkin'' is sometimes use ...

cassava ''Manihot esculenta'', common name, commonly called cassava (), manioc, or yuca (among numerous regional names), is a woody shrub of the spurge family, Euphorbiaceae, native to South America. Although a perennial plant, cassava is extensively ...

Absorption from these foods is enhanced if eaten with fats, as carotenes are fat soluble, and if the food is cooked for a few minutes until the plant

cell wall A cell wall is a structural layer surrounding some types of cells, just outside the cell membrane. It can be tough, flexible, and sometimes rigid. It provides the cell with both structural support and protection, and also acts as a filtering mech ...

splits and the color is released into any liquid. 12 μg of dietary β-carotene supplies the equivalent of 1 μg of retinol, and 24 µg of α-carotene or β-cryptoxanthin provides the equivalent of 1 µg of retinol.

Forms of carotene

The two primary

s of carotene, α-carotene and β-carotene, differ in the position of a

double bond In chemistry, a double bond is a covalent bond between two atoms involving four bonding electrons as opposed to two in a single bond. Double bonds occur most commonly between two carbon atoms, for example in alkenes. Many double bonds exist betw ...

(and thus a hydrogen) in the cyclic group at one end (the right end in the diagram at right).

is the more common form and can be found in

yellow Yellow is the color between green and orange on the spectrum of light. It is evoked by light with a dominant wavelength of roughly 575585 nm. It is a primary color in subtractive color systems, used in painting or color printing. In the R ...

orange Orange most often refers to: *Orange (fruit), the fruit of the tree species '' Citrus'' × ''sinensis'' ** Orange blossom, its fragrant flower *Orange (colour), from the color of an orange, occurs between red and yellow in the visible spectrum * ...

, and

green Green is the color between cyan and yellow on the visible spectrum. It is evoked by light which has a dominant wavelength of roughly 495570 Nanometre, nm. In subtractive color systems, used in painting and color printing, it is created by ...

leafy

fruit In botany, a fruit is the seed-bearing structure in flowering plants that is formed from the ovary after flowering. Fruits are the means by which flowering plants (also known as angiosperms) disseminate their seeds. Edible fruits in particu ...

s and

vegetable Vegetables are parts of plants that are consumed by humans or other animals as food. The original meaning is still commonly used and is applied to plants collectively to refer to all edible plant matter, including the flowers, fruits, stems, ...

s. As a

rule of thumb In English, the phrase ''rule of thumb'' refers to an approximate method for doing something, based on practical experience rather than theory. This usage of the phrase can be traced back to the 17th century and has been associated with various t ...

, the greater the intensity of the orange colour of the fruit or vegetable, the more β-carotene it contains. Carotene protects plant cells against the destructive effects of ultraviolet light so β-Carotene is an

antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubricant ...

β-Carotene and physiology

β-Carotene and cancer

An article on the

American Cancer Society The American Cancer Society (ACS) is a nationwide voluntary health organization dedicated to eliminating cancer. Established in 1913, the society is organized into six geographical regions of both medical and lay volunteers operating in more than ...

says that The Cancer Research Campaign has called for warning labels on β-carotene supplements to caution smokers that such supplements may increase the risk of lung cancer.

The New England Journal of Medicine ''The New England Journal of Medicine'' (''NEJM'') is a weekly medical journal published by the Massachusetts Medical Society. It is among the most prestigious peer-reviewed medical journals as well as the oldest continuously published one. His ...

published an article in 1994 about a trial which examined the relationship between daily supplementation of β-carotene and

vitamin E Vitamin E is a group of eight fat soluble compounds that include four tocopherols and four tocotrienols. Vitamin E deficiency, which is rare and usually due to an underlying problem with digesting dietary fat rather than from a diet low in vitami ...

(α-tocopherol) and the incidence of lung cancer. The study was done using supplements and researchers were aware of the epidemiological correlation between carotenoid-rich fruits and vegetables and lower lung cancer rates. The research concluded that no reduction in lung cancer was found in the participants using these supplements, and furthermore, these supplements may, in fact, have harmful effects. The Journal of the

National Cancer Institute The National Cancer Institute (NCI) coordinates the United States National Cancer Program and is part of the National Institutes of Health (NIH), which is one of eleven agencies that are part of the U.S. Department of Health and Human Services. ...

and The New England Journal of Medicine published articles in 1996 about a trial with a goal to determine if vitamin A (in the form of

retinyl palmitate Retinyl palmitate, or vitamin A palmitate, is the ester of retinol (vitamin A) and palmitic acid, with formula C36H60O2. It is the most abundant form of vitamin A storage in animals. An alternate spelling, retinol palmitate, which violates the - ...

) and β-carotene (at about 30 mg/day, which is 10 times the

Reference Daily Intake The Reference Daily Intake (RDI) used in nutrition labeling on food and dietary supplement products in the U.S. and Canada is the daily intake level of a nutrient that is considered to be sufficient to meet the requirements of 97–98% of health ...

) supplements had any beneficial effects to prevent cancer. The results indicated an ''increased'' risk of lung and prostate cancers for the participants who consumed the β-carotene supplement and who had lung irritation from

smoking Smoking is a practice in which a substance is burned and the resulting smoke is typically breathed in to be tasted and absorbed into the bloodstream. Most commonly, the substance used is the dried leaves of the tobacco plant, which have bee ...

asbestos Asbestos () is a naturally occurring fibrous silicate mineral. There are six types, all of which are composed of long and thin fibrous crystals, each fibre being composed of many microscopic "fibrils" that can be released into the atmosphere b ...

exposure, causing the trial to be stopped early. A review of all randomized controlled trials in the scientific literature by the

Cochrane Collaboration Cochrane (previously known as the Cochrane Collaboration) is a British international charitable organisation formed to organise medical research findings to facilitate evidence-based choices about health interventions involving health profess ...

published in ''

JAMA ''The Journal of the American Medical Association'' (''JAMA'') is a peer-reviewed medical journal published 48 times a year by the American Medical Association. It publishes original research, reviews, and editorials covering all aspects of biom ...

'' in 2007 found that synthetic β-carotene ''increased'' mortality by 1-8 % (Relative Risk 1.05, 95% confidence interval 1.01–1.08). However, this meta-analysis included two large studies of smokers, so it is not clear that the results apply to the general population. The review only studied the influence of synthetic antioxidants and the results should not be translated to potential effects of fruits and vegetables.

β-Carotene and photosensitivity

Oral β-carotene is prescribed to people suffering from

erythropoietic protoporphyria Erythropoietic protoporphyria (or commonly called EPP) is a form of porphyria, which varies in severity and can be very painful. It arises from a deficiency in the enzyme ferrochelatase, leading to abnormally high levels of protoporphyrin in the ...

. It provides them some relief from photosensitivity.

Carotenemia

Carotenemia or hypercarotenemia is excess carotene, but unlike excess vitamin A, carotene is non-toxic. Although hypercarotenemia is not particularly dangerous, it can lead to an oranging of the skin (carotenodermia), but not the

conjunctiva The conjunctiva is a thin mucous membrane that lines the inside of the eyelids and covers the sclera (the white of the eye). It is composed of non-keratinized, stratified squamous epithelium with goblet cells, stratified columnar epithelium ...

of eyes (thus easily distinguishing it visually from

jaundice Jaundice, also known as icterus, is a yellowish or greenish pigmentation of the skin and sclera due to high bilirubin levels. Jaundice in adults is typically a sign indicating the presence of underlying diseases involving abnormal heme meta ...

). It is most commonly associated with consumption of an abundance of

s, but it also can be a

medical sign Signs and symptoms are the observed or detectable signs, and experienced symptoms of an illness, injury, or condition. A sign for example may be a higher or lower temperature than normal, raised or lowered blood pressure or an abnormality showin ...

of more dangerous conditions.

Production

Carotenes are produced in a general manner for other terpenoids and terpenes, i.e. by coupling, cyclization, and oxygenation reactions of

derivatives.

Lycopene Lycopene is an organic compound classified as a tetraterpene and a carotene. Lycopene (from the neo-Latin ''Lycopersicum'', the tomato species) is a bright red carotenoid hydrocarbon found in tomatoes and other red fruits and vegetables. Occu ...

is the key precursor to carotenoids. It is formed by coupling of

geranylgeranyl pyrophosphate Geranylgeranyl pyrophosphate is an intermediate in the biosynthesis of diterpenes and diterpenoids. It is also the precursor to carotenoids, gibberellins, tocopherols, and chlorophylls. It is also a precursor to geranylgeranylated proteins, whi ...

and eranyllinalyl_pyrophosphate. Most_of_the_world's_synthetic_supply_of_carotene_comes_from_a_manufacturing_complex_located_in_Freeport,_Texas_and_owned_by_DSM_(company).html" "title="Freeport,_Texas.html" ;"title="eranyllinalyl pyrophosphate. Most of the world's synthetic supply of carotene comes from a manufacturing complex located in Freeport, Texas">eranyllinalyl pyrophosphate. Most of the world's synthetic supply of carotene comes from a manufacturing complex located in Freeport, Texas and owned by DSM (company)">DSM DSM or dsm may refer to: Science and technology * Deep space maneuver * Design structure matrix or dependency structure matrix, a representation of a system or project * Diagnostic and Statistical Manual of Mental Disorders ** DSM-5, the fifth ed ...

. The other major supplier

BASF BASF Societas Europaea, SE () is a German multinational corporation, multinational chemical company and the List of largest chemical producers, largest chemical producer in the world. Its headquarters is located in Ludwigshafen, Germany. The ...

also uses a chemical process to produce β-carotene. Together these suppliers account for about 85% of the β-carotene on the market. In Spain Vitatene produces natural β-carotene from fungus

Blakeslea trispora ''Blakeslea trispora'' is a mould and member of the division Zygomycota. This species has been well studied for its ability to produce carotenoids, particularly, β-carotene and lycopene. β-carotene is a vitamin A precursor and both of β-carot ...

, as does DSM but at much lower amount when compared to its synthetic β-carotene operation. In Australia, organic β-carotene is produced by Aquacarotene Limited from dried marine algae ''

Dunaliella salina ''Dunaliella salina'' is a type of halophile green unicellular micro-algae especially found in hypersaline environments, such as salt lakes and salt evaporation ponds. Known for its antioxidant activity because of its ability to create large ...

'' grown in harvesting ponds situated in

Karratha, Western Australia Karratha is a city in the Pilbara region of Western Australia, adjoining the port of Dampier. It was established in 1968 to accommodate the processing and exportation workforce of the Hamersley Iron mining company and, in the 1980s, the petrol ...

. BASF Australia is also producing β-carotene from microalgae grown in two sites in Australia that are the world's largest algae farms. In

Portugal Portugal, officially the Portuguese Republic ( pt, República Portuguesa, links=yes ), is a country whose mainland is located on the Iberian Peninsula of Southwestern Europe, and whose territory also includes the Atlantic archipelagos of ...

, the

industrial biotechnology Biotechnology is the integration of natural sciences and engineering sciences in order to achieve the application of organisms, cells, parts thereof and molecular analogues for products and services. The term ''biotechnology'' was first used b ...

company Biotrend is producing natural all-''trans''-β-carotene from a non-genetically-modified bacteria of the genus ''

Sphingomonas ''Sphingomonas'' was defined in 1990 as a group of Gram-negative, rod-shaped, chemoheterotrophic, strictly aerobic bacteria. They possess ubiquinone 10 as their major respiratory quinone, contain glycosphingolipids (GSLs), specifically ceramide ...

'' isolated from soil. Carotenes are also found in palm oil, corn, and in the milk of dairy cows, causing cow's milk to be light yellow, depending on the feed of the cattle, and the amount of fat in the milk (high-fat milks, such as those produced by

Guernsey Guernsey (; Guernésiais: ''Guernési''; french: Guernesey) is an island in the English Channel off the coast of Normandy that is part of the Bailiwick of Guernsey, a British Crown Dependency. It is the second largest of the Channel Islands ...

cows, tend to be yellower because their fat content causes them to contain more carotene). Carotenes are also found in some species of termites, where they apparently have been picked up from the diet of the insects.

Synthesis

There are currently two commonly used methods of

total synthesis Total synthesis is the complete chemical synthesis of a complex molecule, often a natural product, from simple, commercially-available precursors. It usually refers to a process not involving the aid of biological processes, which distinguishes ...

of β-carotene. The first was developed by

and is based on the

Wittig reaction The Wittig reaction or Wittig olefination is a chemical reaction of an aldehyde or ketone with a triphenyl phosphonium ylide called a Wittig reagent. Wittig reactions are most commonly used to convert aldehydes and ketones to alkenes. Most o ...

with Wittig himself as patent holder:Wittig G.; Pommer H.: ''DBP 954247, 1956Wittig G.; Pommer H. (1959). ''Chem. Abstr''. 53: 2279 : Wittig-9

The second is a

Grignard reaction The Grignard reaction () is an organometallic chemical reaction in which alkyl, allyl, vinyl, or aryl-magnesium halides ( Grignard reagent) is added to a carbonyl group in an aldehyde or ketone. This reaction is important for the formation of ...

, elaborated by

Hoffman-La Roche F. Hoffmann-La Roche AG, commonly known as Roche, is a Swiss multinational healthcare company that operates worldwide under two divisions: Pharmaceuticals and Diagnostics. Its holding company, Roche Holding AG, has shares listed on the SIX S ...

from the original synthesis of Inhoffen et al. They are both symmetrical; the BASF synthesis is C20 + C20, and the Hoffman-La Roche synthesis is C19 + C2 + C19.

Nomenclature

Carotenes are carotenoids containing no oxygen. Carotenoids containing some oxygen are known as

s. The two ends of the β-carotene molecule are structurally identical, and are called β-rings. Specifically, the group of nine carbon atoms at each end form a β-ring. The α-carotene molecule has a β-ring at one end; the other end is called an ε-ring. There is no such thing as an "α-ring". These and similar names for the ends of the carotenoid molecules form the basis of a systematic naming scheme, according to which: * α-carotene is β,ε-carotene; * β-carotene is β,β-carotene; * γ-carotene (with one β ring and one uncyclized end that is labelled ''

psi Psi, PSI or Ψ may refer to: Alphabetic letters * Psi (Greek) (Ψ, ψ), the 23rd letter of the Greek alphabet * Psi (Cyrillic) (Ѱ, ѱ), letter of the early Cyrillic alphabet, adopted from Greek Arts and entertainment * "Psi" as an abbreviatio ...

'') is β,ψ-carotene; * δ-carotene (with one ε ring and one uncyclized end) is ε,ψ-carotene; * ε-carotene is ε,ε-carotene *

is ψ,ψ-carotene ζ-Carotene is the

biosynthetic Biosynthesis is a multi-step, enzyme-Catalysis, catalyzed process where substrate (chemistry), substrates are converted into more complex Product (chemistry), products in living organisms. In biosynthesis, simple Chemical compound, compounds are mo ...

precursor Precursor or Precursors may refer to: * Precursor (religion), a forerunner, predecessor ** The Precursor, John the Baptist Science and technology * Precursor (bird), a hypothesized genus of fossil birds that was composed of fossilized parts of u ...

neurosporene Neurosporene is a carotenoid pigment. It is an intermediate in the biosynthesis of lycopene Lycopene is an organic compound classified as a tetraterpene and a carotene. Lycopene (from the neo-Latin '' Lycopersicum'', the tomato species) is ...

, which is the precursor of lycopene, which, in turn, is the precursor of the carotenes α through ε.

Food additive

Carotene is used to colour products such as juice, cakes, desserts, butter and margarine. It is approved for use as a food additive in the EU (listed as additive E160a) Australia and New Zealand (listed as 160a) and the US.US FDA:

References

External links

* {{Authority control Vitamin A Food colorings Carotenoids Hydrocarbons E-number additives