title: Synthesis, Structure, and Tandem Mass Spectrometric Characterization of the Diastereomers of Quinic Acid.
abstract: (-)-Quinic acid possess eight possible stereoisomers, which occur both naturally and as products of thermal food processing. In this contribution, we have selectively synthesized four isomers, namely, epi-quinic acid, muco-quinic acid, cis-quinic acid, and scyllo-quinic acid, to develop a tandem LC-MS method identifying all stereoisomeric quinic acids. Four derivatives have been unambiguously characterized by single-crystal X-ray crystallography. The missing diastereomers of quinic acid were obtained by nonselective isomerization of (-)-quinic acid using acetic acid/concentrated H2SO4 allowing chromatographic separation and assignment of all diastereomers of quinic acid. We report for the first time that a full set of stereoisomers are reliably distinguishable on the basis of their tandem mass spectrometric fragment spectra as well as their elution order. A rationale for characteristic fragmentation mechanisms is proposed. In this study, we also observed that muco-quinic acid, scyllo-quinic acid, and epi-quinic acid are present in hydrolyzed Guatemalan roasted coffee sample as possible products of roasting.
authors: Department of Life Sciences and Chemistry, Jacobs University Bremen , 28759 Bremen, Germany.
authors: Sagar
authors: S
authors: Deshpande
authors: Department of Life Sciences and Chemistry, Jacobs University Bremen , 28759 Bremen, Germany.
authors: Marius Febi
authors: MF
authors: Matei
authors: Department of Life Sciences and Chemistry, Jacobs University Bremen , 28759 Bremen, Germany.
authors: Rakesh
authors: R
authors: Jaiswal
authors: Department of Life Sciences and Chemistry, Jacobs University Bremen , 28759 Bremen, Germany.
authors: Bassem S
authors: BS
authors: Bassil
authors: Department of Life Sciences and Chemistry, Jacobs University Bremen , 28759 Bremen, Germany.
authors: Ulrich
authors: U
authors: Kortz
authors: Department of Life Sciences and Chemistry, Jacobs University Bremen , 28759 Bremen, Germany.
authors: Nikolai
authors: N
authors: Kuhnert
mesh_terms: D002853:Chromatography, Liquid; D003069:Coffee / Q000737:chemistry; D018360:Crystallography, X-Ray; D005511:Food Handling; D011801:Quinic Acid / Q000737:chemistry*; D013237:Stereoisomerism; D053719:Tandem Mass Spectrometry
chemical_list: D003069:Coffee; D011801:Quinic Acid
keywords: cis-quinic acid; coffee; epi-quinic acid; muco-quinic acid; scyllo-quinic acid