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 C40Hx, 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 potatoes,
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, co ...
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 adu ...
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. They also protect plant tissues by helping to absorb the energy from singlet oxygen, 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 ...
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
...
to
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, inc ...
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 (, "lea ...
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-
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, inc ...
) containing carotenoids to retinals. Carnivores in general are poor converters of dietary ionone-containing carotenoids. Pure carnivores such as ferrets 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 ...
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 stability. It is conventionally represented as ...
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 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
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 (, "lea ...
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'(
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 ...
in
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 chlorophyll, assigned the composition of C40H56, distinguishing it from the similar but oxygenated
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 (, "lea ...
, 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,
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 ...
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:
*
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 ...
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 ...
*
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 ...
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 cla ...
*
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 ...
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
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 ...
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 betwee ...
(and thus a hydrogen) in the cyclic group at one end (the right end in the diagram at right).
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 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 ...
,
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 nm. In subtractive color systems, used in painting and color printing, it is created by a combi ...
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, 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 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.
Hi ...
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 vi ...
(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 healt ...
) 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 ...
or
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
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 ...
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 isoprene 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 di terpenoids. It is also the precursor to carotenoids, gibberellins, tocopherols, and chlorophylls.
It is also a precursor to geranylgeranylated proteins, wh ...
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 SE () is a German multinational chemical company and the largest chemical producer in the world. Its headquarters is located in Ludwigshafen, Germany.
The BASF Group comprises subsidiaries and joint ventures in more than 80 countries ...
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 i ...
of β-carotene. The first was developed by
BASF
BASF SE () is a German multinational chemical company and the largest chemical producer in the world. Its headquarters is located in Ludwigshafen, Germany.
The BASF Group comprises subsidiaries and joint ventures in more than 80 countries ...
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. Mos ...
with Wittig himself as patent holder:Wittig G.; Pommer H.: ''DBP 954247, 1956Wittig G.; Pommer H. (1959). ''Chem. Abstr''. 53: 2279
:
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
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 (, "lea ...
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
*
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 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 ...
of
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:
See also
*
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 ...