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Author Correction: Relative configuration of micrograms of natural compounds using proton residual chemical shift anisotropy
No full textAn amendment to this paper has been published and can be accessed via a link at the top of the paper
Residual‐Chemical‐Shift‐Anisotropy‐Based Enantiodifferentiation in Lyotropic Liquid Crystalline Phases Based on Helically Chiral Polyacetylenes
Full text linkAnisotropic NMR spectroscopy, revealing residual dipolar couplings (RDCs) and residual chemical shift anisotropies (RCSAs) has emerged as a powerful tool to determine the configurations of synthetic and complex natural compounds. The deduction of the absolute in addition to the relative configuration is one of the primary goals in the field. Therefore, the investigation of the enantiodiscriminating capabilities of chiral alignment media becomes essential. While RDCs and RCSAs are now used for the determination of the relative configuration routinely, RCSAs have not been measured in chiral alignment media such as chiral liquid crystals. Herein, we present this application by measuring RCSAs for chiral analytes such as indanol and isopinocampheol in the lyotropic liquid crystalline phase of an L-valine derived helically chiral polyacetylenes. We have also demonstrated that a single 1D 13C−{1H} NMR spectrum suffices to get the RCSAs circumventing the necessity to acquire two spectra at two alignment conditions
Connection of isolated stereoclusters by combining 13C-RCSA, RDC, and J-based configurational analyses and structural revision of a tetraprenyltoluquinol chromane meroterpenoid from Sargassum muticum
Full text linkThe seaweed Sargassum muticum, collected on the southern coast of Galicia, yielded a tetraprenyltoluquinol chromane meroditerpene compound known as 1b, whose structure is revised. The relative configuration of 1b was determined by J-based configurational methodology combined with an iJ/DP4 statistical analysis and further confirmed by measuring two anisotropic properties: carbon residual chemical shift anisotropies (13C-RCSAs) and one-bond 1H-13C residual dipolar couplings (1DCH-RDCs). The absolute configuration of 1b was deduced by ECD/OR/TD-DFT methods and established as 3R,7S,11R.Agencia Estatal de Investigación (AEI) de España | Ref. RTI2018-093634-B-C22Interreg España-Portugal | Ref. 0474_BLUEBIOLAB_1_EXunta de Galicia | Ref. GRC2018/039Xunta de Galicia | Ref. ED431E 2018/03Max Planck Society | Ref. CAPES 418729698SERB, New Delhi | Ref. ECR/2017/00181
Quantification of geometric isomers of citral and minor oleochemicals in Cymbopogon flexuosus (lemongrass) and Cymbopogon nardus (citronella) essential oils by <sup>1</sup>H qNMR method
No full textThe 1H quantitative Nuclear Magnetic Resonance (qNMR) has emerged as a powerful analytical tool due to its high sensitivity, ability to provide absolute quantification, and most importantly, its univocal structural assignment. So far, 1H qNMR has been used to quantify only the major constituents of the essential oils (EOs). Since the minor constituents of the EOs play a role in its various properties, quantification of minor constituents is essential. In this study, a 1H qNMR method is developed to quantify major and minor oleochemicals in the multifaceted Cymbopogon flexuosus (lemongrass) and Cymbopogon nardus (citronella) EOs. The 1H qNMR method is validated in terms of selectivity, linearity, robustness, and accuracy/precision using the 1H NMR spectra of citral. The use of a high-field 800 MHz NMR provides high spectral resolution, allowing discrimination between closely spaced signals. This enables in-depth analysis of the complex mixtures of essential oils, facilitating the quantification of twelve distinct components, including some at concentrations in the double-digit μg range. These results align with prior reports demonstrating the suitability of high-field NMR spectrometers for accurate quantification of analytes at low μg/mL concentrations. This method demonstrates high sensitivity, with a limit of detection (LOD) of 30.09 μg/mL and a limit of quantification (LOQ) of 90.93 μg/mL. It also proves to be highly reliable, showing a coefficient of variation (CV) of less than 1% across different acquisition and processing conditions tested. The key distinction between lemongrass and citronella oils lies in their citral content, which ranges from 72 to 74% in lemongrass oil compared to only 12–18% in citronella oil. The quantification of both major as well as minor constituents highlights the applicability of the 1H qNMR method for comprehensive profiling of EOs
Multistage Detection of Tetrodotoxin Traces in Diodon hystrix Collected in El Salvador
No full textThis study describes a multistage methodology to detect minute amounts of tetrodotoxin in fishes, a plan that may be broadened to include other marine organisms. This methodology was applied to porcupinefish (Diodon hystrix) collected in Punta Chiquirín, El Salvador. A three-stage approach along with post-acquisition processing was employed, to wit: (a) Sample screening by selected reaction monitoring (HPLC-MS/MS-SRM) analyses to quickly identify possible toxin presence via a LC/MS/MS API 3200 system with a triple quadrupole; (b) HPLC-HRFTMS-full scan analyses using an ion trap-Orbitrap spectrometer combined with an MZmine 2-enhanced dereplication-like workflow to collect high-resolution mass spectra; and (c) HPLC-HRMS2 analyses. This is the first time tetrodotoxin has been reported in D. hystrix specimens collected in El Salvador
Hypalocrinins, Taurine-Conjugated Anthraquinone and Biaryl Pigments from the Deep Sea Crinoid <i>Hypalocrinus naresianus</i>
Full text linkFive new water-soluble amido- and
aminoanthraquinone pigments,
hypalocrinins A–E (1–5), the
new amidoanthraquinone biaryls hypalocrinin F (6) and
hypalocrinin G (7), and the known compounds 6-bromoemodic
acid (8), crinemodin (9), and crinemodin
sulfate (10) were isolated from the deep sea crinoid Hypalocrinus naresianus collected off Japan. The structures
of the compounds were elucidated by NMR spectroscopy and mass spectrometry.
Amido- and aminoquinones are quite unusual among natural products.
The hypalocrinins are the first naturally occurring anthraquinones
and anthraquinone biaryls conjugated with taurine
Structure and absolute configuration of phenanthro-perylene quinone pigments from the deep-sea crinoid Hypalocrinus naresianus
Full text linkTwo new water-soluble phenanthroperylene quinones, gymnochrome H (2) and monosulfated gymnochrome A (3), as well as the known compounds gymnochrome A (4) and monosulfated gymnochrome D (5) were isolated from the deep-sea crinoid Hypalocrinus naresianus, which had been collected in the deep sea of Japan. The structures of the compounds were elucidated by spectroscopic analysis including HRMS, 1D 1H and 13C NMR, and 2D NMR. The absolute configuration was determined by ECD spectroscopy, analysis of J-couplings and ROE contacts, and DFT calculations. The configuration of the axial chirality of all isolated phenanthroperylene quinones (2–5) was determined to be (P). For gymnochrome H (2) and monosulfated gymnochrome A (3), a (2′S,2″R) configuration was determined, whereas for monosulfated gymnochrome D (5) a (2′R,2″R), configuration was determined. Acetylated quinones are unusual among natural products from an echinoderm and gymnochrome H (2) together with the recently reported gymnochrome G (1) represent the first isolated acetylated phenanthroperylene quinones
Nuevos avances en la RMN anisotrópica y detección de productos naturales marinos bioactivos
Full text link[Resumen]
A continuación, se presenta un breve resumen de cada capítulo:
Capítulo 1:
El uso de RMN anisotrópica en el análisis estructural de moléculas pequeñas quirales se ha expandido en
los años recientes. En la actualidad, las Constantes Dipolares Residuales (CDR) pueden ser aplicadas como
una herramienta estándar en el mejoramiento eficiente de la determinación de la configuración relativa
de compuestos de pequeño tamaño mediante RMN estándar.
En la presente tesis doctoral hemos desarrollado otra metodología de RMN anisotrópica basada en
medidas de anisotropía de desplazamiento químico residual de protones (1H RCSA) que ha sido aplicada,
primero a moléculas modelo, estricnina, estrona, retrorsina y a-santonina, y posteriormente a nuevos
productos naturales: a un meroditerpeno aislado del alga parda Sargassum muticum, a las
tricloromammindas A y B aisladas del hongo no comestible Tricholoma equestre y, finalmente a un
briarano de origen marino aislado de la gorgonia Briareum asbestinum recolectada de la penísula de Yucatán. Toda esta nueva metodología se ha podido realizar a través de la mejora de nuevos dispositivos de
compresión y extensión de geles aplicados a tubos de RMN de menos de 5 mm. Este desarrollo de este
tipo de dispositivos es una herramienta adicional que puede ser utilizada en el futuro por
espectroscopistas en el campo de RMN anisotrópica.
Por último, también hemos introducido un nuevo gel deuterado (PMMA-d8) derivado de
polimetilmetacrilato deuterado como medio alineante. Capítulo 2:
La detección y cuantificación de productos naturales presentes en trazas en mezclas complejas es aún un
campo de investigación activo para los químicos. Desde la introducción en el mercado del detector de
masas Orbitrap® se iniciado una revolución en las técnicas analíticas de detección. En la presente Tesis
Doctoral hemos aprovechado esta tecnología para la detección y, en algunos casos, el aislamiento y la
cuantificación de algunos productos naturales de origen marino de interés biológico.
Las distintas aproximaciones en las técnicas de LC/HRMS empleadas fueron aplicadas a:
La detection y el aislamiento de la producción de sideróforos en varias bacteria marinas patógenas: tipo
vancrobactina en tres especies de Vibrio, tipo piscibactina en una cepa mutante de Vibrio alginolyticus, el
sideróforo producido por las bacterias Edwardsiella tarda y Photobacterium damselae subsp. damselae.
Detección y cuantification de AHLs en tres especies patógenas de Vibrio.
Detección de (TTX) en el pez Diodon hystrix recolectado en El Salvador.[Resumo]
A continuación amósase un resumo de cada capítulo.
Capítulo 1
O uso da RMN anisotrópica na análise estrutural de moléculas pequenas quiraies, expandiuse nos anos
recentes. Na actualidade, as Constantes Dipolares Residuais (CDR)poden ser aplicadas como unha
ferramenta estándar na millora eficiente da determinación da configuración relativa de compostos de
pequeno tamano mediante RMN estándar.
Na presente Tese Doutoral desenvolvemos outra metodoloxía de RMN anisotrópica baseada en medidas
de anisotropía de desprazamento químico residual de protones (1H RCSA) que foi aplicada, primeiro a
moléculas modelo, estricnina, estrona, retrorsina e [alfa]-santonina, e posteriormente a novos produtos
naturais: a un meroditerpeno illado do alga parda Sargassum muticum, ás tricloromammindas A e B
illadas do fungo non comestible Tricholoma equestre e, finalmente a un briarano de orixe mariña illada
da gorgonia Briareum asbestinum colleitada da penísula de Iucatán: Toda esta nova metodoloxía púidose realizar a través da mellora de novos dispositivos de compresión e
extensión de xeles aplicados a tubos de RMN de menos de 5 mm. Este desenvolvemento deste tipo de
dispositivos é unha ferramenta adicional que pode ser utilizada no futuro por espectroscopistas no campo
de RMN anisotrópica.
Por último, tamén introducimos un novo xel deuterado (PMMA-d8) derivado de polimetilmetacrilato
deuterado como medio alineante. Capítulo 2
A detección e cuantificación de produtos naturais presentes en trazas en mesturas complexas é aínda un
campo de investigación activo para os químicos. Desde a introdución no mercado do detector de masas
Orbitrap® #iniciar unha revolución nas técnicas analíticas de detección. Na presente Tese Doutoral
aproveitamos esta tecnoloxía para a detección e, nalgúns casos, o illamento e a cuantificación dalgúns
produtos naturais de orixe mariña de interese biolóxico.
As distintas aproximacións nas técnicas de LC/HRMS empregadas foron aplicadas a:
A detection e o illamento da produción de sideróforos en varias bacteria mariñas patógenas: tipo
vancrobactina en tres especies de Vibrio, tipo piscibactina nunha cepa mutante de Vibrio alginolyticus,
o sideróforo producido polas bacterias Edwardsiella tarda e Photobacterium damselae subsp. damselae.
Detección e cuantification de AHLs en tres especies patóxenas de Vibrio.
Detección de (TTX) no peixe Diodon hystrix colleitado no Salvador.[Abstract]
A summary of each chapter shall be presented below.
Chapter 1:
The use of anisotropic NMR in the structural analysis of chiral small molecules has expanded in
recent years. Currently, Residual Dipolar Constants (RDC) can be applied as a standard tool in
the efficient improvement of the determination of the relative configuration of small-sized
compounds by standard NMR.
In the present Thesis dissertation, we have developed another methodology of anisotropic NMR
based on measures of anisotropy of residual chemical proton displacement (1H RCSA) that has
been applied, firstly to compound-models, strychnine, estrone, retrorsine and [alfa]-santonin, and
subsequently to new natural products: to an isolated meroditerpene of the brown alga
Sargassum muticum, the trichloromaminades A and B isolated from the non-edible fungus
Tricholoma equestre and, finally to a briarane of marine origin isolated from the gorgonian
Briareum asbestinum collected from the peninsula of Yucatan (México). Chapter 2:
The detection and quantification of natural products present in traces in complex mixtures is still an active
field of research for chemists. Since the introduction of the Orbitrap® mass detector into the market, a
revolution in analytical detection techniques has begun. In this Doctoral Thesis we have taken advantage
of this technology for the detection and, in some cases, the isolation and quantification of natural
products of marine origin of biological interest.
The different approaches in the LC / HRMS techniques used were applied to: Detection and isolation of siderophore production in several pathogenic marine bacteria: vanchrovatin
type in three Vibrio species, piscibactin type in a mutant strain of Vibrio alginolyticus, the siderophore
produced by the bacteria Edwardsiella tarda and Photobacterium damselae subsp. damselae
Detection and quantification of AHLs in three pathogenic Vibrio species.
Detection of TTX in the fish Diodon hystrix collected in El Salvador
Relative Configuration of Micrograms of Natural Compounds Using Proton Residual Chemical Shift Anisotropy
Full text link[Abstract] 3D molecular structure determination is a challenge for organic compounds or natural products available in minute amounts. Proton/proton and proton/carbon correlations yield the constitution. J couplings and NOEs oftentimes supported by one-bond 1H,13C residual dipolar couplings (RDCs) or by 13C residual chemical shift anisotropies (RCSAs) provide the relative configuration. However, these RDCs or carbon RCSAs rely on 1% natural abundance of 13C preventing their use for compounds available only in quantities of a few 10’s of µgs. By contrast, 1H RCSAs provide similar information on spatial orientation of structural moieties within a molecule, while using the abundant 1H spin. Herein, 1H RCSAs are accurately measured using constrained aligning gels or liquid crystals and applied to the 3D structural determination of molecules with varying complexities. Even more, deuterated alignment media allow the elucidation of the relative configuration of around 35 µg of a briarane compound isolated from Briareum asbestinum.This work was supported by the Max Planck Society and grew out of a collaboration in the context of the Forschergruppe (FOR 934) continued now by the DFG (Gr1211/19–1 and Re1007/9–1)/CAPES 418729698 project. N.N. gratefully acknowledges the financial support by SERB, New Delhi for ECR Grant with File No.: ECR/2017/001811. This work was also funded by grants RTI2018-093634-B-C22 from the State Agency for Research (AEI) of Spain, both co-funded by the FEDER Programme from the European Union, BLUEBIOLAB (0474_BLUEBIOLAB_1_E), Programme INTERREG V A of Spain-Portugal (POCTEP) and GRC2018/039 and Agrupación Estratégica CICA-INIBIC ED431E 2018/03 from Xunta de Galicia. C.J., J.R., and D.P.P. acknowledge CESGA for the computational support. J.C.F. acknowledges predoctoral research stay grant Inditex-UDC. D.P.P. received a fellowship from the program National Council of Science and Technology (CONACYT) of Mexico and the Secretariat of Research, Innovation and Higher Education (SIIES) of Yucatan (Mexico). We also thank Dr. G. Jithender Reddy for one isotropic measurement. We also thank Dr. Christian Schmidt for his cooperation in the manufacturing of micro stretching device. ANV thanks CNPq for a research fellowship and financial support M(426216/2018–0)German Research Foundation; Gr1211/19–1German Research Foundation; Re1007/9–1Brasil. Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); 418729698República de la India. Science and Engineering Research Board; ECR/2017/001811Xunta de Galicia; 0474_BLUEBIOLAB_1_EXunta de Galicia; GRC2018/039Xunta de Galicia; ED431E 2018/03Brasil. Conselho Nacional de Desenvolvimento Científico e Tecnológico; M(426216/2018–0
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