Wiley InterScience Backfile Collection 1832-2000
Chemistry and Pharmacology
Luteochrome isolated from the tubers of a white-fleshed variety of sweet potato (Ipomoea batatas LAM.) has been shown by HPLC, 1H-NMR and CD spectra to consist of a mixture of (5R,6S,5′R,8′R)- and (5R,6S,5′R,8′S)- 5,6:5′,8′-diepoxy-5,6,5′,8′-tetrahydro-β,β-carotene (1 and 2, resp.). Therefore, its precursor is (5R,6S,5′R,6′S)-5,6:5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β,β-carotene (4). This is the first identification of luteochrome as a naturally occurring carotenoid and, at the same time, gives the first clue to the as yet unknown chirality of the widespread β,β-carotene diepoxide. These facts demonstrate that the enzymic epoxidation of the β-end group occurs from the α-side, irrespective of the presence of OH groups on the ring.
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