Hop-induced formation of ethyl esters in dry-hopped beer

Fruity smelling esters play an important role for the aroma of hops and beer and they have been characterized as key aroma compounds in different hop varieties.Studies on the transfer of hop-derived compounds into beer during dry-hopping showed calculated transfer rates of different ethyl esters far above 100%,leading to the assumption that these esters must be newly formed.To investigate this formation,dry-hopping was imitated in water to eliminate the influence of the beer matrix on the formation of these odorants.Thereby,the formation of ethyl esters of 2-methylbutanoic acid,3-methylbutanoic acid,and methylpropanoic acid,induced by the addition of hops,was shown.Different approaches inhibiting enzyme activities and experiments with different hop extracts might lead to the assumption that enzymes are involved in the formation of these esters,beside possible transesterification.

Design,Synthesis,and Biological Evaluation of 5H-Thiazolo[3,2-a]pyrimidine-6-carboxylic Acid Ethyl Ester Derivatives as a Novel Series of Acetylcholinesterase Inhibitors

Acetylcholinesterase inhibitors are the most frequently prescribed anti-Alzheimer＇s drugs. A series of 5H-thiazolo[3,2-a]pyrimidine-6-carboxylic acid ethyl ester derivatives as the novel acetylcholinesterase inhibitors was designed based on virtual screening methods. The target compounds were synthesized with Biginelli reaction and Hantzsch-type condensation of dihydropyrimidines with substituted phenacyl chlorides, and were characterized with elemental analysis, IR, MS, ^1H NMR, and ^13C NMR. The biological evaluation against human acetylcholinesterase in vitro indicated all the target compounds show more than 50% inhibition at 10μmol/L by means of the Ellman method. The results provide a starting point for the development of novel drugs to treat Alzheimer＇s disease and lay the foundation of searching for improved acetylcholinesterase inhibitors with the novel scaffolds.

Synthesis and Physicochemical Properties of L-(+)-a-(Positive Butyl)-Leucine Ethyl Ester Chiral Ionic Liquids

L-（＋）-α-（positive butyl）-leucine ethyl ester bromide chiral ionic liquid was synthesized by using microwave-assisted synthesis method and L-（＋）-α-（positive butyl）-leucine ethyl ester terafluoroborate and hexafluorophosphate chiral ionic liquids were synthesized by the anion exchange reaction. The structures were characterized by IR, ~1HNMR and structure optimization calculation. The results of studies on physicochemical properties show that they possess better thermal stability, solubility, bio-solubility and high conductivity. They can serve as effective reaction media as well as chiral catalysts. They are presently being investigated as dispersion agents in molecular imprinting ployer.

Synthesis, Crystal Structure and Inhibition of N-2-Thiophenesulfonyl-α-L-phenylalanine Ethyl Ester on K562 Cell Proliferation

The title compound N-2-thiophenesulfonyl-a-L-phenylalanine ethyl ester has been synthesized. Complete assignments were achieved by IR, MS, ^1H NMR and single-crystal X-ray diffraction analyses. Using MTT assay, the inhibitory rate of the title compound on K562 cells （chronic myeloid leukemic cells） was measured and the result of preliminary bioassay showed that the title compound possesses antiproliferation effects on K562 cells. In order to investigate the relationship between structure and activity of the target compound, we report its crystal structure and biological behavior in the present paper. Crystallographic data： C15H17NO4S2, Mr = 339.42, monoclinic, space group P21, flack = -0.15（12）, a = 5.7916（10）, b = 11.5078（19）, c = 12.924（2） A, β = 97.781（3）°, Z = 2, V = 853.4（2） A^3, De = 1.321 g/cm^3, F（000） = 356, -7≤h≤7, -10≤k≤14, -15 ≤ l≤15, R = 0.0628, wR = 0.1540 and μ（MoKa） = 0.327 mm^-1. The molecule comprises a benzene and a thiofuran rings, and the intramolecular N（1）-H（1A）…O（1） makes a five-membered ring of O（1）--C（6）-C（5）--N（1）--H（1A）.

Vapor-Liquid Equilibrium of Ethyl Acetate+C_nH_(2n+1)OH(n=1,2,3) Binary Systems at 0.3 MPa

Vapor-liquid equilibrium data for the binary systems of ethyl acetate + methanol,ethyl acetate + ethanol and ethyl acetate + 1-propanol at 0.3 MPa were determined.The experimental data were verified with the point-to-point test of van Ness(1973).All these systems present an azeotropic point at 0.3 MPa that increases in ester composition for longer alcohol chains.The UNIFAC in different versions and ASOG prediction models were applied.

Synthesis and Crystal Structure of 4-(4,6-Dimethoxylpyrimidin-2-yl)-3-thiourea Carboxylic Acid Ethyl Ester

4-（4,6-Dimethoxyl-pyrimidin-2-yl）-3-thiourea carboxylic acid ethyl ester was synthesized by the reaction of 2-amino-4,6-dimethoxyl pyrimidine, potassium thiocyanate and methyl chloroformate in ethyl acetate. Single crystals suitable for X-ray measurement were obtained by recrystallization with the solvent of dimethyl formamide at room temperature. The crystal structure was determined by X-ray diffraction analysis. Crystallographic data： C10H14N4O4S, M, = 286.31, monoclinic, space group C2/c with a = 2.5309（3）, b = 0.67682（6）, c = 1.74237（19） nm, β = 114.744（3）°, V= 2.7106（5） nm3, Dc = 1.403 g/cm3, p = 0.225 mm-1, F（000） = 1200, Z= 8, R= 0.0514 and wR= 0.1529.

2-乙酰己酸乙酯的质谱分析

2-Acetyl-hexanoic acid ethyl ester is one of important derivatives.It has been used widely useful materials as anesthetics,spice,medicine and so on.The reaction liquid of acetyl-acetic acid ethyl ester with n-butane bromide was analyzed by gas chromatograph-mass spectrometry.The results show that there are four kinds of compounds in the reaction liquid.The main yield is 2-acetyl-hexanoic acid ethyl ester,while by-products are 2-acetyl-2-butyl-hexanoic acid ethyl ester and 3-butoxy-2-butenoic acid ethyl ester.

黄连中1个新型生物碱的研究

目的 研究黄连Coptis chinensis Franch中1个新型生物碱。方法 黄连75%乙醇提取物采用硅胶、ODS、semi-pre HPLC进行分离纯化,根据理化性质及波谱数据对鉴定所得化合物的结构。结果 从中分离得到3个化合物,分别鉴定为6-([1,3]dioxolo[4,5-g]isoquinoline-5-carbonyl)-2,3-dimethoxybenzoic acid ethyl ester(1)、oxohydrastinine(2)、pinoresinol(3)。结论 化合物1为新型苄基异喹啉生物碱。

Crystal Structures of 2-Aminobenzothiazole-based Inhibitors in Complexes with Urokinase-type Plasminogen Activator

Urokinase-type plasminogen activator （uPA） plays a crucial role in the regulation of plasminogen activation, tumor cell adhesion and migration. The inhibition of uPA activity is a promising mechanism for anti-cancer therapy. Most current uPA inhibitors employ a highly basic group （either amidine or guanidine group） to target the S1 pocket of uPA active site, which leads to poor oral bioavailability. Here we study the possibility of using less basic 2-aminobenzothiazole （ABT） as S1 pocket binding group. We report the crystal structures of uPA complexes with ABT or 2-amino-benzothiazole-6-carboxylic acid ethyl ester （ABTCE）. The inhibitory constants of these two inhibitors were measured by a chromogenic competitive assay, and it was found that ABTCE is a better inhibitor for uPA （Ki = 656 μM） than ABT （Ki = 5.03 mM）. This work shows that 2-amniobenzothiazole can be used as P1 group which may have better oral bioavailability than the commonly used amidine or guanidine group. We also found the ethyl ester group occupies the characteristic oxyanion hole and contacts to uPA 37- and 60-loops. Such work provides structural information for further improvements of potency and selectivity of this new class of uPA inhibitor.

Synthesis of o-L-α-glycerylphosphoryl-L-serine

A new efficient method for preparing o-L-α-glycerylphosphoryl-L-serine was presented. D-α, β-isopropylidene glycerol was phosphorylated with phenylphosphoryl dichloride and the resulting o-D-α,β-isopropylidene glycerylphenylphosphoryl chloride was esterified with N-tert-butoxycarbonyl-L-serine ethyl ester in the presence of pyridine to give acetone L-α-glycerylphenylphosphoryl-N-tert-butoxycarbonyl-L-serine ethyl ester. Finally, the protective groups were removed by two-step hydrolysis while strictly controlling pH value. The reaction to produce (1, 2), (5, 6)-diisopropylidene-D-mannitol, which is the key precursor for the preparation of D-α, β-isopropylidene glycerol, was monitored by using gas chromatography-mass spectrometer in order to obtain an optimum yield of 65%. All compounds were characterized through elemental analysis, infrared spectra, 1H, 13C, 31P-nuclear magnetic resonance spectra and mass spectra.

Production of Biodiesel with Seed Soybean and Supercritical Ethanol

This paper presents a study of biodiesel production by a non-catalytical process. The innovation in this study is the use of novel materials for production: seed soybean (Glycine Max) “in natura” and ethanol in a supercritical state. To conduct the experiments, a bench reactor with a capacity of 150 mL, resistant to pressure of up to 300 bar and temperature of 350°C was developed. The fractional factorial experimental design () was used to evaluate the temperature, seed granulometry, molar ratio ethanol/oil and water percent of the mixture. The best yield observed was that of 94.07%, 10 minutes after the reactor entered a supercritical condition. Significant effects on seed granulometry, molar ratio ethanol, oil and temperature were verified. From the proposed process, biodiesel and toasted soybean seed were obtained. To purify the biodiesel sample it was necessary to use ultra-centrifugation to separate seed particles, and rotoevaporation to separate the fatty acid ethyl ester and unreacted ethanol. The chemical analyses were conducted directly by gas chromatography. The yield was calculated in accordance with concentrations obtained in the chromatographic analysis and seed mass of the experiment. Also checked was the presence of palmitate esters, stearate, oleate, linoleate and linolenate. By analyzing the ester composition it was possible to assess whether a good quality biodiesel was available. The roasted soybean seeds obtained after the reaction showed a calorific potential of 2203.17 kcal/kg and also be used as fuel.

HeI photoelectron spectroscopic (PES) studies of the electronic structure in ω-heterocycle a-cyano polyenic ethyl ester compounds

HeI photoelectron spectra of w-heterocycle a-cyano polyenic ethyl ester compounds (1-6) have been given in this paper. Assignment of the spectra is also done with the aid of HeI photoelectron spectroscopic (PES) results of smaller molecules which have similar atomic group to the molecules studied, and the aid of MNDO molecules orbital calculations. The lowest PES experimental ionization potentials (IPs in eV) of different molecules reduce gradually with the increasing number of ethylenic group. The -CO2C2H5 group can be only considered as a substituent.

Synthesis of biodegradable poly (methylparaben/glycine ethyl ester) phosphazene and further research of its degradation in vitro

Polydichlorophosphazene(PDCP)was synthesized from PCl5 and NH4Cl via a one-pot approach,and then further reacted with glycine ethyl ester and methylparaben via a two-step nucleophilic substitution approach to give poly(methylparaben/glycine ethyl ester)phosphazene(PMGP),which was a kind of mix-substituted biodegradable polymer.NMR and FT-IR were used to characterize its structure.A series of experiments were conducted to study the effects of the ratio of methylparaben to glycine ethyl ester and the experimental conditions to the degradability of PMGP samples.The degradability of PMGP can be adjusted by altering the ratio of methylparaben to glycine ethyl ester easily.

Sensitized photooxygenation^+——VI. Kinetic studies on the singlet oxygenation of 6-ethyl-3,4-dihydro-2H-pyran-5-carboxylic acid ethyl ester and 6-isopropyl-3,4-dihydro-2H-pyran-5-carboxylic acid ethyl ester

Kinetic studies of the singlet oxygenation of the title compounds were performed accord- ing to Monroe's method. The reaction rate increases with temperature decreasing, leading to a ne- gative activation enthalpy and a large negative activation entropy. These data are interpreted as the evidence for the intermediacy of an exciplex. The solvent effect on the reaction rate suggests that the “dioxetane” path involves a transition state or an intermediate with significant zwitterionic character. The electronic effect of the substituent is obvious, with electron-withdrawing substituent retarding the reaction and electron-donating substituent increasing the reaction rate. However, steric bulkiness at the 6-position does not play an important role in the reaction rate.

Highly selective kinetic resolution of D/L-syn-p-sulfone phenylserine catalyzed by D-threonine aldolase in two-phase ionic solvent

In the chemical synthesis of L-syn-p-methylsulfoxide phenylserine ethyl ester(D-ethyl ester),L-tartaric acid or enzymatic resolution is employed to resolve the racemate,and thus obtain the target compound,and the remaining isomer can be recycled to obtain the raw material.In this study,high-purity L-syn-p-methylsulfoxide phenylserine(L-syn-MPS)was obtained.The kinetics of the D-threonine aldolase enzymatic hydrolysis reaction reveals that D-syn-p-sulfoxylphenylserine resolves well in[BMIM][BF 4]ionic solvents.The D/L-syn-MPS racemate was resolved using a two-phase ionic solvent[BMIM][NTf 2]to afford L-syn-MPS(ee(enantiomeric excess)>99%)and a white solid in 41.7%yield.Therefore,this system is suitable for the separation of insoluble aldehydes and successfully avoids the condensation of hydroxyl aldehydes to form D-anti-MPS.

SELF-HEALING BIODEGRADABLE POLY(UREA-URETHANE) ELASTOMERS BASED ON HYDROGEN BONDING INTERACTIONS

Self-healing poly（urea-urethane）s （PUUs） showing a tolerance to mechanical damage are particularly desirable for high-performance elastomeric biomaterials. In this study a kind of biodegradable PUUs was synthesized from poly（e-caprolactone） diol with L-lysine ethyl ester diisocyanate （LDI） extended with L-lysine ethyl ester dihydrochloride （LEED） in DMF and characterized by using 1H-NMR, FTIR, DSC, XRD, SEM and tensile tests. Interestingly, they exhibited a self-healing characteristic upon exposure to 37℃ for as short as 30 min with the tensile strength keeping at 4.23 MPa and the elongation at break reaching to 627%. It is revealed that increasing the hard segment content in PUUs benefits the self-healing performance, and on the opposite increasing the soft segment content contributes to the biodegradability.

Supercritical fluid extraction and gas chromatography analysis of arsenic species from solid matrices

A method in combination with derivatization-supercritical fluid extraction（SFE） and gas chromatography（GC） for the speciation and quantitative determination of dimethylarsinate（DMA）, monomethylarsonate（MMA） and inorganic arsenic in solid matrices was investigated. Thioglycolic acid methyl ester（TGM） and thioglycolic acid ethyl ester（TGE） were evaluated as derivatization reagents. The effects of pressure, temperature, flow rate of supercritical CO_2, extraction time, modifier and microemulsion on the efficiency of extraction were systematically investigated. The procedure was applied to the analysis of real soil and sediment samples. Results showed that TGE was more effective for arsenic speciation as a derivatization reagent. Modifying supercritical CO_2 with methanol can greatly improve the extraction efficiency. Further, the addition of microemulsion containing surfactant Triton X-100 can further enhance recoveries of arsenic species. The optimum extraction conditions were 100 ℃, 30 MPa, 10 min static and 25 min dynamic extraction with 5%（v/v） methanol, and surfactant modified supercritical CO_2. Detection limits in solid matrices were 0.15, 0.3 and 1.2 mg/kg for DMA, MMA and inorganic arsenic,respectively. The method was validated by the recovery data. The resulting method was fast, easy to perform and selective in the extraction and detection of various arsenic species in solid matrices.

A New Natural Compound with Cytotoxic Activity from Tripterygium hypoglaucum

Objective To find antitumor constituents from Tripterygium hypoglaucum.Methods The chloroform extract of T.hypoglaucum was separated by silica gel column chromatography and preparative HPLC.The structures of compounds isolated were identified by spectral analysis and chemical evidence.Results Seven compounds were isolated and identified as rhein ethyl ester(1),chrysophenol(2),physcion(3),emodin(4),wilfordine(5),wilforgine(6),and wilforine(7).The cytotoxic activities of the compounds against cancer cell lines were assayed.Conclusion Compound 1 is a new natural compound with strong activities against human cancer cell lines(A2780 and OVCAR-3) .Compounds 2-4 are isolated from this genus plants for the first time.The possible structure-activity relationship among compounds 1-4 shows that the methoxy group or oxyethyl moiety might be responsible for the cytotoxity.