Editing Carotene (section)

==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]] recognised its hydrocarbon nature in 1847, but his analyses gave him a composition of C<sub>5</sub>H<sub>8</sub>. It was [[Léon-Albert Arnaud]] in 1886 who confirmed its hydrocarbon nature and gave the formula C<sub>26</sub>H<sub>38</sub>, which is close to the theoretical composition of C<sub>40</sub>H<sub>56</sub>. [[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 C<sub>40</sub>H<sub>56</sub>, distinguishing it from the similar but oxygenated [[xanthophyll]], C<sub>40</sub>H<sub>56</sub>O<sub>2</sub>. With Heinrich Escher, in 1910, [[lycopene]] was isolated from tomatoes and shown to be an [[isomer]] of carotene. Later work by Escher also differentiated the '[[luteal]]' pigments in egg yolk from that of the carotenes in cow corpus luteum.<ref>Theodore L. Sourkes, "The Discovery and Early History of Carotene," http://acshist.scs.illinois.edu/bulletin_open_access/v34-1/v34-1%20p32-38.pdf</ref>