with hydrophobic molecules this could be self-assembly. with amphiphilic or hydrophilic compounds the use of lycosome or supercritical co2 technologies, or other methods, are required. carotenoids in these complexes provide a new modality of supporting and boosting tissue oxygenation, which could be synergistically beneficial to the therapeutic objectives of different nutraceutical or pharmaceutical molecules. physiological effects reviews of epidemiological 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. another 2015 review looking at whether carotenoids can prevent prostate cancer 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. another 2014 review found no conflicting results in studies of dietary consumption of carotenoids and the risk of getting breast cancer. carotenoids are also important components of the dark brown pigment melanin, 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 (dry eye, headaches, and blurred vision) and improve night vision. humans and other animals are mostly incapable of synthesizing carotenoids, and must obtain them through their diet. carotenoids are a common and often ornamental feature in animals. for example, the pink color of salmon, and the red coloring of cooked lobsters and scales of the yellow morph of common wall lizards are due to carotenoids. it has been proposed that carotenoids are used in ornamental traits (for extreme examples see puffin birds) because, given their physiological and chemical properties, they can be used as visible indicators of individual health, and hence are used by animals when selecting potential mates. plant colors yellow and orange leaf colors in autumn are due to carotenoids, which are visible after chlorophyll degrades for the season. apricots, rich in carotenoids the most common carotenoids include lycopene and the vitamin a precursor β-carotene. in plants, the xanthophyll lutein is the most abundant carotenoid and its role in preventing age-related eye disease is currently under investigation. lutein and the other carotenoid pigments found in mature leaves are often not obvious because of the masking presence of chlorophyll. when chlorophyll is not present, as in autumn foliage, the yellows and oranges of the carotenoids are predominant. for the same reason, carotenoid colors often predominate in ripe fruit after being unmasked by the disappearance of chlorophyll. carotenoids are responsible for the brilliant yellows and oranges that tint deciduous foliage (such as dying autumn leaves) of certain hardwood species as hickories, ash, maple, yellow poplar, aspen, birch, black cherry, sycamore, cottonwood, sassafras, and alder. carotenoids are the dominant pigment in autumn leaf coloration of about 15-30% of tree species. however, the reds, the purples, and their blended combinations that decorate autumn foliage usually come from another group of pigments in the cells called anthocyanins. unlike the carotenoids, these pigments are not present in the leaf throughout the growing season, but are actively produced towards the end of summer. 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 utilize these pigments for external coloration has evolved independently many times throughout avian evolutionary history. carotenoid coloration exhibits high levels of sexual dimorphism, with adult male birds generally displaying more vibrant coloration than females of the same species. these differences arise due to the selection of yellow and red coloration in males by female preference. in many species of birds, females invest greater time and resources into raising offspring than their male partners. therefore, it 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 due to increased presence of carotenoid antioxidants. however, there is also evidence that attractive male coloration may be a faulty signal of male quality. among stickleback fish, males that are more attractive to females due to carotenoid colorants appear to under-allocate carotenoids to their germline cells. since carotinoids are beneficial antioxidants, their under-allocation to germline cells can lead to increased oxidative dna damage to these cells. therefore, female sticklebacks may risk fertility and the viability of their offspring by choosing redder, but more deteriorated partners with reduced sperm quality. aroma chemicals products of carotenoid degradation such as ionones, damascones and damascenones are also important fragrance chemicals that are used extensively in the perfumes and fragrance industry. both β-damascenone and β-ionone although low in concentration in rose distillates are the key odor-contributing compounds in flowers. in fact, the sweet floral smells present in black tea, aged tobacco, grape, and many fruits 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 their name is a carotenoid called staphyloxanthin. this carotenoid is a virulence factor with an antioxidant action that helps the microbe evade death by reactive oxygen species 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 lycopene hexahydrolycopene 15-cis-7,8,11,12,7',8'-hexahydro-γ,γ-carotene torulene 3',4'-didehydro-β,γ-carotene α-zeacarotene 7',8'-dihydro-ε,γ-carotene α-carotene β-carotene γ-carotene δ-carotene ε-carotene ζ-carotene alcohols alloxanthin bacterioruberin 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 (3r,3′r,6′r)-β,ε-carotene-3,3′-diol lycoxanthin γ,γ-caroten-16-ol rhodopin 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 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 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 5,8-epoxy-5,8-dihydro-β,β-carotene-3,3'-diol neochrome 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 canthaxanthin a.k.a. aphanicin, chlorellaxanthin β,β-carotene-4,4'-dione capsanthin (3r,3's,5'r)-3,3'-dihydroxy-β,κ-caroten-6'-one capsorubin (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 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 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 apocarotenoids 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 6'-methyl hydrogen 9'-cis-6,6'-diapocarotene-6,6'-dioate citranaxanthin 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 8,8'-diapo-8,8'-carotenedioic acid crocetinsemialdehyde 8'-oxo-8,8'-diapo-8-carotenoic acid crocin 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 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--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 bacterioruberin 2,2'-bis(3-hydroxy-3-methylbutyl)-3,4,3',4'-tetradehydro-1,2,1',2'-tetrahydro-γ,γ-carotene-1,1'-diol