Simultaneous determination of scopolamine, hyoscyamine and littorine in plants and different hairy root clones of Hyoscyamus muticus by micellar electrokinetic chromatography

Analysis of scopolamine and its related substances by means of high-performance liquid chromatography

The retention behaviour of scopolamine (hyoscine) and its related compounds (norhyoscine, atropine, homatropine, and noratropine) was investigated on the silica-based HPLC stationary phase. The retention of investigated tropane alkaloids was interpreted by using the Soczewiński-Wachtmeister equation. A high correlation between the retention parameter (log k) and lipophilicity (log P) (R = 0.9923) confirms the significant influence of hydrophobic interactions on the retention behaviour of the aforementioned compounds. It was found that by increasing the acetonitrile fraction, a decrease in retention of the more polar epoxide derivatives (scopolamine, norhyoscine) and an increase in retention of the more lipophilic derivatives (atropine, noratropine, homatropine) is obtained. The best separation of the tropane alkaloids was achieved by a simple procedure that involved a mobile phase composed of acetonitrile and 40 mM ammonium acetate/0.05% TEA, pH 6.5; 50:50 v/v. Selected conditions were assumed for the determination of scopolamine hydrochloride in the eye drops (Scopolamini hydrobromidum 0.25%). The method was validated and it was found as selective, sensitive, precise, accurate, and robust for the further qualitative analysis of the scopolamine-related compounds.

Effects of various Agrobacterium rhizogenes strains on hairy root induction and analyses of primary and secondary metabolites in Ocimum basilicum

The hairy root (HR) culture system is an excellent alternative strategy to the whole plant system for producing valuable compounds. However, selection of suitable Agrobacterium strain for the successful induction of HR is an essential step for enhanced production of beneficial secondary metabolites. In this study, we examined the transformation efficiency of various A. rhizogenes strains (ATCC 13333, ATCC 15834, A4, R1000, R1200, and R1601) for transgenic HRs induction in Ocimum basilicum. Among the tested strains, the R1601 was found to be one of the most promising strain for mass production of HR in terms of transformation efficiency (94%) and the number and length of HR (8.4 ± 0.52 and 1.68 ± 0.14 cm). The HR induced by the same strain exhibited highest levels of rosmarinic acid level (62.05 ± 4.94 µg/g DW) and total phenolic content (62.3 ± 4.95 µg/g DW). A total of 55 metabolites were identified using high-performance liquid chromatography (HPLC) and gas chromatography-time-of-flight mass spectrometry (GC-TOFMS). The PCA and PLS-DA plot of the identified metabolites showed that HR induced by A4 and ATCC 15834 displayed variation in primary and secondary metabolite contents. Analysis of the metabolic pathway identified a total of 56 pathways, among which 35 were found to be impacted. A heat map and hierarchical clustering analysis indicated that HR induced by different Agrobacterium strains exhibited differential metabolites profiles. In conclusion, Agrobacterium strains R1601 is one of the best and most promising strains for inducing mass HR production and enhanced levels of secondary metabolites in O. basilicum.

Development of CE-C4D Method for Determination Tropane Alkaloids

A fast method for the determination of tropane alkaloids, using a portable CE instrument with a capacitively coupled contactless conductivity detector (CE-C⁴D) was developed and validated for determination of atropine and scopolamine in seeds from Solanaceae family plants. Separation was obtained within 5 min, using an optimized background electrolyte consisting of 0.5 M acetic acid with 0.25% (w/v) β-CD. The limit of detection and quantification was 0.5 µg/mL and 1.5 µg/mL, respectively, for both atropine and scopolamine. The developed method was validated with the following parameters—precision (CV): 1.07–2.08%, accuracy of the assay (recovery, RE): 101.0–102.7% and matrix effect (ME): 92.99–94.23%. Moreover, the optimized CE-C⁴D method was applied to the analysis of plant extracts and pharmaceuticals, proving its applicability and accuracy.

Effect of ontogeny on the content of the hallucinogenic alkaloids atropine and scopolamine in the different organs of some Solanaceae plants

The content of atropine and scopolamine is known to vary with ontogeny and plant organs selected which makes it necessary to define the optimal stage for harvesting of each plant organ. The present study aims at investigating the effect of ontogeny on the accumulation of atropine and scopolamine in the leaves, stems, roots, flowers and fruits of the Solanaceae plants Burgmansia suaveolens Bercht. & J.Presl, Datura stramonium L., D. arborea L., D. inoxia Mill. and Hyoscyamus albus L. Results showed that the highest content of atropine and scopolamine was observed during the flowering stage of most organs. H. albus L. leaves collected during flowering stage exhibited the highest content of atropine (746.66 ug/g) followed by the pre-flowering leaves of D. stramonium L. and the flowering stage stems of H. albus L. while D. inoxia Mill. pre-flowering leaves and flowering stems had significantly higher content of scopolamine among all the tested extracts with a concentration of 555.04 ug/g and 244.26 ug/g, respectively.

Genetically engineered hairy root cultures of Hyoscyamus senecionis and H. muticus: ploidy as a promising parameter in the metabolic engineering of tropane alkaloids

Tetraploidy improves overexpression of h6h and scopolamine production of H. muticus, while in H. senecionis, pmt overexpression and elicitation can be used as effective methods for increasing tropane alkaloids. The effects of metabolic engineering in a polyploid context were studied by overexpression of h6h in the tetraploid hairy root cultures of H. muticus. Flow cytometry analysis indicated genetic stability in the majority of the clones, while only a few clones showed genetic instability. Among all the diploid and tetraploid clones, the highest level of h6h transgene expression and scopolamine accumulation was interestingly observed in the tetraploid clones of H. muticus. Therefore, metabolic engineering of the tropane biosynthetic pathway in polyploids is suggested as a potential system for increasing the production of tropane alkaloids. Transgenic hairy root cultures of Hyoscyamus senecionis were also established. While overexpression of pmt in H. senecionis was correlated with a sharp increase in hyoscyamine production, the h6h-overexpressing clones were not able to accumulate higher levels of scopolamine than the leaves of intact plants. Applying methyl jasmonate was followed by a sharp increase in the expression of pmt and a drop in the expression of tropinone reductase II (trII) which consequently resulted in the higher biosynthesis of hyoscyamine and total alkaloids in H. senecionis.

Comparison of Different Strains of Agrobacterium rhizogenes for Hairy Root Induction and Betulin and Betulinic Acid Production in Morus alba

Three Agrobacterium rhizogenes strains were tested for their ability to transform the plant Morus alba L. and to induce production of the secondary metabolites betulin and betulinic acid. All the tested strains of A. rhizogenes (R1601, LBA9402 and R1000) were able to induce hairy root formation in leaf tissue explants. Strain LBA9402 had the highest rate of infection (92.7% ± 8.8%), whereas strain R1601 had the lowest rate (87.4% ± 9.3%). The highest number of hairy roots per explant (5.6 ± 0.5) and the greatest root length (2.4 ± 0.2 mm) were obtained with strain LBA9402. We also evaluated dry weight (a measure of growth) and betulin and betulinic acid production in hairy roots and found that the highest growth (167.8 ± 14.5 mg/flask) occurred after infection with strain LBA9402. Furthermore the highest production of betulin (5.4 ± 0.4 mg/g dry weight) and betulinic acid (2.3 ± 0.2 mg/g dry weight) was noted using strain LBA9402. Among three elicitors, yeast extract showed the highest induction of betulin production (8.7 ± 0.4 mg/g) and silver nitrate induced the highest yield of betulinic acid (4.1 ± 0.2 mg/g). Our study showed that A. rhizogenes strain LBA9402 was the most effective of the three tested strains for production of transformed root cultures and betulin and betulinic acid.

FRET-based nanobiosensor for detection of scopolamine in hairy root extraction of Atropa belladonna

A simple, sensitive, selective, and rapid optical nanobiosensor based on FRET was designed to detect tropane alkaloids as anti-cholinergic agents in natural and transgenic hairy roots extracts of Atropa belladonna. To achieve that, conjugation of tioglycolyic acid capped cadmium telluride quantum Dots, M₂ muscarinic receptor (Cd/Te QDs-M₂R) and conjugation of scopolamine-rhodamine123 (Sc-Rho123) were performed. More specifically, proportional amounts of M₂ muscarinic receptor and quantum dots (QDs) were conjugated while scopolamine (as a tropane alkaloid) and rhodamine123 were also combined and these moieties functioned as donor and acceptor pairs, respectively. The system response was linear over the range of 0.01-4µmolL^-1 of scopolamine hydrochloride concentration with a detection limit of 0.001µmolL^-1. The developed nanobiosensor was successfully used for in vitro recognition of scopolamine as an anti-cholinergic agent in the investigated plant extracts. In addition, Agrobacterium rhizogenesis mediated gene transfer technique was employed to generate hairy roots and to enhance the production of tropane alkaloids in the studied medicinal plant.

Isolation of atropine and scopolamine from plant material using liquid-liquid extraction and EXtrelut® columns

Tropane alkaloids are toxic secondary metabolites produced by Solanaceae plants. Among them, plants from Datura genus produce significant amounts of scopolamine and hyoscyamine; the latter undergoes racemization to atropine during isolation. Because of their biological importance, toxic properties and commonly reported food and animal feed contamination by different Datura sp. organs, there is a constant need for reliable methods for the analysis of tropane alkaloids in many matrices. In the current study, three extraction and sample-clean up procedures for the determination of scopolamine and atropine in plant material were compared in terms of their effectiveness and repeatability. Standard liquid-liquid extraction (LLE) and EXtrelut^® NT 3 columns were used for the sample clean-up. Combined ultrasound-assisted extraction and 24h static extraction using ethyl acetate, followed by multiple LLE steps was found the most effective separation method among tested. However, absolute extraction recovery was relatively low and reached 45-67% for atropine and 52-73% for scopolamine, depending on the compound concentration. The same method was also the most effective one for the isolation of target compounds from Datura stramonium leaves. EXtrelut^® columns, on the other hand, displayed relatively low effectiveness in isolating atropine and scopolamine from such a complex matrix and hence could not be recommended. The most effective method was also applied to the extraction of alkaloids from roots and stems of D. stramonium. Quantitative analyses were performed using validated method based on gas chromatography with flame ionization detector (GC-FID). Based on the results, the importance of the proper selection of internal standards in the analysis of tropane alkaloids was stressed out.

An atypical pattern of accumulation of scopolamine and other tropane alkaloids and expression of alkaloid pathway genes in Hyoscyamus senecionis

A cDNA encoding hyoscyamine 6β-hydroxylase (H6H, EC 1.14.11.11), a bifunctional enzyme catalyzing the last two steps in the scopolamine biosynthetic pathway, was isolated from Hyoscyamus senecionis, a medicinal plant endemic to the Iranian plateau. Expression analysis indicates that Hsh6h is expressed in all tested organs of H. senecionis including roots, rhizomes, leaves, stems and flowers unlike the other tropane alkaloid producing species. In parallel to this, in leaves, levels of scopolamine, the product of H6H, were higher than the substrate hyoscyamine. These data suggest that not only does the conversion of hyoscyamine to scopolamine take place in the root, followed by translocation to aerial parts, but also accumulated hyoscyamine in the aerial parts may be converted to scopolamine by activity of HsH6H. Analysis of expression profiles of putrescine N-methyltransferase and tropinone reductase I and II genes also indicates the organ-independent expression of these genes. Here we also introduce H. senecionis as an important tropane alkaloid producing species with its thick underground parts as a source of hyoscyamine, while its leaves can be considered as a source of scopolamine.

Fifty years of alkaloid biosynthesis in Phytochemistry

An overview is presented of the studies related to the biosynthesis of alkaloids published in Phytochemistry in the past 50 years.

Production of triterpenoid anti-cancer compound taraxerol in Agrobacterium-transformed root cultures of butterfly pea (Clitoria ternatea L.)

Independent transformed root somaclones (rhizoclones) of butterfly pea (Clitoria ternatea L.) were established using explant co-cultivation with Agrobacterium rhizogenes. Rhizoclones capable of sustained growth were maintained under low illumination in auxin-free agar-solidified MS medium through subcultures at periodic intervals. Integration of T(L)-DNA rolB gene in the transformed rhizoclone genome was verified by Southern blot hybridization, and the transcript expression of T(R)-DNA ags and man2 genes was ascertained by reverse transcription polymerase chain reaction analysis. The major compound isolated and purified from the transformed root extracts was identified as the pentacyclic triterpenoid compound taraxerol using IR, (1)H-NMR, and (13)C-NMR spectroscopy. The taraxerol yield in cultured hairy roots, as quantified by HPTLC analysis, was up to 4-fold on dry weight basis compared to that in natural roots. Scanning of bands from cultured transformed roots and natural roots gave super-imposable spectra with standard taraxerol, suggesting a remarkable homology in composition. To date, this is the first report claiming production of the cancer therapeutic phytochemical taraxerol in genetically transformed root cultures as a viable alternative to in vivo roots of naturally occurring plant species.

An efficient protocol for genetic transformation of Platycodon grandiflorum with Agrobacterium rhizogenes

The balloon flower (Platycodon grandiflorum) is a popular traditional medicinal plant used in Korea to treat conditions such as bronchitis, asthma, tuberculosis, diabetes, and inflammatory diseases. Recently, immunopharmacological research identified triterpenoid and saponin as important active compounds in P. grandiflorum. To study and extract these compounds and other metabolites from P. grandiflorum, a technique was developed for producing hairy root cultures, which are a reliable source of plant compounds. To achieve this, the activity of Agrobacterium rhizogenes was exploited, which can transfer DNA segments into plant genomes after infecting them. In this study, the A. rhizogenes strain R1000 was determined that had the highest infection frequency (87.5%) and induced the most hairy roots per plant, and the concentration of antibiotics (75 mg/l kanamycin) was elucidated for selection after transformation. Wild-type and transgenic hairy roots contained various phenolic compounds, although both of them had similar concentrations of phenolic compounds. In the future, the protocols described here should be useful for studying and extracting valuable metabolites such as phenolic compounds from P. grandiflorum hairy root cultures.

Simultaneous determination of atropine, anisodamine, and scopolamine in plant extract by nonaqueous capillary electrophoresis coupled with electrochemiluminescence and electrochemistry dual detection

A rapid and simple method was demonstrated for the analysis of atropine, anisodamine, and scopolamine by nonaqueous capillary electrophoresis (NACE) coupled with electrochemiluminescence (ECL) and electrochemistry (EC) dual detection. The mixture of acetonitrile (ACN) and 2-propanol containing 1M acetic acid (HAc), 20mM sodium acetate (NaAc), and 2.5mM tetrabutylammonium perchlorate (TBAP) was used as the electrophoretic buffer. Although a short capillary of 18cm was used, the decoupler was not needed and the separation efficiency was good. The linear ranges of atropine, anisodamine, and scopolamine were 0.5-50, 5-2000, and 50-2000microM, respectively. For six replicate measurements of 100microM scopolamine, 15microM atropine, and 200microM anisodamine, the RSDs of ECL intensity, EC current, and migration time were less than 3.6%, 4.5%, and 0.3%, respectively. In addition, because the organic buffer was used, the working electrode (Pt) was not easily fouled and did not need reactivation. The method was also applied for the determination of these three alkaloids in Flos daturae extract.

Opportunities in metabolic engineering to facilitate scalable alkaloid production

Numerous drugs and drug precursors in the current pharmacopoeia originate from plant sources. The limited yield of some bioactive compounds in plant tissues, however, presents a significant challenge for large-scale drug development. Metabolic engineering has facilitated the development of plant cell and tissue systems as alternative production platforms that can be scaled up in a controlled environment. Nevertheless, effective metabolic engineering approaches and the predictability of genetic transformations are often obscured due to the myriad cellular complexities. Progress in systems biology has aided the understanding of genome-wide interconnectivities in plant-based systems. In parallel, the bottom-up assembly of plant biosynthetic pathways in microorganisms demonstrated the possibilities of a new means of production. In this Perspective, we discuss the opportunities and challenges of implementing metabolic engineering in various platforms for the synthesis of natural and unnatural plant alkaloids.

Molecular cloning and characterization of a new cDNA encoding hyoscyamine 6beta-hydroxylase from roots of Anisodus acutangulus

A new full-length cDNA encoding hyoscyamine 6beta-hydroxylase (designated as aah6h, GenBank Accession No. EF187826), which catalyzes the last committed step in the scopolamine biosynthetic pathway, was isolated from young roots of Anisodus acutangulus by rapid amplification of cDNA ends (RACE) for the first time. The full-length cDNA of aah6h was 1380 bp and contained a 1035 bp open reading frame (ORF) encoding a deduced protein of 344 amino acid residues. The deduced protein had an isoelectric point (pI) of 5.09 and a calculated molecular mass of about 38.7 kDa. Sequence analyses showed that AaH6H had high homology with other H6Hs isolated from some scopolamine-producing plants such as Hyoscyamus niger, Datura metel and Atropa belladonna etc. Bioinformatics analyses results indicated AaH6H belongs to 2-oxoglutarate-dependent dioxygenase superfamily. Phylogenetic tree analysis showed that AaH6H had closest relationship with H6H from A. tanguticus. Southern hybridization analysis of the genomic DNA revealed that aah6h belonged to a multi-copy gene family. Tissue expression pattern analysis firstly founded that aah6h expressed in all the tested tissues including roots, stems and leaves and indicated that aah6h was a constitutive-expression gene, which was the first reported tissue-independent h6h gene compared to other known h6h genes.

Capillary electrophoresis of tropane alkaloids and glycoalkaloids occurring in Solanaceae plants

This chapter examines the role of capillary electrophoresis (CE) in the separation of tropane alkaloids, glycoalkaloids, and closely related compounds that have either pharmaceutical value or toxicological effects on humans. The latest significant developments in CE analysis have been selected and critically discussed. When the conventional CE mode was found unable to provide an acceptable selectivity towards the analytes, the addition of either an organic solvent, a chiral selector, or a surfactant to the running buffers was exploited. Likewise, nonaqueous CE (NACE) was also employed to increase solute solubilities and for a better compatibility of this media with mass spectrometry. It turns out that, upon selecting the most appropriate experimental conditions, the CE separation of tropane alkaloids and steroidal glycoalkaloids of Solanaceae plants was successfully accomplished. All major steps involved in the separation and detection of these secondary metabolites in complex samples are described and the relevant aspects of each application are examined with emphasis on the main aspects entailed a typical assay. More applications have yet to be developed in order to encourage more labs to exploit the tremendous potential of capillary electrophoresis.

Simultaneous analysis of alkaloids from Zanthoxylum nitidum by high performance liquid chromatography–diode array detector–electrospray tandem mass spectrometry

The chemical profiles of nine alkaloids in Zanthoxylum nitidum, including berberubine, coptisine, sanguinarine, nitidine, chelerythrine, liriodenine, 6,7,8-trimethoxy-2,3-methylendioxybenzophenantridine, oxyavicine and dihydrochelerythrine, were identified by using high performance liquid chromatography-diode array detector-electrospray tandem mass spectrometry (HPLC-DAD-ESI-MS), and a novel and sensitive HPLC-UV method had been developed to simultaneously determine these alkaloids in 70% methanol extract of Zanthoxylum nitidum. The chromatographic separation was performed on an Agilent C(18) analytical column (5 microm, 4.6 mm i.d., 250 mm length) with a gradient solvent system of acetonitrile-0.1% formic buffer (adjusted to pH 4.5 with triethylamine). The methodological validation was carried out and the linearities (r(2)>0.9997) and recoveries (ranged from 98.3% to 101.1%) were acceptable. The limits of detection (LOD) of these alkaloids were ranged from 0.6 ng to 1.5 ng. The results indicated that the contents of alkaloids in Zanthoxylum nitidum varied significantly from habitat to habitat with contents ranged from 0.03 mg/g to 3.34 mg/g. The proposed method is simple, effective and suitable for the quality control of this traditional Chinese medicine (TCM). It suggests that it is necessary to control its quality so as to insure efficacy and safety of TCM.

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.

Separation and determination of toxic pyrrolizidine alkaloids in traditional Chinese herbal medicines by micellar electrokinetic chromatography with organic modifier

A simple and rapid micellar electrokinetic chromatography (MEKC) method was developed for the separation and determination of four toxic pyrrolizidine alkaloids (PAs) (senkirkine, senecionine, retrorsine, and seneciphylline) in two traditional Chinese herbal medicines (Qian liguang and Kuan donghua). Separation was performed in the running buffer consisting of 20 mM borate, 30 mM SDS, and 20% methanol at pH 9.1. With the optimized separation conditions, four PAs were separated in 17 min by a single run. The calibration curves showed good linearity with correlation efficiencies (R(2)) between 0.9940 and 0.9988. RSDs in migration time and peak area were 0.31, 0.40, 0.39, 0.48% and 3.28, 3.48, 4.16, 3.42% for senkirkine, senecionine, retrorsine, and seneciphylline, respectively. Limits of detection (S/N = 3) varied from 1.19 to 2.70 microg/mL. The proposed method was applied to determine the PAs extracted from Chinese herbal medicines (Qian liguang and Kuan donghua). PA of senkirkine in Kuan donghua was detected and the amount was found to be 79.1 microg/g. The results obtained indicate that the proposed MEKC method could potentially become an effective alternative tool for qualification control and quantitative analysis of herbal medicines in pharmaceutical industry.

Simultaneous analysis of hyoscyamine, scopolamine, 6β-hydroxyhyoscyamine and apoatropine in Solanaceous hairy roots by reversed-phase high-performance liquid chromatography

A new high-performance liquid chromatographic method is described for tropane alkaloid analysis in genetically transformed root cultures of Datura innoxia Mill. and Atropa belladonna L. Sample preparation, tropane alkaloid extraction with chloroform-methanol-concentrated ammonia 15:5:1 (v/v/v), was followed by solid-phase extraction on Supelclean LC-18 cartridges. Optimized conditions and careful pH control resulted in high recovery and reproducibility. Simultaneous determination of apoatropine, 6beta-hydroxyhyoscyamine, hyoscyamine and scopolamine was performed by HPLC on C18 (2) reversed-phase column. The application of Luna new-generation silica-based stationary phase resulted in excellent peak shapes using an ion-pair reagent and triethanolamine free mobile phase and allowed to exploit the full power of pH-dependent selectivity. Simplicity and improved selectivity make this method a preferred alternative of published ion-pair chromatographic methods. Validation studies proved that the global method has good repeatability and satisfactory recovery. Absolute limits of detection were 0.6, 0.6, and 0.8 ng for hyoscyamine, 6beta-hydroxyhyoscyamine, and scopolamine respectively.

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.

Potentiometric PVC membrane sensor for the determination of scopolamine in some pharmaceutical formulations

A novel PVC membrane electrode for the determination of scopolamine ion based on the formation of an ion-association complex of scopolamine with the phosphotungstate counter anion as an electroactive material dispersed in a PVC matrix is described. The sensor shows a fast, stable, near-Nenstian response for 1 x 10(-2) mol dm(-3) to 1 x 10(-6) mol dm(-3) scopolamine at 25 degrees C over the pH range of 3 - 7 with a cationic slope of 54.5 +/- 0.5 mV/decade. The lower detection limit is 8 x 10(-7) mol dm(-3) and the response time is 15 -45 s. The selectivity coefficients for scopolamine relative to the number of interfering substances were investigated. There was negligible interference from the studied cations, anions, and pharmaceutical excipients. The determination of scopolamine in aqueous solution shows an average recovery of 100.0% and a mean relative standard deviation (RSD) of 1.5% at 500 microg/cm3. The direct determination of scopolamine in some formulations (scopolamine injection and eye drops) gave results that compare favorably with those obtained by the United State of Pharmacopoeia method. Potentiometric titration of scopolamine with sodium tetraphenylborate and phosphotungstic acid as a titrant was monitored with the developed scopolamine electrode as an end point indicator electrode.

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.