Identification of novel circulating coffee metabolites in human plasma by liquid chromatography-mass spectrometry

This study reports a liquid chromatography-mass spectrometry method for the detection of polyphenol-derived metabolites in human plasma without enzymatic treatment after coffee consumption. Separation of available standards was achieved by reversed-phase ultra performance liquid chromatography and detection was performed by high resolution mass spectrometry in negative electrospray ionization mode. This analytical method was then applied for the identification and relative quantification of circulating coffee metabolites. A total of 34 coffee metabolites (mainly reduced, sulfated and methylated forms of caffeic acid, coumaric acid, caffeoylquinic acid and caffeoylquinic acid lactone) were identified based on mass accuracy (<4 ppm for most metabolites), specific fragmentation pattern and co-chromatography (when standard available). Among them, 19 circulating coffee metabolites were identified for the first time in human plasma such as feruloylquinic acid lactone, sulfated and glucuronidated forms of feruloylquinic acid lactone and sulfated forms of coumaric acid. Phenolic acid derivatives such as dihydroferulic acid, dihydroferulic acid 4'-O-sulfate, caffeic acid 3'-O-sulfate, dimethoxycinnamic acid, dihydrocaffeic acid and coumaric acid O-sulfate appeared to be the main metabolites circulating in human plasma after coffee consumption. The described method is a sensitive and reliable approach for the identification of coffee metabolites in biological fluids. In future, this analytical method will give more confidence in compound identification to provide a more comprehensive assessment of coffee polyphenol bioavailability studies in humans.     

Rotational analysis of bands in the high-resolution infrared spectra of cis,cis- and trans,trans-1,4-difluorobutadiene-2-d1

Pure samples of cis,cis- and trans,trans-1,4-difluorobutadiene-2-d₁ have been synthesized, and high-resolution (0.0015 cm^?1) infrared spectra have been recorded for these nonpolar molecules in the gas phase. For the cis,cis isomer, the rotational structure in two C-type bands at 775 and 666 cm^?1 and one A-type band at 866 cm^?1 has been analyzed to yield a combined set of 2020 ground state combination differences (GSCDs). Ground state rotational constants fit to these GSCDs are A₀ = 0.4195790(4), B₀ = 0.0536508(8), and C₀ = 0.0475802(9) cm^?1. For the trans,trans isomer, three C-type bands at 856, 839, and 709 cm^?1 have been investigated to give a combined set of 1624 GSCDs. Resulting ground state rotational constants for this isomer are A₀ = 0.9390117(8), B₀ = 0.0389225(4), and C₀ = 0.0373778(3) cm^?1. Small inertial defects confirm the planarity of both isomers in the ground state. Upper state rotational constants have been determined for most of the transitions. The ground state rotational constants for the two isotopologues will contribute to the data set needed for determining semiexperimental equilibrium structures for the nonpolar isomers of 1,4-difluorobutadiene.     

Epicatechin B-ring conjugates: first enantioselective synthesis and evidence for their occurrence in human biological fluids

Herein, the first enantioselective total synthesis of a number of biologically relevant (-)-epicatechin conjugates is described. The success of this synthesis relied on (i) optimized conditions for the stereospecific cyclization step leading to the catechin C ring; on (ii) efficient conjugation reactions; and on (iii) optimized deprotection sequences. These standard compounds have been subsequently used to elucidate for the first time the pattern of (-)-epicatechin conjugates present in four different human biological fluids following (-)-epicatechin absorption.     

Orthorhombic Polymorphs of 1-Phenyl-3-(3-Hydroxyphenyl)-2-Propen-1-One

Abstract  

Chalcones, 1,3-diphenyl-2-propene-1-ones, exist naturally and synthetically, and are characterized by the linkage of two aromatic rings joining a three carbon α-β-unsaturated carbonyl entity. We report the observation of two new polymorphs of a hydroxy chalcone, C₆H₅–CO–CH=CH–C₆H₄ (m-OH), identified as a result of a Claisen–Schmidt synthesis and manual screening technique. One polymorph of this compound has been reported previously and exists in the monoclinic system, space group P2/n, with unit cell parameters a = 13.295(6) ?, b = 5.659(2) ?, c = 16.144(8) ?, β = 109.73(5)°, V = 1143.3(9) ?³, and Z = 4. Two crystalline forms (II and III) reported herein, are polymorphs of the reported monoclinic form (I). Form II exists in the orthorhombic system, space group Pca2₁, with unit cell constants a = 11.631 (2) ?, b = 13.163 (3) ?, c = 7.3977 (14) ?, V = 1132.6 (4) ?³, and Z = 4. Form III also crystallizes in the orthorhombic system, however in space group Pbca, with unit cell parameters a = 11.8100(8) ?, b = 7.4075(5) ?, c = 25.8729(19) ?, V = 2263.4(3) ?³, and Z = 8. Variations in the hydrogen bonding connectivity help to distinguish these two forms from the monoclinic, whereas crystal packing differentiates the two orthorhombic forms. The conformation of the C=C (C2–C3) is E for both orthorhombic forms.     

A bimetallic aluminium(salen) complex for asymmetric cyanohydrin synthesis

In the presence of a phosphine oxide cocatalyst, a bimetallic aluminium(salen) complex was found to catalyse the asymmetric addition of trimethylsilyl cyanide to aldehydes. Under optimised conditions, enantioselectivities of 53-96% were obtained using 2 mol % of the catalyst. An analysis of the reaction kinetics showed that the reactions exhibited first-order kinetics, with the rate of reaction being independent of the aldehyde concentration.     

Modeling of K-shell Al and Mg radiation from compact single, double planar and cylindrical alloyed Al wire array plasmas produced on the 1 MA Zebra generator at UNR

Radiative emission from alloyed Al single, double and compact cylindrical wire arrays have been studied using the 1 MA Zebra UNR generator. Single planar wire arrays using ten wires and double planar wire arrays and compact cylindrical wire arrays (CCWA) that both had sixteen wires were utilized. The wire composition is Al-5056 (95% of Al and 5% of Mg). We have observed that implosion of these alloyed Al wire loads generated optically thick Al plasmas that can be diagnosed using K-shell Mg lines. In particular, among the considered loads, the K-shell lines of Al from implosions of the double planar wire arrays have the highest optical depth for He-like Al resonance transitions, which occurred near the stagnation phase. X-ray time-gated and time-integrated spectra and pinhole images as well as photoconductive detectors signals were analyzed to provide information on the plasma parameters; electron temperatures and densities, implosion dynamics features and power and yields of the X-ray radiation. Previously developed non-LTE models were applied to model axially-resolved time-integrated, as well as time-gated spatially-integrated, K-shell spectra from Al and Mg. The derived time-dependent electron temperature, density and axial opacity were studied and compared. In addition, the wire ablation dynamics model (WADM) was used to calculate the kinetic energy of the plasma, which with the aid of a Local Thermal Equilibrium (LTE) magneto-hydrodynamics (MHD) simulation, allowed to estimate the precursor and stagnated z-pinch plasma electron temperatures from implosions of wire array loads.     

The effect of end conditions on the vortex-induced vibration of cylinders

In the present investigation we study the effect of end conditions on the vortex-induced vibration of an elastically mounted rigid cylinder. This work was triggered by some initial controlled vibration experiments which showed that spanwise end conditions can have a large effect on measured fluid forces on a cylinder, and this suggested that some of the disparity amongst previous free vibration studies may possibly be attributed to differences in end conditions. In the principal experiments here, we are concerned with a vertical cylinder piercing the clean free surface of a water channel, and attached to a carriage system mounted atop the channel. The upper end of the submerged cylinder is thus the free surface, while the lower end is manipulated to yield three different conditions, namely: an attached endplate; an unattached endplate fixed to the channel floor (with a variable gap between cylinder and plate); and a condition of no endplate at all. Interestingly, we find that the free vibration response for the attached and unattached endplate cases were nearly identical. One expectation was that the case without an endplate would lead to a flow around the end of the body, modifying the vortex dynamics, and thereby reducing the correlation of the induced fluid forces on the body. Surprisingly, over the entire response plot, the vibration amplitude is markedly higher in the absence of an endplate, with the exception of the peak amplitude, which remains nearly unchanged. Unexpectedly, the vibrations become much more steady at flow velocities in the vicinity of the peak response, if the endplate is removed. In a further set of experiments, we undertake controlled vibration, where we vary the gap between cylinder and endplate. We discover a large discontinuous jump in the magnitude of fluid excitation, when the gap exceeds 15% of a diameter. For larger gaps, the fluid excitation becomes independent of the gap size, effectively equivalent to having no plate at all. This study is consistent with some of the disparity between the character of vibration response plots in previous studies, if one takes into account the particular end conditions chosen in those studies.