title: An HPLC-MS/MS method for the separation of α-retinyl esters from retinyl esters.
abstract: Enzymatic cleavage of the nonsymmetric provitamin A carotenoid α-carotene results in one molecule of retinal (vitamin A), and one molecule of α-retinal, a biologically inactive analog of true vitamin A. Due to structural similarities, α-retinyl esters and vitamin A esters typically coelute, resulting in the overestimation of vitamin A originating from α-carotene. Herein, we present a set of tools to identify and separate α-retinol products from vitamin A. α-Retinyl palmitate (αRP) standard was synthesized from α-ionone following a Wittig-Horner approach. A high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method employing a C30 column was then developed to separate the species. Authentic standards of retinyl esters and the synthesized α-RP confirmed respective identities, while other α-retinyl esters (i.e. myristate, linoleate, oleate, and stearate) were evidenced by their pseudomolecular ions observed in electrospray ionization (ESI) mode, fragmentation, and elution order. For quantitation, an atmospheric pressure chemical ionization (APCI) source operated in positive ion mode was used, and retinol, the predominant in-source parent ion was selected and fragmented. The application of this method to a chylomicron-rich fraction of human plasma is demonstrated. This method can be used to better determine the quantity of vitamin A derived from foods containing α-carotene.
authors.affiliation: Department of Food Science & Technology, The Ohio State University, Columbus, OH, United States.
authors.forename: Hilary J
authors.initials: HJ
authors.lastname: Goetz
authors.affiliation: Department of Food Science & Technology, The Ohio State University, Columbus, OH, United States; INRA, UMR 408 Sécurité et Qualité des Produits d'Origine Végétale, Avignon, France.
authors.forename: Rachel E
authors.initials: RE
authors.lastname: Kopec
authors.affiliation: Department of Food Science & Technology, The Ohio State University, Columbus, OH, United States.
authors.forename: Ken M
authors.initials: KM
authors.lastname: Riedl
authors.affiliation: Department of Food Science & Technology, The Ohio State University, Columbus, OH, United States.
authors.forename: Jessica L
authors.initials: JL
authors.lastname: Cooperstone
authors.affiliation: Department of Medicinal Chemistry, The Ohio State University, Columbus, OH, United States.
authors.forename: Sureshbabu
authors.initials: S
authors.lastname: Narayanasamy
authors.affiliation: Department of Medicinal Chemistry, The Ohio State University, Columbus, OH, United States.
authors.forename: Robert W
authors.initials: RW
authors.lastname: Curley
authors.affiliation: Department of Food Science & Technology, The Ohio State University, Columbus, OH, United States. Electronic address: schwartz.177@osu.edu.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Schwartz
mesh_terms: D002338:Carotenoids / Q000097:blood / Q000302:isolation & purification*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004224:Diterpenes; D004952:Esters / Q000097:blood / Q000302:isolation & purification; D006801:Humans; D000084562:Retinyl Esters; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry / Q000379:methods; D014801:Vitamin A / Q000031:analogs & derivatives* / Q000097:blood / Q000302:isolation & purification*
chemical_list: D004224:Diterpenes; D004952:Esters; D000084562:Retinyl Esters; D014801:Vitamin A; C014794:retinol palmitate; D002338:Carotenoids; C041635:alpha-carotene
keywords: HPLC–MS/MS; Provitamin A carotenoids; Retinyl esters; Synthesis; α-Retinol; α-Retinyl palmitate