Spectrum–effect relationship study between HPLC fingerprints and antioxidant of honeysuckle extract

Honeysuckle (Lonicera japonica flos) is a well‐known agent of edible and medicinal value in China and its antioxidative activity makes a major contribution to its dual use. However, the compounds responsible for its antioxidative activity are still unknown. In this study, 10 batches of honeysuckle were collected from different origins in China. The fingerprints were established by HPLC technique to investigate the compounds and a 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical scavenging activity assay was carried out to evaluate their antioxidant activity. partial least squares regression analysis was applied to set up the regression equation between DPPH radical scavenging activity and average peak area of common peaks of fingerprints. The results showed that peaks 10 (isochlorogenic acid B), 12 (isochlorogenic acid C), 11 (isochlorogenic acid A) and 9 (cynaroside) in the fingerprints were closely related to the antioxidant activity of 50% methanol extracts of honeysuckle. This study successfully established the spectrum–effect relationship between HPLC fingerprints and DPPH radical scavenging activity and provided a general model for exploring active components with a combination of chromatography and efficacy.     

Curcumaromins A,B, and C,Three Novel Curcuminoids from Curcuma aromatica

Three novel curcuminoids, curcumaromins A–C ( 1 – 3 , resp.), along with a known compound, longiferone B ( 4 ) were isolated from Curcuma aromatica Salisb . The structures of the new compounds were elucidated as (1E,4Z,6E)‐5‐hydroxy‐7‐{4‐hydroxy‐3‐[(1R*,6R*)‐3‐methyl‐6‐(propan‐2‐yl)cyclohex‐2‐en‐1‐yl)phenyl}‐1‐(4‐hydroxyphenyl)hepta‐1,4,6‐trien‐3‐one ( 1 ), 2,3‐dihydro‐2‐(4‐hydroxyphenyl)‐6‐[(E)‐2‐(4‐hydroxyphenyl)ethenyl]‐5‐[(1R*,6R*)‐3‐methyl‐6‐(propan‐2‐yl)cyclohex‐2‐en‐1‐yl]‐4H‐pyran‐4‐one ( 2 ), and (1E,6E)‐1,7‐bis(4‐hydroxyphenyl)‐4‐[(1R*,6R*)‐3‐methyl‐6‐(propan‐2‐yl)cyclohex‐2‐en‐1‐yl]hepta‐1,6‐diene‐3,5‐dione ( 3 ) on the basis of spectroscopic analysis. Curcumaromins A–C ( 1 – 3 ) represented the first examples of menthane monoterpene‐coupled curcuminoids. The known compound, longiferone B ( 4 ), was the first daucane sesquiterpene isolated from the genus Curcuma.     

Screening of analgesic and anti‐inflammatory active component in Fructus Alpiniae zerumbet based on spectrum–effect relationship and GC–MS

Fructus Alpiniae zerumbet is widely used in Guizhou province as a miao folk herb with anti‐inflammatory, analgesic, protection against cardiovascular diseases, antihypertension and antioxidant activities. To further investigate the chemical material basis, the spectrum–effect relationship was established using gray relational analysis between the chromatographic fingerprint and its bioactivities. Herein, the fingerprints of essential oils from Fructus Alpiniae zerumbet (EOFAZ) from various sources were determined by gas chromatography mass spectrometry, and the analgesic and anti‐inflammatory bioactivities were investigated using the mouse model of acetic acid‐induced writhing test and dimethylbenzene‐induced mouse ear edema test. Finally, 17 common peaks were identified from nine batches of A. zerumbet, by comparison with the standard mass spectra in Nist2005, Wiley275 library. Meanwhile, the results showed significant analgesic and anti‐inflammatory effects in all of the different sources of EOFAZ. In particularly, peak 1 (α‐pipene), peak 3 (β‐pinene), peak 9 (camphor) and peak 16 (α‐cadinol) might be the main bioactive ingredients for analgesic and anti‐inflammatory activities. The model of the spectrum–effect relationships of EOFAZ was successfully discovered, which provided a novel platform for finding the bioactive components, a theoretical foundation for its further study and helping to establish quality control of Fructus A. zerumbet.     

Material Basis Elucidation and Quantification of Dandelion through Spectrum–Effect Relationship Study between UHPLC Fingerprint and Antioxidant Activity via Multivariate Statistical Analysis

The excessive expression of reactive oxygen species is closely connected to many diseases. Considerable studies have demonstrated dandelion as well as its ingredients exhibited antioxidant activity. However, specific material basis reflecting the antioxidant activity has not been comprehensively investigated. In this study, a spectrum–effect relationship study on dandelion between fingerprinting and antioxidant activity was analyzed in detail, while a UHPLC quantification method developed and completely validated for simultaneous determination of active ingredients in dandelion. With the establishment of dandelion fingerprints of different regions, 24 common peaks were characterized. The classic FRAP method and ABTS methods were then used to detect their antioxidant activity. Partial least squares regression analysis, bivariate correlation analysis and grey correlation method were used to accomplish the spectrum–effect relationship. Eventually, the ingredients with antioxidant activity which could be considered as candidate quality markers of dandelion were discovered through spectrum–effect relationship analysis. The six compounds including caftaric acid, chlorogenic acid, caffeic acid, chicoric acid, isochlorogenic acid A, and isochlorogenic acid C were quantitatively determined. The developed UHPLC assay method was accurate, precise, and reliable. The study has elucidated the antioxidant material basis of dandelion and provided a scientific basis for the quality control of dandelion.     

Screening of Potential Thrombin and Factor Xa Inhibitors from the Danshen–Chuanxiong Herbal Pair through a Spectrum–Effect Relationship Analysis

In this study; a spectrum–effect relationship analysis combined with a high-performance liquid chromatography–mass spectrometry (LC–MS) analysis was established to screen and identify active components that can inhibit thrombin and factor Xa (THR and FXa) in Salviae Miltiorrhizae Radix et Rhizoma–Chuanxiong Rhizoma (Danshen–Chuanxiong) herbal pair. Ten potential active compounds were predicted through a canonical correlation analysis (CCA), and eight of them were tentatively identified through an LC–MS analysis. Furthermore; the enzyme inhibitory activity of six available compounds; chlorogenic acid; Z-ligustilide; caffeic acid; ferulic acid; tanshinone I and tanshinone IIA; were tested to verify the feasibility of the method. Among them; chlorogenic acid was validated to possess a good THR inhibitory activity with IC₅₀ of 185.08 µM. Tanshinone I and tanshinone IIA are potential FXa inhibitors with IC₅₀ of 112.59 µM and 138.19 µM; respectively. Meanwhile; molecular docking results show that tanshinone I and tanshinone IIA; which both have binding energies of less than −7.0 kcal·mol⁻¹; can interact with FXa by forming H-bonds with residues of SER214; GLY219 and GLN192. In short; the THR and FXa inhibitors in the Danshen–Chuanxiong herbal pair have been successfully characterized through a spectrum–effect relationship analysis and an LC–MS analysis.     

郁金中姜黄素类化合物的毛细管区带电泳法测定

本文在提取中药郁金中姜黄素类化合物的基础上,利用毛细管区带电泳法对郁金中所含黄素类化合物进行了分离研究,确定了最佳分离条件:9mmol/L单-6-O-苯基氨甲酰基-β-CD(mono-6-O-phenylcarbamoyl-β-CD),40mmol/L硼砂缓冲液,分离电压为15kV,毛细管柱温度为22℃,紫外检测波长为214nm,pH值为9.0。双去甲氧基姜黄素、去甲氧基姜黄素和姜黄素在此条件下10 m in内能够达到基线分离,方法快速、简便、且消耗试剂少,不污染环境。     

Simultaneous screening of four epidermal growth factor receptor antagonists from Curcuma longa via cell membrane chromatography online coupled with HPLC–MS

The epidermal growth factor receptors (EGFRs) are significant targets for screening active compounds. In this work, an analytical method was established for rapid screening, separation, and identification of EGFRs antagonists from Curcuma longa. Human embryonic kidney 293 cells with a steadily high expression of EGFRs were used to prepare the cell membrane stationary phase in a cell membrane chromatography model for screening active compounds. Separation and identification of the retention chromatographic peaks was achieved by HPLC–MS. The active sites, docking extents and inhibitory effects of the active compounds were also demonstrated. The screening result found that ar‐turmerone, curcumin, demethoxycurcumin, and bisdemethoxycurcumin from Curcuma longa could be active components in a similar manner to gefitinib. Biological trials showed that all of four compounds can inhibit EGFRs protein secretion and cell growth in a dose‐dependent manner, and downregulate the phosphorylation of EGFRs. This analytical method demonstrated fast and effective characteristics for screening, separation and identification of the active compounds from a complex system and should be useful for drug discovery with natural medicinal herbs.     

Structure–activity relationship of N‐heterocyclic carbene–Pd(II)–imidazole complexes in Suzuki–Miyaura coupling between 4‐methoxyphenyl chloride and phenylboronic acid

A series of N‐heterocyclic carbene–PdCl₂–imidazole [NHC–Pd(II)–Im] complexes were synthesized and the structure of most of them was unambiguously determined by X‐ray single‐crystal diffraction. The structure–activity relationship of these complexes was investigated for the Suzuki–Miyaura coupling between 4‐methoxyphenyl chloride and phenylboronic acid, and the effect of the NHCs and Im moieties were fully discussed. The sterically hindered IPr‐based complex showed the highest catalytic activity. Copyright © 2013 John Wiley & Sons, Ltd.     

Synergistic Effect between Metal–Nitrogen–Carbon Sheets and NiO Nanoparticles for Enhanced Electrochemical Water‐Oxidation Performance

Identifying effective means to improve the electrochemical performance of oxygen‐evolution catalysts represents a significant challenge in several emerging renewable energy technologies. Herein, we consider metal–nitrogen–carbon sheets which are commonly used for catalyzing the oxygen‐reduction reaction (ORR), as the support to load NiO nanoparticles for the oxygen‐evolution reaction (OER). FeNC sheets, as the advanced supports, synergistically promote the NiO nanocatalysts to exhibit superior performance in alkaline media, which is confirmed by experimental observations and density functional theory (DFT) calculations. Our findings show the advantages in considering the support effect for designing highly active, durable, and cost‐effective OER electrocatalysts.     

Rational Design of Push–Pull Fluorene Dyes: Synthesis and Structure–Photophysics Relationship

Our work surveyed experimental and theoretical investigations to construct highly emissive D –π–A (D=donor, A=acceptor) fluorenes. The synthetic routes were optimised to be concise and gram‐scalable. The molecular design was first rationalised by varying the electron‐withdrawing group from an aldehyde, ketotriazole or succinyl to methylenemalonitrile or benzothiadiazole. The electron‐donating group was next varied from aliphatic or aromatic amines to saturated cyclic amines ranging from aziridine to azepane. Spectroscopic studies correlated with TD‐DFT calculations provided the optimised structures. The selected push–pull dyes exhibited visible absorptions, significant brightness, important solvatofluorochromism, mega‐Stokes shifts (>250 nm) and dramatic shifts in emission to the near‐infrared. The current library includes the comprehensive characterization of 16 prospective dyes for fluorescence applications. Among them, several fluorene derivatives bearing different conjugation anchors were tested for coupling and demonstrated to preserve the photophysical responses once further bound.     

Correlation of gas–liquid partition coefficients using a generalized linear solvation energy relationship

In a number of previous communications, we reported on the utility of the solvatochromic linear solvation energy relationship (LSER) method for the correlation of a number of solute and solvent-dependent properties. In those studies, it was our practice to examine the effect of a variety of solvents on a given solute or a number of solutes in a given solvent. Here we report on a novel generalized LSER in which the solute and solvent were both simultaneously varied so as to assess the validity of the entire LSER concept and define its limits. The Hildebrand solubility parameter, δ_H, the Kamlet–Taft solvatochromic parameters, π*, α, β and the solute molar volume, V₂, were used as the explanatory variables. The gas–liquid partition coefficient (K) was the property of interest. We have found that the correlation using the generalized linear solvation energy relationship is statistically as good as the previous LSER correlations despite the use of a far smaller number of freely adjustable parameters. Furthermore, the new approach is able to give reasonable predictions of K values of systems not included in the data set upon which the regression is based.     

Liquid–gas–liquid technique for microextraction and preconcentration of short chain fatty acids from aqueous samples

In this study, an organic solvent‐free microextraction technique termed liquid–gas–liquid microextraction (LGLME) was applied for cleanup and preconcentration of volatile short chain fatty acids in beverages and dairy products. Various parameters affecting the extraction efficiency such as extraction time, stirring speed, sodium chloride content, concentration and volume of donor and acceptor phases, and extraction temperature were studied. Repeatability (RSD, 4.2–8.5%), correlation coefficients (0.998–0.999), LODs (10–20 μg/L) and enrichment factors (152–249) were also investigated. Recoveries were achieved in the range of 90–102% in different matrices. The presented method was applied for the analysis of target analytes in some samples such as grape juice, vinegar and dairy products.     

电子亲合力与诱导效应的定量关系

本文提出了电子亲合力与诱导效应之间的定量关系。通过计算说明了电子亲合力与诱导效应的定量相关比电负性与诱导效应的定量相关好得多；并应用其定量关系式预测尚未实测到的取代基的电子亲合力值；根据计算结果, 可从不同实验方法测得的电子亲合力值中选择正确的实验值。该定量关系式能更加准确和定量地表征出诱导效应的作用。     

Intrinsic viscosity–molecular weight relationship for chitosan

The intrinsic viscosity–molecular weight relationship for chitosan was determined in 0.25 M acetic acid/0.25M sodium acetate. Chitosan samples with a degree of acetylation (DA) between 20 and 26% were prepared from shrimp‐shell chitosan by acid hydrolysis (HCl) and oxidative fragmentation (NaNO₂). Absolute molecular weights were measured by light scattering and membrane osmometry. Size exclusion chromatography (SEC) was used to determine average molecular weights (M_n, M_v, and M_w) and polydispersity. The following Mark–Houwink–Sakurada equation (MHS) is proposed for chitosan of M_w in the range of 35–2220 kDa: The value of the MHS exponent a suggests that chitosan behaves as a flexible chain in this solvent. Examination of MHS constants obtained in this work and those available in the literature with other solvents indicates that a and K are inversely related and that they are influenced by DA, and pH and ionic strength of the solvent. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 2591–2598, 2000     

Formulation of unrestricted and restricted Hartree–Fock–Bogoliubov equations

The Hartree–Fock–Bogoliubov (HFB) method, dealing with Bogoliubov orbitals, which consist of particle and hole part, can provide states with pair correlations associated with Cooper pairs. The dimension of HFB Fock matrices can be reduced by restrictions of spin states of Bogoliubov orbitals similarly to ordinary Hartree–Fock (HF) equations such as restricted HF (RHF), unrestricted HF (UHF), and generalized HF (GHF). However, there are few studies of moderate restricted HFB equations such as UHF‐based HFB equations. In this article, formulation and calculations of restricted HFB equations are described. The solutions of general and restricted HFB equations are compared. Pair correlations taking account of restricted and general HFB equations are discussed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004     

The Poole–Frenkel effect on nitrated poly(N-vinylcarbazole)

In studying electrical conduction of nitrated poly(N-vinylcarbazole) (PNVC), several homodispersed samples of PNVC were nitrated by using two different nitration methods, resulting in mononitrated and dinitrated PNVC, respectively, with a really distinct polymer bulk structure which is responsible for the response of the charge carriers to an applied electric field. Electrical behavior in mononitrated PNVC is due to charge transfer complexes, while in dinitrated PNVC it is due to a dipole orientation effect.     

Effect of nitrogen on mechanical,oxidation and structural behaviour of Ti–Si–B–C–N nanocomposite hard coatings deposited by DC sputtering

Ti–Si–B–C–N film was deposited by DC magnetron sputtering at different argon and nitrogen ratios such as N₂/Ar = 1 : 5, 2 : 4, 3 : 3, 4 : 1 and 5 : 0. The formation of TiN and TiB phases was observed because of incorporation of nitrogen. The hardness, modulus, microstructure, structure and bond formation with different nitrogen contents during the deposition were studied by nanoindentation, scanning electron microscope, X‐ray diffraction and X‐ray photoelectron spectroscopy, respectively. The oxidation kinetics of Ti–Si–B–C–N was investigated. The nitrogen incorporation during deposition influences different properties of the coating. Hardness and modulus decreased, and microstructure showed very fine grain presence, and film changes to fully amorphous because of incorporation of nitrogen in the film. Copyright © 2016 John Wiley & Sons, Ltd.