Tropane alkaloid analysis by chromatographic and electrophoretic techniques: An update

Tropane alkaloids like atropine are antidotes applied against organophosphorus intoxications. Atropine is toxic itself and should be closely monitored during treatment. Hence, simple, fast, and sensitive determination methods for tropane alkaloids in serum are desirable. Mostly adopted methods of analysis are gas chromatography (GC); high performance liquid chromatography (HPLC), and capillary electrophoresis (CE). Various liquid and solid capillary fillings used in micellar electrokinetic chromatography, microemulsion electrokinetic chromatography, capillary electrochromatography, and enantioseparation provide high versatility to CE applications. In HPLC, specialised columns enhance separation efficacy. Ultraviolet light detection is common practise, but recently sensitivity and analyte identification were enhanced by coupling GC, HPLC, and CE to mass spectrometry. Apart from medical treatment, tropane alkaloids, cocaine in particular, are abused with various intentions. Forensic analysis of tropane alkaloids and their metabolites comprises the additional difficulty of unequivocal drug identification. Because of severe legal consequences, sophisticated analytical methods were developed and may provide additional techniques for therapeutic drug monitoring. Examples from forensic cocaine analysis and from doping analysis are included in this review.     

Separation methods for antibacterial and antirheumatism agents in plant medicines

Traditional oriental medicines (TOM), with a very long history and many remarkable features, are very popular in Asian countries, especially in China, Japan and Korea. With the development of advanced analytical techniques, the modernization of traditional medicine has become a hot area in recent years and some herbal medicines have been increasingly accepted in western countries. Separation and determination of active components in various herbal medicines are considered to be critical for the modernization process. Antibacterial and antirheumatism agents are widely distributed in many medical plants and commonly used in clinical treatment. Therefore, the development of effective separation methods for the quality control of herbal medicines is absolutely important. In this article, the separation methods for the analysis of antibacterial and antirheumatism compounds in TOM were reviewed, including thin layer chromatography (TLC), gas chromatography (GC), supercritical fluid chromatography (SFC), high-performance liquid chromatography (HPLC), capillary electrophoresis (CE) and related hyphenation techniques. Sample preparation procedures and further development of these methods were also discussed.     

Separation methods for pharmacologically active xanthones

Xanthones, as a kind of polyphenolic natural products with many strong bioactivities, are attractive for separation scientists due to the similarity and diversity of their structures resulting in difficult separation by chromatographic methods. High performance liquid chromatography (HPLC) and thin layer chromatography (TLC) are traditional methods to separate xanthones. Recently, capillary electrophoresis (CE), as a micro-column technique driven by electroosmotic flow (EOF), with its high efficiency and high-speed separation, has been employed to separate xanthones and determine their physicochemical properties such as binding constants with cyclodextrin (CD) and ionization constants. Since xanthones have been used in clinic treatment, the development of chromatographic and CE methods for the separation and determination of xanthones plays an essential role in the quality control of some herbal medicines containing xanthones. This article reviewed the separation of xanthones by HPLC, TLC and CE, citing 72 literatures. This review focused on the CE separation for xanthones due to its unique advantages compared to chromatographic methods. The comparison of separation selectivity of different CE modes including capillary zone electrophoresis (CZE), micellar electrokinetic chromatography (MEKC), microemulsion electrokinetic capillary chromatography (MEEKC) and capillary electrochromatography (CEC) was discussed. Compared with traditional chromatographic methods such as HPLC and TLC, CE has higher separation efficiency, faster separation, lower cost and more flexible modes. However, because of low sensitivity of UV detector and low contents of xanthones in herbal medicines, CE methods have seldom been applied to the analysis of real samples although CE showed great potential for xanthone separation. The determination of xanthones in herbal medicines has been often achieved by HPLC. Hence, how to enhance CE detection sensitivity for real sample analysis, e.g. by on-line preconcentration and CE-MS, would be a key to achieve the quantitation of xanthones.     

手性药物分析方法研究进展

综述了近10 年来手性药物分离检测方法的发展,包括高效液相色谱法、气相色谱法、毛细管电泳法,以及超临界流体色谱法等,旨在为该领域的进一步发展提供参考。     

Analytical methods to determine phytoestrogenic compounds

The analytical methods for the determination of phytoestrogenic compounds in edible plants, plant products and biological matrices are reviewed. The detection, qualitative and quantitative methods based on different chromatographic separations of gas chromatography (GC), high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) coupled with various detections by ultraviolet absorption (UV), electrochemical detection (ED), fluorescence detection, mass spectrometry (MS) and nuclear magnetic resonance spectroscopy (NMR), as well as non-chromatographic immunoassay are each extensively examined and compared. An overview on phytoestrogen chemistry, bioactivities and health effects, plant precursors, metabolism and sample preparation is also presented.     

Enantiomeric separation of organophosphorus pesticides by high-performance liquid chromatography,gas chromatography and capillary electrophoresis and their applications to environmental fate and toxicity assays

In recent years, the continuous evolution of the field of stereochemistry has produced a heightened awareness of the applications of pure enantiomers of agrochemicals. This review describes reports of the enantiomeric separation of commercial organophosphorus pesticides (OPs) and the applications of these methods to research on the enantioselectivity of the toxicity and environmental fate of these compounds. Chiral OPs can be analysed by high-performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrophoresis (CE). These different separation techniques for OP enantiomers are briefly discussed, and their applications are presented.     

Determination of enantiomerization barriers by dynamic and stopped-flow chromatographic methods

In recent years, dynamic chromatography and stopped-flow chromatographic techniques have become versatile tools for the determination of enantiomerization and isomerization barriers. Increasing demands for the stereochemical safety of chiral drugs contributed to the rapid development of new techniques. New computer-aided evaluation systems allow the on-line determination of interconversion barriers from the experimental chromatograms. Both dynamic chromatography and stopped-flow chromatography have been applied to the entire range of chromatographic methods (GC, SFC, HPLC, CE).     

Affinity chromatography as a method for sample preparation in gas chromatography/mass spectrometry.

Analytical chemistry aims at developing analytical methods and techniques for unequivocal identification and accurate quantitation of natural and synthetic compounds in a given matrix. Analytical methods based on the mass spectrometry (MS) technology, e.g., GC/MS and LC/MS and their variants, GC/tandem MS and LC/tandem MS, are best suited both for qualitative and quantitative analyses. GC/MS methods not only serve as reference methods, e.g., in clinical chemistry, but they are now widely and routinely used for quantitative determination of numerous analytes. However, despite inherent accuracy, analytical methods based on GC/MS commonly consist of several analytical steps, including extraction and derivatization of the analyte. In general, unequivocal identification and accurate quantification of an analyte in very low concentrations in complex matrices require further chromatographic techniques, such as high-performance liquid chromatography (HPLC) and thin-layer chromatography (TLC) for sample purification. In recent years, affinity chromatography (e.g., boronate and immunoaffinity chromatography) has been developed to a superior technique for sample preparation of numerous classes of compounds in GC/MS. In this article, the application and importance of affinity chromatography as a method for sample preparation in modern quantitative GC/MS method is described and discussed, using as examples various natural and synthetic compounds, such as arachidonic acid derivates, nitrosylated and nitrated proteins, steroids, drugs, and toxins.     

Analytical characterisation of crude extracts from an African Ancistrocladus species using high-performance liquid chromatography and capillary electrophoresis coupled to ion trap mass spectrometry

The analysis by HPLC, CE and CE-MS/MS of root bark extracts of a, so far undescribed, Central-African Ancistrocladus species (family Ancistrocladaceae) is described. Owing to the complexity of the extract, the application of reversed-phase HPLC resulted in a partially incomplete separation of the naphthylisoquinoline alkaloids, whilst CE using a non-aqueous buffer proved to be a very valuable complementary method for a first characterisation of the crude extract. By performing additional CE-MS/MS experiments, in combination with parallel isolation studies and structural elucidation using conventional methods, six alkaloidal substances present in the plant could be identified.     

γ-羟基丁酸的分析研究进展

作为高效能的中枢神经抑制剂,γ-羟基丁酸（GHB）其相关物质γ-丁内酯（GBL）和1,4-丁二醇（1,4-BD）的滥用现象越来越严重,由于它们强烈的镇静及健忘效果常常被用作迷奸药,带来了严重的社会问题。由于在体内天然存在GHB,而且其在摄入后消除迅速,这增加了体内GHB及其相关物质的检测和分析评价难度。本文在对GHB及其相关物质的理化性质阐述基础上,综述了它们的提取技术及分析方法研究进展,主要阐述了液．液提取、固相萃取等提取方法与气相色谱法、气相色谱-质谱联用法、高效液相色谱法、液相色谱．质谱联用法、毛细管电泳法等在分析不同检材中GHB及其相关物质的应用,这也为国内法庭案件中GHB及其相关物质的滥用及相关案件提供了可供参考的法庭科学检测、分析研究方法。     

Analysis of sugars in traditional Chinese drugs

This review is presented of chromatography and electromigration methods currently in use to determine sugars in traditional Chinese drugs: gas chromatography (GC), high-performance liquid chromatography (HPLC), ion-exchange chromatography, gel column chromatography (GCC), paper chromatography (PC) and thin layer chromatography (TLC), capillary electrophoresis (CE) and gel electrophoresis (GEP). The detection methods combined with above separation methods including ultra-violet, mass spectra, fluorescent light, refractive index (RI), electrochemical detection are also described. For the complicacy of structural analysis of polysaccharides in traditional Chinese drugs, the hyphenation procedures concerned with this analysis are introduced in this article too.     

Current methodologies for the analysis of aminoglycosides

The aminoglycosides are a large and diverse class of antibiotics that characteristically contain two or more aminosugars linked by glycosidic bonds to an aminocyclitol component. Structures are presented for over 30 of the most important members of this family of compounds. The use of aminoglycosides in clinical and veterinary medicine and in agriculture is described. Qualitative methods for aminoglycoside analysis include X-ray crystallography, nuclear magnetic resonance (NMR) spectroscopy and mass spectrometry (MS). The major part of this article comprises a comprehensive review of quantitative methods for the determination of aminoglycosides. These are microbiological assay, radiochemical assay, radioimmunoassay, enzyme immunoassay, fluoroimmunoassay and other immunoassays, spectrophotometric and other non-separative methods, gas chromatography (GC), thin-layer chromatography (TLC), high-performance liquid chromatography (HPLC), and capillary electrophoresis (CE). Simple spectrophotometric methods may be adequate for the assay of bulk pharmaceuticals and their formulations. Microbiological assays make useful semi-quantitative screening tests for the analysis of veterinary drug residues in food, but rapid enzyme immunoassays are more suitable for accurate measurements of aminoglycosides in complex matrices. Automated immunoassays are the most appropriate methods for serum aminoglycoside determinations during therapeutic drug monitoring. HPLC techniques provide the specificity and sensitivity required for pharmacokinetic and other research studies, while HPLC–MS is employed for the confirmation of veterinary drug residues. The potential for further development of chromatographic and CE methods for the analysis of biological samples is outlined.     

Microbial and bioconversion production of D-xylitol and its detection and application

D-Xylitol is found in low content as a natural constituent of many fruits and vegetables. It is a five-carbon sugar polyol and has been used as a food additive and sweetening agent to replace sucrose, especially for non-insulin dependent diabetics. It has multiple beneficial health effects, such as the prevention of dental caries, and acute otitis media. In industry, it has been produced by chemical reduction of D-xylose mainly from photosynthetic biomass hydrolysates. As an alternative method of chemical reduction, biosynthesis of D-xylitol has been focused on the metabolically engineered Saccharomyces cerevisiae and Candida strains. In order to detect D-xylitol in the production processes, several detection methods have been established, such as gas chromatography (GC)-based methods, high performance liquid chromatography (HPLC)-based methods, LC-MS methods, and capillary electrophoresis methods (CE). The advantages and disadvantages of these methods are compared in this review.     

Development of comparative methods using gas chromatography-mass spectrometry and capillary electrophoresis for determination of endocrine disrupting chemicals in bio-solids

Two analytical separation techniques are being investigated for their potential in determining a wide range of endocrine disrupting chemicals (EDCs) in the environment. Capillary electrophoresis (CE) in the micellar mode in conjunction with a cyclodextrin (CD) modifier is shown to have potential for determination of alkylphenol breakdown products. Gas chromatography with mass spectrometric (GC-MS) detection is being utilised for validation of the CE method development and in addition as a separation technique to optimise preconcentration using solid-phase extraction. GC has demonstrated potential for the separation of 26 priority chemicals suspected as being endocrine disrupting compounds. The challenge of the method development process lies in the fact that these compounds are of differing polarities, size and charge and therefore are difficult to separate in a single run. Capillary electrophoresis in the CD-MEKC (micellar electrokinetic chromatography) mode is showing potential in this regard. Limits of determination are in the low mg/l range for CE and GC, however, using preconcentration it is possible to improve detection sensitivity with >80% recovery for some analytes and up to 100% recovery for most target species.     

Advances of infrared spectroscopy in natural product research

Natural product's properties are related to certain classes of compounds such as alkaloids, flavonoids, essential oils and others. Traditionally, separation techniques including thin layer chromatography (TLC), liquid chromatography (LC), gas chromatography (GC) and capillary electrophoresis (CE) even hyphenated to mass spectrometry (MS) were used for the elucidation, qualitative and quantitative analysis of individual compounds.In food industry, spectroscopic investigations using infrared radiation have been used to monitor and evaluate the composition and quality already since the early sixties. During the last four decades near-infrared spectroscopy (NIR; 800–2500 nm; 12,500–4000 cm⁻¹) has become one of the most attractive and used methods for analysis for the following reasons: it represents a non-invasive analytical tool allowing a fast and simultaneous qualitative and quantitative characterization of natural products and their constituents. Additionally, the development of custom-made hand-held instruments enables in-field measurement for determining the optimum harvest time.Attenuated total reflection (ATR) and Fourier transform infrared (FTIR) spectroscopic imaging are suitable not only for the differentiation of different plant species, but also to distinct various ingredients within a plant. FTIR spectroscopic microscopy enables molecular imaging of complex botanical samples and therefore the detection and characterization of the molecular components of biological tissue.In the present contribution, the principle, technique and methodology of the different infrared spectroscopic methods are described followed by a discussion of quantitative and qualitative application possibilities in the field of natural product analysis.     

Chromatographic and capillary electrophoretic methods for the analysis of nicotinic acid and its metabolites

Methods for the assay of nicotinic acid (NiAc) and its metabolites in biological fluids using high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE) are reviewed. Most of the references cited in this review concern HPLC methods. A few CE methods that have been recently reported are also included. As these compounds are relatively polar and have a wide range of physico-chemical properties, the sample pre-treatment or clean-up process prior to analysis is included. Most HPLC methods using an isocratic elution system allow determination of a single or few metabolites, but gradient HPLC methods enable simultaneous determination of five to eight compounds. Simultaneous determination of NiAc including many metabolites in a single run can be achieved by CE. We also discuss the pharmacokinetics of NiAc and some of its metabolites.     

Chirality of organophosphorus pesticides: Analysis and toxicity

Although the importance of chirality in organophosphorus compounds (OPs) is well recognized in relation to their biological effects, as with most chiral pesticides, OPs are generally marketed, used and released to the environment as racemates (i.e., equimolar mixtures of enantiomers). In addition, research on enantioselective environmental fate and effects of chiral OPs is still limited, particularly in the evaluation of enantioselectivity in their environmental degradation. A large number of OPs are chiral compounds, and yet enantioselectivity in their environmental fate and effects is rarely addressed. This paper highlights the current state of knowledge on the environmental occurrence and behavior of chiral OP pesticides. Developments in enantioselective analytical techniques, specifically gas chromatography (GC), high-performance liquid chromatography (HPLC) and capillary electrophoresis (CE), as applied in the evaluation of enantiomer-specific fate and effects of chiral OPs, are also discussed.     

Analysis of Catharanthus roseus alkaloids by HPLC

Catharanthus roseus is a medicinal plant from which secondary metabolites used in chemotherapy to treat diverse cancers are extracted. The well known high value metabolites vincristine and vinblastine are just 2 of 130 alkaloids that can be found in C. roseus. However, only few (∼11) of this high number of chemical entities are frequently analyzed and even fewer (∼8) are available commercially. For more than 30 years, different analytical techniques have been developed to isolate and identify C. roseus metabolites, and then allowing revealing the therapeutic potential of C. roseus metabolites. Among few approaches, high performance liquid chromatography (HPLC) technique is still widely used for the separation and analysis of secondary metabolites such as those from C. roseus. This article thus reviews the most recent developments in HPLC analysis of alkaloids from C. roseus. Diverse considerations that are crucial to the efficiency of secondary metabolites separation and identification steps, such as biomass manipulation, extraction phase and protocols, HPLC separation and analysis protocols are reviewed in details. Examples of spectra obtained using the most common detectors are also shown and suggestions are made on how to proceed in developing efficient separation and identification methods at the analytical and semi-preparative scales.     

Separation methods used in the determination of choline and acetylcholine

Cholinergic neurotransmission has been the subject of intensive investigations in recent years due to increasing recognition of the importance of its roles in physiology, pathology and pharmacology. The fact that the disposition of a neurotransmitter may reflect its functional status has made the measurement of acetylcholine and/or its precursors and metabolites in biological fluids an integral part of cholinergic research. With evolving complexity in experimental approaches and designs, and correspondingly increasing demand on sensitivity, specificity and accuracy matching advancements in sophistication in analytical methods have been made. The present review attempts to survey the array of analytical techniques that have been adopted for the measurement of acetylcholine or its main precursor/metabolite choline ranging from simple bioassays, radioenzymatic assays, gas chromatography (GC) with flame ionization detection, GC with mass spectrometry (GC–MS) detection, high-performance liquid chromatography (HPLC) with electrochemical detection (ED), HPLC with MS (HPLC–MS) to the sophisticated combination of micro-immobilized enzymatic reactor, microbore HPLC and modified electrode technology for the detection of ultra-low levels with particular emphasis on the state of the art techniques.     

Binding of an oxindole alkaloid from Uncaria tomentosa to amyloid protein (Abeta1-40)

The primary aim of this work was to determine the interactions of an oxindole alkaloid (mitraphylline) isolated from Uncaria tomentosa with beta-amyloid 1-40 (Abeta1-40 protein) applying the capillary electrophoresis (CE) method. Specifically the Hummel-Dreyer method and Scatchard analysis were performed to study the binding of oxindole alkaloids with Abeta1-40 protein. Prior to these studies extraction of the alkaloid of interest was carried out. Identification of the isolated alkaloid was performed by the use of thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC) combined with electrospray ionization mass spectrometry (ESI-MS). The proposed approach was proved to be an efficient and accurate method for specific compound isolation and identification purposes. Moreover, analytical information from the CE approach can be considered as the valuable tool for binding constant determination. The binding constant of mitraphylline with Abeta1-40 protein determined by the Hummel-Dreyer method and Scatchard analysis equals K = 9.95 x 10(5) M(-1). The results obtained showed the significant binding of the tested compound with Abeta1-40 protein. These results are discussed and interpreted in the view of developing a strategy for identification of novel compounds of great importance in Alzheimer disease therapy.