CARACTERIZACIÓN QUÍMICA Y FUNCIONAL DE METABOLITOS ANTIMICROBIANOS AISLADOS DE ASCIDIAN RHOPALAEA BIRKELANDI

Marine ecosystems have a very large diversity of resources, most of them still partially unknown, and a few others exploited for development of new industrial and toxicological products. The objective of this investigation was to determine whether the acetone extract of the ascidia R. birkelandi from the Pacific coast of Costa Rica showed qualitative antimicrobial activity against the S. aureus bacteria and the G. candidum fungus, and to verify their main secondary metabolites in the active extract using chromatographic and spectroscopic techniques. Ascidians were collected at Tambor, Guanacaste, Costa Rica, between December 2007 and March 2008. Activity against the Gram positive bacteria and fungi was evaluated using ethanolic (95%) and acetonic extracts. Both extracts showed activity against G. candidum; however, only the acetonic extract showed activity against S. aureus. A coumarin and a hydroxyanthraquinone were isolated from a crude extract of R. birkelandi as metabolites present in the active fraction. Purification and isolation were performed by chromatographic techniques and solid phase extraction. Structural information was obtained by spectroscopic analyses: Ultraviolet (UV-Visible), Fourier Transform Infrared (FT-IR), Liquid Chromatography Tandem Mass Spectrometry (LC/MS/MS), Gas Chromatography Mass Spectrometry (GC/MS), Proton Nuclear Magnetic Resonance (1HNMR), and Carbon-13 Magnetic Resonance (13C-NMR). Further studies are recommended for characterization and quantification of the active components of this extract and the possible elucidation of the mechanisms of action. Los ecosistemas marinos poseen una gran cantidad de recursos, muchos de ellos todavía desconocidos y muy pocos de ellos explotados para el desarrollo de nuevos productos industriales y toxicológicos. Los objetivos de esta investigación fueron determinar si el extracto acetónico de la ascidia R. birkelandi de la costa pacífica de Costa Rica presenta actividad antimicrobial cualitativa contra la bacteria S. aureus y el hongo G. candidum, y determinar por técnicas cromatográficas y espectroscópicas los metabolitos secundarios principales presentes en el extracto activo. Se recolectó la ascidia en la zona de Tambor en la provincia de Guanacaste, Costa Rica, entre los meses de diciembre del 2007 y marzo del 2008. Se realizaron extractos crudos en acetona y etanol al 95% para evaluar la actividad contra una bacteria Gram positiva y un hongo. Ambos extractos presentaron actividad contra G. candidum, pero solo el extracto acetónico mostró actividad contra S. aureus. Se logró aislar y caracterizar una cumarina y una hidroxiantraquinona del extracto crudo de R. birkelandi como metabolitos presentes en la fracción responsable de la actividad biológica presentada. La purificación y el aislamiento fueron llevados a cabo con técnicas cromatográficas y de extracción en fase sólida. La información estructural fue obtenida por análisis espectroscópicos: Ultravioleta (UV-Visible), Infrarrojo con Transformada de Fourier (FT-IR), Cromatografía Líquida acoplada a Espectrometría de Masas (LC/MS/MS), Cromatografía de Gases acoplada a Masas (GC-MS), Resonancia Magnética Nuclear de Protón (1H-NMR) y Resonancia Magnética de Carbono 13 (13C-NMR). Se recomiendan estudios futuros para la caracterización y la cuantificación de los principios activos de este extracto y una posible elucidación de sus mecanismos de acción.

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Synthesis and structural characterization of organotin(IV) complexes formed with [o,o] donor atoms of carboxylic acids

Journal of the Serbian Chemical Society ◽

10.2298/jsc0802179h ◽

2008 ◽

Vol 73 (2) ◽

pp. 179-187 ◽

Cited By ~ 9

Author(s):

Mukhtiar Hussain ◽

Muhammad Zaman ◽

Muhammad Hanif ◽

Saqib Ali ◽

Muhammad Danish

Keyword(s):

Mass Spectrometry ◽

Elevated Temperature ◽

13C Nmr ◽

Solid Phase ◽

Spectroscopic Techniques ◽

Tetrahedral Geometry ◽

Distorted Tetrahedral Geometry ◽

Trigonal Bipyramidal ◽

Ft Ir

Organotin(IV) carboxylates of the general formula RnSnL4-n (where R = Me, n-Bu or Ph, and L = ?-phenyl-2,3-(methylenedioxy)cinnamate anion or 2-(2,3-dimethlylanilino)nicotinate anion) have been prepared. The mono-, di- and tri-organotin(IV) carboxylates were synthesized by the reaction of organotin(IV) oxides or hydroxides with a stoichiometric amount of the ligand acids at an elevated temperature in dry toluene. The composition of the synthesized organotin(IV) complexes, the bonding behavior of the donor groups and structural assignments were studied by elemental analysis, FT-IR, 1H-, 13C-NMR and mass spectrometry. The spectral data suggest that the ligand acts in a bidentate manner, coordinating through the oxygen atoms. These spectroscopic techniques revealed a distorted tetrahedral geometry in the solution state for the tri-organotins, while a mean coordination number between five to six for the diorganotin(IV) dicarboxylates. In the solid phase, the tri-organotins were essentially trigonal bipyramidal polymeric while the di-organotins were octa?hedral. However, mono-organotin tricarboxylates were predicted to exist in the octahedral state both in solution as well as in the solid phase.

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ISOLATION OF 2-CHLOROBENZIMIDAZOLE FROM MELIA DUBIA LEAF EXTRACT AND ITS STRUCTURAL CHARACTERISATION

International Journal of Pharmacy and Pharmaceutical Sciences ◽

10.22159/ijpps.2017v9i10.20573 ◽

2017 ◽

Vol 9 (10) ◽

pp. 67 ◽

Cited By ~ 2

Author(s):

G. Dayana Jeyaleela ◽

S. Irudaya Monisha ◽

J. Rosaline Vimala ◽

A. Anitha Immaculate

Keyword(s):

Mass Spectrometry ◽

1H Nmr ◽

Research Work ◽

Proton Nuclear Magnetic Resonance ◽

Resonance Spectroscopy ◽

Ft Ir ◽

Uv Visible ◽

Isolated Compound ◽

Promising Source

Objective: Natural products from medicinal plants, either as isolated compounds or as standardized plant extracts exhibit promising source of medicinal activity against various diseases. The aim of the present work was to make an attempt of isolation of bioactive principle and characterization of the isolated compound, from the medicinal plant Melia dubaiMethods: The extraction was done by a cold percolation method and the compound was separated and isolated by chromatography technique such as a thin layer chromatography (TLC), column chromatography and high-performance liquid chromatography (HPLC). The isolated compound was crystallized and the structural characterization of the isolated compound was made using UV-Visible, FT-IR, 1H-NMR, GC-MS and MS techniques which confirmed the structure of the isolated compound.Results: The separated and isolated compound was characterized by both physical and spectral methods like Ultraviolet-Visible spectroscopy (UV-Visible), Fourier transform infrared spectroscopy (FT-IR), Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), Gas chromatography-mass spectrometry (GC-MS), and Mass spectrometry(MS). Based on the studies, organizational characteristics of one bioactive principle were deciphered. The results revealed that the isolated species is 2-chlorobenzimidazole and it agreed well with the reported value and spectra for 2-chlorobenzimidazole.Conclusion: The above results obtained in this research work clearly indicated the promising occurrence of 2-chlorobenzimidazole in Media dubia plant leaves. The future scope of these studies may guide us to view the biological activity of the isolated compound.

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A novel carborane-containing ceramic precursor: Synthesis, characterization, and ceramic conversion mechanism

High Performance Polymers ◽

10.1177/0954008318788389 ◽

2018 ◽

Vol 31 (6) ◽

pp. 694-706 ◽

Cited By ~ 1

Author(s):

Dejin Tong ◽

Haipeng Wang ◽

Lei Chen ◽

Lei Wang ◽

Zhanxiong Li

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Oxidative Stability ◽

Energy Demand ◽

Proton Nuclear Magnetic Resonance ◽

Gas Chromatography Mass Spectrometry ◽

Linear Polymers ◽

Model Free ◽

Ft Ir ◽

Nuclear Magnetic

Linear carborane-carbosilane-phenylacetylene polymers have been synthesized as precursors for ceramic and characterized by Fourier transform infrared (FT-IR), proton nuclear magnetic resonance (1H-NMR), and carbon-nuclear magnetic resonance (13C-NMR). Novel linear polymers have the advantage of being extremely easy to process and convert into ceramics, since they are either viscous liquids or low melting solids at room temperature and are soluble in most organic solvents. Ceramic conversion reaction of the polymers was studied, and the conversion mechanism using thermogravimetric analyzer, FT-IR, and pyrolysis-gas chromatography-mass spectrometry was proposed. During the early heating period in the mechanism, the precursor polymer is cured and oligomer is formed. Then the degradation of oligomer takes place at higher temperatures with the weak bond cleaved and cross-linked simultaneously. Ceramic yield of the polymer after heating up to 1000°C in nitrogen (N2) was 77.6%. The derived ceramics exhibit excellent thermal and thermo-oxidative stability, whose 5% mass loss temperature was identified to be 650°C in N2 and 665°C in air, respectively. Boron appears to be the key element to achieve the outstanding thermo-oxidative stability. The relevant kinetic data were obtained by two kinds of model-free-kinetic algorithms, differential Friedman and integral Kissinger–Akahira–Sunose. These two methods were combined to give the energy profile, which has been identified to be a function of the transformation degree ( α), since the energy demand at each degradation stage is different depending on α.

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Development and Evaluation of a HS-SPME GC-MS Method for Determining the Retention of Volatile Phenols by Cyclodextrin in Model Wine

Molecules ◽

10.3390/molecules24193432 ◽

2019 ◽

Vol 24 (19) ◽

pp. 3432 ◽

Cited By ~ 3

Author(s):

Chao Dang ◽

Kerry L. Wilkinson ◽

Vladimir Jiranek ◽

Dennis K. Taylor

Keyword(s):

Mass Spectrometry ◽

Nuclear Magnetic Resonance ◽

Gas Chromatography ◽

Liquid Phase ◽

Magnetic Resonance ◽

Solid Phase Microextraction ◽

Nmr Spectra ◽

Solid Phase ◽

Gas Chromatography Mass Spectrometry ◽

Volatile Phenols

Volatile phenols exist in wine and can be markers for Brettanomyces and smoke taint off-odors. Cyclodextrins (CDs) are found to be capable of forming inclusion complexes with volatile phenols. Cross peaks on 2D 1H ROESY nuclear magnetic resonance (NMR) spectra demonstrated inclusion of volatile phenols in the β-CD cavity, while difference tests confirmed this resulted in a perceptible reduction of their sensory impact. However, a conventional headspace solid phase microextraction (HS-SPME) method using an isotopically labelled normalizing standard failed to quantify the residual volatile phenols by gas chromatography-mass spectrometry (GC-MS) because of inclusion of the standard by the CDs. A new method involving an additional liquid phase was developed and validated for quantitation of volatile phenols in the presence of CDs. The retention of eight volatile phenols by α-, β-, and γ-CD was subsequently studied.

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Yield and Selectivity Improvement in the Synthesis of Carbonated Linseed Oil by Catalytic Conversion of Carbon Dioxide

Polymers ◽

10.3390/polym13060852 ◽

2021 ◽

Vol 13 (6) ◽

pp. 852

Author(s):

David Alejandro González Martínez ◽

Enrique Vigueras Santiago ◽

Susana Hernández López

Keyword(s):

Carbon Dioxide ◽

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

13C Nmr ◽

Catalyst Concentration ◽

Linseed Oil ◽

Proton Nuclear Magnetic Resonance ◽

Ft Ir ◽

Epoxidized Linseed Oil ◽

Nuclear Magnetic

Carbonation of epoxidized linseed oil (CELO) containing five-membered cyclic carbonate (CC5) groups has been optimized to 95% by reacting epoxidized linseed oil (ELO) with carbon dioxide (CO2) and tetrabutylammonium bromide (TBAB) as catalysts. The effect of reaction variables (temperature, CO2 pressure, and catalyst concentration) on the reaction parameters (conversion, carbonation and selectivity) in an autoclave system was investigated. The reactions were monitored, and the products were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), carbon-13 nuclear magnetic resonance (13C-NMR) and proton nuclear magnetic resonance (1H-NMR) spectroscopies. The results showed that when carrying out the reaction at high temperature (from 90 °C to 120 °C) and CO2 pressure (60–120 psi), the reaction’s conversion improves; however, the selectivity of the reaction decreases due to the promotion of side reactions. Regarding the catalyst, increasing the TBAB concentration from 2.0 to 5.0 w/w% favors selectivity. The presence of a secondary mechanism is based on the formation of a carboxylate ion, which was formed due to the interaction of CO2 with the catalyst and was demonstrated through 13C-NMR and FT-IR. The combination of these factors makes it possible to obtain the largest conversion (96%), carbonation (95%), and selectivity (99%) values reported until now, which are obtained at low temperature (90 °C), low pressure (60 psi) and high catalyst concentration (5.0% TBAB).

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The regioselective catalyst-free synthesis of bis-quinoxalines and bis-pyrido[2,3-b]pyrazines by double condensation of 1,4-phenylene-bis-glyoxal with 1,2-diamines

Heterocyclic Communications ◽

10.1515/hc-2018-0039 ◽

2018 ◽

Vol 24 (4) ◽

pp. 193-196 ◽

Cited By ~ 3

Author(s):

Mehdi Ahmadi Sabegh ◽

Jabbar Khalafy

Keyword(s):

Mass Spectrometry ◽

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

New Products ◽

Proton Nuclear Magnetic Resonance ◽

Efficient Synthesis ◽

H Nmr ◽

Ft Ir ◽

C Nmr ◽

Nuclear Magnetic

AbstractThe oxidation of 1,4-diacetylbenzene using several oxidizing agents gave 1,4-phenylene-bis-glyoxal in 61–85% yields. A convenient and efficient synthesis of bis-quinoxaline and bis-pyrido[2,3-b]pyrazine derivatives involves the double condensation of 1,2-diamines with 1,4-phenylene-bis-glyoxal in ethanol under reflux conditions. The structures of the new products were defined by proton nuclear magnetic resonance (1H NMR), carbon-13 nuclear magnetic resonance (13C NMR), Fourier-transform infrared spectroscopy (FT-IR) and mass spectrometry (MS).

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Reactions of MoOCl4 and MoO2Cl2 with Heterocyclic Thioamides

Oriental Journal Of Chemistry ◽

10.13005/ojc/370228 ◽

2021 ◽

Vol 37 (2) ◽

pp. 459-466

Author(s):

Deepika Rani ◽

Gursharan Singh ◽

Seema Sharma

Keyword(s):

Mass Spectrometry ◽

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Nitrogen Atmosphere ◽

Proton Nuclear Magnetic Resonance ◽

Gas Chromatography Mass Spectrometry ◽

Vacuum Line ◽

13C Nuclear Magnetic Resonance ◽

Nuclear Magnetic

MoOCl4/MoO2Cl2 were reacted with 2-mercaptopyridine (IUPAC: pyridine-2-thiol)/4-phenylimidazole-2-thiol (IUPAC: 4-phenyl-1, 3-dihydroimidazole-2-thione)/6-mercaptopurine (IUPAC: 1, 7-dihydro-purine-6-thione) in acetonitrile medium using equal/twice molar concentrations at normal temperature. The reactions yielded products: MoOCl3(C5H4NS-SNH4C5).2HCl, [1]; Mo3O3Cl12(C5H4NS-SNH4C5)(CH3CN)2, [2]; Mo2OCl6(C9H7N2S)4, [3] and Mo2O2Cl8(C5H4N4S)(CH3CN), [4]. The various techniques used for characterization of compounds are: Fourier transform infrared, proton nuclear magnetic resonance, 13C nuclear magnetic resonance, liquid/gas chromatography mass spectrometry and C, H, N, S, Mo, Cl analysis. The products are prone to oxidation/hydrolysis by air/moisture, so all procedures were executed in vacuum line using dry nitrogen atmosphere. Elemental analysis and fragments recorded in mass spectrometry are in tune with the formulae proposed.

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