Interactions between bioactive ferulic acid and fumed silica by UV–vis spectroscopy, FT-IR, TPD MS investigation and quantum chemical methods

The interactions of bioactive ferulic acid with fumed silica were studied by UV/vis spectroscopy, FT-IR, TPD MS techniques and quantum chemical methods. It was found that surface complexes may form through phenol or carboxyl group of ferulic acid depending on its coverage value. The structure of surface complexes and mechanisms of the ferulic acid chemosorption on the silica surface are discussed. The kinetic parameters of the chemical reactions on silica surface are calculated. The mechanisms of thermal transformations of the ferulic chemosorbed surface complexes are proposed.     

A convenient synthesis of dihydrocoumarins from phenols and cinnamic acid derivatives

A facile procedure for synthesis of dihydrocoumarin derivatives was described. Although the yield of the products in the reaction of phenols with acrylates in trifluoroacetic acid in the presence of Pd(OAc)₂ giving coumarins was found to be very low, dihydrocoumarin derivatives were obtained in good to high yields in the absence of Pd(OAc)₂ when ethyl cinnamates bearing electron-donating groups were employed in this reaction.     

Study on the interaction of CdTe quantum dots with coumaric acid and caffeic acid based on fluorescence reversible tune

This paper describes the synthesis of CdTe quantum dots (QDs) together capped by glutathione and thioglycolic acid (GSH and TGA) in aqueous solution. The narrow photoluminescence (fwhm ≤ 40 nm) CdTe QDs, whose emission spans most of the visible spectrum from green through red, has a quantum yield (QY) of 68% at room temperature. GSH/TGA-CdTe QDs are characterized by various experimental techniques such as optical absorption, photoluminescence and AFM measurements. Coumaric acid and caffeic acid is able to quench the fluorescence of GSH/TGA-CdTe QDs, and the fluorescence intensity is linearly proportional to the concentration of quenchers. The addition of bovine serum albumin (BSA) restores the fluorescence intensity of GSH/TGA-CdTe QDs-coumaric acid system and GSH/TGA-CdTe QDs-caffeic acid system. The fluorescence recovery was due to the interaction of BSA with coumaric acid and caffeic acid, leading to the freeing of the GSH/TGA-CdTe QDs. The fluorescence quenching mechanism of GSH/TGA-CdTe QDs was discussed. The binding constant and thermodynamics parameters of BSA-coumaric acid and BSA-caffeic acid during the binding process were calculated in the paper.     

在线扫集-胶束毛细管电动色谱法测定扛板归中的阿魏酸、咖啡酸和原儿茶酸

采用在线扫集-胶束毛细管电动色谱法(sweeping-MEKC)分离测定扛板归中的阿魏酸、咖啡酸和原儿茶酸。采用未涂层熔融石英毛细管(50 cm×50μm,有效柱长36 cm);环境温度25℃;缓冲体系为20 mmol/L NaH2PO4-80mmol/L十二烷基磺酸钠(SDS)-12.5%乙腈(V/V)(pH 2.20),紫外检测波长为216 nm,运行分离电压-20 kV,进样时间100 s。在优化条件下,3种有机酸均在20 min内出峰,峰面积RSD均小于5%。检出限分别达到98.52,118.73和27.27μg/L。     

高效液相色谱-串联质谱法同时测定水溶性迷迭香提取物中迷迭香酸、阿魏酸和咖啡酸的含量

本文建立了一种同时快速测定水溶性迷迭香提取物中迷迭香酸、阿魏酸和咖啡酸含量的高效液相色谱-串联质谱(HPLC/MS/MS)分析方法。以甲醇和0.1%乙酸铵溶液为HPLC的流动相;MS/MS使用多反应监测(MRM)扫描方式,在3 min内可完成迷迭香酸、阿魏酸和咖啡酸三种化合物的分离分析。上述三种分析物在5~500 ng/mL范围内线性良好(r>0.999);检出限均低于5.0 ng/mL。本法操作简便、分析速度快、灵敏度高,可用于水溶性迷迭香提取物中迷迭香酸、阿魏酸和咖啡酸含量的测定。     

聚苯乙烯固载聚乙二醇-600催化合成肉桂酸

本文采用固载化聚乙二醇-600为相转移催化剂，高收率地合成了肉桂酸，并对催化剂用量，反应时间和催化剂的重复使用性能对产品收率的影响进行了研究．     

Graphene‐sensitized microporous membrane/solvent microextraction for the preconcentration of cinnamic acid derivatives in Rhizoma Typhonii

A novel graphene‐sensitized microporous membrane/solvent microextraction method named microporous membrane/graphene/solvent synergistic microextraction, coupled with high‐performance liquid chromatography and UV detection, was developed and introduced for the extraction and determination of three cinnamic acid derivatives in Rhizoma Typhonii. Several factors affecting performance were investigated and optimized, including the types of graphene and extraction solvent, concentration of graphene dispersed in octanol, sample phase pH, ionic strength, stirring rate, extraction time, extraction temperature, and sample volume. Under optimized conditions, the enrichment factors of cinnamic acid derivatives ranged from 75 to 269. Good linearities were obtained from 0.01 to 10 μg/mL for all analytes with regression coefficients between 0.9927 and 0.9994. The limits of quantification were <1 ng/mL, and satisfactory recoveries (99–104%) and precision (1.1–10.8%) were also achieved. The synergistic microextraction mechanism based on graphene sensitization was analyzed and described. The experimental results showed that the method was simple, sensitive, practical, and effective for the preconcentration and determination of cinnamic acid derivatives in Rhizoma Typhonii.     

BTISA-catalyzed Friedel-Crafts bimolecular cyclization of cinnamic acid under superelectrophilic solvation conditions

Friedel-Crafts bimolecular cyclizations of cinnamic acid and cinnamoyl chloride with aromatic compounds in strong and superstrong acids in present of 1 mol% BTISA were investigated. It was demonstrated that catalytic amounts of this new superacid have essential effect on such type of reactions. Its use makes possible the preparation of indanones with quantitative yields.     

High-performance liquid chromatographic analysis of secoisolariciresinol diglucoside and hydroxycinnamic acid glucosides in flaxseed by alkaline extraction

A HPLC method was developed for the analysis of secoisolariciresinol diglucoside (SDG) and hydroxycinnamic acid glucosides in milled defatted flaxseed flour. Direct extraction by 1 M NaOH for 1 h at 20 degrees C resulted in a higher yield than that obtained by hydrolysis of alcoholic extracts. An internal standard, o-coumaric acid, was used and the method was found to be easy, fast, and with good repeatability. On dry matter basis, different samples of flaxseeds varied considerably in their content of (+)-SDG (11.9-25.9 mg/g), (-)-SDG (2.2-5.0 mg/g), p-coumaric acid glucoside (1.2-8.5 mg/g), and ferulic acid glucoside (1.6-5.0 mg/g).     

Effect of surfactants on temperature-dependent self-assembling property of copolyethylenimine/cinnamic acid aqueous mixture

The transmittance of polyethylenimine (PEI)/cinnamic acid (CA) aqueous mixture was close to zero at 20–40°C, and it began to increase around 40°C due to the disassembling of the self-assembly of the PEI/CA conjugate. As the concentration of sodium dodecyl sulfate (SDS) increased, the increasing rate of the transmittance decreased and the onset temperature increased, indicating that the self-assembly of the PEI/CA conjugate became more stable against heat with the aid of SDS. Tween 20 could also suppress the thermally induced disassembling of the self-assembly, possibly because poly(ethylene oxide) chains of the surfactant could be entangled with the PEI chains. Dodecyltrimethyl ammonium bromide (DTAB) did not have an effect on the temperature-dependent self-assembling phenomena as much as SDS and Tween 20 did. The interfacial tension of the PEI/CA/SDS aqueous mixture and that of the PEI/CA/Tween 20 aqueous mixture at 70°C were lower than the respective tensions observed at 25°C. On the contrary, the interfacial tension of the PEI/CA/DTAB aqueous mixture at 70°C was higher than that observed at 25°C, possibly because the PEI/CA conjugate could lose its surface activity at the higher temperature due to the adsorption of DTAB on CA molecules.     

Purification of hydroxyanthraquinones and cinnamic acid from the roots of Rheum officinale Baill

A chromatographic method for isolation and purification of chemical constituents from the well-known traditional Chinese drug Da-huang (roots of Rheum officinale Baill.) was established by using 12% cross-linked agarose gel, Superose 12, as the separation media. A two-step separation procedure is employed. Sixty five percent methanol was used as the eluent for separation of cinnamic acid, rhein, physcion and emodin form Da-huang crude extract. The fraction containing aloe-emodin and chrysophanol was then separated by using 55% methanol containing 0.5% acetic acid as the eluent. As a result, cinnamic acid and five kinds of hydroxyanthraquinones including rhein, aloe-emodin, chrysophanol, physcion and emodin were obtained. The retention behavior of hydroxyanthraquinones on Superose 12 was also studied. The retention of hydroxyanthraquinones on Superose 12 is based on a mixture of hydrogen bonding and hydrophobic interactions between the hydroxyl groups of the hydroxyanthraquinones and the residues of the cross-linking reagents used in the manufacturing process of Superose 12.     

Solubilities of cinnamic acid esters in binary mixtures of ionic liquids and organic solvents

The solubilities of three cinnamic acid esters, namely, methyl ferulate, methyl p-coumarate, and methyl sinapate, have been measured in mixed solvent systems of tert-butanol with 1-butyl-3-methyl-imidazolium hexafluorophosphate ([BMIM][PF₆]), 1-butyl-3-methyl-imidazolium tetrafluoroborate ([BMIM][BF₄]) and 1-methyl-3-octyl-imidazolium tetrafluoroborate ([OMIM][BF₄]) at 303.15 and 321.15 K, and in mixed solvent systems of ethyl acetate with [BMIM][BF₄] and [OMIM][BF₄] at 303.15 K. In eight cases, out of the 22 data sets, an additive behaviour of the solubility was observed, positive deviations from additivity were observed in six cases, a positive synergistic effect in five cases, and, finally, negative deviations from additivity in the remaining three cases. Prediction of the solubilities of the solutes in the various ternary systems was performed with the NRTL and UNIQUAC activity coefficient models. The binary interaction parameters of the models between solute and solvent molecules were taken from the literature. When the parameters between the solvent molecules are fitted to literature data, satisfactory predictions are not always obtained. On the other hand, very good predictions are obtained when only one of the two interaction parameters between the two solvent molecules is fitted to one single point of the solubility isotherm and the other interaction parameter is set equal to zero.     

Separation and fragmentation study of isocoproporphyrin derivatives by UHPLC‐ESI‐exact mass MS/MS and identification of a new isocoproporphyrin sulfonic acid metabolite

Isocoproporphyrin and its derivatives are commonly used as biomarkers of porphyria cutanea tarda, heavy metal toxicity and hexachlorobenzene (HCB) intoxication in humans and animals. However, most are isobaric with other porphyrins and reference materials are unavailable commercially. The structural characterisation of these porphyrins is important but very little data is available. We report here the separation and characterisation of isocoproporphyrin, deethylisocoproporphyrin, hydroxyisocoproporphyrin and ketoisocoproporphyrin, isolated in the faeces of rats fed with a diet containing HCB, by ultra high performance liquid chromatography‐exact mass tandem mass spectrometry (UHPLC‐MS/MS). Furthermore, we report the identification and characterisation of a previously unreported porphyrin metabolite, isocoproporphyrin sulfonic acid isolated in the rat faeces. The measured mass‐to‐charge ratio (m/z) of the precursor ion was m/z 735.2338, corresponding to a molecular formula of C₃₆H₃₉N₄O₁₁S with an error of 0.3 ppm from the calculated m/z 735.2336. The MS/MS data was consistent with an isocoproporphyrin sulfonic acid structure, derived from dehydroisocoproporphyrinogen by sulfonation of the vinyl group. The metabolite was present in a greater abundance than other isocoproporphyrin derivatives and may be a more useful biomarker for HCB intoxication. Copyright © 2014 John Wiley & Sons, Ltd.     

Simultaneous determination of caffeic acid and its major pharmacologically active metabolites in rat plasma by LC‐MS/MS and its application in pharmacokinetic study

A simple, sensitive and selective high‐performance liquid chromatography electrospray ionization tandem mass spectrometry (LC‐MS/MS) method was developed for simultaneous determination and pharmacokinetic study of caffeic acid (CA) and its active metabolites. The separation with isocratic elution used a mobile phase composed of methanol and water (containing 0.1% formic acid) at a flow rate of 0.2 mL/min. The detection of target compounds was done in selected reaction monitoring (SRM) mode. The SRM detection was operated in the negative electrospray ionization mode using the transitions m/z 179 ([M ? H]^?) → 135 for CA, m/z 193 ([M ? H]^?) → 134.8 for ferulic acid and isoferulic acid and m/z 153 ([M ? H]^?) → 108 for protocatechuic acid. The method was linear for all analytes over the investigated range with all correlation coefficients 0.9931. The lower limits of quantification were 5.0 ng/mL for analytes. The intra‐ and inter‐day precisions (relative standard deviation) were <5.86 and <6.52%, and accuracy (relative error) was between ?5.95 and 0.35% (n = 6). The developed method was applied to study the pharmacokinetics of CA and its major active metabolites in rat plasma after oral and intravenous administration of CA. Copyright © 2014 John Wiley & Sons, Ltd.     

Solvent-free synthesis of 4-aryl-3,4-dihydrobenzopyran-2-ones via [3+3] cyclocoupling of phenols with cinnamic acid catalyzed by molecular iodine

Molecular iodine was used as a catalyst in the [3+3] cyclocoupling of phenols and cinnamic acids which proceeds via a tandem esterification-hydroarylation process at 120-130 °C under solvent-free conditions. Substituted 4-aryl-3,4-dihydrobenzopyran-2-ones were obtained in good yields.     

Simultaneous quantification of mycophenolic acid and its glucuronide metabolites in human plasma by an UPLC–MS/MS assay

The aim of this study was to develop a reliable UPLC–MS/MS assay for accurate quantification of mycophenolic acid (MPA) and its glucuronide conjugates in human plasma. Plasma proteins were precipitated with acetonitrile and the chromatographic separation was achieved on a C₁₈ column with a gradient elution. The detection was performed by a triple quadrupole mass spectrometer in the positive electrospray ionization and multiple reaction monitoring mode. Linearity of the assay was demonstrated over the range of 20–10,000 ng/mL for MPA and MPA glucuronide (MPAG), and 2–1000 ng/mL for acyl MPA glucuronide in human plasma. The assay was precise and accurate with coefficient of variation and bias <15%. MPA and MPAG were stable at 25 °C up to 1 day in both heparin‐ and EDTA‐treated blood. In heparin‐ and EDTA‐plasma, MPA and MPAG were stable for at least 1 week at 25 and 4 °C, and 1 month at ?20 °C. However, 99% acyl MPA glucuronide degraded in both heparin‐ and EDTA‐blood as well as plasma when stored at room temperature for 1 day. All the analytes remained stable for at least 3 months in acidified EDTA‐plasma at ?80 °C. The assay was successfully applied on patients post hematopoietic stem cell transplantation. Copyright © 2016 John Wiley & Sons, Ltd.     

胶束扫集-电动色谱分离-毛细管电泳法测定升麻中三种有机酸含量

采用电场增强胶束扫集-电动色谱-毛细管电泳法对升麻中异阿魏酸、阿魏酸和咖啡酸的含量进行了测定,电泳缓冲体系为90 mmol·L~(-1)SDS-20 mmol·L~(-1)NaH_2PO_4(pH 2.20)-甲醇(10+90),分离电压为20 kV,检测波长214 nm。在优化的试验条件下,胶束扫集-电动色谱法对异阿魏酸、阿魏酸和咖啡酸富集倍数为4.3,4.8,2.9,3种有机酸均在14 min内出峰,线性范围分别为0.50～20.0,0.50～20.0,1.0～40.0 mg·L~(-1)。应用此方法分析了升麻样品并进行了回收率和精密度试验,测得回收率在93.2%～113.3%之间,测定值的相对标准偏差(n=5)小于6%。     

Synthesis and electrochemistry of tetrakis(7-coumarinthio-4-methyl)-phthalocyanines,and preparation of their cinnamic acid and sodium cinnamate derivatives

Novel water soluble free-base, Zn(II) and Co(II) metallo phthalocyanines with four cinnamic acid moieties were prepared from the corresponding tetrakis(7-coumarinthio-4-methyl)-phthalocyanine by the lactone ring opening reaction. The new compounds were purified and characterized by elemental analysis, ¹H NMR, Maldi-TOF, FT-IR and UV–Vis spectral data. Cyclic and differential pulse voltammetry and in situ spectroelectrochemistry of the 2,9,16,23-tetrakis(7-coumarinthio-4-methyl) substituted free-base 1a, Zn(II) 1b and Co(II) 1c phthalocyanines, employed as the starting compounds have been studied. This allowed us not only to identify metal- and phthalocyanine ring-based redox processes of the complexes, but also the effect of aggregation on these processes.     

Polydopamine‐coated magnetic molecularly imprinted polymer for the selective solid‐phase extraction of cinnamic acid,ferulic acid and caffeic acid from radix scrophulariae sample

We describe novel cinnamic acid polydopamine‐coated magnetic imprinted polymers for the simultaneous selective extraction of cinnamic acid, ferulic acid and caffeic acid from radix scrophulariae sample. The novel magnetic imprinted polymers were synthesized by surface imprinting polymerization using magnetic multi‐walled carbon nanotubes as the support material, cinnamic acid as the template and dopamine as the functional monomer. The magnetic imprinted polymers were characterized by transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and vibrating sample magnetometry. The results revealed that the magnetic imprinted polymers had outstanding magnetic properties, high adsorption capacity, selectivity and fast kinetic binding toward cinnamic acid, ferulic acid and caffeic acid. Coupled with high‐performance liquid chromatography, the extraction conditions of the magnetic imprinted polymers as a magnetic solid‐phase extraction sorbent were investigated in detail. The proposed imprinted magnetic solid phase extraction procedure has been used for the purification and enrichment of cinnamic acid, ferulic acid and caffeic acid successfully from radix scrophulariae extraction sample with recoveries of 92.4–115.0% for cinnamic acid, 89.4–103.0% for ferulic acid and 86.6–96.0% for caffeic acid.     

Thermal investigation by simultaneous TG/DTG-DTA and IR spectroscopy of new lanthanide complexes with salicylhydroxamic acid

Summary The reaction of a hydrated nitrate salt of lanthanide (Ln=Pr, Nd, Gd, Dy, Er) with the polyfunctional ligand salicylhydroxamic acid (H₃sha), in the presence of base, afforded solid compounds, insoluble in common organic solvents and in water. The new complexes characterized by means of elemental analyses (C, H, N, Ln), magnetic moment determinations and spectroscopic data (IR, MS). It is proposed that they are neutral, with a possible polymeric structure of the general type: [Ln₂(Hsha)₂(H₂sha)(DMF)_x(CH₃O)(H₂O)]_n×2H₂O Their thermal decomposition was studied in nitrogen and/or oxygen atmosphere, between 25-1000°C by using simultaneous TG/DTG-DTA technique. The IR spectroscopy used to determine the intermediates and the final products. The intermediates at 180°C suggest the formation of N-hydroxylactam complex, which upon further heating gives a carbonaceous residue of Ln₂O₃ at 1000°C in nitrogen, while in oxygen the stable oxides are formed at 600°C.