Structural speculation and identification of alkaloids in Macleaya cordata fruits by high‐performance liquid chromatography/quadrupole‐time‐of‐flight mass spectrometry combined with a screening procedure

Abstract

RATIONALE Alkaloids with significant therapeutic effects are the main active constituents of Macleaya cordata, which is a perennial herb plant in the Papaveraceae family. A systematic and novel method for speculating and identifying the structures of alkaloids in M. cordata fruits by high‐performance liquid chromatography/quadrupole‐time‐of‐flight mass spectrometry (HPLC/Q‐TOF‐MS) with a screening procedure was reported. METHODS Investigation of mass spectral fragmentation of alkaloids was carried out based on the tandem mass spectrometry (MS/MS) data analyses of eight reference substances. The skeletons of alkaloids were determined by their ultraviolet spectra (UV) and MS/MS data. The substituent groups of the alkaloids were acquired through a screening procedure developed in our laboratory and MS/MS data. The substituent linkage sites were deduced by MS/MS fragmentation behavior, as well as biosynthetic pathways of related alkaloids. RESULTS The structures of 21 alkaloids were speculated in this study, 10 of which were reported for the first time in M. cordata. Furthermore, benzyltetrahydroisoquinoline and N‐methyltetrahydroprotoberberine‐type alkaloids were discovered, which indirectly proved that the biosynthetic pathways of benzophenanthridine alkaloids reported in Eschscholtzia california existed in M. cordata as well. CONCLUSIONS HPLC/Q‐TOF‐MS combined with a screening procedure was a systematic and reliable method for speculating and elucidating the structures of alkaloids. This study might be useful for the identification of other compounds in herbal medicines. Copyright © 2014 John Wiley & Sons, Ltd.

Simultaneous qualitative and quantitative evaluation of Toddalia asiatica root by using HPLC‐DAD and UPLC‐QTOF‐MS/MS

“…The predominant ion appeared at m/z 348.1238 for 8‐acetonyldihydrochelerythrine (53 b ) corresponding to a loss of the acetonyl (CH 3 COCH 3 ) at C‐6 and the vicinal hydrogen atom. The fragment ions of this type of alkaloid were produced mainly through the loss of some substituent groups, such as loss of CH 3 , CH 4 , CH 3 COCH 3 , etc., and its fragmentation behaviour could be extended to the other dihydrobenzophenanthridine alkaloid …”

Identification of allocryptopine and protopine metabolites in rat liver S9 by high‐performance liquid chromatography/quadrupole‐time‐of‐flight mass spectrometry

“…The product ions at m / z 208 and 165 were formed by RDA reaction from m / z 372. The ion that appeared at m / z 208 indicated that a hydroxyl and a methoxyl were linked to C‐2 and C‐3, respectively, and the methoxyl radical connected to C‐3 was likely provided by the biosynthetic pathway of benzophenanthridine alkaloids …”

“…The product ions at m / z 177 and 176 were formed by the loss of the OH radical and H 2 O from m / z 194, respectively. Based on these observations, AL4 was identified as vaillatine …”

“…The product ions at m / z 189 and 188 were formed by the loss of the OH radical and H 2 O from m / z 206, respectively. These fragmentation patterns were also reported in the literature for Macleaya fruits …”

“…The product ion at m/z 292 was formed by the loss of NH 2 CH 3 and OCH 3 The ion that appeared at m/z 208 indicated that a hydroxyl and a methoxyl were linked to C-2 and C-3, respectively, and the methoxyl radical connected to C-3 was likely provided by the biosynthetic pathway of benzophenanthridine alkaloids. [29] In addition, the product ion at m/z 165 suggested that the vicinal methoxyl group was connected to C-9, C-10.…”