Friday, February 10, 2023

History of β-carotene

β-carotene is a vitamin A precursor (retinol) and the most important of the provitamins A. It is cleaved to form two molecules of retinal, one of which is further metabolized to form retinol and retinoic acid. β-carotene was discovered by the scientist Heinrich Wilhelm Ferdinand Wackenroder, who crystallized it from carrots in 1831.

In June, 1826 Wackenroder published his doctoral dissertation, “On Anthelminthics in the Vegetable Kingdom,” as presented to Göttingen University. The thesis earned him very high praise, as well as the Royal Prize.

A few years later he published the results of his examination of carrots, one of the purposes of that research being the search for the presence in the juice of that vegetable of an effective anthelminthic. He obtained it in small ruby-red flakes soluble in ether, which when dissolved in fats gave 'a beautiful yellow color'.

William Christopher Zeise, Danish organic chemist. recognized 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. In 1887 the French Academy of Sciences awarded Arnaud one-half of the Jecker Prize on the basis of his determination of the correct formula of carotene and the fact that it accompanied chlorophyll in the leaves of all plants

Not until 1907 was the empirical formula of β-carotene, C40H56, established by Willstatter and Mieg. The structure was elucidated by Paul Karrer in 1930-31. Paul Karrer succeeded in extracting vitamin A from cod-liver oil and in determining its composition. This was the first time that the structure of any vitamin or provitamin had been established, and he received a Nobel prize for his work.

Steenbock suggested in 1919 that there could be a relationship between beta-carotene and vitamin A. It was not until Jim Olson and DeWitt Goodman independently showed in 1965 the formation of retinal, the aldehyde form of vitamin A from beta-carotene in cell-free extracts of liver and intestine, that this vital pathway of beta-carotene was recognized.
History of β-carotene

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