title: Rapid structural determination of new trace cassaine-type diterpenoid amides in fractions from Erythrophleum fordii by liquid chromatography-diode-array detection/electrospray ionization tandem mass spectrometry and liquid chromatography/nuclear magnetic resonance.
abstract: Electrospray ionization multi-stage tandem mass spectrometry (ESI-MSn), and combination with HPLC (HPLC/ESI-MSn), have been extensively applied to on-line analysis of natural products. Hyphenation of liquid chromatography to nuclear magnetic resonance spectroscopy (HPLC/NMR) has been developed in the last decade, which is utilized for the analysis of metabolites and drug impurities. In the study reported here, the fragmentation behaviors of eight cassaine-type diterpenoid amides from Erythrophleum fordii were investigated by ESI-MSn. The fragmentation rules and NMR spectral characteristics are summarized, and the relationship among the rules, characteristics and the structures is described. According to the fragmentation rules and NMR spectral characteristics, seven trace constituents and two formerly obtained compounds of cassaine-type diterpenoid amides in the fractions from E. fordii were structurally characterized on the basis of HPLC/HRMS, HPLC-DAD/ESI-MSn, HPLC/1H NMR and HPLC/1H-1H COSY rapidly. Among them, constituents 1-5 are new compounds, and 6 and 7 are reported from E. fordii for the first time. The aim is to develop an effective analytical method for structural identification of new trace natural products in plants.
authors.affiliation: Key Laboratory of Bioactive Substances and Resources Utilization of Chinese Herbal Medicine, Ministry of Education, Institute of Materia Medica, Peking Union Medical College & Chinese Academy of Medical Sciences, Beijing, P. R. China.
authors.forename: Jing
authors.initials: J
authors.lastname: Qu
authors.forename: Ying-Hong
authors.initials: YH
authors.lastname: Wang
authors.forename: Jian-Bei
authors.initials: JB
authors.lastname: Li
authors.forename: Shi-Shan
authors.initials: SS
authors.lastname: Yu
authors.forename: Yuan
authors.initials: Y
authors.lastname: Li
authors.forename: Yun-Bao
authors.initials: YB
authors.lastname: Liu
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D004224:Diterpenes / Q000032:analysis* / Q000737:chemistry / Q000302:isolation & purification; D000431:Ethanol / Q000737:chemistry; D007887:Fabaceae / Q000737:chemistry*; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D024301:Plant Bark / Q000737:chemistry; D010936:Plant Extracts / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*; D053719:Tandem Mass Spectrometry / Q000379:methods*; D013997:Time Factors; D014867:Water / Q000737:chemistry
chemical_list: D004224:Diterpenes; D010936:Plant Extracts; D014867:Water; D000431:Ethanol