Authentication of herbal medicines from multiple botanical origins with cross-validation mebabolomics,absolute quantification and support vector machine model,a case study of Rhizoma Alismatis

Accurate identification of the botanical origins of Rhizoma Alismatis (RA) is pivotal to its precise clinical usage. We herein present a strategy, by integrating untargeted metabolomics, data cross validation, absolute quantification, and vector machine model, for species discrimination and source recognition of Rhizoma Alismatis for the first time. An ultra-high-performance liquid chromatography/LTQ-Orbitrap mass spectrometry with precursor ions list-including data-dependent acquisition approach was developed for metabolite profiling. Holistic, continuous, and pattern recognition chemometrics could make it feasible to unveil forty-one markers, with “multi-duplicated and traceability samples comparison” cross validation to narrow down to twelve robust markers, some of which were further validated by absolute quantification. A support vector machine model was eventually developed to distinguish these two species and predict origins of commercially available varieties. This was the first report on systematic comparison and discrimination of two original species of RA. This integral strategy, in contrast to conventional approaches, renders more convincing data supporting for the discovery of multi-source chemical makers of traditional Chinese medicines (TCM).     

Authentication of Dendrobium Species Using Near-Infrared and Ultraviolet–Visible Spectroscopy with Chemometrics and Data Fusion

Herbal products produced from multiple plants have special characteristics in the clinical practice of traditional Chinese medicine. These traits provide the opportunity for fraudulent merchants to mix other herbal products similar in appearance into authentic herbal medicine. Shihu is a tonic herbal medicine from the Dendrobium plants with complex botanical origins. In this context, 11 Dendrobium plants including 109 individuals from China were collected for authentication work. Nine species have been described as herbal medicines in the literature while D. hookerianum and D. xichouense are not reported to have medicinal benefits. A key feature of this study was that multiple recognition approaches, based on near-infrared and ultraviolet–visible spectra as well as their combination, were compared to investigate their classification performance. Intuitively, score plots using principal component analysis and hierarchical cluster diagrams were used to evaluate the genetic relationships among these species. Compared with support vector machine discrimination analysis and k-nearest neighbor models, the partial least square discrimination analysis model combined with low-level data fusion provided excellent performance for authentication and was the most robust model with 100% accuracy rates for the training and prediction sets. The results indicated that near-infrared and ultraviolet–visible spectra and their fusion dataset combined with supervised recognition analysis are effective and therefore recommended for the authentication of genuine and sham of herbal Shihu species.     

Site‐Selective Functionalization of Periodic Mesoporous Organosilica (PMO) with Macrocyclic Host for Specific and Reversible Recognition of Heavy Metal

A novel kind of macrocyclic‐host‐functionalized periodic mesoporous organosilica (PMO) with excellent and reversible recognition of Pb^II was developed. The macrocyclic host molecule cis‐dicyclohexano[18]crown‐6, with strong affinity to Pb^II, was carefully modified as a bridged precursor to build the PMO material. To break down the limit of the functionalization degree for PMOs incorporated with large‐sized moieties, a site‐selective post‐functionalization method was proposed to further decorate the external surface of the PMO material. The selective recognition ability of the upgraded PMO material towards Pb^II was remarkably enhanced without destroying the mesoporous ordering. Solid‐state ¹³C and ²⁹Si NMR spectroscopy, X‐ray photoelectron spectroscopy (XPS), XRD, TEM, and nitrogen adsorption–desorption isotherm measurements were utilized for a full characterization of the structure, micromorphology, and surface properties. Reversible binding of Pb^II was realized in the binding–elution cycle experiments. The mechanism of the supramolecular interaction between the macrocyclic host and metal ion was discussed. The synthetic strategy can be considered a general way to optimize the properties of PMOs as binding materials for practical use while preserving the mesostructure.     

Geographical Authentication of Gentiana Rigescens by High-Performance Liquid Chromatography and Infrared Spectroscopy

The chemical characteristics of Gentiana rigescens are extremely variable due to their geographical origins which should be determined to evaluate the quality of this species. Different with other herbs with official tissue for classification materials, the geographical characterization of raw herbal materials on the basis of nonmedicinal parts is rarely discussed. Chromatographic active components were used as references to characterize the chemical profiles of samples from various geographical origins. Based on spectra data matrix of different botanical parts, the chemometric methods of partial least square discrimination analysis and support vector machine discrimination analysis were used to develop mathematical models to classify samples from different geographical origins. In terms of six active components, we found that significant differences were present in the tissue of G. rigescens based on geographical origins. In addition, the region with higher content of gentiopicroside was selected to be the optimal cultivated location. Chemometric results indicated that leaves were the optimal material for geographical characterization of G. rigescens with 100% accuracy by support vector machine while the accuracies of roots, stems, and flowers were 90.91, 96.10, and 97.01%, respectively. Partial least square discrimination analysis showed that accuracy values for roots, stems, leaves, and flowers were 35.65, 67.53, 76.62, and 50.75%, respectively, which also indicated that leaves are the optimal material. In conclusion, northwest Yunnan Province with higher content of gentiopicroside was selected to be the optimal cultivation location. Furthermore, leaves should be used for the most accurate geographical authentication.     

Accurate discrimination of Gastrodia elata from different geographical origins using high‐performance liquid chromatography fingerprint combined with boosting partial least‐squares discriminant analysis

Gastrodia elata from different geographical origins varies in quality and pharmacological activity. This study focused on the classification and identification of Gastrodia elata from six producing areas using high‐performance liquid chromatography fingerprint combined with boosting partial least‐squares discriminant analysis. Before recognition analysis, a principal component analysis was applied to ascertain the discrimination possibility with high‐performance liquid chromatography fingerprints. And then, boosting partial least‐squares discriminant analysis and conventional partial least‐squares discriminant analysis were applied in this study. Experimental results indicated that the adaptive iteratively reweighted penalized least‐squares algorithm could eliminate the baseline drift of high‐performance liquid chromatography chromatograms effectively. And compared with partial least‐squares discriminant analysis, the total recognition rates using high‐performance liquid chromatography fingerprint combined with boosting partial least‐squares discriminant analysis for the calibration sets and prediction sets were improved from 94 to 100% and 86 to 97%, respectively. In conclusion, high‐performance liquid chromatography combined with boosting partial least‐squares discriminant analysis, which has such advantages as effective, specific, accurate, non‐polluting, has an edge for discrimination of traditional Chinese medicine from different geographical origins. And the proposed methodology is a useful tool to classify and identify Gastrodia elata from different geographical origins.     

Non‐targeted volatile profiles for the classification of the botanical origin of Chinese honey by solid‐phase microextraction and gas chromatography–mass spectrometry combined with chemometrics

A potential method for the discrimination and prediction of honey samples of various botanical origins was developed based on the non‐targeted volatile profiles obtained by solid‐phase microextraction with gas chromatography and mass spectrometry combined with chemometrics. The blind analysis of non‐targeted volatile profiles was carried out using solid‐phase microextraction with gas chromatography and mass spectrometry for 87 authentic honey samples from four botanical origins (acacia, linden, vitex, and rape). The number of variables was reduced from 2734 to 70 by using a series of filters. Based on the optimized 70 variables, 79.12% of the variance was explained by the first four principal components. Partial least squares discriminant analysis, naïve Bayes analysis, and back‐propagation artificial neural network were used to develop the classification and prediction models. The 100% accuracy revealed a perfect classification of the botanical origins. In addition, the reliability and practicability of the models were validated by an independent set of additional 20 authentic honey samples. All 20 samples were accurately classified. The confidence measures indicated that the performance of the naïve Bayes model was better than the other two models. Finally, the characteristic volatile compounds of linden honey were tentatively identified. The proposed method is reliable and accurate for the classification of honey of various botanical origins.     

A Chiral Halogen‐Bonding [3]Rotaxane for the Recognition and Sensing of Biologically Relevant Dicarboxylate Anions

The unprecedented application of a chiral halogen‐bonding [3]rotaxane host system for the discrimination of stereo‐ and E/Z geometric isomers of a dicarboxylate anion guest is described. Synthesised by a chloride anion templation strategy, the [3]rotaxane host recognises dicarboxylates through the formation of 1:1 stoichiometric sandwich complexes. This process was analysed by molecular dynamics simulations, which revealed the critical synergy of halogen and hydrogen bonding interactions in anion discrimination. In addition, the centrally located chiral (S)‐BINOL motif of the [3]rotaxane axle component facilitates the complexed dicarboxylate species to be sensed via a fluorescence response.     

A Chiral Recognition System Orchestrated by Self‐Assembly: Molecular Chirality,Self‐Assembly Morphology,and Fluorescence Response

The newly developed oligophenylenevinylene (OPV)‐based fluorescent (FL) chiral chemosensor (OPV‐Me) for the representative enantiomeric guest, 1,2‐cyclohexanedicarboxylic acid (1,2‐CHDA: RR ‐ and SS ‐form) showed the high chiral discrimination ability, resulting in the different aggregation modes of OPV‐Me self‐assembly: RR ‐CHDA directed the fibrous supramolecular aggregate, whereas SS ‐CHDA directed the finite aggregate. The consequent FL intensity toward RR ‐CHDA was up to 30 times larger than that toward SS ‐CHDA. Accordingly, highly enantioselective recognition was achieved. Application to the chirality sensing was also possible: OPV‐Me exhibited a linear relationship between the FL intensity and the enantiomeric excess through the morphological development of stereocomplex aggregates. These results clearly show that the chiral recognition ability is manifested by the amplification cascade of the chirality difference through self‐assembly.     

Halide Anion Mediated Dimerization of a meso‐Unsubstituted N‐Confused Porphyrin

The new N‐confused porphyrin (NCP) derivatives, meso‐unsubstituted β‐alkyl‐3‐oxo N‐confused porphyrin (3‐oxo‐NCP) and related macrocycles, were synthesized from appropriate pyrrolic precursors by a [3+1]‐type condensation reaction. 3‐Oxo‐NCP forms a self‐assembled dimer in dichloromethane that is stabilized by complementary hydrogen‐bonding interactions arising from the peripheral amide‐like moieties. The protonated form of 3‐oxo‐NCP was observed to bind halide anions (F^?, Cl^?) through the outer NH and the inner pyrrolic NH groups, thus affording a dimer in dichloromethane. The structure of the chloride‐bridged dimer in the solid state was determined by X‐ray diffraction analysis.     

Optically active polyacrylamides bearing an oxazoline pendant: Influence of stereoregularity on both chiroptical properties and chiral recognition

Enantiopure acrylamide derivatives, N‐[o‐(4‐methyl‐4,5‐dihydro‐1,3‐oxazol‐2‐yl) phenyl]acrylamide (MeOPAM), N‐[o‐(4‐isopropyl‐4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenyl]acrylamide (PrⁱOPAM), and N‐[o‐(4‐phenyl‐4,5‐dihydro‐1,3‐oxazol‐2‐yl)phenyl]acrylamide (PhOPAM), were synthesized and radically polymerized in the presence of rare earth metal trifluoromethanesulfonates (Ln(OTf)₃, Ln = La, Nd, Sm, and Y) to yield corresponding optically active polymers. Among these Lewis acids, Y(OTf)₃ was found to be most effective for increasing the isotactic specificity during the radical polymerizations when using n‐butanol as solvent. Also, the effect of the Lewis acids was significantly influenced by the ratio of Ln(OTf)₃ to monomer. The relationship of both chiroptical property and the chiral recognition with the stereoregularity was then examined for the resulting polymers having various tacticity by spectroscopic techniques such as NMR, fluorescence, and circular dichroism. The results indicated that the polymers rich in isotacticity exhibited a favorable enantioselective discrimination ability toward 1,1′‐bi‐2‐naphthol as evidenced by ¹H NMR study, where the characteristic hydroxyl proton signal was split into two peaks that ascribed respectively to the levo‐ and dextro‐isomer; furthermore, the splitting magnitude was linearly correlated with the diad isotacticity of the polymers. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2010     

Chiral Recognition of Proline Enantiomers by the Catalytic Oxygen Reduction and Formation of Cu(II)‐Polymer Complex Crystals

A Cu(II)‐Poly(terthiophene carboxylic acid) (pTTC)/Nafion modified glassy carbon electrode has been used for the chiral recognition and discrimination of d‐ and l‐prolines by the catalytic oxygen reduction process and the shape of crystals formed on the electrode surface. The cyclic voltammetry with the modified electrode in the presence of oxygen recognized d‐ and l‐form of prolines by exhibiting a difference in the peak potential and the peak current of the oxygen reduction. The effect of pH and proline concentration on the peak current and the peak potential of oxygen have been studied. The SEM studies on the nature of crystals formed on a proline‐Cu(II)pTTC complex. The oxidation state of the copper species present at the electrode surface was characterized by ESCA.     

Intramolecular Hydrogen Bonding in Benzoxazines: When Structural Design Becomes Functional

The future evolution of benzoxazines and polybenzoxazines as advanced molecular, structural, functional, engineering, and newly commercial materials depends to a great extent on a deeper and more fundamental understanding at the molecular level. In this contribution, the field of benzoxazines is briefly introduced along with a more detailed review of ortho‐amide‐functional benzoxazines, which are the main subjects of this article. Provided in this article are the detailed and solid scientific evidences of intramolecular five‐membered‐ring hydrogen bonding, which is supposed to be responsible for the unique and characteristic features exhibited by this ever‐growing family of ortho‐functionalized benzoxazines. One‐dimensional (1D) ¹H NMR spectroscopy was used to study various concentrations of benzoxazines in various solvents with different hydrogen‐bonding capability and at various temperatures to investigate in detail the nature of hydrogen bonding in both ortho‐amide‐functionalized benzoxazine and its para counterpart. These materials were further investigated by two‐dimensional (2D) ¹H–¹H nuclear Overhauser effect spectroscopy (NOESY) to verify and support the conclusions derived during the 1D ¹H NMR experiments. Only highly purified single‐crystal benzoxazine samples have been used for this study to avoid additional interactions caused by any impurities.     

Classification of the medicinal plants of the genus Atractylodes using high‐performance liquid chromatography with diode array and tandem mass spectrometry detection combined with multivariate statistical analysis

Analytical methods using high‐performance liquid chromatography with diode array and tandem mass spectrometry detection were developed for the discrimination of the rhizomes of four Atractylodes medicinal plants: A. japonica, A. macrocephala, A. chinensis, and A. lancea. A quantitative study was performed, selecting five bioactive components, including atractylenolide I, II, III, eudesma‐4(14),7(11)‐dien‐8‐one and atractylodin, on twenty‐six Atractylodes samples of various origins. Sample extraction was optimized to sonication with 80% methanol for 40 min at room temperature. High‐performance liquid chromatography with diode array detection was established using a C₁₈ column with a water/acetonitrile gradient system at a flow rate of 1.0 mL/min, and the detection wavelength was set at 236 nm. Liquid chromatography with tandem mass spectrometry was applied to certify the reliability of the quantitative results. The developed methods were validated by ensuring specificity, linearity, limit of quantification, accuracy, precision, recovery, robustness, and stability. Results showed that cangzhu contained higher amounts of atractylenolide I and atractylodin than baizhu, and especially atractylodin contents showed the greatest variation between baizhu and cangzhu. Multivariate statistical analysis, such as principal component analysis and hierarchical cluster analysis, were also employed for further classification of the Atractylodes plants. The established method was suitable for quality control of the Atractylodes plants.     

Ultrasensitive electrochemical analysis of two analytes by using an autonomous DNA machine that works in a two-cycle mode

We report a novel autonomous DNA machine for amplified electrochemical analysis of two DNAs. The DNA machine operates in a two‐cycle working mode to amplify DNA recognition events; the working mode is assisted by two different nicking endonucleases (NEases). Two bio‐barcode probes, a ZnS nanoparticle (NP)–DNA probe and a CdS NP–DNA probe, were used to trace two target DNAs. The detection system was based on a sensitive differential pulse anodic stripping voltammetry (DPASV) method for the simultaneous detection of Zn^II and Cd^II tracers, which were obtained by dissolving the two probes. Under the optimised conditions, detection limits as low as 5.6×10^?17 (3σ) and 4.1×10^?17 M (3σ) for the two target DNAs were achieved. It has been proven that the DNA machine system can simultaneously amplify two target DNAs by more than four orders of magnitude within 30 min at room temperature. In addition, in combination with an aptamer recognition strategy, the DNA machine was further used in the aptamer‐based amplification analysis of adenosine triphosphate (ATP) and lysozyme. With the amplification of the DNA machine, detection limits as low as 5.6×10^?9 M (3σ) for ATP and 5.2×10^?13 M (3σ) for lysozyme were simultaneously obtained. The satisfactory determination of ATP and lysozyme in Ramos cells reveals the good selectivity and feasibility of this protocol. The DNA machine is a promising tool for ultrasensitive and simultaneous multianalysis because of its remarkable signal amplification and simple machine‐like operation.     

A microfluidic chip‐based fluorescent biosensor for the sensitive and specific detection of label‐free single‐base mismatch via magnetic beads‐based “sandwich” hybridization strategy

A novel microfluidic chip‐based fluorescent DNA biosensor, which utilized the electrophoretic driving mode and magnetic beads‐based “sandwich” hybridization strategy, was developed for the sensitive and ultra‐specific detection of single‐base mismatch DNA in this study. In comparison with previous biosensors, the proposed DNA biosensor has much more robust resistibility to the complex matrix of real saliva and serum samples, shorter analysis time, and much higher discrimination ability for the detection of single‐base mismatch. These features, as well as its easiness of fabrication, operation convenience, stability, better reusability, and low cost, make it a promising alternative to the SNPs genotyping/detection in clinical diagnosis. By using the biosensor, we have successfully determined oral cancer‐related DNA in saliva and serum samples without sample labeling and any preseparation or dilution with a detection limit of 5.6 × 10^?11 M, a RSD (n = 5) < 5% and a discrimination factor of 3.58–4.54 for one‐base mismatch.     

Fast determination of five components of coumarin,alkaloids and bibenzyls in Dendrobium spp. using pressurized liquid extraction and ultra‐performance liquid chromatography

A fast method for simultaneous determination of five compounds (one coumarin, two alkaloids and two bibenzyls) in Dendrobium spp. using pressurized liquid extraction and ultra‐performance liquid chromatography coupled with photo diode array detection was developed. The separation was performed on an Acquity UPLC BEH C₁₈ column (50 mm×2.1 mm id, 1.7 μm) with gradient elution of phosphate buffer (pH=7.1, 20 mM) and acetonitrile within 6 min. The method was validated for linearity, LOD and LOQ, precision and accuracy. All calibration curves showed good linearity (R²≥0.9999) within test ranges. The overall intra‐ and inter‐day variations (RSDs) of five analytes were less than 2.5%, and the detection recoveries were between 95.6 and 102.3%. The developed method was successfully applied to quantitative analysis of five investigated compounds in different species of Dendrobium. The results showed that there were great variations of their contents, though all these materials were officially used as Chinese herb, Shihu. In addition, the chromatographic fingerprints of Dendrobium spp. were also investigated.     

Chiral Recognition of Tryptophan Enantiomers Based on β‐Cyclodextrin‐platinum Nanoparticles/Graphene Nanohybrids Modified Electrode

The nanohybrids which based on β‐cyclodextrin, platinum nanoparticles and graphene (β‐CD‐PtNPs/GNs) were successfully synthesized and characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT‐IR) and electrochemical impedance spectroscopy (EIS). Then they were used to construct a simple and reliable chiral sensing platform to interact with tryptophan (Trp) enantiomers. Differential pulse voltammetry (DPV) was used to investigate the stereo selectivity of β‐CD‐PtNPs/GNs to Trp enantiomers. After interaction, the obvious difference of peak currents of L‐Trp and D‐Trp was obtained, indicating this strategy could be employed to chiral recognition of Trp enantiomers. Under the optimum conditions, the chiral sensor exhibited a good linear response to Trp enantiomers in a linear range of 5.0×10^?5 to 5.0×10^?3 M with a low limit of detection of 1.7×10^?5 M (S/N=3). This approach provided a new available platform to recognize and determine Trp enantiomers.     

Metabolite identification of the antimalarial naphthoquine using liquid chromatography–tandem high‐resolution mass spectrometry in combination with multiple data‐mining tools

Naphthoquine (NQ) is one of important partner drugs of artemisinin‐based combination therapy (ACT), which is recommended for the treatment of uncomplicated Plasmodium falciparum. NQ shows a high cure rate after a single oral administration. It is absorbed quickly (time to peak concentration 2–4 h) and has a long elimination half‐life (255 h). However, the metabolism of NQ has not been clarified. In this work, the metabolite profiling of NQ was studied in six liver microsomal incubates (human, cynomolgus monkey, beagle dog, mini pig, rat and CD1 mouse), seven recombinant CYP enzymes (1A2, 2B6, 2C8, 2C9, 2C19, 2D6 and 3A4) and rat (plasma, urine, bile and feces) using liquid chromatography tandem high‐resolution LTQ‐Orbitrap mass spectrometry (HRMSⁿ) in conjunction with online hydrogen/deuterium exchange. The biological samples were pretreated by protein precipitation and solid‐phase extraction. For data processing, multiple data‐mining tools were applied in tandem, i.e. background subtraction and followed by mass defect filter. NQ metabolites were characterized by accurate MS/MS fragmentation characteristics, the hydrogen/deuterium exchange data and cLogP simulation. As a result, five phase I metabolites (M1–M5) of NQ were characterized for the first time. Two metabolic pathways were involved: hydroxylation and N‐oxidation. This study demonstrates that LC‐HRMSⁿ in combination with multiple data‐mining tools in tandem can be a valuable analytical strategy for rapid metabolite profiling of drugs.     

Dereplication‐guided isolation of a new indole alkaloid triglycoside from the hooks of Uncaria rhynchophylla by LC with ion trap time‐of‐flight MS

Uncaria rhynchophylla (Gou‐Teng) as the monarch herb of many formulae (Fufang), e.g. “Tian‐Ma‐Gou‐Teng‐Yin,” “Ling‐Jiao‐Gou‐Teng‐Yin,” and “Yi‐Gan‐San”, is a famous traditional Chinese medicine documented in the Chinese pharmacopoeia for mental and cardiovascular diseases. In the traditional Chinese medicine system, only the hook‐bearing stems are used as the crude materials for Gou‐Teng, and the hooks are always considered more effective than the stems. Focusing on the mono‐herb and its active constituents from combinatorial formulae is the core idea of reductionism of traditional Chinese medicine theory. Detailed liquid chromatography with mass spectrometry analysis on the hooks of U. rhynchophylla was performed to profile the chemical constituents based on tandem mass spectrometry fragmentation and UV absorption. Under the guidance of liquid chromatography with ion trap/time‐of‐flight mass spectrometry, one new indole alkaloid triglycoside ( 1 ), together with five known compounds 2 – 6 as the main constituents, were isolated from the hooks of U. rhynchophylla by various column chromatography methods. Compound 1 showed moderate activity on MT₁ and MT₂ melatonin receptors with agonistic rates of 79.6 and 46.3% at the concentration of 1 mM. This dereplication strategy can be equally applicable to rapidly disclose the active constituents of other Chinese herbs through targeted purification.     

Structural Elucidation of the Mechanism of Molecular Recognition in Chiral Crystalline Sponges

To gain insight into chiral recognition in porous materials we have prepared a family of fourth generation chiral metal–organic frameworks (MOFs) that have rigid frameworks and adaptable (flexible) pores. The previously reported parent material, [Co₂(S‐mandelate)₂(4,4′‐bipyridine)₃](NO₃)₂, CMOM‐ 1S , is a modular MOF; five new variants in which counterions (BF₄^?, CMOM‐ 2S ) or mandelate ligands are substituted (2‐Cl, CMOM‐ 11R ; 3‐Cl, CMOM‐ 21R ; 4‐Cl, CMOM‐ 31R ; 4‐CH₃, CMOM‐ 41R ) and the existing CF₃SO₃^? variant CMOM‐ 3S are studied herein. Fine‐tuning of pore size, shape, and chemistry afforded a series of distinct host–guest binding sites with variable chiral separation properties with respect to three structural isomers of phenylpropanol. Structural analysis of the resulting crystalline sponge phases revealed that host–guest interactions, guest–guest interactions, and pore adaptability collectively determine chiral discrimination.