Carotenoid Composition of <i>Calendula officinalis</i> Flowers with Identification of the Configuration of 5,8-Epoxy-carotenoids

Abstract

High Resolution Image Download MS PowerPoint Slide The carotenoid composition of petals, florets, and full inflorescences of Calendula officinalis grown in sun and shade was investigated by the HPLC-DAD-MS method. The total carotenoid content of flowers grown in the shade was higher than those grown in the sun (1.154 and 0.872 mg/g in petals), while no differences were found in the proportion of individual carotenoids. In all samples, 29 components were identified, from which the main carotenoids, besides lutein, were 5,8-epoxy-carotenoids with 8 S and 8′ R configurations. The main 5,8-epoxy-carotenoid was chrysanthemaxanthin with the 8 S configuration and not flavoxanthin with the 8 R configuration, as published earlier. In addition, (all- E,8′ R )- and (9 Z,8′ R )-luteoxanthin were detected in larger amounts. The 5,8-epoxy-carotenoids (flavoxanthin, chrysanthemaxanthin, and luteoxanthin epimers) were also prepared via an acid-catalyzed reaction of the parent carotenoid 5,6-epoxides. The structures of the epimers were elucidated by NMR measurements.