Identification and metabolite profiling of alkaloids in aerial parts of Papaver rhoeas by liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry

Abstract

Papaver plants can produce diverse bioactive alkaloids. Papaver rhoeas Linnaeus (common poppy or corn poppy) is an annual flowering medicinal plant used for treating cough, sleep disorder, and as a sedative, pain reliever, and food. It contains various powerful alkaloids like rhoeadine, benzylisoquinoline, and proaporphine. To investigate and identify alkaloids in the aerial parts of P. rhoeas, samples were collected at different growth stages and analyzed using liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry. A liquid chromatography with mass spectrometry method was developed for the identification and metabolite profiling of alkaloids for P. rhoeas by comparing with Papaver somniferum. Eighteen alkaloids involved in benzylisoquinoline alkaloid biosynthesis were used to optimize the liquid chromatography gradient and mass spectrometry conditions. Fifty-five alkaloids, including protoberberine, benzylisoquinoline, aporphine, benzophenanthridine, and rhoeadine-type alkaloids, were identified authentically or tentatively by liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry in samples taken during various growth stages. Rhoeadine alkaloids were observed only in P. rhoeas samples, and codeine and morphine were tentatively identified in P. somniferum. The liquid chromatography coupled with quadrupole time-of-flight tandem mass spectrometry method can be a powerful tool for the identification of diverse metabolites in the genus Papaver. These results may help understand the biosynthesis of alkaloids in P. rhoeas and evaluate the quality of this plant for possible medicinal applications.

Keywords: Papaver rhoeas; Papaver somniferum; alkaloids; liquid chromatography; metabolite profiling.

Figure 1

Representative extracted ion chromatography (XIC) of 18 authentic standards with different mobile phase compositions: 5 mM ammonium formate in water/acetonitrile (A), 0.1% formic acid in water/acetonitrile (B), 2.5 mM ammonium formate and 0.05% formic acid in water/acetonitrile (C); (1) dl‐demethylcoclaurine, (2) coclaurine, (3) tetrahydropapaverine, (4) S‐reticuline, (5) corytuberine, (6) l‐reticuline, (7) tetrahydrocolumbamine, (8) scoulerine, (9) l‐tetrahydropalmatine, (10) tetrahydroberberine, (11) berberine, (12) stylopine, (13) dihydrosanguinarine, (14) sanguinarine, (15) protopine, (16) chelidonine, (17) allocryptopine, and (18) dihydroberberine

Figure 2

Representative base peak ion chromatograph (BPC) of the ethanol extracts of RS at 90 days (A), RA at 90 days (B), and PS at 90 days (C). The two types of Papaver rhoeas seeds have different origins; one (resource name: Shiri) originated from Moscow, Russia (RS) and the other (resource name: WS2981) originated from Hoengseong in the Province of Gangwon, South Korea (RA)

Figure 3

Representative metabolite intensities as determined by LC–QTOF analysis for samples at different growth stages (30, 60, and 90 cultivating days): dl‐demethylcoclaurine (1), coclaurine (2), tetrahydropapaverine (3), (R/S)‐reticuline (4 and 6), corytuberine (5), l‐tetrahydropalmatine (7), scoulerine (8), l‐tetrahydropalmatine (9), tetrahydroberberine (10), berberine (11), stylopine (12), dihydrosanguinarine (13), sanguinarine (14), protopine (15), allocryptopine (16), and rhoeadine (42). The ratio is the peak intensity of a metabolite in a sample that was divided by the peak intensity of a blank sample and expressed in a logarithmic scale. Compounds 1–16 were identified by authentic standards and the remaining 43 were identified tentatively by isotope patterns and comparison to database or previous literature