Beitrag zur Analytik und Synthese von 3‐Hydroxy‐4‐oxocarotinoiden

Abstract

Contribution to the Analytical Separation and the Synthesis of 3‐Hydroxy‐4‐oxocarotenoids (3RS,3′RS)‐Astaxanthin (= 3,3′‐dihydroxy‐β,β‐carotene‐4,4′‐dione, 1:1‐mixture of racemate and meso‐form; 1) can be separated into its optical isomers (3S,3′S)‐1a, (3R,3′R)‐1b and meso‐(3R,3′S)‐1c via the corresponding diastereomeric di‐(−)‐camphanates. Some aspects of the configurational stability of astaxanthin are discussed. ‐ HPLC. analysis of the (−)‐camphanates of 3‐hydroxy‐4‐oxocarotenoids provides, in suitable cases and supported by spectroscopic data, an analytical method for the simultaneous determination of constitution and chirality.

Aggregation-Induced Resonance Raman Optical Activity (AIRROA) and Time-Dependent Helicity Switching of Astaxanthin Supramolecular Assemblies

“…The ECD profiles of (3 R ,3′ R )-AXT and (3 S ,3′ S )-AXT H2 aggregates are mirror images of each other, which means that the structures of the obtained aggregates are also mirror images. The racemic mixture of AXT (3 R ,3′ R / meso /3 S ,3′ S ; 1:2:1) does not possess any rotational strength because Cotton effects from enantiomers of opposite sign are canceled out, whereas the meso compound is supposed to form nonchiral aggregates. Exciton splitting of the obtained ECD bands suggests that (3 R ,3′ R )-AXT and (3 S ,3′ S )-AXT H2 aggregates are left- and right-handed helices, respectively …”

Synthese von Astaxanthin aus β‐Jonon. I. Erschliessung der enantiomeren C15‐Wittigsalze durch chemische und mikrobiologische Racematspaltung von (±)‐3‐Acetoxy‐4‐oxo‐β‐jonon

“…Ausbeute kristallin fassen liess. Meist wurde aber das trockene Rohprodukt in Pyridin mit dem kauflichen4) (-)-Camphanoylchlorid [31] trat bei der Verseifung mit 1 N NaOH in Methanol bei -5 bis 0" zu ca. 1,5-3% Racemisierung ein, eine methodologische Einschrankung, die vorlaufig fur die alkalische Verseifung der Camphansaureester von a-Hydroxycarbonyl-Verbindungen allgemein zu gelten scheint.…”

Astaxanthin Level of Dominant Mangrove Floral Species in Indian Sundarbans

“…Astaxanthin occurs in several different forms and can be classified into stereoisomer's, geometric isomers and free or esterified forms. All these forms are found in various natural sources e.g., the predominant stereoisomers of astaxanthin found in the Antarctic krill Euphausia superba is 3R,3 / R and the majority of this is esterified [14][15][16][17][18]. The relative distribution of esters and optical isomers in some organisms is shown in table 3.…”