Eine weitere, diesmal erfolgreiche Suche nach 3′‐Epilutein in Pflanzen

Abstract

The 3'-epilutein, an extremely rare carotenoid, found till now in only one plant, was detected in anthers of flowers of several roses and in those of peonies. Das 3'-Epilutein (1) ist im Pflanzenreich bisher erst in Bliiten von Caltha palustris (Sumpfdotterblume) entdeckt worden [2] [3]. Es wird dort begleitet von 3',0-Didehydrolutein (2) und Lutein (3) [4], was darauf hinweist, dass seine Bildung auf einen Dehydrierungs-und (nicht-stereospezifischen) Reduktionsprozess am allylischen OH-C(3) zuriickzufiihren ist. Im Tierreich ist 1 erstmals im Goldfisch (Carassius auratus) aufgefunden worden [5]. Neuere Untersuchungen haben gezeigt, dass 1 und weitere Stereoisomere in Tieren weitverbreitet vorkommen [6]. OH no HO 1 3 0 HO no 2 4

Lutein Isomers: Preparation, Separation, Structure Elucidation, and Occurrence in 20 Medicinal Plants

“…The 3′ hydroxyl group is allylic, unlike in its regioisomer, zeaxanthin (3) (Figure S1). Some stereoisomers can be found in nature, such as 3′-epilutein (2) with an (all-E,3R,3′S,6′R) configuration, which has been isolated from goldfish (Carassius auratus) [9], marsh marigold (Caltha palustris) [10][11][12], and other flowers [13]. Moreover, 3′-epilutein (2) forms from lutein (1) under acid-catalyzed epimerization in processed plants [14,15].…”

“…The main mono-Z-isomers (9Z, 9′Z, 13Z, and 13′Z) of both lutein (1) and 3′-epilutein (2), as well as a di-Z-isomer (9Z,9′Z) of lutein, were prepared via the thermal and the I2-catalyzed photoisomerization of their solutions [20][21][22]. In 1981, our research group isolated and identified these isomers via open column chromatography on calcium carbonate, and 13 C-NMR studies confirmed the existence of four mono-cis isomers at positions 9, 9′, l3, and 13′, respectively. In 2001, geometrical isomers of lutein (1) and zeaxanthin (3) were separated using hyphenated HPLC-MS and HPLC-NMR systems on a C30 column [23].…”

“Eco‐Friendly” Epimerization of Lutein to 3′‐Epilutein Under Solvent‐Free Mechanochemical Conditions by Using a Strongly Acidic Cation‐Exchange Resin

“…The route is commonly based on two reaction steps namely 1) the acid-mediated epimerization of 3′-allyl alcohol by using aqueous solutions of strong mineral acids such as HCl, H 2 SO 4 , HClO 4 , or CF 3 COOH in THF (room temp., 12-72 h) [11,[24][25][26][27][28] to obtain a mixture of lutein/3′-epilutein in a diastereomeric ratio of 1:1 to 1:5 and 2) a base-mediated isomerization reaction (ε-rearrangement) of the corresponding lutein/3′-epilutein mixtures to yield meso/trans-zeaxanthin by use of polar protic solvents at high temperatures (Figure 1B). [27,[29][30][31] It is worth mentioning that 3′-epilutein (4) has been discovered in a few plant species, such as lichens of the Bialowieza forest, [32] Caltha palustris flowers, [33] peonies and anthers of roses, [34] and marigold extracts, [35] as well as in the tissues of animals, predominantly fish species. [22] Recently, the influence of 3′-epilutein (4) on the increase in macular pigment optical density (MPOD) was demonstrated in patients with age-related macular degeneration (AMD).…”

Epimerisation of lutein to 3′-epilutein in processed foods

“…5,6 In contrast with lutein, from plants, 3 0 -epilutein was only isolated from the petals of Caltha palustris 7 and it was detected in anthers of flowers of several roses and in those of peonies. 8 Determination of the biological activity of different carotenoid stereoisomers requires careful qualitative and quantitative analysis of the functional foods during cooking processes. There is a perception that carotenoids are destroyed by the heat processes involved in cooking vegetables.…”