Hans-Martin Schiebel

Identification and quantification of synthetic cannabinoids in 'spice-like' herbal mixtures: a snapshot of the German situation in the autumn of 2012.

Synthetic compounds mimicking cannabis-like effects are a recent trend. Currently, these so-called synthetic cannabinoids are the largest and fastest growing class of newly appearing designer drugs. Many national authorities are continuously adapting their regulations to keep pace with the permanently changing variety of compounds. We have analyzed eight herbal smoking blends containing synthetic cannabinoids. Altogether, nine compounds could be identified, namely AM-2201, AM-2201-pMe (MAM-2201), AM-1220, AM-1220-azepane, UR-144, XLR-11, JWH-122-pentenyl, AM-2232, and STS-135. Newly appearing compounds were isolated by column chromatography and their structures elucidated by 1D- and 2D-nuclear magnetic resonance (NMR) experiments. In addition, the compounds were investigated by electron ionization-mass spectrometry (EI-MS) and electrospray ionization-tandem mass spectrometry (ESI-MS/MS) to complete the physicochemical dataset. Based on the purified compounds a universal gas chromatography-mass spectrometry (GC-MS) method was developed for the identification and quantification of these compounds in commercial smoking blends. By applying this method, up to five different compounds could be found in such products showing total concentrations from 72 to 303 mg/g smoking blend while individual compounds ranged from 0.4 to 303 mg/g. (1)H NMR spectra of the chiral compounds AM-1220 and its azepane-isomer recorded in the presence of 1 equivalent of (R)-(+)-α-methoxy-α-trifluoromethylphenylacetic acid (MTPA, Moshers acid) showed them to be racemic mixtures.

Synthetic cannabinoids in “spice-like” herbal blends: First appearance of JWH-307 and recurrence of JWH-018 on the German market

Herbal smoking blends, available on the German market were analyzed and several known synthetic cannabinoids were identified (JWH-122 and JWH-018). In addition, we isolated a new active ingredient by silica gel column chromatography and elucidated the structure by nuclear magnetic resonance (NMR) methods. The compound was identified as JWH-307, a synthetic cannabinoid of the phenyl-pyrrole subclass with known in vitro binding affinities for cannabinoid receptors. To date, this is the first appearance of this subclass of cannabimimetics in such products. JWH-307 has been further characterized by gas chromatography accurate mass spectrometry (GC-HRMS), electrospray tandem mass spectrometry (ESI-MS/MS), ultraviolet (UV) and infrared (IR) spectroscopy. JWH-018 was among the first compounds banned by many countries world-wide including Germany. The identification of JWH-018 was striking, since this is the first report where JWH-018 recurred on the German market thus violating existing laws. A generic method was established to quantify synthetic cannabinoids in herbal smoking blends. Quantification was achieved using an isotopically labeled standard (JWH-018-D(3)). JWH-018 was found at a level of 150 mg/g while JWH-122 and JWH-307 occurred as a mixture at a total level of 232 mg/g.

Pyrrolizidine Alkaloids in the Food Chain: Development, Validation, and Application of a New HPLC-ESI-MS/MS Sum Parameter Method

Contamination of food and feed with pyrrolizidine alkaloids is currently discussed as a potential health risk. Here, we report the development of a new HPLC-ESI-MS/MS sum parameter method to quantitate the pyrrolizidine alkaloid content in complex food matrices. The procedure was validated for honey and culinary herbs. Isotopically labeled 7-O-9-O-dibutyroyl-[9,9-(2)H2]-retronecine was synthesized and utilized as an internal standard for validation and quantitation. The total pyrrolizidine alkaloid content of a sample is expressed as a single sum parameter: retronecine equivalents (RE). Ld/Lq for honey was 0.1 μg RE/kg/0.3 μg RE/kg. For culinary herbs, 1.0 μg RE/kg/3.0 μg RE/kg (dry weight, dw) and 0.1 μg RE/kg/0.3 μg RE/kg (fresh weight, fw) were determined, respectively. The new method was applied to analyze 21 herbal convenience products. Fifteen products (71%) were pyrrolizidine alkaloid positive showing pyrrolizidine alkaloid concentrations ranging from 0.9 to 74 μg RE/kg fw.

Isolation of an immunosuppressive metabolite of FK506 generated by human microsome preparations

Metabolism of FK506, a 23 member macrolide under clinical investigation as immunosuppressant after transplantation, was studied using human liver microsomes. Two fractions isolated by semi-preparative HPLC were identified by negative fast atom bombardment mass spectrometry as FK506 metabolites with mass peaks at m/z = 790 indicating demethylation of the mother compound. The immunosuppressive activity of one metabolite was evaluated in a ConA-stimulated peripheral rat lymphocyte assay. FK506 had an IC50 of 0.186 nmol/L and the metabolite tested of 1.89 nmol/L.

Investigations on the metabolic pathways of cyclosporine: II. Elucidation of the metabolic pathways in vitro by human liver microsomes

1. Cyclosporine and its metabolites, isolated from human bile and identified by FAB mass spectrometry and 1H-n.m.r. spectroscopy, were metabolized by human liver microsomes for the identification of new cyclosporine metabolites. From these data a metabolic pathway for cyclosporine, which includes these new cyclosporine metabolites, has been proposed. The new metabolites were isolated by semi-preparative h.p.l.c. and their chemical structures were elucidated by FAB mass spectrometry. These isolated metabolites were further metabolized and the products identified by FAB mass spectrometry. 2. Fourteen metabolites, whose structure has not yet been elucidated, were isolated after metabolism of structurally identified cyclosporine metabolites, and chemical structures for five of these metabolites were proposed. 3. The structures of the new cyclosporine metabolites were: (i) a N-demethylated, carboxylated derivative (AM1A4N), (ii) a di-hydroxylated, N-demethylated derivative (AM14N9), (iii) a hydroxylated and carboxylated derivative (AM1A9), (iv) a di-hydroxylated, cyclized and N-demethylated derivative (AM1c4N9) and (v) a cyclized and carboxylated (AM1cA) derivative. 4. A proposed cyclosporine metabolic pathway comprises a total of 29 metabolites. It consists of four main branches originating from metabolites AM1, AM1c, AM9 and AM4N.

Unexpected reaction of [Ni(CO)4-n(R2PCl)n] (n = 1, 2 ; R = But, Cy, Ph) with Na2[Fe2(CO)8]. Synthesis and electronic structure of the anions [Fe2(μ-CO)(CO)6(μ-PR2)]- and their reactions with H+ and [M(PPh3)]+ (M = Cu, Ag, Au)

Treatment of [Ni(CO)4-n(R2PCl)n] (n = 1, 2; R = Bu(t), Cy, Ph) with Na2[Fe2(CO)8] gave, depending on n and R, either the doubly phosphido-bridged complexes [Fe2(CO)6(mu-PR2)2] or the anions [Fe2(mu-CO)(CO)6(mu-PR2)]-. These anions can also be obtained by the reaction of [Fe(CO)4(PR2)]- with either [Fe2(CO)9] or [Fe(CO)5] via the intermediate [Fe2(CO)8(mu-PR2)]-. The electronic structure of the anions [Fe2(mu-CO) (CO)6(mu-PR2)]- has been studied by an EHT calculation which supports their ambident oxygen- or metal-nucleophilicity. The metal-centred nucleophilic reactions of the anion [Fe2(mu-CO)(CO)6(mu-PBu(t)2)]- with H+ and [M(PPh3)]+, (M = Cu, Ag, Au), respectively, are described. The new complexes have been characterized by various spectroscopic methods and the structure of [Fe2{mu-Ag(PPh3)}(mu-CO)(CO)6(mu-PBu(t)2)] has been established by X-ray analysis.

Investigation of the stereoselective in vitro biotransformation of glutethimide by high-performance liquid chromatography and capillary electrophoresis☆

Due to our interest in drugs with a glutarimide structure, we reinvestigated the stereoselectivity of the in vitro biotransformation of the chiral hypnotic-sedative drug glutethimide. Glutethimide enantiomers were separated on a preparative scale by HPLC on cellulose tris(4-methylbenzoate) as chiral stationary phase. The enantiomeric purity was higher than 99%. A reversed-phase HPLC method was developed to determine the metabolites of glutethimide. After incubations with rat liver microsomes both enantiomers formed 5-hydroxyglutethimide as the main metabolite, as well as additional metabolites, of which some were formed stereoselectively. Mass spectrometry of the unknown metabolites indicated a hydroxylation in the ethyl side chain for two of the metabolites. A third metabolite was tentatively identified as desethylglutethimide.

Durch wasserstoff-transfer induzierte radikal-eliminierungen aus ortho-substituierten benzoesäuremethylestern

Abstract The investigation of some 2H-labelled compounds as well as the analysis of energetic properties (appearance potential measurement, kinetic energy release) reveal some unusual elimination of radicals (CH3., OH. resp. CHO.) from ortho substituted bencoic acid methyl esters. It can be shown that most of the reactions are induced by a novel hydrogen transfer to the carboxyl function.

Field desorption mass spectrometry of natural products—III: Corrinoid metal complexes derived from vitamin B12

Abstract Charged and uncharged metal complexes of secocorrin which are model compounds for the synthesis of biogenetically and pharmacologically interesting metal analogs of vitamin B 12 , were investigated by field desorption mass spectrometry. The data contained in the spectra of these compounds permit an exact and reliable determination of the molecular weight. In addition structural information can be obtained based on typical fragmentation reactions. The support of the results received by high resolution and precise mass measurement was made by a direct analysis of the isotopic pattern of the corrinoid metal complexes. The first use of this combined method for field desorption mass spectrometry of a series of natural products of high molecular weight revealed that important indications can be obtained for the identification and characterisation of these compounds.

Identification of conjugated metabolites of antipyrine in urine by pyrolysis-electron-impact mass spectrometry

Abstract Pyrolysis-electron-impact mass spectrometry can be employed as a fast and sensitive method for the identification of unconjugated and conjugated metabolites of antipyrine at different stages of the work-up procedure. The method avoids derivatization of the highly polar conjugates, generally a basic requirement for electron-impact investigation. Using crude extracts of human and rat urine, endogeneous products of the metabolic process did not interfere with the studied metabolite. It is demonstrated that all phase-I metabolites so far described in the literature can be thermally liberated from their corresponding conjugates and subsequently identified by electron-impact mass spectrometry. The isomeric main metabolites 3-hydroxymethylantipyrine and 4-hydroxyantipyrine can be distinguished by specific pyrolytic reactions. The different temperatures of decomposition of the conjugated sulphates and glucuronides give additional information on the nature of the conjugates. Thus, the characteristic difference in the metabolic patterns in man and rat is reflected in the mass thermograms of the aglycones obtained by thermal decomposition of the conjugate mixtures.