LC–HRMS and Chemical Derivatization Strategies for the Structure Elucidation of Caribbean Ciguatoxins: Identification of C-CTX-3 and -4

Ciguatera poisoning is linked to the ingestion of seafood that is contaminated with ciguatoxins (CTXs). The structural variability of these polyether toxins in nature remains poorly understood due to the low concentrations present even in highly toxic fish, which makes isolation and chemical characterization difficult. We studied the mass spectrometric fragmentation of Caribbean CTXs, i.e., the epimers C-CTX-1 and -2 (1 and 2), using a sensitive UHPLC–HRMS/MS approach in order to identify product ions of diagnostic value. We found that the fragmentation of the ladder-frame backbone follows a characteristic pattern and propose a generalized nomenclature for the ions formed. These data were applied to the structural characterization of a pair of so far poorly characterized isomers, C-CTX-3 and -4 (3 and 4), which we found to be reduced at C-56 relative to 1 and 2. Furthermore, we tested and applied reduction and oxidation reactions, monitored by LC–HRMS, in order to confirm the structures of 3 and 4. Reduction of 1 and 2 with NaBH4 afforded 3 and 4, thereby unambiguously confirming the identities of 3 and 4. In summary, this work provides a foundation for mass spectrometry-based characterization of new C-CTXs, including a suite of simple chemical reactions to assist the examination of structural modifications.

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Ammonia RF−Plasma on PTFE Surfaces: Chemical Characterization of the Species Created on the Surface by Vapor−Phase Chemical Derivatization

The Journal of Physical Chemistry B ◽

10.1021/jp011607k ◽

2001 ◽

Vol 105 (50) ◽

pp. 12490-12497 ◽

Cited By ~ 93

Author(s):

P. Chevallier ◽

M. Castonguay ◽

S. Turgeon ◽

N. Dubrulle ◽

D. Mantovani ◽

...

Keyword(s):

Vapor Phase ◽

Chemical Characterization ◽

Rf Plasma ◽

Chemical Derivatization ◽

Phase Chemical

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Stereoselective Synthesis of Novel Sphingoid Bases Utilized for Exploring the Secrets of Sphinx

International Journal of Molecular Sciences ◽

10.3390/ijms22158171 ◽

2021 ◽

Vol 22 (15) ◽

pp. 8171

Author(s):

Essa M. Saied ◽

Christoph Arenz

Keyword(s):

Plasma Membranes ◽

Stereoselective Synthesis ◽

Chemical Characterization ◽

Great Promise ◽

Sphingoid Bases ◽

Animal Physiology ◽

Pathological Conditions ◽

Low Concentrations ◽

Derivatives Of

Sphingolipids are ubiquitous in eukaryotic plasma membranes and play major roles in human and animal physiology and disease. This class of lipids is usually defined as being derivatives of sphingosine, a long-chain 1,3-dihydroxy-2-amino alcohol. Various pathological conditions such as diabetes or neuropathy have been associated with changes in the sphingolipidome and an increased biosynthesis of structurally altered non-canonical sphingolipid derivatives. These unusual or non-canonical sphingolipids hold great promise as potential diagnostic markers. However, due to their low concentrations and the unavailability of suitable standards, the research to explore the secret of this class of ‘Sphinx’ lipids is ultimately hampered. Therefore, the development of efficient and facile syntheses of standard compounds is a key endeavor. Here, we present various chemical approaches for stereoselective synthesis and in-depth chemical characterization of a set of novel sphingoid bases which were recently utilized as valuable tools to explore the metabolism and biophysical properties of sphingolipids, but also to develop efficient analytical methods for their detection and quantification.

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Chemical Characterization of Kraft Lignin Prepared from Mixed Hardwoods

Molecules ◽

10.3390/molecules26164861 ◽

2021 ◽

Vol 26 (16) ◽

pp. 4861

Author(s):

Ji-Sun Mun ◽

Justin-Alfred Pe Pe III ◽

Sung-Phil Mun

Keyword(s):

Carbon Content ◽

Structural Changes ◽

Chemical Characterization ◽

Structural Features ◽

Kraft Lignin ◽

Kraft Pulping ◽

Nucleophilic Attack ◽

Low Oxygen ◽

Structural Modifications

Chemical characterization of kraft lignin (KL) from mixed hardwoods (Acacia spp. from Vietnam and mixed hardwoods (mainly Quercus spp.) from Korea) was conducted for its future applications. To compare the structural changes that occurred in KL, two milled wood lignins (MWLs) were prepared from the same hardwood samples used in the production of KL. Elemental analysis showed that the MWL from acacia (MWL-aca) and mixed hardwood (MWL-mhw) had almost similar carbon content, methoxyl content, and C9 formula. KL had high carbon content but low oxygen and methoxyl contents compared to MWLs. The C9 formula of KL was determined to be C9H7.29O2.26N0.07S0.12(OCH3)1.24. The Mw of KL and MWLs was about 3000 Da and 12,000–13,000 Da, respectively. The structural features of KL and MWLs were investigated by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectrometry (1H, 13C NMR). The analyses indicated that KL underwent severe structural modifications, such as γ-carbon cleavage, demethylation, and polycondensation reactions during kraft pulping, which resulted in increased aromatic content and decreased aliphatic content. The main linkages in lignin, β-O-4 moieties, were hardly detected in the analysis as these linkages were extensively cleaved by nucleophilic attack of SH- and OH- during pulping.

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Physical-Chemical Characterization and Mineralogic Analysis of Hydrothermal Systems Located in the Coconuco and the San Juan Sectors in Cauca, Colombia

Geofluids ◽

10.1155/2019/9176925 ◽

2019 ◽

Vol 2019 ◽

pp. 1-19

Author(s):

Darwin Augusto Torres-Ceron ◽

Carlos Daniel Acosta-Medina ◽

Elisabeth Restrepo-Parra

Keyword(s):

Hot Springs ◽

Major Ions ◽

Hot Spring ◽

Volcanic Rocks ◽

Chemical Characterization ◽

Hydrothermal Systems ◽

San Juan ◽

Low Concentrations ◽

Agricultural Applications

Hot springs of the volcanic zones are characterized for having high sulfur content in the form of sulphate and other ions resulting from chemical reactions. Sources with these types of elements are of great interest for the tourism and geothermal industry because of their highlighted properties which include therapeutic treatments, relaxation baths, agricultural applications, and preservation of flora and fauna among others. For these reasons, research oriented to carry out the characterization of these factors is of great importance to determine the availability of places with such characteristics. This work shows the characterization of 17 hot spring sources located in the Coconuco and San Juan sectors (Cauca, Colombia, South America). Water samples were taken in May 2017, and laboratory analyses were carried out by the Water Laboratory at Universidad Nacional de Colombia-Manizales, based on the Standard Methods (APHA-AWWA-WEF). Rock samples were taken in November 2017, and laboratory analyses were carried out by the GMAS+ Laboratory (Bogotá, Colombia). The Piper, Stiff, and ternary (Giggenbach) diagrams were used for the classification of major ions. Mineralogy composition was determined through XRD and XRF. Results indicate that most sources are of the sulphated type according to the anions and of the calcium type according to the cations. In concordance with Giggenbach diagrams, most of the sources are immature waters and, despite their interaction with rocks, they have not achieved the equilibrium. Likewise, these sources are of heated vapor type and, considering that they consist of sulphated acid sources, it is not possible to evaluate the reservoir temperatures from Na/K cations. The low Ca2+/Mg2+ ratio in the sources indicates the lack of direct migration of fluids and the high content of Ca2+ and Mg2+ regarding Na+ and K+, which suggests that fluids possibly are mixed with cold waters rich in Ca2+ and Mg2+. From the mineralogic characterization, it was observed that volcanic rocks are composed of cristobalite and albite with TiO2, Fe2O3, and CaO traces and mineral sulfur. Metals like Cr, considered in this case as contaminants, are found in low concentrations in rocks and are not detected in these waters.

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Use of cooling tower blow down in ethanol fermentation

Water Science & Technology ◽

10.2166/wst.2010.507 ◽

2010 ◽

Vol 62 (10) ◽

pp. 2263-2269 ◽

Cited By ~ 1

Author(s):

N. Rajagopalan ◽

V. Singh ◽

B. Panno ◽

M. Wilcoxon

Keyword(s):

Water Consumption ◽

Cooling Tower ◽

Chemical Characterization ◽

Production Costs ◽

Blow Down ◽

Good Tolerance ◽

Low Concentrations ◽

Residual Glucose ◽

Control Study

Reducing water consumption in bioethanol production conserves an increasingly scarce natural resource, lowers production costs, and minimizes effluent management issues. The suitability of cooling tower blow down water for reuse in fermentation was investigated as a means to lower water consumption. Extensive chemical characterization of the blow down water revealed low concentrations of toxic elements and total dissolved solids. Fermentation carried out with cooling tower blow down water resulted in similar levels of ethanol and residual glucose as a control study using deionized water. The study noted good tolerance by yeast to the specific scale and corrosion inhibitors found in the cooling tower blow down water. This research indicates that, under appropriate conditions, reuse of blow down water from cooling towers in fermentation is feasible.

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Olfactory and Chemical Characterization of Indoor Air-Towards a Psychophysical Model for Air Quality

PsycEXTRA Dataset ◽

10.1037/e612282010-001 ◽

1981 ◽

Author(s):

Birgitta Berglund ◽

Ulf Berglund ◽

Thomas Lindvall ◽

Helene Nicander-Bredberg

Keyword(s):

Air Quality ◽

Indoor Air ◽

Chemical Characterization

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The physical and chemical characterization of active carbons, by adsorption and immersion techniques

Journal de Chimie Physique ◽

10.1051/jcp/1984810785 ◽

1984 ◽

Vol 81 ◽

pp. 785-790 ◽

Cited By ~ 9

Author(s):

F. Stoeckli ◽

F. Kraehenbuehl ◽

A. Lavanchy ◽

U. Huber

Keyword(s):

Chemical Characterization ◽

Active Carbons ◽

Physical And Chemical Characterization ◽

Physical And Chemical

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Biological and physico-chemical characterization of ultra high diluted Hydrastis canadensis and in vitro studies on mammalian cells

Allgemeine Homöopathische Zeitung ◽

10.1055/s-0037-1601241 ◽

2017 ◽

Vol 262 (02) ◽

pp. 2-76

Author(s):

N Chandrakar ◽

MK Temgire ◽

SG Kane ◽

AK Suresh ◽

J Bellare

Keyword(s):

Mammalian Cells ◽

Chemical Characterization ◽

In Vitro Studies ◽

Hydrastis Canadensis ◽

Physico Chemical

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PURIFICATION AND PARTIAL CHEMICAL CHARACTERIZATION OF SHEEP NEUROPHYSIN

Acta Endocrinologica ◽

10.1530/acta.0.0740226 ◽

1973 ◽

Vol 74 (2) ◽

pp. 226-236 ◽

Cited By ~ 6

Author(s):

Michel Chrétien ◽

Claude Gilardeau

Keyword(s):

Amino Acid ◽

Polyacrylamide Gel Electrophoresis ◽

Chemical Characterization ◽

Terminal Amino Acid ◽

Amino Acid Determination ◽

Pituitary Glands ◽

Terminal Amino ◽

Partial Chemical ◽

Acid Determination

ABSTRACT A protein isolated from ovine pituitary glands has been purified, and its homogeneity assessed by NH2- and COOH-terminal amino acid determination, ultracentrifugation studies, and polyacrylamide gel electrophoresis after carboxymethylation. Its chemical and immunochemical properties are closely similar to those of beef and pork neurophysins, less similar to those of human neurophysins. It contains no tryptophan (like other neurophysins) or histidine (like all except bovine neurophysin-I and human neurophysins). It has alanine at the NH2-terminus and valine at the COOH-terminus. Its amino acid composition is similar to, but not identical with those of porcine and bovine neurophysins.

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