Enantiomeric separation of atropine in Scopolia extract and Scopolia Rhizome by capillary electrophoresis using cyclodextrins as chiral selectors

Complexation of tropane alkaloids by cyclodextrins

Complexes of atropine, homatropine, scopolamine, and ipratropium with cyclodextrins were investigated by NMR and capillary electrophoresis. It has been demonstrated that tropane alkaloids form complexes with β- and γ-cyclodextrins of 1:1 stoichiometry. NMR measurements indicate the formation of complexes where both aliphatic and aromatic parts of tropane alkaloids interact with β-cyclodextrin. The stability constants of the investigated alkaloids with β- and γ-cyclodextrins were determined by capillary electrophoresis. It has been found that β-cyclodextrin forms ten times more stable complexes than γ-cyclodextrin. Moreover, the analysis of the obtained crystal structure of β-cyclodextrin/(-)-hyoscyamine complex reveals that two molecules of (-)-hyoscyamine oriented in head-to-tail mode are tightly fitted inside head-to-head β-cyclodextrin dimer. Conformation of (-)-hyoscyamine as well as scopolamine changes substantially upon complexation adapting to the cavity of β-cyclodextrin as shown by X-ray analysis, NMR and DFT calculations data.

Enantiomeric separation and simulation study of eight anticholinergic drugs on an immobilized polysaccharide-based chiral stationary phase by HPLC

Enantiomeric separation process of anticholinergic drugs and chiral recognition mechanisms on Chiralpak ID column.

Chiral high-performance liquid chromatographic separation of the enantiomers of tetrahydropalmatine and tetrahydroberberine, isolated from Corydalis yanhusuo

HPLC methods have been developed for chiral resolution of the enantiomers of dl-tetrahydropalmatine (THP) and dl-tetrahydroberberine (THB), two active constituents of Corydalis yanhusuo W.T. Wang. On the analytical scale, good baseline separation of the enantiomers was achieved using cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phases in both normal-phase and polar organic modes. Validation of the analytical methods, including linearity, limits of detection, recovery, and precision, and semipreparative resolution of dl-THP and dl-THB, were achieved with methanol as mobile phase, without any basic additives, in polar organic mode using cellulose tris(3,5-dimethylphenylcarbamate) chiral stationary phases. On the semipreparative scale, small quantities of the individual enantiomers of THP and THB were isolated for study of the chiroptical properties of the individual enantiomers.

Sensitive and specific liquid chromatographic–tandem mass spectrometric assay for atropine and its eleven metabolites in rat urine

A sensitive and specific method is described for the simultaneous determination of atropine and its metabolites in rat urine by combining liquid chromatography and tandem mass spectrometry (LC-MS(n)). Various extraction techniques (free fraction, acid hydrolyses and enzyme hydrolyses) and their comparison were carried out for investigation of the metabolism of atropine. After extraction procedure the pretreated samples were separated on a reversed-phase C18 column using a mobile phase of methanol/ammonium acetate (2 mM, adjusted to pH 3.5 with formic acid) (70: 30,v/v) and detected by an on-line LC-MS(n) system. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular masses (DeltaM), retention-times and full scan MS(n) spectra with those of the parent drug. The results revealed that at least eleven metabolites (N-demethyltropine, tropine, N-demethylatropine, p-hydroxyatropine, p-hydroxyatropine N-oxide, glucuronide conjugates and sulfate conjugates of N-demethylatropine, p-hydroxyatropine and the parent drug) and the parent drug existed in rat urine after ingesting 25 mg/kg atropine. p-Hydroxyatropine and the parent drug were detected in rat urine for up 106 h after ingestion of atropine.

PVC membrane ion-selective electrodes for the determination of Hyoscyamine in pure solution and in pharmaceutical preparations under batch and flow modes

New PVC membrane electrodes selective for the determination of hyoscyamine ion (Hy(+)) based on hyoscyamine tetraphenylborate (Hy-TPB) or hyoscyamine phosphotungstate (Hy-PT) ion-exchangers as electroactive materials are described. The electrodes show a linear response for Hy(+) over the concentration range of 1.00 x 10(-5) to 1.26 x 10(-2) mol L(-1) and 1.00 x 10(-4) to 1.00 x 10(-2) mol L(-1) in case of Hy-TPB electrode applying batch and flow injection analysis (FIA), respectively, and 1.00 x 10(-5) to 4.52 x 10(-3) mol L(-1) and 6.31 x 10(-5) to 1.00 x 10(-2) mol L(-1) in case of Hy-PT electrode for batch and FIA, respectively. The lower detection limits are 3.90 x 10(-6) and 4.51 x 10(-6) at 25 degrees C for Hy-TPB and Hy-PT electrodes, respectively. The electrodes posses near Nernstian slopes of 56.5 and 57.8 mV/decade for Hy-TPB and Hy-PT electrodes, respectively, and a fast potential response of < or =20 s which is almost constant over a pH range of 3-10. Selectivity coefficient data for some common inorganic cations, sugars, amino acids and the components, other than hyoscyamine, of the mixed drugs investigated show negligible interference. The electrodes have been applied to the potentiometric determination of hyoscyamine in pure solution and in pharmaceutical preparations under batch and FIA conditions and as end point indicator electrode for the determination of hyoscyanine using potentiometric titration. For the concentrations (1.08 x 10(-5) mol L(-1) to 3.16 x 10(-3) mol L(-1)) an average recovery of 99.95% with relative standard deviation of 0.63% has been achieved. The effect of temperature on the electrodes was also studied.

Uniformly sized molecularly imprinted polymer for atropine and its application to the determination of atropine and scopolamine in pharmaceutical preparations containing Scopolia extract

A uniformly sized molecularly imprinted polymer (MIP) for atropine has been prepared. The MIP was prepared using 2-(trifluoromethyl) acrylic acid and ethylene glycol dimethacrylate as a functional monomer and cross-linker, respectively, by a multi-step swelling and thermal polymerization method. The selectivity factor, which is defined as the ratio of the retention factors (k) on the molecularly imprinted and non-imprinted polymers, k(imprinted)/k(non-imprinted), was 2.2 for atropine on the MIP. The obtained MIP was applied for the determination of tropane alkaloids (atropine and scopolamine) in a commercial gastrointestinal drug by a column-switching HPLC system, consisting of an MIP material as a pre-column, and a conventional cation-exchange analytical column. An interference peak was observed at the retention time of atropine derived from pre-column. However, since the peak area was less than 0.5% the peak area of atropine of a standard solution under the analytical conditions of this study (0.2 microg of atropine was loaded), this interference was negligible in the determination of atropine. On the other hand, no interference peak was observed at the retention time of scopolamine. Calibration curves of atropine and scopolamine showed good linearity in the range of 0.02-0.9 microg/ml (r=0.9999) and 0.003-0.09 microg/ml (r=0.9998), respectively. The mean recoveries of atropine and scopolamine from a placebo pharmaceutical preparation sample were 98.9 and 99.9%, respectively. The intra-day precision (measured by relative standard deviation, R.S.D. (%)) of both ingredients was less than 2.0%. The optimized column-switching system was applied successfully to the determination of atropine and scopolamine in a commercial gastrointestinal drug.

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.

Integrated bioprocessing for plant cell cultures

Plant cell suspension culture has become the focus of much attention as a tool for the production of secondary metabolites including paclitaxel, a well-known anticancer agent. Recently, it has also been regarded as one of the host systems for the production of recombinant proteins. In order to produce phytochemicals using plant cell cultures, efficient processes must be developed with adequate bioreactor design. Most of the plant secondary metabolites are toxic to cells at the high concentrations required during culture. Therefore, if the product could be removed in situ during culture, productivity might be enhanced due to the alleviation of this toxicity. In situ removal or extractive bioconversion of such products can be performed by in situ extraction with various kinds of organic solvents. In situ adsorption using polymeric resins is another possibility. Using the fact that secondary metabolites are generally hydrophobic, various integrated bioprocessing techniques can be designed not only to lower toxicity, but also to enhance productivity. In this article, in situ extraction, in situ adsorption, utilization of cyclodextrins, and the application of aqueous two-phase systems in plant cell cultures are reviewed.

Recent developments in chiral capillary electrophoresis and applications of this technique to pharmaceutical and biomedical analysis

This paper provides an overview of the current status of chiral capillary electrophoresis (CE). The emphasis is placed on the application of CE in chiral separation of various racemic compounds. During the last two years about 280 papers, several review articles, and two entire issues, edited by S. Fanali (Electrophoresis 1999, 20, 2577-2798, and H. Nishi and S. Terabe (J. Chromatogr. A 2000, 879, 1-471.) have been devoted to chiral CE. Enantiomeric separations of various compounds, e.g., pharmaceuticals, drug candidates, drugs and related metabolites in biological fluids, amino acids, di- and tri peptides, pesticides and fungicides, have been performed using different chiral selectors. Native and derivatized cyclodextrins continue to be the most widely used chiral selectors. Other chiral selectors such as natural and synthetic chiral micelles, crown ethers, chiral ligands, proteins, oligo- and polysaccharides, and macrocyclic antibiotics have also been applied to chiral CE separations.

Enantioseparation of atropine by capillary electrophoresis using sulfated beta-cyclodextrin: application to a plant extract

A capillary zone electrophoresis (CZE) method, with sulfated beta-CD as chiral selector, was optimized by means of an experimental design for the enantioseparation of atropine. In this study, a central composite design was used and the following factors were varied simultaneously: buffer concentration, buffer pH and sulfated beta-CD concentration. The resolutions between littorine and its positional isomer ((-)-hyoscyamine) and between atropine enantiomers, as well as the separation time and generated current were established as responses. A model was obtained for each response by linear multiple regression of a second-degree mathematical expression. The most favorable conditions were determined by maximizing the resolution between atropine enantiomers and by setting the other responses at threshold values. Successful results were obtained with a 55 mM phosphate buffer at pH 7 in the presence of 2.9 mM sulfated-beta-CD at 20 degrees C and 20 kV. Under these optimized conditions, a baseline separation of littorine and atropine enantiomers was achieved in less than 5 min. Finally, the method allowed the enantiomeric separation of atropine in a pharmaceutical formulation and was also found to be suitable for the enantiomeric purity evaluation of (-)-hyoscyamine in plant extracts, in relation with the extraction procedure. It was demonstrated that supercritical fluid extraction induced less racemization than classical liquid-solid extraction procedures.