Analysis of tropane alkaloids with thermospray high-performance liquid chromatography-mass spectrometry

Overview of the major classes of new psychoactive substances, psychoactive effects, analytical determination and conformational analysis of selected illegal drugs

The misuse of psychoactive substances is attracting a great deal of attention from the general public. An increase use of psychoactive substances is observed among young people who do not have enough awareness of the harmful effects of these substances. Easy access to illicit drugs at low cost and lack of effective means of routine screening for new psychoactive substances (NPS) have contributed to the rapid increase in their use. New research and evidence suggest that drug use can cause a variety of adverse psychological and physiological effects on human health (anxiety, panic, paranoia, psychosis, and seizures). We describe different classes of these NPS drugs with emphasis on the methods used to identify them and the identification of their metabolites in biological specimens. This is the first review that thoroughly gives the literature on both natural and synthetic illegal drugs with old known data and very hot new topics and investigations, which enables the researcher to use it as a starting point in the literature exploration and planning of the own research. For the first time, the conformational analysis was done for selected illegal drugs, giving rise to the search of the biologically active conformations both theoretically and using lab experiments.

Biomedical analysis of New Psychoactive Substances (NPS) of natural origin

New psychoactive substances (NPS) can be divided into two main groups: synthetic molecules and active principles of natural origin. With respect to this latter group, a wide range of alkaloids contained in plants, mainly from Asia and South America, can be included in the class of NPS of natural origin. The majority NPS of natural origin presents stimulant and/or hallucinogenic effects (e.g. Catha edulis and Ayahuasca, respectively) while few of them show sedative and relaxing properties (e.g. kratom). Few information is available in relation to the analytical identification of psychoactive principles contained in the plant material. Moreover, to our knowledge, scarce data are present in literature, about the characterization and quantification of the parent drug in biological matrices from intoxication and fatality cases. In addition, the metabolism of natural active principles has not been yet fully investigated for most of the psychoactive substances from plant material. Consequently, their identification is not frequently performed and produced metabolites are often unknown. To fill this gap, we reviewed the currently available analytical methodologies for the identification and quantification of NPS of natural origin in plant material and, whenever possible, in conventional and non-conventional biological matrices of intoxicated and dead subjects. The psychoactive principles contained in the following plants were investigated: Areca catechu, Argyreia nervosa, Ayahuasca, Catha edulis, Ipomoea violacea, Mandragora officinarum, Mitragyna speciosa, Pausinystalia yohimbe, Piper methisticum, Psilocybe, Rivea corymbosa, Salvia divinorum, Sceletium tortuosum, Lactuca virosa. From the results obtained, it can be evidenced that although several analytical methods for the simultaneous quantification of different molecules from the same plants have been developed and validated, a comprehensive method to detect active compounds from different natural specimens both in biological and non-biological matrices is still lacking.

Solid–liquid extraction and cation-exchange solid-phase extraction using a mixed-mode polymeric sorbent of Datura and related alkaloids

Tropane alkaloids solid-liquid extraction methods were developed and comprised ambient pressure ones: extraction with hot solvent, extraction at room temperature, on ultrasonic bath as well as pressurised liquid extraction (PLE) techniques. The highest yields of l-hyoscyamine in methanol PLE method (3 x 5 min, 110 degrees C) and scopolamine extracted with 1% tartaric acid in methanol (15 min, 90 degrees C) were determined. A mixed-mode reversed-phase cation-exchange solid-phase extraction (SPE) procedure was optimised for simultaneous recoveries of L-hyoscyamine, scopolamine, scopolamine-N-oxide from plant extracts as well as quaternary alkaloid representative: scopolamine-N-methyl bromide. First three alkaloids were efficiently eluted (recoveries 80-100%) from an Oasis MCX cartridge with methanol-10% ammonia (3:1, v/v) solution, whereas for the quaternary salt tetrahydrofuran-methanol-25% ammonia (6:1:3, v/v) was used with recoveries 52-6%. HPTLC-densitometric assay on silica gel plates was elaborated at 205 nm without derivatization and included: single development (over a distance 9.5 cm) with acetone-methanol-water-25% ammonia (85:5:5:8, v/v) mobile phase for L-hyoscyamine and scopolamine separation, whereas for scopolamine-N-oxide and scopolamine-N-methyl bromide a second development (to a distance 5.5 cm) with acetonitrile-methanol-85% formic acid (120:5:5, v/v) was applied. Newly elaborated RP-HPLC-diode array detection method was performed on Waters XTerra RP-18 column with gradient of acetonitrile in 15 mM ammonia solution and alkaloids were baseline separated within 20 min. Both chromatographic methods were validated and their quantitative results were compared. Good correlation between HPLC and HPTLC quantitative results was measured (correlation coefficients of mean values were 0.92086 and 0.99995 for L-hyoscyamine and scopolamine, respectively). In the RP-HPLC method, which was from 1.5- up to 7-fold more sensitive than HPTLC, limits of detection (LOD) and limits of quantitation (LOQ, in bracket) were (in ng/microl) as follows: 0.25 (0.82) for L-hyoscyamine, 0.29 (0.97) for scopolamine, 0.13 (0.45) for scopolamine-N-oxide and 0.58 (1.91) for scopolamine-N-methyl bromide. By the use of the optimised chromatographic methods, 14 various samples from the leaves and fruits of Datura sp. were screened for L-hyoscyamine and scopolamine contents and the most promising samples were established.

Pharmacokinetics and pharmacodynamics in clinical use of scopolamine

The alkaloid L-(-)-scopolamine [L-(-)-hyoscine] competitively inhibits muscarinic receptors for acetylcholine and acts as a nonselective muscarinic antagonist, producing both peripheral antimuscarinic properties and central sedative, antiemetic, and amnestic effects. The parasympatholytic scopolamine, structurally very similar to atropine (racemate of hyoscyamine), is used in conditions requiring decreased parasympathetic activity, primarily for its effect on the eye, gastrointestinal tract, heart, and salivary and bronchial secretion glands, and in special circumstances for a CNS action. Therefore, scopolamine is most suitable for premedication before anesthesia and for antiemetic effects. This alkaloid is the most effective single agent to prevent motion sickness. Scopolamine was the first drug to be made commercially available in a transdermal therapeutic system (TTS-patch) delivering alkaloid. Recently, pharmacokinetic data on scopolamine in different biozlogic matrices were obtained most efficiently using liquid chromatographic-tandem mass spectrometric (LC-MS/MS) or gas chromatography online coupled to mass spectrometry. Pharmacokinetic parameters are dependent on the dosage form (oral dose, tablets; parenteral application; IV infusion; SC and IM injection). Scopolamine has a limited bioavailability if orally administered. The maximum drug concentration occurs approximately 0.5 hours after oral administration. Because only 2.6% of nonmetabolized L-(-)-scopolamine is excreted in urine, a first-pass metabolism is suggested to occur after oral administration of scopolamine. Because of its short half-life in plasma and dose-dependent adverse effects (in particular hallucinations and the less serious reactions, eg, vertigo, dry mouth, drowsiness), the clinical use of scopolamine administered orally or parenterally is limited. To minimize the relatively high incidence of side effects, the transdermal dosage form has been developed. The commercially available TTS-patch contains a 1.5-mg drug reservoir and a priming dose (140 microg) to reach the steady-state concentration of scopolamine quickly. The patch releases 0.5 mg alkaloid over a period of 3 days (releasing rate 5 microg/h). Following the transdermal application of scopolamine, the plasma concentrations of the drug indicate major interindividual variations. Peak plasma concentrations (Cmax) of approximately 100 pg/mL (range 11-240 pg/mL) of the alkaloid are reached after about 8 hours and achieve steady state. During a period of 72 hours the plaster releases scopolamine, so constantly high plasma levels (concentration range 56-245 pg/mL) are obtained, followed by a plateau of urinary scopolamine excretion. Although scopolamine has been used in clinical practice for many years, data concerning its metabolism and the renal excretion in man are limited. After incubation with beta-glucuronidase and sulfatase, the recovery of scopolamine in human urine increased from 3% to approximately 30% of the drug dose (intravenously administered). According to these results from enzymatic hydrolysis of scopolamine metabolites, the glucuronide conjugation of scopolamine could be the relevant pathway in healthy volunteers. However, scopolamine metabolism in man has not been verified stringently. An elucidation of the chemical structures of the metabolites extracted from human urine is still lacking. Scopolamine has been shown to undergo an oxidative demethylation during incubation with CYP3A (cytochrome P-450 subfamily). To inhibit the CYP3A located in the intestinal mucosa, components of grapefruit juice are very suitable. When scopolamine was administered together with 150 mL grapefruit juice, the alkaloid concentrations continued to increase, resulting in an evident prolongation of tmax (59.5 +/- 25.0 minutes; P < 0.001). The AUC0-24h values of scopolamine were higher during the grapefruit juice period. They reached approximately 142% of the values associated with the control group (P < 0.005). Consequently, the related absolute bioavailabilities (range 6% to 37%) were significantly higher than the corresponding values of the drug orally administered together with water (range 3% to 27%). The effect of the alkaloid on quantitative electroencephalogram (qEEG) and cognitive performance correlated with pharmacokinetics was shown in studies with healthy volunteers. From pharmacokinetic-pharmacodynamic modeling techniques, a direct correlation between serum concentrations of scopolamine and changes in total power in alpha-frequency band (EEG) in healthy volunteers was provided. The alkaloid readily crosses the placenta. Therefore, scopolamine should be administered to pregnant women only under observation. The drug is compatible with nursing and is considered to be nonteratogenic. In conclusion, scopolamine is used for premedication in anesthesia and for the prevention of nausea and vomiting associated with motion sickness. Pharmacokinetics and pharmacodynamics of scopolamine depend on the dosage form. Effects on different cognitive functions have been extensively documented.

Analysis of tropane and related alkaloids

The current methods for tropane alkaloid chromatographic separation and determination are summarised. The alkaloids included are: the medicinally applied tropic acid esters hyoscyamine and scopolamine and their derivatives, cocaine and derivatives, the metabolites and degradation products of these compounds occurring in plant material, calystegines as nortropane alkaloids, anatoxins as homonortropane alkaloids, pelletierines and pseudopelletierines as alkaloids with isomeric structures. Developments in GC, HPLC, CE and TLC are presented and the advantages of each method for plant analysis are discussed. A summary for each chromatographic method lists the instrumentation and parameters applied for tropane alkaloids.

Quantitative analysis of tropane alkaloids in biological materials by gas chromatography-mass spectrometry

A simple and rapid method for quantitation of tropane alkaloids in biological materials has been developed using an Extrelut column with gas chromatography-mass spectrometry (GC-MS). Biological materials (serum and urine) were mixed with a borate buffer and then applied to an Extrelut column. The adsorbed tropane alkaloids were eluted with dichloromethane before a GC-MS analysis. Atropine-d(3) was used as an internal standard. The extracted tropane alkaloids were converted to trimethylsilyl derivatives prior to GC analysis, to improve the instability of tropane alkaloids from heating and the property of them for a GC column. The recoveries of the compounds, which had been spiked to biological materials, were more than 80%. The GC separation of the derivatives from endogenous impurities was generally satisfactory with the use of a semi-polar capillary column. Tropane alkaloids showed excellent linearity in the range of 10-5000 ng/ml and the limit of detection was 5.0 ng/ml for biological materials. The present method is simple and more rapid than those previously reported, and was applied to a poisoning case. It is useful for the routine analysis of tropane alkaloids in cases of suspected tropane alkaloids poisoning.

[Studies on structural elucidation of Aconitum diterpenoid alkaloid by LC-APCI-MS and effects of Aconitum diterpenoid alkaloid on cutaneous blood flow]

The chemical constituents of Aconitum yesoense var. macroyesoense and Aconitum japonicum were examined using high-resolution spectral analysis. Twelve novel alkaloids were isolated from A. yesoense var. macroyesoense together with 20 known alkaloids. Eight novel alkaloids were isolated from A. japonicum together with 15 known alkaloids. An HPLC-atmospheric pressure chemical ionization-mass spectrometry (HPLC-APCI-MS) method was useful for the simultaneous determination of 21 Aconitum alkaloids found in A. yesoense var. macroyesoense and A. japonicum. These compounds were fairly stable under the conditions used, and the protonated molecules or fragment ions characteristic of the molecule appeared as base peaks in the mass spectra and were used for selected ion monitoring. HPLC-APCI-MS is a very promising approach for structural investigations of positional isomers and stereoisomers. This method was applied successfully to stereoisomeric Aconitum alkaloids differing in configuration at C-1, -6, or -12. Comparison of the APCI spectra showed that the abundance of fragment ions was significantly higher for the C-1, -6, or -12 beta-form alkaloid than for C-1, -6, or -12 alpha-form alkaloid. The main alkaloid constituents in the root of A. yesoense var. macroyesoense, Aconitum alkaloids of the C20-diterpenoid type, kobusine and pseudokobusine, and their acyl derivatives were examined for their peripheral vasoactivities by measuring laser-flowmetrically the cutaneous blood flow in the hind foot of mice after intravenous administration. It is thought that the hydroxyl groups of alkaloids, especially a free OH group of pseudokobusine at C-6, were important for action on the peripheral vasculature leading to dilatation, and the results indicated that esterification of the hydroxyl group at C-15 with either anisoate, veratroate, or p-nitroben-zoate may contribute to enhancement of the activity of the parent alkaloids.

On-line capillary electrophoresis-electrospray mass spectrometry for the stereoselective analysis of drugs and metabolites

The on-line combination of partial-filling capillary electrophoresis and electrospray ionization mass spectrometry was demonstrated for the enantioseparation of pharmaceutical drugs and metabolites, namely amphetamines, methadone, venlafaxine and selected tropane alkaloids. The partial-filling technique proved to be a suitable and efficient approach to avoid mass spectrometry (MS) source contamination, as well as signal suppression due to nonvolatile additives. To achieve chiral separation, various chiral selectors were applied, including neutral and particularly negatively charged cyclodextrins. Because of the countercurrent contribution, charged cyclodextrins were found more suitable for the on-line MS detection of separated enantiomers. Hyphenation of capillary electrophoresis (CE) with mass spectrometry was found appropriate for the stereoselective analysis of methadone in real serum samples. Moreover, the use of MS in the selected ion monitoring mode resulted in a very high selectivity, as well as improved sensitivity compared to UV detection. Finally, with atropine as a model compound, the quantitative performances of the method were evaluated and showed high sensitivity, as well as good repeatability in terms of migration time and peak area ratio.

Determination of scopolamine in human serum and microdialysis samples by liquid chromatography-tandem mass spectrometry

A liquid chromatographic-tandem mass spectrometric (LC-MS-MS) method with a rapid and simple sample preparation was developed for the determination of scopolamine in biological fluids. Scopolamine and the internal standard atropine in serum samples were extracted and cleaned up by using an automated solid phase extraction method. Microdialysis samples were directly injected into the LC-MS system. The mass spectrometer was operated in the multi reaction monitoring mode. A good linear response over the range of 20 pg/ml to 5 ng/ml was demonstrated. The accuracy for added scopolamine ranged from 95.0 to 104.0%. The lower limit of quantification was 20 pg/ml. This method is suitable for pharmacokinetic studies.

Development of a packed-column supercritical fluid chromatography/atmospheric pressure chemical-ionisation mass spectrometric technique for the analysis of atropine

A packed-column supercritical fluid chromatography/atmospheric pressure chemical-ionisation mass spectrometry (pSFC-APCI/MS) method has been developed for the determination of atropine from Atropa belladonna L extracts. The technique does not require any kind of derivatisation prior to the analysis. The optimum conditions were studied by using the pure substance in methanol (MeOH). All samples were simply dissolved in MeOH and injected into the mobile phase. Detection was achieved by using mass spectrometry (MS) with atmospheric pressure chemical ionisation (APCI). Terbutaline was used as an internal standard for the determination of the analytical reproducibility. The supercritical carbon dioxide (scCO(2)) mobile phase was modified by 15% MeOH containing 0.5% trifluoroacetic acid (TFAA) and 0.5% diethylamine (DEA) additives. Concentrations of atropine were determined with a relative standard deviation of less than 1% by the pSFC-APCI/MS procedure for a sample containing atropine and terbutaline. The correlation coefficient was 0.997 and detection limit 700 pg. The absolute retention time was 9.87 min with a standard deviation of 5.2x10(-3) min and a relative standard deviation of 0.61% with respect to terbutaline.

Capillary electrophoresis-diode array detection--electrospray mass spectrometry for the analysis of selected tropane alkaloids in plant extracts

Capillary zone electrophoresis, coupled to UV and interfaced with electrospray ionization mass spectrometry (ESI-MS), is described for the simultaneous analysis of hyoscyamine and scopolamine. On-line UV detection occurred at 22 cm from the inlet of the capillary and ESI-MS monitoring was performed along the entire length of the capillary (85 cm). An alkaline solution of 40 mM ammonium acetate at pH 8.5 was suitable for the analysis of the alkaloids under consideration. Under the optimized conditions, including CE and ESI-MS parameters, the two alkaloids were resolved within a short time and with very high sensitivity. The differentiation of hyoscyamine and its positional isomer littorine, commonly encountered in plant material, is also presented using up-front collision-induced dissociation. Finally, the developed method was applied to the analysis of these alkaloids in Belladonna leaf extract and in Datura candida x D. aurea hairy root extract.

Poisoning by plant material: review of human cases and analytical determination of main toxins by high-performance liquid chromatography-(tandem) mass spectrometry

The authors have reviewed the main toxic plants responsible for human deaths throughout the world. Forty plants (genera or species) were listed in order to establish an inventory of the active molecules that could be identified, the already published analytical methods and the reported human fatal cases. In a second step, the authors have developed a general method for the detection of various toxins in whole blood by high-performance liquid chromatography coupled to mass spectrometry or tandem mass spectrometry. Sample preparation was realized by liquid-liquid extraction at pH 9.5 for oleandrine, taxol and the alkaloids. These latter compounds were divided into two groups following their chemical properties and could be subsequently purified by acid/base clean up. Cyanogenic compounds and atractyloside were isolated by precipitation of the protein content with acetone and purified for atractyloside by washing with chloroform. Separation of the drugs occurred under reversed-phase conditions on a C18 analytical column 150x2 mm I.D. (5 microm particle size) using two different mobile phases. The first one, formiate buffer 2 mM acidified at pH 3.0, was used for the separation of atractyloside, oleandrine, taxol, the cyanogenic molecules and some alkaloids. The second mobile phase, formiate buffer 10 mM made basic at pH 8.2 was used for the majority of other alkaloids. A gradient elution mode was chosen using acetonitrile or acetonitrile-methanol (50:50, v/v) as the eluting solvent. Detection under positive ionization mode was the mode of choice for all compounds except for atractyloside (negative ions) and for taxol (mixed mode available). Application to real forensic cases has been demonstrated.

Determination of scopolamine in human serum by gas chromatography-ion trap tandem mass spectrometry

The objective of this study was to develop a very sensitive and selective method for the determination of scopolamine in serum with a rapid and simple sample preparation. A capillary column gas chromatographic-ion trap tandem mass spectrometric technique has been applied. Scopolamine and the internal standard mexiletine were extracted from serum samples and cleaned up by using a single step liquid-liquid extraction. Derivatization was carried out using 2,2,2-trifluoro-N-methyl-N-trimethylsilylacetamide. The mass spectrometer was operated with positive ions in the selected reaction mode with chemical ionisation using methane. The sum of peak height of two daughter ions was used for quantification. The detection limit was 50 pg/ml in serum.