Carotene
The carotenes α-carotene and γ-carotene, due to their single retinyl group (β-ionone ring), also have some vitamin A activity (though less than β-carotene), as does the xanthophyll carotenoid β-cryptoxanthin.
Carotenes are found in plants in two primary forms designated by characters from the Greek alphabet: alpha-carotene (α-carotene) and beta-carotene (β-carotene).
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".
Adolf Lieben in studies, also published in 1886, of the colouring matter in corpora lutea, first came across carotenoids in animal tissue, but did not recognise the nature of the pigment.
Johann Ludwig Wilhelm Thudichum, in 1868–1869, after stereoscopic spectral examination, applied the term 'luteine' (lutein) to this class of yellow crystallizable substances found in animals and plants.
Richard Martin Willstätter, who gained the Nobel Prize in Chemistry in 1915, mainly for his work on chlorophyll, assigned the composition of C40H56, distinguishing it from the similar but oxygenated xanthophyll, C40H56O2.
[11] The New England Journal of Medicine published an article[12] in 1994 about a trial which examined the relationship between daily supplementation of β-carotene and vitamin E (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.
[14] A review of all randomized controlled trials in the scientific literature by the Cochrane Collaboration published in JAMA in 2007 found that synthetic β-carotene increased mortality by 1–8% (Relative Risk 1.05, 95% confidence interval 1.01–1.08).
[16] The review only studied the influence of synthetic antioxidants and the results should not be translated to potential effects of fruits and vegetables.
Although hypercarotenemia is not particularly dangerous, it can lead to an oranging of the skin (carotenodermia), but not the conjunctiva of eyes (thus easily distinguishing it visually from jaundice).
Carotenes are produced in a general manner for other terpenoids and terpenes, i.e. by coupling, cyclization, and oxygenation reactions of isoprene derivatives.
[18] Most of the world's synthetic supply of carotene comes from a manufacturing complex located in Freeport, Texas and owned by DSM.
In Portugal, the industrial biotechnology company Biotrend is producing natural all-trans-β-carotene from a non-genetically modified bacteria of the genus Sphingomonas isolated from soil.
