title: Investigation of isomeric transformations of chlorogenic acid in buffers and biological matrixes by ultraperformance liquid chromatography coupled with hybrid quadrupole/ion mobility/orthogonal acceleration time-of-flight mass spectrometry.
abstract: Ultraperformance liquid chromatography coupled with hybrid quadrupole/ion mobility/orthogonal acceleration time-of-flight (oa-TOF) mass spectrometry (UPLC-IM-MS) was used to study the isomeric transformations of trans-5-caffeoylquinic acid, an extremely active compound present in multiple vegetables, fruits, and beverages. The UPLC/oa-TOF MS results proved that in phosphate buffer (pH 7.4), plasma, or urine sample, trans-5-caffeoylquinic acid first isomerizes to trans-4-caffeoylquinic acid and then to trans-3-caffeoylquinic acid by intramolecular acyl migration. When exposed to UV light, trans-3-, -4-, and -5-caffeoylquinic acids undergo cis/trans isomerization to form cis isomers. The isomerization was solely dependent on the pH of the matrix, as well as the incubation temperature, and was independent of metabolic enzymes. UPLC-IM-MS results revealed that a reversible cis/trans isomerization of caffeoylquinic acids could also be induced by the electric field in an electrospray source. Thus, understanding the possible role of electric field-induced isomerization of caffeoylquinic acids may help lessen the confusion between gas phase phenomena and liquid state chemistry when applying IM-MS analysis. The comprehensive understanding of caffeoylquinic acid isomerization transformations is crucial for the appropriate handling of samples and interpretation of experimental data.
authors.affiliation: Shanghai Institute of Materia Medica, Chinese Academy of Sciences, 501 Haike Road, Shanghai 201203, PR China.
authors.forename: Cen
authors.initials: C
authors.lastname: Xie
authors.forename: Kate
authors.initials: K
authors.lastname: Yu
authors.forename: Dafang
authors.initials: D
authors.lastname: Zhong
authors.forename: Tao
authors.initials: T
authors.lastname: Yuan
authors.forename: Fei
authors.initials: F
authors.lastname: Ye
authors.forename: Joseph Andy
authors.initials: JA
authors.lastname: Jarrell
authors.forename: Alan
authors.initials: A
authors.lastname: Millar
authors.forename: Xiaoyan
authors.initials: X
authors.lastname: Chen
mesh_terms: D002021:Buffers; D002726:Chlorogenic Acid / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D007536:Isomerism; D013058:Mass Spectrometry / Q000379:methods*; D011801:Quinic Acid / Q000031:analogs & derivatives / Q000737:chemistry
chemical_list: D002021:Buffers; C472707:caffeoylquinic acid; D011801:Quinic Acid; D002726:Chlorogenic Acid