title: Construction of an Ultrahigh Pressure Liquid Chromatography-Tandem Mass Spectral Library of Plant Natural Products and Comparative Spectral Analyses.
abstract: A plant natural product tandem mass spectral library has been constructed using authentic standards and purified compounds. Currently, the library contains 1734 tandem mass spectra for 289 compounds, with the majority (76%) of the compounds being plant phenolics such as flavonoids, isoflavonoids, and phenylpropanoids. Tandem mass spectra and chromatographic retention data were acquired on a triple quadrupole mass spectrometer coupled to an ultrahigh pressure liquid chromatograph using six different collision energies (CEs) (10-60 eV). Comparative analyses of the tandem mass spectral data revealed that the loss of ring substituents preceded the C-ring opening during the fragmentation of flavonoids and isoflavonoids. At lower CE (i.e., 10 and 20 eV), the flavonoids and isoflavonoid central ring structures typically remained intact, and fragmentation was characterized by the loss of the substituents (i.e., methyl and glycosyl groups). At higher CE, the flavonoid and isoflavonoid core ring systems underwent C-ring cleavage and/or rearrangement depending on the structure, particularly hydroxylation patterns. In-source electrochemical oxidation was observed for phenolics that had ortho-diphenol moieties (i.e., vicinal hydroxyl groups on the aromatic rings). The ortho-diphenols were oxidized to ortho-quinones, yielding an intensive and, in most cases, a base ion peak corresponding to a [(M - 2H) - H](-) ion in their mass spectra. The library also contains reverse-phase retention times, allowing for the construction, validation, and testing of an artificial neural network retention prediction of other flavonoids and isoflavonoids not contained within the library. The library is freely available for nonprofit, academic use and it can be downloaded at http://www.noble.org/apps/Scientific/WebDownloadManager/DownloadArea.aspx.
authors.affiliation: †Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States.
authors.forename: Zhentian
authors.initials: Z
authors.lastname: Lei
authors.affiliation: †Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States.
authors.forename: Li
authors.initials: L
authors.lastname: Jing
authors.affiliation: †Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States.
authors.forename: Feng
authors.initials: F
authors.lastname: Qiu
authors.affiliation: ‡College of Life Science and Engineering, Chongqing Three Gorges University, Wanzhou, Chongqing 404100, China.
authors.forename: Hua
authors.initials: H
authors.lastname: Zhang
authors.affiliation: †Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States.
authors.forename: David
authors.initials: D
authors.lastname: Huhman
authors.affiliation: §College of Horticulture and Landscape Architecture, Southwest University, Beibei, Chongqing 400716, China.
authors.forename: Zhiqin
authors.initials: Z
authors.lastname: Zhou
authors.affiliation: †Plant Biology Division, The Samuel Roberts Noble Foundation, 2510 Sam Noble Parkway, Ardmore, Oklahoma 73401, United States.
authors.forename: Lloyd W
authors.initials: LW
authors.lastname: Sumner
mesh_terms: D001688:Biological Products / Q000737:chemistry* / Q000302:isolation & purification; D002851:Chromatography, High Pressure Liquid; D062126:Databases, Chemical; D005419:Flavonoids / Q000737:chemistry / Q000302:isolation & purification; D033181:Information Dissemination; D020407:Internet; D007529:Isoflavones / Q000737:chemistry / Q000302:isolation & purification; D015394:Molecular Structure; D010666:Phenylpropionates / Q000737:chemistry / Q000302:isolation & purification*; D010936:Plant Extracts / Q000737:chemistry*; D053719:Tandem Mass Spectrometry
chemical_list: D001688:Biological Products; D005419:Flavonoids; D007529:Isoflavones; D010666:Phenylpropionates; D010936:Plant Extracts