Chemistry of Hermidin: Insights from Extraction Experiments with the Main Alkaloid of Mercurialis perennis L. Tracked by GC/MS and LC/MSⁿ

Abstract

Hermidin (1), a piperidine‐2,3‐dione alkaloid, has been previously detected as a lipophilic constituent in Mercurialis perennis L. and other Mercurialis species. Because of strong electron‐withdrawing effects of its carbonyl groups, an acidic H‐atom is easily subtracted from 1, whereas the latter shows high reactivity towards oxidation reactions or the attack of C‐nucleophilic agents. To obtain a better understanding of possible chemical pathways upon extraction of root parts of M. perennis, the products obtained with different solvents from 1 were investigated. Extraction of M. perennis with aqueous MeOH or EtOH yielded a mixture of hermidin quinone (3), 5‐hydroxy‐4‐methoxy‐5‐(alkoxycarbonyl)‐1‐methyl‐3‐pyrrolin‐2‐ones, 7 and 8, and d,l‐ and meso‐isochrysohermidins, 5 and 6, all of them being investigated by GC/MS and LC/MSn. The latter compounds were supposedly formed by free‐radical reactions, followed by spontaneous benzilic acid rearrangement and esterification. Furthermore, extraction of M. perennis with aqueous Me2CO produced an aldol condensation product, the known alkaloid speranskatine A (9a), which was identified by NMR after chromatographic purification. In a similar manner, a CH2 homolog of speranskatine A (10a) was obtained as a novel compound when ethyl methyl ketone (=butan‐2‐one; EtCOMe) instead of Me2CO was used for extraction. Consequently, 1 easily undergoes artefact formation upon extraction of plant material with polar or slightly polar solvents.

Characterization of Secondary Metabolites in Flowers of Sanguisorba officinalisL. by HPLC‐DAD‐MSn and GC/MS

“…The mass spectrometer was run in electron ionization (EI) mode (70 eV). The software Turbomass (v.5.4.2, PerkinElmer, Inc ., MA, USA) was used for data acquisition and processing …”

Conversion of Plant Secondary Metabolites upon Fermentation of Mercurialis perennis L. Extracts with two Lactobacteria Strains

“…This occurs when plant cell integrity is damaged, e.g., after harvest or upon plant extraction [24,25]. Consequently, 2 further reacts forming the oxidation products hermidin quinone (3) and chrysohermidin (4), which display multifaceted downstream reactions in aqueous solvents [31]. In the present study M. perennis roots, and in a second step also herbal parts, were macerated with water under nitrogen (N 2 ) atmosphere to prevent oxidation reactions of the plant constituents.…”

“…Isochrysohermidin (mixture of d,land meso-dimethyl-2,2 ,5,5 -tetrahydro-5,5 -dihydroxy-4,4 -dimethoxy-1,1 -dimethyl-2,2 -dioxo-1H,1 H-3,3 -bipyrrole-5,5 -dicarboxylate; d,l-13 and meso-13, resp.) was synthesized according to a previously published procedure [31].…”

“…GC-MS analyses were performed with a PerkinElmer Clarus 500 gas chromatograph with split injection (split ratio 30:1, injection volume 1.0 µL) in conjunction with a single quadrupole mass spectrometer. The column and temperature program were used in accordance with a previous publication [31].…”

“…Liquid chromatographic / mass spectrometric analyses (LC-MS) were performed using an Agilent 1200 HPLC system (Agilent Technologies Inc., Palo Alto, USA) coupled to an HCTultra ion trap (Bruker Daltonik GmbH, Bremen, Germany) and an ESI source, controlled by Agilent Chemstation for LC 3D systems (Rev. B01.03SR1 (204)) and EsquireControl software (V7.1) [31]. A Kinetex ® C 18 reversed-phase column (2.6 µm particle size, 150 × 2.1 mm i.d., Phenomenex Ltd., Aschaffenburg, Germany) was used for chromatographic separation at 25 • C and a flow rate of 0.21 mL/min.…”