title: Systematic identification of alkaloids in Macleaya microcarpa fruits by liquid chromatography tandem mass spectrometry combined with the isoquinoline alkaloids biosynthetic pathway.
abstract: Alkaloids in Macleaya microcarpa were characterized systematically by combining liquid chromatography tandem mass spectrometry (LC-MS/MS) with the biosynthetic pathway of isoquinoline alkaloids. The mass spectral fragmentation behaviors of 16 references belonging to eight types of alkaloids that exist in the biosynthetic pathway of isoquinoline were investigated in detail. The benzyltetrahydroisoquinoline and aporphine alkaloids were distinguished by characteristic losses of the NHR1R2 (R1 and R2 represent the substituent groups of the nitrogen atom) radical and the fragment ions below m/z 200. Tetrahydroprotoberberine, N-methyltetrahydroberberine and protopine alkaloids were differentiated by the retro-Diels-Alder (RDA) reaction, α-cleavage and the [M-H2O](+) and [M-CH4](+) ions. Discrimination of protoberberine, benzophenanthridine and dihydrobenzophenanthridine-type alkaloids can be realized through the characteristic [fragment ion-2H](+), [M-H2O](+), [M-CH4](+), [M+H-CH3CH2CH2OH](+) and [M+H-CH3COCH3](+) ions. Forty-one alkaloids, including one benzyltetrahydroisoquinoline, one aporphine, nine protopines, seven protoberberines, one tetrahydroprotoberberine, three N-methyltetrahydroprotoberberines, five benzophenanthridines and fourteen dihydrobenzophenanthridines, were separated and identified simultaneously. Thirty-three of these were reported for the first time in M. microcarpa. The benzyltetrahydroisoquinoline, aporphine, tetrahydroprotoberberine and N-methyltetrahydroprotoberberine-type alkaloids have not been reported previously in M. microcarpa. This method can be applied to the analysis of herbal medicines that possess the biosynthetic pathway of isoquinoline alkaloids.
authors.affiliation: Hunan Co-Innovation Center for Utilization of Botanicals Functional Ingredients (Hunan), Hunan Agricultural University, Changsha 410128, China; School of Pharmacy, Hunan University of Chinese Medicine, Changsha 410208, China.
authors.forename: Zhi-Xing
authors.initials: ZX
authors.lastname: Qing
authors.affiliation: School of Pharmacy, Hunan University of Chinese Medicine, Changsha 410208, China; Hunan Engineering Research Center of Botanical Extraction, Changsha 410331, China.
authors.forename: Pi
authors.initials: P
authors.lastname: Cheng
authors.affiliation: School of Pharmacy, Hunan University of Chinese Medicine, Changsha 410208, China.
authors.forename: Xiu-Bin
authors.initials: XB
authors.lastname: Liu
authors.affiliation: School of Pharmacy, Hunan University of Chinese Medicine, Changsha 410208, China.
authors.forename: Yi-Song
authors.initials: YS
authors.lastname: Liu
authors.affiliation: Hunan Co-Innovation Center for Utilization of Botanicals Functional Ingredients (Hunan), Hunan Agricultural University, Changsha 410128, China; School of Pharmacy, Hunan University of Chinese Medicine, Changsha 410208, China; Hunan Engineering Research Center of Botanical Extraction, Changsha 410331, China. Electronic address: ginkgo_1world@163.com.
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Zeng
mesh_terms: D000470:Alkaloids / Q000032:analysis* / Q000737:chemistry; D002853:Chromatography, Liquid / Q000379:methods*; D028101:Papaveraceae / Q000737:chemistry*; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000470:Alkaloids
keywords: Biosynthetic pathway; Fragmentation pathways; Isoquinoline alkaloids; LC–MS/MS; Macleaya microcarpa