Aerial image of Grand Prismatic Spring (view from the south)

Carotenoids (), also called tetraterpenoids, are yellow, orange, and red

organic Organic may refer to: * Organic, of or relating to an organism, a living entity * Organic, of or relating to an anatomical organ Chemistry * Organic matter, matter that has come from a once-living organism, is capable of decay or is the product ...

pigment A pigment is a colored material that is completely or nearly insoluble in water. In contrast, dyes are typically soluble, at least at some stage in their use. Generally dyes are often organic compounds whereas pigments are often inorganic compo ...

s that are produced by

plant Plants are predominantly photosynthetic eukaryotes of the kingdom Plantae. Historically, the plant kingdom encompassed all living things that were not animals, and included algae and fungi; however, all current definitions of Plantae exclud ...

s and

algae Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

, as well as several bacteria, and

fungi A fungus ( : fungi or funguses) is any member of the group of eukaryotic organisms that includes microorganisms such as yeasts and molds, as well as the more familiar mushrooms. These organisms are classified as a kingdom, separately from ...

. Carotenoids give the characteristic color to

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 ...

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 ...

parsnip The parsnip (''Pastinaca sativa'') is a root vegetable closely related to carrot and parsley, all belonging to the flowering plant family Apiaceae. It is a biennial plant usually grown as an annual. Its long taproot has cream-colored skin an ...

corn Maize ( ; ''Zea mays'' subsp. ''mays'', from es, maíz after tnq, mahiz), also known as corn (North American and Australian English), is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. Th ...

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 ...

es, canaries,

flamingo Flamingos or flamingoes are a type of Wader, wading bird in the Family (biology), family Phoenicopteridae, which is the only extant family in the order Phoenicopteriformes. There are four flamingo species distributed throughout the Americas ...

salmon Salmon () is the common name for several list of commercially important fish species, commercially important species of euryhaline ray-finned fish from the family (biology), family Salmonidae, which are native to tributary, tributaries of the ...

lobster Lobsters are a family (biology), family (Nephropidae, Synonym (taxonomy), synonym Homaridae) of marine crustaceans. They have long bodies with muscular tails and live in crevices or burrows on the sea floor. Three of their five pairs of legs ...

shrimp Shrimp are crustaceans (a form of shellfish) with elongated bodies and a primarily swimming mode of locomotion – most commonly Caridea and Dendrobranchiata of the decapod order, although some crustaceans outside of this order are refer ...

, and

daffodil ''Narcissus'' is a genus of predominantly spring flowering perennial plants of the amaryllis family, Amaryllidaceae. Various common names including daffodil,The word "daffodil" is also applied to related genera such as '' Sternbergia'', ''Is ...

s. Carotenoids can be produced from fats and other basic organic metabolic building blocks by all these organisms. It is also produced by

endosymbiotic An ''endosymbiont'' or ''endobiont'' is any organism that lives within the body or cells of another organism most often, though not always, in a mutualistic relationship. (The term endosymbiosis is from the Greek: ἔνδον ''endon'' "within" ...

bacteria in

whiteflies Whiteflies are Hemipterans that typically feed on the undersides of plant leaves. They comprise the family Aleyrodidae, the only family in the superfamily Aleyrodoidea. More than 1550 species have been described. Description and taxonomy The ...

. Carotenoids from the diet are stored in the fatty tissues of animals, and exclusively

carnivorous A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

animals obtain the compounds from animal fat. In the human diet,

absorption Absorption may refer to: Chemistry and biology * Absorption (biology), digestion **Absorption (small intestine) *Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials *Absorption (skin), a route by which ...

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 In pharmacology, bioavailability is a subcategory of absorption and is the fraction (%) of an administered drug that reaches the systemic circulation. By definition, when a medication is administered intravenously, its bioavailability is 100%. H ...

. There are over 1,100 known carotenoids which can be further categorized into two classes,

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 ...

s (which contain oxygen) and

carotene The term carotene (also carotin, from the Latin ''carota'', "carrot") is used for many related unsaturated hydrocarbon substances having the formula C40Hx, which are synthesized by plants but in general cannot be made by animals (with the exc ...

s (which are purely

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 and contain no oxygen). All are

derivatives The derivative of a function is the rate of change of the function's output relative to its input value. Derivative may also refer to: In mathematics and economics * Brzozowski derivative in the theory of formal languages * Formal derivative, an ...

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 produced from 8

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 ...

molecules 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 Autumn, also known as fall in American English and Canadian English, is one of the four temperate seasons on Earth. Outside the tropics, autumn marks the transition from summer to winter, in September ( Northern Hemisphere) or March ( Sou ...

leaf coloration of about 15-30% of tree species, but many plant colors, especially reds and purples, are due to

polyphenol Polyphenols () are a large family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and structurally diverse. Polyphenols include flavonoids, tannic acid, and ellagitannin, some of ...

Carotenoids serve two key roles in plants and algae: they absorb light energy for use in

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 ...

, and they provide

photoprotection Photoprotection is the biochemical process that helps organisms cope with molecular damage caused by sunlight. Plants and other oxygenic phototrophs have developed a suite of photoprotective mechanisms to prevent photoinhibition and oxidative stre ...

via

non-photochemical quenching Non-photochemical quenching (NPQ) is a mechanism employed by plants and algae to protect themselves from the adverse effects of high light intensity. It involves the quenching of singlet excited state chlorophylls (Chl) via enhanced internal con ...

. Carotenoids that contain unsubstituted beta-ionone rings (including

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 ...

, α-carotene, β-cryptoxanthin, 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 ...

) have

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 ...

activity (meaning that they can be converted to

retinol Retinol, also called vitamin A1, is a fat-soluble vitamin in the vitamin A family found in food and used as a dietary supplement. As a supplement it is used to treat and prevent vitamin A deficiency, especially that which results in xerophtha ...

). In the eye,

lutein Lutein (;"Lutein"

''meso''-zeaxanthin, and

zeaxanthin Zeaxanthin is one of the most common carotenoids in nature, and is used in the xanthophyll cycle. Synthesized in plants and some micro-organisms, it is the pigment that gives paprika (made from bell peppers), corn, saffron, goji ( wolfberries), ...

are present as macular pigments whose importance in visual function, as of 2016, remains under

clinical research Clinical research is a branch of healthcare science that determines the safety and effectiveness ( efficacy) of medications, devices, diagnostic products and treatment regimens intended for human use. These may be used for prevention, treatm ...

Biosynthesis

The basic building blocks of carotenoids are

isopentenyl diphosphate Isopentenyl pyrophosphate (IPP, isopentenyl diphosphate, or IDP) is an isoprenoid precursor. IPP is an intermediate in the classical, HMG-CoA reductase pathway (commonly called the mevalonate pathway) and in the ''non-mevalonate'' MEP pathway of ...

(IPP) and

dimethylallyl diphosphate Dimethylallyl pyrophosphate (DMAPP; or alternatively, dimethylallyl diphosphate (DMADP); also isoprenyl pyrophosphate) is an isoprenoid precursor. It is a product of both the mevalonate pathway and the MEP pathway of isoprenoid precursor biosynt ...

(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: the cytosolic

mevalonic acid Mevalonic acid (MVA) is a key organic compound in biochemistry; the name is a contraction of dihydroxymethylvalerolactone. The carboxylate anion of mevalonic acid, which is the predominant form in biological environments, is known as ''mevalonate ...

pathway (MVA) and the plastidic methylerythritol 4-phosphate (MEP). In animals, the production of

cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell mem ...

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 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 ...

(GGPP). GGPP can be converted into carotenes or xanthophylls by undergoing a number of different steps within the carotenoid biosynthetic pathway.

MEP pathway

Glyceraldehyde 3-phosphate Glyceraldehyde 3-phosphate, also known as triose phosphate or 3-phosphoglyceraldehyde and abbreviated as G3P, GA3P, GADP, GAP, TP, GALP or PGAL, is a metabolite that occurs as an intermediate in several central pathways of all organisms.Nelson, D ...

and

pyruvate Pyruvic acid (CH3COCOOH) is the simplest of the alpha-keto acids, with a carboxylic acid and a ketone functional group. Pyruvate, the conjugate base, CH3COCOO−, is an intermediate in several metabolic pathways throughout the cell. Pyruvic aci ...

, intermediates of

, are converted to deoxy-D-xylulose 5-phosphate (DXP) using the catalyst

DXP synthase In enzymology, a 1-deoxy--xylulose-5-phosphate synthase () is an enzyme in the non-mevalonate pathway that catalyzes the chemical reaction :pyruvate + -glyceraldehyde 3-phosphate \rightleftharpoons 1-deoxy--xylulose 5-phosphate + CO2 Thus, t ...

(DXS).

DXP reductoisomerase DXP reductoisomerase (1-deoxy-D-xylulose 5-phosphate reductoisomerase or DXR) is an enzyme that interconverts 1-deoxy-D-xylulose 5-phosphate (DXP) and 2-C-methyl-D-erythritol 4-phosphate (MEP). Image:DOXP.png, 1-Deoxy-D-xylulose 5-phosphate ...

reduces and rearranges the molecules within DXP in the presence of

NADPH Nicotinamide adenine dinucleotide phosphate, abbreviated NADP or, in older notation, TPN (triphosphopyridine nucleotide), is a cofactor used in anabolic reactions, such as the Calvin cycle and lipid and nucleic acid syntheses, which require NAD ...

, forming MEP. Next, MEP is converted to 4-(cytidine 5’-diphospho)-2-C-methyl-D-erythritol (CDP-ME) in the presence of CTP via 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 the enzyme 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 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 Flavodoxins (Fld) are small, soluble electron-transfer proteins. Flavodoxins contains flavin mononucleotide as prosthetic group. The structure of flavodoxin is characterized by a five-stranded parallel beta sheet, surrounded by five alpha helices. T ...

and NADPH. HMBDP is reduced to IPP in the presence of

ferredoxin Ferredoxins (from Latin ''ferrum'': iron + redox, often abbreviated "fd") are iron–sulfur proteins that mediate electron transfer in a range of metabolic reactions. The term "ferredoxin" was coined by D.C. Wharton of the DuPont Co. and applied t ...

and NADPH by the enzyme HMBDP reductase. The last two steps involving HMBPD synthase and reductase can only occur in completely

anaerobic Anaerobic means "living, active, occurring, or existing in the absence of free oxygen", as opposed to aerobic which means "living, active, or occurring only in the presence of oxygen." Anaerobic may also refer to: * Anaerobic adhesive, a bonding a ...

environments. IPP is then able to isomerize to DMAPP via IPP isomerase.

Carotenoid biosynthetic pathway

Two GGPP molecules condense via

phytoene synthase Phytoene synthase (, ''prephytoene-diphosphate synthase'', ''15-cis-phytoene synthase'', ''PSase'', ''geranylgeranyl-diphosphate geranylgeranyltransferase'') is a transferase enzyme involved in the biosynthesis of carotenoids. It catalyzes the con ...

(PSY), forming the 15-cis

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 ...

phytoene Phytoene () is a 40-carbon intermediate in the biosynthesis of carotenoids. The synthesis of phytoene is the first committed step in the synthesis of carotenoids in plants. Phytoene is produced from two molecules of geranylgeranyl pyrophosphate (G ...

. PSY belongs to the

squalene/phytoene synthase family The squalene/phytoene synthase family represents proteins that catalyze the head-to-head condensation of C15 and C20 prenyl units (i.e. farnesyl diphosphate and genranylgeranyl diphosphate). This enzymatic step constitutes part of steroid and c ...

and is homologous to

squalene synthase Squalene synthase (SQS) or farnesyl-diphosphate:farnesyl-diphosphate farnesyl transferase is an enzyme localized to the membrane of the endoplasmic reticulum. SQS participates in the isoprenoid biosynthetic pathway, catalyzing a two-step react ...

that takes part in

steroid A steroid is a biologically active organic compound with four rings arranged in a specific molecular configuration. Steroids have two principal biological functions: as important components of cell membranes that alter membrane fluidity; and a ...

biosynthesis. The subsequent conversion of phytoene into all-trans-

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 ...

depends on the organism. Bacteria and fungi employ 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 In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. At ...

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 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 Prolycopene isomerase (, ''CRTISO'', ''carotene cis-trans isomerase'', ''ZEBRA2 (gene)'', ''carotene isomerase'', ''carotenoid isomerase'') is an enzyme with systematic name ''7,9,7',9'-tetracis-lycopene cis-trans-isomerase''. This enzyme catalyse ...

, a carotenoid isomerase, is needed to convert the

cis Cis or cis- may refer to: Places * Cis, Trentino, in Italy * In Poland: ** Cis, Świętokrzyskie Voivodeship, south-central ** Cis, Warmian-Masurian Voivodeship, north Math, science and biology * cis (mathematics) (cis(''θ'')), a trigonome ...

-lycopene into an all-trans lycopene in the presence of reduced

FAD A fad or trend is any form of collective behavior that develops within a culture, a generation or social group in which a group of people enthusiastically follow an impulse for a short period. Fads are objects or behaviors that achieve short- ...

. This all-trans lycopene is cyclized;

cyclization A cyclic compound (or ring compound) is a term for a compound in the field of chemistry in which one or more series of atoms in the compound is connected to form a ring. Rings may vary in size from three to many atoms, and include examples where al ...

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 eta-LCYor lycopene epsilon-cyclase psilon-LCY. α-Carotene is produced when the all-trans lycopene first undergoes reaction with epsilon-LCY then a second reaction with beta-LCY; whereas

is produced by two reactions with beta-LCY. α- and β-Carotene are the most common carotenoids in the plant

photosystem Photosystems are functional and structural units of protein complexes involved in photosynthesis. Together they carry out the primary photochemistry of photosynthesis: the absorption of light and the transfer of energy and electrons. Photosystems ...

s but they can still be further converted into xanthophylls by using beta-hydrolase and epsilon-hydrolase, leading to a variety of xanthophylls.

Regulation

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 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

toxin A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849– ...

s that affect enzymes and proteins required for synthesis. Ketoclomazone is derived from

herbicide Herbicides (, ), also commonly known as weedkillers, are substances used to control undesired plants, also known as weeds.EPA. February 201Pesticides Industry. Sales and Usage 2006 and 2007: Market Estimates. Summary in press releasMain page fo ...

s 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 Fosmidomycin is an antibiotic that was originally isolated from culture broths of bacteria of the genus '' Streptomyces''. It specifically inhibits DXP reductoisomerase, a key enzyme in the non-mevalonate pathway of isoprenoid biosynthesis. It ...

, an

antibiotic An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention of ...

, is a

competitive inhibitor Competitive inhibition is interruption of a chemical pathway owing to one chemical substance inhibiting the effect of another by competing with it for binding or bonding. Any metabolic or chemical messenger system can potentially be affected b ...

of DXP reductoisomerase due to its similar structure to the enzyme. Application of said antibiotic prevents reduction of DXP, again halting the MEP pathway.

Structure and function

The structure of carotenoids allows for biological abilities, including

, plant coloration, and

cell signaling In biology, cell signaling (cell signalling in British English) or cell communication is the ability of a cell to receive, process, and transmit signals with its environment and with itself. Cell signaling is a fundamental property of all cellula ...

. The general structure of the carotenoid is a

polyene In organic chemistry, polyenes are poly- unsaturated, organic compounds that contain at least three alternating double () and single () carbon–carbon bonds. These carbon–carbon double bonds interact in a process known as conjugation, resultin ...

chain consisting of 9-11 double bonds and possibly terminating in rings. This structure of

conjugated double bonds 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 ...

leads to a high reducing potential, or the ability to transfer electrons throughout the molecule. Carotenoids can transfer excitation energy in one of two ways: 1) singlet-singlet energy transfer from carotenoid 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 ...

, and 2) triplet-triplet energy transfer from chlorophyll to carotenoid. The singlet-singlet energy transfer is a lower energy state transfer and is used during photosynthesis. The length of the polyene tail enables light absorbance in the photosynthetic range; once it absorbs energy it becomes excited, then transfers the excited electrons to the

for photosynthesis. The triplet-triplet transfer is a higher energy state and is essential in photoprotection. Light produces damaging species during photosynthesis, with the most damaging being

reactive oxygen species In chemistry, reactive oxygen species (ROS) are highly reactive chemicals formed from diatomic oxygen (). Examples of ROS include peroxides, superoxide, hydroxyl radical, singlet oxygen, and alpha-oxygen. The reduction of molecular oxygen () p ...

(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 the most balanced (lowest energy) state for the carotenoid. The length of carotenoids also has a role in plant coloration, as the length of the polyene tail determines which wavelengths of light the plant will absorb. Wavelengths that are not absorbed are reflected and are what we see as the color of a plant. Therefore, differing species will contain carotenoids with differing tail lengths allowing them to absorb and reflect different colors. Carotenoids also participate in different types of cell signaling. They are able to signal the production of absicisic acid, which regulates plant growth,

seed dormancy Seed dormancy is an evolutionary adaptation that prevents seeds from germinating during unsuitable ecological conditions that would typically lead to a low probability of seedling survival. Dormant seeds do not germinate in a specified period of ...

, embryo maturation and

germination Germination is the process by which an organism grows from a seed or spore. The term is applied to the sprouting of a seedling from a seed of an angiosperm or gymnosperm, the growth of a sporeling from a spore, such as the spores of fungi, fer ...

cell division Cell division is the process by which a parent cell (biology), cell divides into two daughter cells. Cell division usually occurs as part of a larger cell cycle in which the cell grows and replicates its chromosome(s) before dividing. In eukar ...

and elongation, floral growth, and stress responses.

Properties

Carotenoids belong to the category of

tetraterpenoid 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 (i.e., they contain 40 carbon atoms, being built from four

terpene Terpenes () are a class of natural products consisting of compounds with the formula (C5H8)n for n > 1. Comprising more than 30,000 compounds, these unsaturated hydrocarbons are produced predominantly by plants, particularly conifers. Terpenes ar ...

units each containing 10 carbon atoms). Structurally, carotenoids take the form of a

hydrocarbon chain which is sometimes terminated by rings, and may or may not have additional oxygen atoms attached. * Carotenoids with molecules containing oxygen, such as

lutein Lutein (;"Lutein"

, are known as

s. * The unoxygenated (oxygen free) carotenoids such as α-carotene,

, and

, are known as

s. Carotenes typically contain only carbon and hydrogen (i.e., are

s), and are in the subclass of

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 ...

s. Their color, ranging from pale yellow through bright orange to deep red, is directly linked to their structure. Xanthophylls are often yellow, hence their class name. The double carbon-carbon bonds interact with each other in a process called

conjugation Conjugation or conjugate may refer to: Linguistics * Grammatical conjugation, the modification of a verb from its basic form * Emotive conjugation or Russell's conjugation, the use of loaded language Mathematics * Complex conjugation, the chang ...

, which allows electrons in the molecule to move freely across these areas of the molecule. As the number of conjugated double bonds increases, electrons associated with conjugated systems have more room to move, and require less energy to change states. This causes the range of energies of light absorbed by the molecule to decrease. As more wavelengths of light are absorbed from the longer end of the visible spectrum, the compounds acquire an increasingly red appearance. Carotenoids are usually

lipophilic Lipophilicity (from Greek λίπος "fat" and φίλος "friendly"), refers to the ability of a chemical compound to dissolve in fats, oils, lipids, and non-polar solvents such as hexane or toluene. Such non-polar solvents are themselves lipop ...

due to the presence of long unsaturated

aliphatic In organic chemistry, hydrocarbons ( compounds composed solely of carbon and hydrogen) are divided into two classes: aromatic compounds and aliphatic compounds (; G. ''aleiphar'', fat, oil). Aliphatic compounds can be saturated, like hexane, or ...

chains as in some

fatty acid In chemistry, particularly in biochemistry, a fatty acid is a carboxylic acid with an aliphatic chain, which is either saturated or unsaturated. Most naturally occurring fatty acids have an unbranched chain of an even number of carbon atoms, fr ...

s. The physiological absorption of these

fat-soluble vitamin A vitamin is an organic molecule (or a set of molecules closely related chemically, i.e. vitamers) that is an essential micronutrient that an organism needs in small quantities for the proper functioning of its metabolism. Essential nutri ...

s in humans and other organisms depends directly on the presence of fats and

bile salt Bile acids are steroid acids found predominantly in the bile of mammals and other vertebrates. Diverse bile acids are synthesized in the liver. Bile acids are conjugated with taurine or glycine residues to give anions called bile salts. Prima ...

Foods

Beta-carotene, found in

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 ...

s and

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 ...

, 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 GAC or Gac may refer to: Companies and organisations * GAC Group, a Chinese automotive company based in Guangzhou, Guangdong * GAC Ireland, an Irish bus manufacturer established with Bombardier (1980–1986) * Games Administration Committee, ...

fruit contains the highest known concentration of the carotenoid

. Although green,

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 ...

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 ...

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 ...

, and

turnip greens The turnip or white turnip (''Brassica rapa'' subsp. ''rapa'') is a root vegetable commonly grown in temperate climates worldwide for its white, fleshy taproot. The word ''turnip'' is a compound of ''turn'' as in turned/rounded on a lathe and ...

contain substantial amounts of beta-carotene. The diet of

s is rich in carotenoids, imparting the orange-colored feathers of these birds.

Morphology

Carotenoids are located primarily outside the

cell nucleus The cell nucleus (pl. nuclei; from Latin or , meaning ''kernel'' or ''seed'') is a membrane-bound organelle found in eukaryotic cells. Eukaryotic cells usually have a single nucleus, but a few cell types, such as mammalian red blood cells, h ...

in different cytoplasm organelles,

lipid droplet Lipid droplets, also referred to as lipid bodies, oil bodies or adiposomes, are lipid-rich cellular organelles that regulate the storage and hydrolysis of neutral lipids and are found largely in the adipose tissue. They also serve as a reservoi ...

s, cytosomes and granules. They have been visualised and quantified by

raman spectroscopy Raman spectroscopy () (named after Indian physicist C. V. Raman) is a spectroscopic technique typically used to determine vibrational modes of molecules, although rotational and other low-frequency modes of systems may also be observed. Raman sp ...

in an

algal Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular mic ...

cell. With the development of

monoclonal antibodies A monoclonal antibody (mAb, more rarely called moAb) is an antibody produced from a cell Lineage made by cloning a unique white blood cell. All subsequent antibodies derived this way trace back to a unique parent cell. Monoclonal antibodies ca ...

to ''trans-''

it was possible to localise this carotenoid in different animal and human cells.

Oxygenation

Carotenoids play an important role in biological oxygenation. In plant cells they are involved in the control of trans-membrane transport of molecular oxygen released in

. In animals carotenoids play an important role to support oxygen in its transport, storage and metabolism.

Transport

Carotenoids are hydrophobic and are typically present in plasma

lipoprotein A lipoprotein is a biochemical assembly whose primary function is to transport hydrophobic lipid (also known as fat) molecules in water, as in blood plasma or other extracellular fluids. They consist of a triglyceride and cholesterol center, sur ...

s and cellular lipid structures. Since molecular oxygen is also a

hydrophobic In chemistry, hydrophobicity is the physical property of a molecule that is seemingly repelled from a mass of water (known as a hydrophobe). In contrast, hydrophiles are attracted to water. Hydrophobic molecules tend to be nonpolar and, th ...

molecule, lipids provide a more favorable environment for O₂ solubility than in aqueous mediums. By protecting lipids from free-radical damage, which generate charged

lipid peroxides Lipid peroxidation is the chain of reactions of oxidative degradation of lipids. It is the process in which free radicals "steal" electrons from the lipids in cell membranes, resulting in cell damage. This process proceeds by a free radical chain ...

and other oxidised derivatives, carotenoids support crystalline architecture and hydrophobicity of lipoproteins and cellular lipid structures, hence oxygen solubility and its diffusion therein.

Storage

It was first suggested that carotenoids can be involved in the intracellular depot of oxygen in 1973 by V.N. Karnaukhov. Later it was discovered that carotenoids can also stimulate the formation of intracellular lipid droplets, which can store additional molecular oxygen. These properties of carotenoids help animals to adapt to environmental stresses,

high altitude Altitude or height (also sometimes known as depth) is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The exact definition and reference datum varies according to the context ...

, intracellular infections and other

hypoxic Hypoxia means a lower than normal level of oxygen, and may refer to: Reduced or insufficient oxygen * Hypoxia (environmental), abnormally low oxygen content of the specific environment * Hypoxia (medical), abnormally low level of oxygen in the t ...

conditions.

Respiration

Carotenoids, by increasing oxygen diffusion and the oxygen carrying capacity of plasma lipoproteins, can stimulate oxygen delivery into body tissues. This improves tissue and cellular oxygenation and stimulates the growth and respiration of

mitochondria A mitochondrion (; ) is an organelle found in the Cell (biology), cells of most Eukaryotes, such as animals, plants and Fungus, fungi. Mitochondria have a double lipid bilayer, membrane structure and use aerobic respiration to generate adenosi ...

Synergetic modality

Oxygen is required in many intracellular reactions including hydroxylation, which is important for metabolic activation of

prodrug A prodrug is a medication or compound that, after intake, is metabolized (i.e., converted within the body) into a pharmacologically active drug. Instead of administering a drug directly, a corresponding prodrug can be used to improve how the drug ...

s and

prohormones A hormone (from the Greek participle , "setting in motion") is a class of signaling molecules in multicellular organisms that are sent to distant organs by complex biological processes to regulate physiology and behavior. Hormones are required fo ...

, such as vitamin D3. Carotenoids not only provide support for intracellular oxygenation but can also improve efficacy of these molecules. Carotenoids can form physical complexes with different molecules. With hydrophobic molecules this could be self-assembly. With

amphiphilic An amphiphile (from the Greek αμφις amphis, both, and φιλíα philia, love, friendship), or amphipath, is a chemical compound possessing both hydrophilic (''water-loving'', polar) and lipophilic (''fat-loving'') properties. Such a compoun ...

hydrophilic A hydrophile is a molecule or other molecular entity that is attracted to water molecules and tends to be dissolved by water.Liddell, H.G. & Scott, R. (1940). ''A Greek-English Lexicon'' Oxford: Clarendon Press. In contrast, hydrophobes are no ...

compounds the use of lycosome or supercritical CO₂ technologies, or other methods, are required.^] Carotenoids in these complexes provide a new Therapy, modality of supporting and boosting tissue oxygenation, which could be synergistically beneficial to the therapeutic objectives of different

nutraceutical A nutraceutical or bioceutical is a pharmaceutical alternative which claims physiological benefits. In the US, "nutraceuticals" are largely unregulated, as they exist in the same category as dietary supplements and food additives by the FDA, unde ...

pharmaceutical A medication (also called medicament, medicine, pharmaceutical drug, medicinal drug or simply drug) is a drug used to diagnose, cure, treat, or prevent disease. Drug therapy (pharmacotherapy) is an important part of the medical field and re ...

molecules.

Physiological effects

Reviews of

epidemiological Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decisions and evidenc ...

studies seeking correlations between carotenoid consumption in food and clinical outcomes have come to various conclusions: * A 2015 review found that foods high in carotenoids appear to be protective against

head and neck cancers Head and neck cancer develops from tissues in the lip and oral cavity (mouth), larynx (throat), salivary glands, nose, sinuses or the skin of the face. The most common types of head and neck cancers occur in the lip, mouth, and larynx. Symptoms ...

. * Another 2015 review looking at whether carotenoids can prevent

prostate cancer Prostate cancer is cancer of the prostate. Prostate cancer is the second most common cancerous tumor worldwide and is the fifth leading cause of cancer-related mortality among men. The prostate is a gland in the male reproductive system that sur ...

found that while several studies found correlations between diets rich in carotenoids appeared to have a protective effect, evidence is lacking to determine whether this is due to carotenoids per se. * A 2014 review found no correlation between consumption of foods high in carotenoids and vitamin A and the risk of getting

Parkinson's disease Parkinson's disease (PD), or simply Parkinson's, is a long-term degenerative disorder of the central nervous system that mainly affects the motor system. The symptoms usually emerge slowly, and as the disease worsens, non-motor symptoms becom ...

. * Another 2014 review found no conflicting results in studies of dietary consumption of carotenoids and the risk of getting

breast cancer Breast cancer is cancer that develops from breast tissue. Signs of breast cancer may include a lump in the breast, a change in breast shape, dimpling of the skin, milk rejection, fluid coming from the nipple, a newly inverted nipple, or a re ...

. Carotenoids are also important components of the dark brown pigment

melanin Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...

, which is found in hair, skin, and eyes. Melanin absorbs high-energy light and protects these organs from intracellular damage. * Several studies have observed positive effects of high-carotenoid diets on the texture, clarity, color, strength, and elasticity of skin. * A 1994 study noted that high carotenoid diets helped reduce symptoms of

eyestrain Eye strain, also known as asthenopia (from Greek ''a-sthen-opia'', grc, ἀσθενωπία, ), is a common eye condition that manifests through non-specific symptoms such as fatigue, pain in or around the eyes, blurred vision, headache, and ...

(dry eye, headaches, and blurred vision) and improve night vision. Humans and other

animal Animals are multicellular, eukaryotic organisms in the Kingdom (biology), biological kingdom Animalia. With few exceptions, animals Heterotroph, consume organic material, Cellular respiration#Aerobic respiration, breathe oxygen, are Motilit ...

s 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

, and the red coloring of cooked

s and scales of the yellow morph of

common wall lizard ''Podarcis muralis'' (common wall lizard) is a species of lizard with a large distribution in Europe and well-established introduced populations in North America, where it is also called the European wall lizard. It can grow to about in tota ...

s are due to carotenoids. It has been proposed that carotenoids are used in ornamental traits (for extreme examples see

puffin Puffins are any of three species of small alcids (auks) in the bird genus ''Fratercula''. These are pelagic seabirds that feed primarily by diving in the water. They breed in large colonies on coastal cliffs or offshore islands, nesting in crev ...

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.

Plant colors

The most common carotenoids include lycopene and the vitamin A precursor β-carotene. In plants, the xanthophyll

lutein Lutein (;"Lutein"

. 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 the disappearance of chlorophyll. Carotenoids are responsible for the brilliant yellows and oranges that tint

deciduous In the fields of horticulture and Botany, the term ''deciduous'' () means "falling off at maturity" and "tending to fall off", in reference to trees and shrubs that seasonally shed leaves, usually in the autumn; to the shedding of petals, aft ...

foliage (such as dying autumn leaves) of certain hardwood species as hickories,

ash Ash or ashes are the solid remnants of fires. Specifically, ''ash'' refers to all non-aqueous, non- gaseous residues that remain after something burns. In analytical chemistry, to analyse the mineral and metal content of chemical samples, ash ...

maple ''Acer'' () is a genus of trees and shrubs commonly known as maples. The genus is placed in the family Sapindaceae.Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 nd more or less continuously updated since http ...

yellow poplar ''Liriodendron tulipifera''—known as the tulip tree, American tulip tree, tulipwood, tuliptree, tulip poplar, whitewood, fiddletree, and yellow-poplar—is the North American representative of the two-species genus ''Liriodendron'' (the other ...

aspen Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section ''Populus'', of the ''Populus'' genus. Species These species are called aspens: *'' Populus adenopoda'' – Chinese aspen (China ...

birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus ''Betula'' contains 30 ...

black cherry ''Prunus serotina'', commonly called black cherry,World Economic Plants: A Standard Reference, Second Edition'. CRC Press; 19 April 2016. . p. 833–. wild black cherry, rum cherry, or mountain black cherry, is a deciduous tree or shrub of the g ...

sycamore Sycamore is a name which has been applied to several types of trees, but with somewhat similar leaf forms. The name derives from the ancient Greek ' (''sūkomoros'') meaning "fig-mulberry". Species of trees known as sycamore: * ''Acer pseudoplata ...

, cottonwood,

sassafras ''Sassafras'' is a genus of three extant and one extinct species of deciduous trees in the family Lauraceae, native to eastern North America and eastern Asia.Wolfe, Jack A. & Wehr, Wesley C. 1987. The sassafras is an ornamental tree. "Middle Eoc ...

, and

alder Alders are trees comprising the genus ''Alnus'' in the birch family Betulaceae. The genus comprises about 35 species of monoecious trees and shrubs, a few reaching a large size, distributed throughout the north temperate zone with a few sp ...

. Carotenoids are the dominant pigment in autumn leaf coloration of about 15-30% of tree species. However, the reds, the purples, and their blended combinations that decorate autumn foliage usually come from another group of pigments in the cells called

anthocyanin Anthocyanins (), also called anthocyans, are water-soluble vacuolar pigments that, depending on their pH, may appear red, purple, blue, or black. In 1835, the German pharmacist Ludwig Clamor Marquart gave the name Anthokyan to a chemical compo ...

s. Unlike the carotenoids, these pigments are not present in the leaf throughout the growing season, but are actively produced towards the end of summer.

Bird colors and sexual selection

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 the ability to italicize these pigments for external coloration has evolved independently many times thought avian evolutionary history. Carotenoid coloration exhibits high levels of

sexual dimorphism Sexual dimorphism is the condition where the sexes of the same animal and/or plant species exhibit different morphological characteristics, particularly characteristics not directly involved in reproduction. The condition occurs in most ani ...

, meaning that male birds tend to display 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 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.

Sexual signaling

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 the bird species '' Parus major'', the more colorfully ornamented males produce sperm that is better protected against

oxidative stress Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily Detoxification, detoxify the reactive intermediates or to repair the resulting damage. Disturbances ...

due to increased presence of carotenoid

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 ...

s. However, there is also evidence that attractive male coloration may be a faulty signal of male quality. Among

stickleback The sticklebacks are a family of ray-finned fishes, the Gasterosteidae which have a Holarctic distribution in fresh, brackish and marine waters. They were thought to be related to the pipefish and seahorses but are now thought to be more closel ...

fish, males that are more attractive to females due to carotenoid colorants appear to under-allocate carotenoids to their germline cells.Kim SY, Velando A. Attractive male sticklebacks carry more oxidative DNA damage in the soma and germline. J Evol Biol. 2020 Jan;33(1):121-126. doi: 10.1111/jeb.13552. Epub 2019 Nov 7. PMID: 31610052 Since carotinoids are beneficial antioxidants, their under-allocation to

germline In biology and genetics, the germline is the population of a multicellular organism's cells that pass on their genetic material to the progeny (offspring). In other words, they are the cells that form the egg, sperm and the fertilised egg. They ...

cells can lead to increased oxidative

DNA damage DNA repair is a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome. In human cells, both normal metabolic activities and environmental factors such as radiation can cause DNA da ...

to these cells. Therefore, female sticklebacks may risk

fertility Fertility is the capability to produce offspring through reproduction following the onset of sexual maturity. The fertility rate is the average number of children born by a female during her lifetime and is quantified demographically. Fertili ...

and the viability of their offspring by choosing redder, but more deteriorated partners with reduced

sperm Sperm is the male reproductive cell, or gamete, in anisogamous forms of sexual reproduction (forms in which there is a larger, female reproductive cell and a smaller, male one). Animals produce motile sperm with a tail known as a flagellum, whi ...

quality.

Aroma chemicals

Products of carotenoid degradation such as

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 ...

damascone Damascones are a series of closely related chemical compounds that are components of a variety of essential oils. The damascones belong to a family of chemicals known as rose ketones, which also includes damascenones and ionones. ''beta''-Damas ...

s and

damascenone Damascenones are a series of closely related chemical compounds that are components of a variety of essential oils. The damascenones belong to a family of chemicals known as rose ketones, which also includes damascones and ionones. ''beta''-Dam ...

s are also important fragrance chemicals that are used extensively in the

perfume Perfume (, ; french: parfum) is a mixture of fragrant essential oils or aroma compounds (fragrances), fixatives and solvents, usually in liquid form, used to give the human body, animals, food, objects, and living-spaces an agreeable scent. Th ...

s and fragrance industry. Both β-damascenone and β-ionone although low in concentration in

rose A rose is either a woody perennial flowering plant of the genus ''Rosa'' (), in the family Rosaceae (), or the flower it bears. There are over three hundred species and tens of thousands of cultivars. They form a group of plants that can be ...

distillates are the key odor-contributing compounds in flowers. In fact, the sweet floral smells present in

black tea Black tea, also translated to red tea in various East Asian languages, is a type of tea that is more oxidized than oolong, yellow, white and green teas. Black tea is generally stronger in flavour than other teas. All five types are made from ...

, aged

tobacco Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...

grape A grape is a fruit, botanically a berry, of the deciduous woody vines of the flowering plant genus ''Vitis''. Grapes are a non- climacteric type of fruit, generally occurring in clusters. The cultivation of grapes began perhaps 8,000 years ago, ...

, and many

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 are due to the aromatic compounds resulting from carotenoid breakdown.

Disease

Some carotenoids are produced by bacteria to protect themselves from oxidative immune attack. The ''aureus'' (golden) pigment that gives some strains of ''

Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...

'' their name is a carotenoid called staphyloxanthin. This carotenoid is a virulence factor with an

action that helps the microbe evade death by

used by the host immune system.

Naturally occurring carotenoids

* Hydrocarbons ** Lycopersene 7,8,11,12,15,7',8',11',12',15'-Decahydro-γ,γ-carotene **

Phytofluene Phytofluene is a colorless carotenoid found naturally in tomatoes and other vegetables. It is the second product of carotenoid biosynthesis. It is formed from phytoene in a desaturation reaction leading to the formation of five conjugated doubl ...

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 ...

** Hexahydrolycopene 15-''cis''-7,8,11,12,7',8'-Hexahydro-γ,γ-carotene **

Torulene Torulene (3',4'-didehydro-β,γ-carotene) is a carotene (a hydrocarbon carotenoid) which is notable for being synthesized by red pea aphids (''Acyrthosiphon pisum''), imparting the natural red color to the aphids, which aids in their camouflage an ...

3',4'-Didehydro-β,γ-carotene ** α-Zeacarotene 7',8'-Dihydro-ε,γ-carotene ** α-Carotene **

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 ...

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 ...

** δ-Carotene ** ε-Carotene ** ζ-Carotene * Alcohols ** Alloxanthin **

Bacterioruberin ''Halobacterium'' (common abbreviation ''Hbt.'') is a genus in the family Halobacteriaceae. The genus ''Halobacterium'' ("salt" or "ocean bacterium") consists of several species of Archaea with an aerobic metabolism which requires an environmen ...

2,2'-Bis(3-hydroxy-3-methylbutyl)-3,4,3',4'-tetradehydro-1,2,1',2'-tetrahydro-γ,γ-carotene-1,1'-diol ** Cynthiaxanthin ** Pectenoxanthin ** Cryptomonaxanthin (3R,3'R)-7,8,7',8'-Tetradehydro-β,β-carotene-3,3'-diol ** Crustaxanthin β,-Carotene-3,4,3',4'-tetrol ** Gazaniaxanthin (3R)-5'-cis-β,γ-Caroten-3-ol ** OH-Chlorobactene 1',2'-Dihydro-f,γ-caroten-1'-ol ** Loroxanthin β,ε-Carotene-3,19,3'-triol **

Lutein Lutein (;"Lutein"

Lycoxanthin γ,γ-Caroten-16-ol **

Rhodopin Rhodopin (1,2-dihydro-ψ,ψ-caroten-1-ol) is a carotenoid. It is a major carotenoid of phototropic Phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur i ...

1,2-Dihydro-γ,γ-caroten-l-ol ** Rhodopinol a.k.a. Warmingol 13-''cis''-1,2-Dihydro-γ,γ-carotene-1,20-diol ** Saproxanthin 3',4'-Didehydro-1',2'-dihydro-β,γ-carotene-3,1'-diol **

Zeaxanthin Zeaxanthin is one of the most common carotenoids in nature, and is used in the xanthophyll cycle. Synthesized in plants and some micro-organisms, it is the pigment that gives paprika (made from bell peppers), corn, saffron, goji ( wolfberries), ...

* Glycosides ** Oscillaxanthin 2,2'-Bis(β-L-rhamnopyranosyloxy)-3,4,3',4'-tetradehydro-1,2,1',2'-tetrahydro-γ,γ-carotene-1,1'-diol ** Phleixanthophyll 1'-(β-D-Glucopyranosyloxy)-3',4'-didehydro-1',2'-dihydro-β,γ-caroten-2'-ol * Ethers ** Rhodovibrin 1'-Methoxy-3',4'-didehydro-1,2,1',2'-tetrahydro-γ,γ-caroten-1-ol ** Spheroidene 1-Methoxy-3,4-didehydro-1,2,7',8'-tetrahydro-γ,γ-carotene * Epoxides **

Diadinoxanthin Diadinoxanthin is a pigment found in phytoplankton. It has the formula C40H54O3. It gives rise to the xanthophylls diatoxanthin and dinoxanthin. Diadinoxanthin is a plastid pigment. Plastid pigments include chlorophylls a and c, fucoxanthin, hete ...

5,6-Epoxy-7',8'-didehydro-5,6-dihydro—carotene-3,3-diol ** Luteoxanthin 5,6: 5',8'-Diepoxy-5,6,5',8'-tetrahydro-β,β-carotene-3,3'-diol ** Mutatoxanthin ** Citroxanthin **

Zeaxanthin furanoxide Zeaxanthin is one of the most common carotenoids in nature, and is used in the xanthophyll cycle. Synthesized in plants and some micro-organisms, it is the pigment that gives paprika (made from bell peppers), corn, saffron, goji ( wolfberries ...

5,8-Epoxy-5,8-dihydro-β,β-carotene-3,3'-diol **

Neochrome NEOchrome is an early color bitmap graphics editor for the Atari ST. It was written by Dave Staugas, a programmer at Atari Corporation and co-author of the ST's operating system. ''NEOchrome'' supports hardware-supported color cycling to give the i ...

5',8'-Epoxy-6,7-didehydro-5,6,5',8'-tetrahydro-β,β-carotene-3,5,3'-triol ** Foliachrome ** Trollichrome ** Vaucheriaxanthin 5',6'-Epoxy-6,7-didehydro-5,6,5',6'-tetrahydro-β,β-carotene-3,5,19,3'-tetrol * Aldehydes ** Rhodopinal ** Warmingone 13-cis-1-Hydroxy-1,2-dihydro-γ,γ-caroten-20-al ** Torularhodinaldehyde 3',4'-Didehydro-β,γ-caroten-16'-al * Acids and acid esters ** Torularhodin 3',4'-Didehydro-β,γ-caroten-16'-oic acid ** Torularhodin methyl ester Methyl 3',4'-didehydro-β,γ-caroten-16'-oate * Ketones ** Astacene **

Astaxanthin Astaxanthin is a keto- carotenoid within a group of chemical compounds known as terpenes. Astaxanthin is a metabolite of zeaxanthin and canthaxanthin, containing both hydroxyl and ketone functional groups. It is a lipid-soluble pigment with r ...

Canthaxanthin Canthaxanthin is a keto-carotenoid pigment widely distributed in nature. Carotenoids belong to a larger class of phytochemicals known as terpenoids. The chemical formula of canthaxanthin is C40H52O2. It was first isolated in edible mushrooms. It ...

a.k.a. Aphanicin, Chlorellaxanthin β,β-Carotene-4,4'-dione **

Capsanthin Capsanthin is a natural red dye of the xanthophyll class of carotenoids. As a food coloring, it has the E number E160c(i). Capsanthin is the main carotenoid in the ''Capsicum annuum'' species of plants including red bell pepper, New Mexico chile ...

(3R,3'S,5'R)-3,3'-Dihydroxy-β,κ-caroten-6'-one **

Capsorubin Capsorubin is a natural red dye of the xanthophyll class. As a food coloring, it has the E number E160c(ii). Capsorubin is a carotenoid found in red bell pepper (''Capsicum annuum'') and a component of paprika oleoresin Paprika oleoresin (als ...

(3S,5R,3'S,5'R)-3,3'-Dihydroxy-κ,κ-carotene-6,6'-dione ** Cryptocapsin (3'R,5'R)-3'-Hydroxy-β,κ-caroten-6'-one ** 2,2'-Diketospirilloxanthin 1,1'-Dimethoxy-3,4,3',4'-tetradehydro-1,2,1',2'-tetrahydro-γ,γ-carotene-2,2'-dione **

Echinenone Echinenone is a xanthophyll, with formula C40H54O. It is found in some cyanobacteria. It is synthesized from β-carotene by the enzyme beta-carotene ketolase (or CrtW). It has also been isolated from sea urchins Sea urchins () are spiny, g ...

β,β-Caroten-4-one ** 3'-Hydroxyechinenone ** Flexixanthin 3,1'-Dihydroxy-3',4'-didehydro-1',2'-dihydro-β,γ-caroten-4-one ** 3-OH-Canthaxanthin a.k.a. Adonirubin a.k.a. Phoenicoxanthin 3-Hydroxy-β,β-carotene-4,4'-dione ** Hydroxyspheriodenone 1'-Hydroxy-1-methoxy-3,4-didehydro-1,2,1',2',7',8'-hexahydro-γ,γ-caroten-2-one ** Okenone 1'-Methoxy-1',2'-dihydro-c,γ-caroten-4'-one ** Pectenolone 3,3'-Dihydroxy-7',8'-didehydro-β,β-caroten-4-one ** Phoeniconone a.k.a. Dehydroadonirubin 3-Hydroxy-2,3-didehydro-β,β-carotene-4,4'-dione ** Phoenicopterone β,ε-caroten-4-one ** Rubixanthone 3-Hydroxy-β,γ-caroten-4'-one ** Siphonaxanthin 3,19,3'-Trihydroxy-7,8-dihydro-β,ε-caroten-8-one * Esters of alcohols ** Astacein 3,3'-Bispalmitoyloxy-2,3,2',3'-tetradehydro-β,β-carotene-4,4'-dione or 3,3'-dihydroxy-2,3,2',3'-tetradehydro-β,β-carotene-4,4'-dione dipalmitate **

Fucoxanthin Fucoxanthin is a xanthophyll, with formula C42H58O6. It is found as an accessory pigment in the chloroplasts of brown algae and most other heterokonts, giving them a brown or olive-green color. Fucoxanthin absorbs light primarily in the blue-green ...

3'-Acetoxy-5,6-epoxy-3,5'-dihydroxy-6',7'-didehydro-5,6,7,8,5',6'-hexahydro-β,β-caroten-8-one ** Isofucoxanthin 3'-Acetoxy-3,5,5'-trihydroxy-6',7'-didehydro-5,8,5',6'-tetrahydro-β,β-caroten-8-one ** Physalien ** Siphonein 3,3'-Dihydroxy-19-lauroyloxy-7,8-dihydro-β,ε-caroten-8-one or 3,19,3'-trihydroxy-7,8-dihydro-β,ε-caroten-8-one 19-laurate *

Apocarotenoid Apocarotenoids are organic compounds which occur widely in living organisms. They are derived from carotenoids by oxidative cleavage, catalyzed by carotenoid oxygenases. Examples include the vitamin A retinoids retinal, retinoic acid, and retinol; a ...

s ** β-Apo-2'-carotenal 3',4'-Didehydro-2'-apo-b-caroten-2'-al ** Apo-2-lycopenal ** Apo-6'-lycopenal 6'-Apo-y-caroten-6'-al ** Azafrinaldehyde 5,6-Dihydroxy-5,6-dihydro-10'-apo-β-caroten-10'-al **

Bixin Bixin is an apocarotenoid found in the seeds of the achiote tree (''Bixa orellana'') from which it derives its name. It is commonly extracted from the seeds to form annatto, a natural food coloring, containing about 5% pigments of which 70-80% ar ...

6'-Methyl hydrogen 9'-cis-6,6'-diapocarotene-6,6'-dioate **

Citranaxanthin Citranaxanthin is a carotenoid pigment used as a food additive under the E number E161i as a food coloring. There are natural sources of citranaxanthin, but it is generally prepared synthetically. It is used as an animal feed additive to impar ...

5',6'-Dihydro-5'-apo-β-caroten-6'-one or 5',6'-dihydro-5'-apo-18'-nor-β-caroten-6'-one or 6'-methyl-6'-apo-β-caroten-6'-one **

Crocetin Crocetin is a natural apocarotenoid dicarboxylic acid that is found in the crocus flower together with its glycoside, crocin, and '' Gardenia jasminoides'' fruits. It forms brick red crystals with a melting point of 285°C. The chemical struct ...

8,8'-Diapo-8,8'-carotenedioic acid ** Crocetinsemialdehyde 8'-Oxo-8,8'-diapo-8-carotenoic acid **

Crocin Crocin is a carotenoid chemical compound that is found in the flowers of crocus and gardenia. Crocin is the chemical primarily responsible for the color of saffron. Chemically, crocin is the diester formed from the disaccharide gentiobiose and ...

Digentiobiosyl 8,8'-diapo-8,8'-carotenedioate ** Hopkinsiaxanthin 3-Hydroxy-7,8-didehydro-7',8'-dihydro-7'-apo-b-carotene-4,8'-dione or 3-hydroxy-8'-methyl-7,8-didehydro-8'-apo-b-carotene-4,8'-dione ** Methyl apo-6'-lycopenoate Methyl 6'-apo-y-caroten-6'-oate ** Paracentrone 3,5-Dihydroxy-6,7-didehydro-5,6,7',8'-tetrahydro-7'-apo-b-caroten-8'-one or 3,5-dihydroxy-8'-methyl-6,7-didehydro-5,6-dihydro-8'-apo-b-caroten-8'-one ** Sintaxanthin 7',8'-Dihydro-7'-apo-b-caroten-8'-one or 8'-methyl-8'-apo-b-caroten-8'-one * Nor- and seco-carotenoids ** Actinioerythrin 3,3'-Bisacyloxy-2,2'-dinor-b,b-carotene-4,4'-dione ** β-Carotenone 5,6:5',6'-Diseco-b,b-carotene-5,6,5',6'-tetrone **

Peridinin Peridinin is a light-harvesting apocarotenoid, a pigment associated with chlorophyll and found in the peridinin-chlorophyll-protein (PCP) light-harvesting complex in dinoflagellates, best studied in ''Amphidinium carterae''. Biological significan ...

3'-Acetoxy-5,6-epoxy-3,5'-dihydroxy-6',7'-didehydro-5,6,5',6'-tetrahydro-12',13',20'-trinor-b,b-caroten-19,11-olide ** Pyrrhoxanthininol 5,6-epoxy-3,3'-dihydroxy-7',8'-didehydro-5,6-dihydro-12',13',20'-trinor-b,b-caroten-19,11-olide ** Semi-α-carotenone 5,6-Seco-b,e-carotene-5,6-dione ** Semi-β-carotenone 5,6-seco-b,b-carotene-5,6-dione or 5',6'-seco-b,b-carotene-5',6'-dione ** Triphasiaxanthin 3-Hydroxysemi-b-carotenone 3'-Hydroxy-5,6-seco-b,b-carotene-5,6-dione or 3-hydroxy-5',6'-seco-b,b-carotene-5',6'-dione * Retro-carotenoids and retro-apo-carotenoids ** Eschscholtzxanthin 4',5'-Didehydro-4,5'-retro-b,b-carotene-3,3'-diol ** Eschscholtzxanthone 3'-Hydroxy-4',5'-didehydro-4,5'-retro-b,b-caroten-3-one ** Rhodoxanthin 4',5'-Didehydro-4,5'-retro-b,b-carotene-3,3'-dione ** Tangeraxanthin 3-Hydroxy-5'-methyl-4,5'-retro-5'-apo-b-caroten-5'-one or 3-hydroxy-4,5'-retro-5'-apo-b-caroten-5'-one * Higher carotenoids ** Nonaprenoxanthin 2-(4-Hydroxy-3-methyl-2-butenyl)-7',8',11',12'-tetrahydro-e,y-carotene ** Decaprenoxanthin 2,2'-Bis(4-hydroxy-3-methyl-2-butenyl)-e,e-carotene ** C.p. 450 2-[4-Hydroxy-3-(hydroxymethyl)-2-butenyl]-2'-(3-methyl-2-butenyl)-b,b-carotene ** C.p. 473 2'-(4-Hydroxy-3-methyl-2-butenyl)-2-(3-methyl-2-butenyl)-3',4'-didehydro-l',2'-dihydro-β,γ-caroten-1'-ol **

2,2'-Bis(3-hydroxy-3-methylbutyl)-3,4,3',4'-tetradehydro-1,2,1',2'-tetrahydro-γ,γ-carotene-1,1'-diol

References

External links

Carotenoid Terpenoids

Carotenoid gene in aphids

International Carotenoid Society
* {{Authority control Bioindicators Carotenoids, Photosynthesis

Biosynthesis

MEP pathway

Carotenoid biosynthetic pathway

Regulation

Structure and function

Properties

Foods

Morphology

Oxygenation

Transport

Storage

Respiration

Synergetic modality

Physiological effects

Plant colors

Bird colors and sexual selection

Sexual signaling

Aroma chemicals

Disease

Naturally occurring carotenoids

See also

References

External links