Determination of three ephedrine psychoactive substances in sewage using solid-phase extraction-ultra-performance liquid chromatography-tandem mass spectrometry.

RATIONALE: In recent years, ephedrine psychoactive substances have attracted much attention due to their prevalence in water bodies and potential threat to aquatic ecosystems. Psychoactive substances have been considered as a new type of environmental pollutant due to their unpredictable potential risks to the behavior and nervous system of non-target organisms. A rapid, sensitive, selective, and robust method for the quantification of three ephedrine psychoactive substances in sewage is needed. METHODS: An ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method was developed for the simultaneous determination of three ephedrine psychoactive substances in water. The optimal processing conditions were determined by optimizing the chromatography-mass spectrometry and solid-phase extraction (SPE) conditions (e.g., the SPE column, sample pH, washing, and elution), and the treatment conditions were determined; this was achieved via positive ion scanning in multiple reaction monitoring mode. Poly-Sery MCX was selected as the extraction column, with samples loaded at pH 3. And 4-mL solution of 2% formic acid (FA) aqueous solution was used as the eluent; the target compounds were eluted with 5 mL of 5% NH4OH in acetonitrile (ACN) solution. The best results were obtained when the residue was resolubulization in ACN after nitrogen evaporation. RESULTS: The developed UPLC-MS/MS showed a good linear relationship in the range of 0-50.00 µg/L, with determination coefficients (R2) greater than 0.9990. The detection limit and quantitation limit were 0.05-0.10 and 0.20-0.50 µg/L, respectively. Recovery rates of the target compounds in blank sewage at three different concentrations ranged from 92.37% to 106.31%, with relative standard deviations (RSDs) of 0.77%-4.83% (n = 7). CONCLUSIONS: This method has been successfully applied to the analysis of surface water and domestic sewage, and the samples were processed stably, indicating that the method is practical for the determination of ephedrine psychoactive drugs in water bodies.

Model compounds for evaluating the reactivity of amphetamine-type stimulants.

The use of controlled precursors for reaction optimisation is not always practical. One approach to limiting the use of controlled substances is to instead use 'model compounds'. Herein, two model compounds resembling norephedrine and ephedrine were selected based on their (i) structural similarity (i.e., presence of key functional groups) and (ii) availability from multiple suppliers without restriction. Model compounds 2-amino-1-phenylethanol and 2-(methylamino)-1-phenylethanol (halostachine), were compared to norephedrine and pseudoephedrine by firstly subjecting them to transformations known in the synthesis of amphetamines, and secondly, comparing the compounds using colourimetric spot tests, FTIR and NMR.

Can the heptapeptide ASSIVSF of the ß2-adrenoceptor recognize ephedrine and pseudoephedrine epimers in a complex system?

Epimer separation is crucial in the field of analytical chemistry, separation science, and the pharmaceutical industry. No reported methods could separate simultaneously epimers or even isomers and remove other unwanted, co-existing, interfering substances from complex systems like herbal extracts. Herein, we prepared a heptapeptide-modified stationary phase for the separation of 1R,2S-(-)-ephedrine [(-)-Ephe] and 1S,2S-(+)-pseudoephedrine [(+)-Pse] epimers from Ephedra sinica Stapf extract and blood samples. The heptapeptide stationary phase was comprehensively characterized by scanning electron microscopy, X-ray photoelectron spectroscopy, and Fourier transform infrared spectroscopy. The separation efficiency of the heptapeptide column was compared with an affinity column packed with full-length ß2-AR functionalized silica gel (ß2-AR column). The binding affinity of the heptapeptide with (+)-Pse was 3-fold greater than that with (-)-Ephe. Their binding mechanisms were extensively characterized by chromatographic analysis, ultraviolet spectra, circular dichroism analysis, isothermal titration calorimetry, and molecule docking. An enhanced hydrogen bonding was clearly observed in the heptapeptide-(+)-Pse complex. Such results demonstrated that the heptapeptide can recognize (+)-Pse and (-)-Ephe epimers in a complex system. This work, we believe, was the first report to simultaneously separate epimers and remove non-specific interfering substances from complex samples. The method was potentially applicable to more challenging sample separation, such as chiral separation from complex systems.

Evaluating the behavior and principle of deep eutectic solvent on ephedrine-type alkaloid extraction from Ephedrae Herba.

In this study, deep eutectic solvent (DES), as a new green solvent, was used to extract bioactive alkaloids from Ephedrae Herba using supersonic extraction. In a variety of tested hydrophilic and hydrophobic DESs, DES composed of choline chloride and xylitol was proved to be the most efficient solvent. Factors affecting extraction efficiency, including the mole ratio of hydrogen bond acceptor/hydrogen bond donor, water contention, and solid/liquid ratio, were optimized individually. Under optimal conditions, the yield of ephedrine (EP) and pseudoephedrine obtained using this new method was 14.24 and 4.32 mg/g, respectively, which was higher than that using the traditional solvent (acidified water and methanol). Furthermore, the extraction mechanism of DES and EP was investigated using molecular dynamics simulation study. Structural properties such as radial distribution functions and average number of hydrogen bonds were then computed. The results showed that hydrogen bonds and van der Waals forces are important driving forces of extraction; in addition, the hydrogen bonds between the Cl atom of choline chloride and N atom of EP played a dominant part in the extraction process. Based on the extraction principle, the extraction method using choline chloride as extraction solvent was also discussed.

Detection, discrimination and quantification of amphetamine, cathinone and nor-ephedrine regioisomers using benchtop 1 H and 19 F nuclear magnetic resonance spectroscopy.

Amphetamine and cathinone derivatives are abused recreationally due to the sense of euphoria they provide to the user. Methodologies for the rapid detection of the drug derivative present in a seized sample, or an indication of the drug class, are beneficial to law enforcement and healthcare providers. Identifying the drug class is prudent because derivatisation of these drugs, to produce regioisomers, for example, occurs frequently to circumvent global and local drug laws. Thus, newly encountered derivatives might not be present in a spectral library. Employment of benchtop nuclear magnetic resonance (NMR) could be used to provide rapid analysis of seized samples as well as identifying the class of drug present. Discrimination of individual amphetamine-, methcathinone-, N-ethylcathinone and nor-ephedrine-derived fluorinated and methylated regioisomers is achieved herein using qualitative automated 1 H NMR analysis and compared to gas chromatography-mass spectrometry (GC-MS) data. Two seized drug samples, SS1 and SS2, were identified to contain 4-fluoroamphetamine by 1 H NMR (match score median = 0.9933) and GC-MS (RRt = 5.42-5.43 min). The amount of 4-fluoroamphetamine present was 42.8%-43.4% w/w and 48.7%-49.2% w/w for SS1 and SS2, respectively, from quantitative 19 F NMR analysis, which is in agreement with the amount determined by GC-MS (39.9%-41.4% w/w and 49.0%-49.3% w/w). The total time for the qualitative 1 H NMR and quantitative 19 F NMR analysis is ~10 min. This contrasts to ~40 min for the GC-MS method. The NMR method also benefits from minimal sample preparation. Thus, benchtop NMR affords rapid, and discriminatory, analysis of the drug present in a seized sample.

[Mahuang (herbaceous stem of Ephedra spp.): chemistry, pharmacodynamics, and pharmacokinetics].

The Chinese medicinal herb Mahuang is herbaceous stem of Ephedra sinica, E. intermedia, or E. equisetina(Family, Ephedraceae). In China, Mahuang has been used, all the way over a millennium, as a key component herb of many herbal medicines for management of epidemics of acute respiratory illness and is also used in officially recommended herbal medicines for COVID-19. Mahuang is the first-line medicinal herb for cold and wheezing and also an effective diuretic herb for edema. However, Mahuang can also exert significant adverse effects. The key to safety and effectiveness is rational and precise use of the herb. In this review article, we comprehensively summarize chemical composition of Mahuang and associated differences in pharmacognosy, pharmacodynamics and pharmacokinetics of Mahuang compounds, along with the adverse effects of Mahuang compounds and products. Based on full understanding of how Mahuang is used in Chinese traditional medicine, systematic research on Mahuang in line with contemporary standards of pharmaceutical sciences will facilitate promoting Chinese herbal medicines to become more efficient in management of epidemic illnesses, such as COVID-19. To this end, we recommend research on Mahuang of two aspects, i.e., pharmacological investigation for its multicompound-involved therapeutic effects and toxicological investigation for clinical manifestation of the adverse effects, chemicals responsible for the adverse effects, and conditions for safe use of the herb and the herb-containing medicines.

Qualitative and quantitative analysis of ephedrine stimulants in urine by ultra-performance liquid chromatography-tandem mass spectrometry.

RATIONALE: Ephedrine analogues are stimulants that are explicitly required to be quantified and characterized in the Anti-Doping Prohibited List of the World Anti-Doping Agency. Given the difficulty of distinguishing diastereoisomers, the qualitative and quantitative analyses of ephedrine diastereoisomers are difficult. METHODS: An ultra-performance liquid chromatography-tandem mass spectrometry (UHPLC/MS/MS) method was developed to detect five ephedrine analogues, and two pairs of diastereoisomers were identified using this method. The samples were analyzed qualitatively and quantitatively using a tandem mass spectrometer with an electrospray ionization source in multiple reaction detection mode after one-step dilution. RESULTS: The effective detection limits of this method were below 0.5 ng/mL. A matrix effect (range: 83.4% to 102%) was observed in quality control samples. The intra- and inter-day precision was lower than 9.16% and 8.60%, respectively, and the accuracy was within ±8.0%. CONCLUSIONS: The method is efficient, accurate, stable and sensitive, and fully meets the requirements for the detection of ephedrine substances in stimulants.

Therapeutic appraisal of ephedrine against rheumatoid arthritis: A new indication.

Ephedra, natural flora has been used traditionally to treat rheumatism since decades. The scientific evidence of anti-rheumatic effect of this plant has also been reported. But the anti-rheumatic activity of major constituent of this plant (ephedrine) has not been evaluated. Based on this, the current study was aimed to assess anti-arthritic activity of ephedrine by using in vitro and in vivo approaches. Correspondingly, enzyme linked immunosorbent assay was performed for the estimation of prostaglandins E2 (PGE2) and tumor necrosis factor-α (TNF-α) in serum of formaldehyde-induced arthritic animals. The results elaborated significant reduction in albumin denaturation and remarkable progress on stabilization of red blood cells outer membrane at higher concentration during in vitro experiments. The ephedrine (40mg/kg) revealed noteworthy (p<0.001) inhibition in paw swelling in animals intoxicated with albumin as well as formaldehyde as compared to animals of control group by in vivo results. In this assay, ephedrine (20 & 40 mg/kg orally) significantly suppressed the level of these inflammatory markers (PGE2 & TNF-α). Ephedrine exhibited anti-arthritic effect by decreasing pro-inflammatory cytokines (PGE2 & TNF-α). This experimental work pharmacologically supports the use of ephedrine as anti-rheumatic drug but limited to evaluate in immunological arthritic model.

Over a century since ephedrine discovery: an updated revisit to its pharmacological aspects, functionality and toxicity in comparison to its herbal extracts.

Ephedrine, a sympathomimetic amine that exhibits several adrenaline actions, is a plant alkaloid that is a common ingredient in several cold, asthma and narcolepsy treatment preparations, and in obesity management and sport medicine. Its principal action mechanism relies on its direct adrenergic actions as well as indirect role that involves the release of epinephrine and norepinephrine, thus increasing the activity of epinephrine and norepinephrine at the postsynaptic α and ß receptors. Nevertheless, its serious side effects, including stroke, heart attack, drug abuse and interactions, have never been comprehensively reviewed. We conducted a systematic review of data on ephedrine, including its occurrence in functional foods, pharmacological aspects, metabolism, pharmaco/toxicokinetics and clinical features. Furthermore, a review of ephedrine natural structural analogues with regards to their differential adrenergic receptor binding affinities, food interaction, and their impact on the pharmacokinetics and effects relative to ephedrine are presented for the first time, and in comparison to its action when present in herbs.

[NMR Study of the Discrimination of Enantiomers of Methamphetamine and Its Raw Materials Using Chiral Solvating Agents].

Some controlled substances, such as stimulants and narcotics, have asymmetric carbons in their molecules. Because the enantiomers do not always show the same pharmacological effects, and there are substances with different controls due to differences in their stereochemistry, a simple and unambiguous method for assessment of the composition of enantiomers is necessary. In this study, to develop a simple and rapid stereoscopic identification method for methamphetamine and its raw materials (ephedrine and pseudoephedrine), the 1H-NMR method was studied using three commercially available chiral solvating agents (CSAs); 1,1'-bi(2-naphthol)(BINOL), 2,2,2-trifluoro-1-(9-anthryl)ethanol (TFAE) and α-methoxy-α-(trifluoromethyl)phenylacetic acid (MTPA). In addition, the accuracy of the optical purity, which was measured using samples mixed with enantiomers in various ratios, was investigated. The NMR peaks of the enantiomers were separated by adding (R)- or (S)-form of BINOL, TFAE or MTPA to the chloroform-d solution of methamphetamine, ephedrine or pseudoephedrine. A sufficient discrimination of enantiomers was obtained by adding about 10 equal amounts of each CSA to the solutions. With regard to the optical purity, it was possible to determine accurately the mixing of small amounts of enantiomers of about 5% even if the NMR peaks did not reach the baseline separation, when impurity peaks do not overlap. This method will be one of the useful techniques for the rapid and simple discrimination of enantiomers of illegal methamphetamine and its raw materials.

Therapeutic effects of Gambi-jung for the treatment of obesity.

Obesity is known as metabolic syndrome and it affects many tissues including adipose tissue, liver, and central nervous system (CVS). Gambi-jung (GBJ) is a modified prescription of Taeumjowi-tang (TJT), which has been used to treat obesity in Korea. GBJ is composed of 90% Ephedra sinica Stapf (ES). Therefore, the present study was designed to assess the antiobesity effects of GBJ and to compare the effects of GBJ and ES on obesity. GBJ administration remarkably reduced the body weight, Body mass index (BMI), and body fat percentage compared to the ES administration in human subjects. GBJ-treated mice had lower white adipose tissue (WAT) amounts than ES-treated mice. GBJ and ES administration enhanced adenosine monophosphate-activated protein kinase (AMPK) expression in 3T3-L1 adipocytes, epididymal WAT and liver of HFD-induced obese mice. Moreover, GBJ and ES reduced food intake by suppressing the mRNA levels of orexigenic peptides, agouti-related protein (AgRP) and neuropeptide-Y (NPY), as well as AMPK in the brain of HFD-induced obese mice. Furthermore, GBJ-treated mice had dramatically lower expression of macrophage marker F4/80 in epididymal WAT than those of ES-treated mice. Based on these results, we suggest the use of GBJ as a natural drug to control weight gain.

Electrochemical study of ephedrine at the polarized liquid-liquid interface supported with a 3D printed cell.

In this work, we have examined an electrochemical behavior of the ephedrine at the polarized liquid-liquid interface (water/1,2-dichloroethane). In this respect, we first designed and then 3D printed polyamide-based electrochemical cell that was used as the liquid-liquid interface support during electroanalytical measurements. The protonated ephedrine undergoes a reversible ion transfer reaction with the standard Galvani potential difference equal to +0.269 V. This value was used to calculate the water - 1,2-dichloroethane logP equal to -4.6. Ion transfer voltammetry was used to build the calibration curve and allowed for the ephedrine detection from concentration equal to 20 µM. By varying the pH of the aqueous phase from 2 up to 12 we were able to plot the ion partition diagram that was further analyzed and provided several pharmacochemical information. To further push this work towards practical utility, we have formulated the artificial urine and studied the interfacial behavior of all its components at the polarized liquid-liquid interface. Ephedrine detection from real spiked urine samples was also performed.

Studying the effect of vasopressors on therapeutic drug monitoring of two local anesthetics using hybrid micelle liquid chromatography as an analysis tool.

A hybrid micelle based mobile phase was used to develop and validate a liquid chromatographic method for the separation and quantification of two local anesthetics namely; lidocaine hydrochloride (LID), and bupivacaine hydrochloride (BPV) in presence of the frequently co administered vasopressors phenyl ephrine (PHR) and ephedrine (EPH). Optimization of chromatographic separation conditions was performed applying experimental one factor at a time tool, and design of experiment, where the retention behavior of all analytes using both optimization protocols was in accordance. Chromatographic separation was carried on a C8 column operating at 40 °C at a flow rate of 1.5 mL/min. using a mobile phase consisting of 0.18 M sodium dodecyl sulphate, 10% acetonitrile, containing 0.3% triethyl amine and adjusted to pH 7 using 2 M ortho phosphoric acid, adopting UV detection at 230 nm. The proposed method was fully validated and applied to both in vitro and in vivo analysis of rat blood samples. The pharmacokinetics of both LID and BPV was followed when they were solitary injected or when co administered with either PHR or EPH. Moreover, the in vitro spiked experiment was also subjected to documented bio-analytical validation procedures.

Application of a chiral high-performance liquid chromatography-tandem mass spectrometry method for the determination of 13 related amphetamine-type stimulants to forensic samples: Interpretative hypotheses.

Interpretation of amphetamine-type stimulant (ATS) findings in urine samples can be challenging without chiral information. We present a sensitive enantioselective high-performance liquid chromatography-tandem mass spectrometry method for the quantification of (R)-amphetamine, (S)-amphetamine, (R)-methamphetamine, (S)-methamphetamine, (1R,2R)-pseudoephedrine, (1S,2S)-pseudoephedrine, (1R,2S)-ephedrine, (1S,2R)-ephedrine, (1R,2S)-norephedrine, (1S,2R)-norephedrine, (R)-cathinone, (S)-cathinone, and (1S,2S)-norpseudoephedrine (cathine) in urine. The method was successfully applied to more than 100 authentic urine samples from forensic casework. In addition, samples from a controlled self-administration of (1S,2S)-pseudoephedrine (Rinoral, 1200 mg within 6 days) were analyzed. The results strengthen the hypothesis that (1R,2S)-norephedrine is a minor metabolite of amphetamine and methamphetamine. We suggest cathine and (1S,2R)-norephedrine as minor metabolites of amphetamine racemate in humans. Small methamphetamine concentrations detected in samples with high concentrations of amphetamine could result from a metabolic formation by methylation of amphetamine although in samples with an (R)/(S) ratio for methamphetamine < 1 an additional (previous) (S)-methamphetamine consumption seems likely. Our data suggest that even amphetamine concentrations exceeding methamphetamine concentrations in urine can be caused by the biotransformation of methamphetamine to amphetamine as long as no (R)-amphetamine is detected. However, without chiral information, such findings might be (falsely) assumed as a co-consumption of both substances. Cathinone enantiomers detected in urine samples with high amphetamine concentrations can be interpreted as metabolites of amphetamine. In addition, the results of the self-administration study revealed that both cathinone enantiomers are minor metabolites of (1S,2S)-pseudoephedrine, which is the active ingredient of various medicines used for cold. The enantioselective analysis is a powerful tool to avoid the misinterpretation of ATS findings in urine samples.

Comparison of four documents describing adrenaline purification, and the work of three important scientists, Keizo Uenaka, Nagai Nagayoshi and Jokichi Takamine.

The name of Keizo Uenaka has not been documented in textbooks. However, Uenaka was the scientist who worked on ephedrine and played a practical role in the purification and crystallization of adrenaline. His handwritten memorandum, "On Adrenaline, Memorandum, July to December, 1900" is now stored in a Buddhist temple, Kyougyou-ji in Nashio, Japan. In the present report, we compared Uenaka's original description and Jokichi Takamine's published scientific reports, and examined how each statement in four documents are related to each other in terms of successful adrenaline crystallization. Uenaka's memorandum contained precise procedures and experimental tips for successful purification. The experimental steps were considered to transcribed in the first published document in The American Journal of Pharmacy by Takamine in 1901, and summarized in another document in ``Journal of Physiology'' in 1901. A Japanese version was published in ``Yakugakuzasshi'' in 1903 by translating the English paper in the American Journal of Pharmacy published in 1901. Reading Uenaka's memorandum, we realized that he tirelessly and diligently undertook routine experiments that to some of us might seem boring and laborious. Although the name of Uenaka is not globally well known, he was the main scientist who did the actual work of purifying adrenaline.

Quality Evaluation and Characterization of Fractions with Biological Activity from Ephedra Herb Extract and Ephedrine Alkaloids-Free Ephedra Herb Extract.

Previously, we reported that the c-Met inhibitory effect of Ephedra Herb extract (EHE) is derived from ingredients besides ephedrine alkaloids. Moreover, analgesic and anti-influenza activities of EHE and ephedrine alkaloids-free Ephedra Herb extract (EFE) have been reported recently. In this study, we examined the fractions containing c-Met kinase inhibitory activity from EHE and the fractions with analgesic and anti-influenza activities from EFE, and elucidated the structural characteristics of the active fractions. Significant c-Met kinase activity was observed in 30, 40, and 50% methanol (MeOH) eluate fractions obtained from water extract of EHE using Diaion HP-20 column chromatography. Similarly, 20 and 40% MeOH, and MeOH eluate fractions obtained from water extract of EFE were found to display analgesic and anti-influenza activities. Reversed phase-HPLC analysis of the active fractions commonly showed broad peaks characteristic of high-molecular mass condensed tannin. The active fractions were analyzed using 13C-NMR and decomposition reactions; the deduced structures of active components were high-molecular mass condensed tannins, which were mainly procyanidin B-type and partly procyanidin A-type, including pyrogallol- and catechol-type flavan 3-ols as extension and terminal units. HPLC and gel permeation chromatography (GPC) analyses estimated that the ratio of pyrogallol- and catechol-type was approximately 9 : 2, and the weight-average molecular weight based on the polystyrene standard was >45000. Furthermore, GPC-based analysis was proposed as the quality evaluation method for high-molecular mass condensed tannin in EHE and EFE.

Biodegradation of Ephedrine Isomers by Arthrobacter sp. Strain TS-15: Discovery of Novel Ephedrine and Pseudoephedrine Dehydrogenases.

The Gram-positive soil bacterium Arthrobacter sp. strain TS-15 (DSM 32400), which is capable of metabolizing ephedrine as a sole source of carbon and energy, was isolated. According to 16S rRNA gene sequences and comparative genomic analysis, Arthrobacter sp. TS-15 is closely related to Arthrobacter aurescens Distinct from all known physiological paths, ephedrine metabolism by Arthrobacter sp. TS-15 is initiated by the selective oxidation of the hydroxyl function at the α-C atom, yielding methcathinone as the primary degradation product. Rational genome mining revealed a gene cluster potentially encoding the novel pathway. Two genes from the cluster, which encoded putative short-chain dehydrogenases, were cloned and expressed in Escherichia coli The obtained enzymes were strictly NAD+ dependent and catalyzed the oxidation of ephedrine to methcathinone. Pseudoephedrine dehydrogenase (PseDH) selectively converted (S,S)-(+)-pseudoephedrine and (S,R)-(+)-ephedrine to (S)- and (R)-methcathinone, respectively. Ephedrine dehydrogenase (EDH) exhibited strict selectivity for the oxidation of the diastereomers (R,S)-(-)-ephedrine and (R,R)-(-)-pseudoephedrine.IMPORTANCEArthrobacter sp. TS-15 is a newly isolated bacterium with the unique ability to degrade ephedrine isomers. The initiating steps of the novel metabolic pathway are described. Arthrobacter sp. TS-15 and its isolated ephedrine-oxidizing enzymes have potential for use in decontamination and synthetic applications.

Fullerene C24 as a potential carrier of ephedrine drug - a computational study of interactions and influence of temperature.

Interactions between fullerene C24 and a frequently used supplement for sport activities, ephedrine (EPH), have been studied in detail by a combination of density functional theory (DFT), time dependent DFT (TD-DFT) calculations, the symmetry-adapted perturbation theory (SAPT) approach and molecular dynamics (MD) simulations. Information about interaction energies and non-covalent interactions formed between C24 and EPH have been obtained by DFT calculations. TD-DFT calculations have been used in order to obtain UV/vis spectra and to check whether the presence of the EPH molecule produces significant changes in the spectrum. The SAPT approach has been employed in order to decompose the interaction energy into components and therefore to better understand the physical origins of interaction between C24 and EPH. Last, but not least, MD simulations have been used in order to track the influence of temperature on the interactions between C24 and EPH.

Characterization of the heterogeneous adsorption of three drugs on immobilized bovine serum albumin by adsorption energy distribution.

Characterization of the heterogeneity of a protein surface is important for understanding the binding mechanism of a drug to the protein. A systematic methodology of integrated adsorption energy distribution (AED) calculation with the Scatchard plot was used to characterize the heterogeneous binding of drugs to bovine serum albumin (BSA). Frontal affinity chromatography (FAC) was applied to generate the adsorption data of three drugs on the immobilized BSA column. The concave Scatchard plots cannot distinguish the heterogeneous model between Toth and bi-Langmuir. The calculation of AED profiles allowed the accurate selection of adsorption models to reveal the physical sense of the drugs. Warfarin-BSA complex proved to be the bi-Langmuir model with association constants of 6.6 × 105 M-1 and 2.4 × 103 M-1, respectively. These results were highly consistent with traditional frontal analysis, ultrafiltration, and dynamic dialysis. Applying the AED related method, we achieved multiple and single kinds of binding sites for ephedrine-BSA and L-tryptophan-BSA complexes. Site-specific competitive studies exhibited non-competitive binding of ephedrine with warfarin or L-tryptophan on BSA, underlining that the location of ephedrine binding sites in the subdomain IIIB of BSA. This method permits an accurate heterogeneous characterization of drugs on a protein surface and has great potential in the reliable drug-protein interaction analysis.

Enantioseparation by Capillary Electrophoresis Using Cyclodextrins in an Amino Acid-Based Ionic Liquid Running Buffer.

For enantioseparations of chiral drugs in capillary electrophoresis, chiral ionic liquids (CIL) can be employed instead of traditional running buffer containing a chiral selector. CILs can be applied solely or in addition to the often used cyclodextrin derivatives. Here the separation of phenethylamines, especially of ephedrine, is described using tetrabutylammonium L-argininate (125 mM) in phosphate buffer (75 mM, pH 1.5) in addition to ß-cyclodextrin (30 mM). Using this dual-chiral running buffer system ephedrine, pseudoephedrine and methylephedrine, but not norephedrine, could be easily resolved.