Characterization of Asphaltenes Precipitated at Different Solvent Power Conditions Using Atmospheric Pressure Photoionization (APPI) and Laser Desorption Ionization (LDI) Coupled to Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR MS)

In the present work, asphaltenes obtained using different <i>n</i>-heptane/crude oil ratios (HCORs) were analyzed using atmospheric pressure photoionization (APPI) and laser desorption ionization (LDI) coupled to Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS). The main objective was to improve the understanding of the components of the crude oil that precipitate under different solvent power conditions. Analysis of the compositional distribution of the asphaltenes reveals that the decrease in solvent power produces an increase in double bond equivalent (DBE) and the number of heteroatoms per molecule, while the carbon number remains almost unaltered. This finding seems to indicate that one of the main drivers for precipitation is aromaticity as HCOR increases and, consequently, the solvent power decreases. Both APPI and LDI FT-ICR MS produce average values that describe the general tendencies obtained using other techniques. Additionally, APPI FT-ICR MS closely matches bulk data of the most aromatic asphaltenes obtained in this study

Isoflavonoids and Coumarins from <i>Glycyrrhiza uralensis</i>: Antibacterial Activity against Oral Pathogens and Conversion of Isoflavans into Isoflavan-Quinones during Purification

Phytochemical investigation of a supercritical fluid extract of <i>Glycyrrhiza uralensis</i> has led to the isolation of 20 known isoflavonoids and coumarins, and glycycarpan (<b>7</b>), a new pterocarpan. The presence of two isoflavan-quinones, licoriquinone A (<b>8</b>) and licoriquinone B (<b>9</b>), in a fraction subjected to gel filtration on Sephadex LH-20 is due to suspected metal-catalyzed oxidative degradation of licoricidin (<b>1</b>) and licorisoflavan A (<b>2</b>). The major compounds in the extract, as well as <b>8</b>, were evaluated for their ability to inhibit the growth of several major oral pathogens. Compounds <b>1</b> and <b>2</b> showed the most potent antibacterial activities, causing a marked growth inhibition of the cariogenic species <i>Streptococcus mutans</i> and <i>Streptococcus sobrinus</i> at 10 μg/mL and the periodontopathogenic species <i>Porphyromonas gingivalis</i> (at 5 μg/mL) and <i>Prevotella intermedia</i> (at 5 μg/mL for <b>1</b> and 2.5 μg/mL for <b>2</b>). Only <b>1</b> moderately inhibited growth of <i>Fusobacterium nucleatum</i> at the highest concentration tested (10 μg/mL)

High-Resolution Quantitative Metabolome Analysis of Urine by Automated Flow Injection NMR

Metabolism is essential to understand human health. To characterize human metabolism, a high-resolution read-out of the metabolic status under various physiological conditions, either in health or disease, is needed. Metabolomics offers an unprecedented approach for generating system-specific biochemical definitions of a human phenotype through the capture of a variety of metabolites in a single measurement. The emergence of large cohorts in clinical studies increases the demand of technologies able to analyze a large number of measurements, in an automated fashion, in the most robust way. NMR is an established metabolomics tool for obtaining metabolic phenotypes. Here, we describe the analysis of NMR-based urinary profiles for metabolic studies, challenged to a large human study (3007 samples). This method includes the acquisition of nuclear Overhauser effect spectroscopy one-dimensional and <i>J</i>-resolved two-dimensional (<i>J</i>-Res-2D) ¹H NMR spectra obtained on a 600 MHz spectrometer, equipped with a 120 μL flow probe, coupled to a flow-injection analysis system, in full automation under the control of a sampler manager. Samples were acquired at a throughput of ∼20 (or 40 when <i>J</i>-Res-2D is included) min/sample. The associated technical analysis error over the full series of analysis is 12%, which demonstrates the robustness of the method. With the aim to describe an overall metabolomics workflow, the quantification of 36 metabolites, mainly related to central carbon metabolism and gut microbial host cometabolism, was obtained, as well as multivariate data analysis of the full spectral profiles. The metabolic read-outs generated using our analytical workflow can therefore be considered for further pathway modeling and/or biological interpretation

EPI bond distances obtained through x-ray diffraction (Experimental) and DFT results (Calculated).

<p>Atom labels accordingly to <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0066702#pone-0066702-g004" target="_blank">Figure 4</a>.</p

Scheme of all necessary steps in obtaining Epiisopiloturine with >98% purity from Jaborandi leaves.

<p>Scheme of all necessary steps in obtaining Epiisopiloturine with >98% purity from Jaborandi leaves.</p

Mass spectrum obtained from ESI+/Ion Trap.

<p>(A) free EPI with a pseudo molecular ion m/z 287.1 Da [M+H]⁺, (B) MS² with characteristic fragment at m/z 269.1 Da [M – H₂O + H]⁺, (C) MS³ with fragments at m/z 251.0 Da [M – 2H₂O + H⁺] and 168.06 Da with proposed chemical structure.</p

Analytical HPLC used LiChrospher 60 RP column and eluted with potassium phosphate

<p>. (A) Standard EPI (20 µg/mL), (B) Standard pilocarpine (50 µg/mL), (C) “cultivated jaborandi leaves” solution, resulted from first extraction step, (D) “cultivated jaborandi acid” solution, obtained EPI under salt form, (E) Solution of “crude EPI” with some impurities as pilocarpine and other alkaloids, (F) last step of isolation showing EPI >98% purity.</p

Infrared (IR) and Raman wavenumbers (cm⁻¹) of solid state EPI.

<p>Calculated vibrational wavenumbers (cm-1) for the isolated EPI molecule. A tentative assignment of the observed vibrational modes is also shown. See text for theoretical details. ν =  stretching, δ =  bending, β =  bending in plane, γ =  bending out of plane, r =  rocking, τ =  twist, sc =  scissoring, ω =  wagging, νs =  symmetric stretching, νa =  antisymmetric stretching, sh  =  shoulder.</p

Epiisopiloturine FT-IR spectra: A) experimental and B) calculated.

<p>Epiisopiloturine FT-IR spectra: A) experimental and B) calculated.</p

Isolated Epiisopiloturine molecular structure.

<p>Isolated Epiisopiloturine molecular structure.</p