Search results for "Spectroscopy"

Low temperature optical spectroscopy of cobalt-substituted hemocyanin from Carcinus maenas

1993

In this work we report the optical absorption spectra of three cobalt-substituted derivatives of hemocyanin (He) from Carcinus maenas, in the temperature range 300–20 K. The derivatives studied are the mononuclear (Co2+)-He with a single cobalt ion in the “CuA” site, the binuclear (Co2+)2-He and the binuclear mixed metal (Co2+-Cu1+)-He. At low temperature three main bands are clearly resolved; the temperature dependence of their zeroth, first and second moments sheds light on the stereodynamic properties in the surroundings of the chromophore. Within the limits of the reported analysis, in the binuclear derivatives the motions coupled to the chromophore appear to be “essentially harmonic” i…

Effect of organic matrices on the determination of the trace element chemistry (Mg, Sr, Mg/Ca, Sr/Ca) of aragonitic bivalve shells (<i>Arctica …

2010

The element chemistry of biogenic carbonates can provide important data on past environments. However, the Sr/Ca and Mg/Ca ratios as well as the Mg and Sr concentrations of biological carbonates, especially aragonitic bivalves often depart from apparent thermodynamic equilibrium. When measured in situ by means of LA-ICP-MS, the Mg concentration is often substantially enriched (two- to threefold) near the organic-rich, annual growth lines. To test the hypothesis that some organic components exert a major influence on the skeletal metal content, the element chemistry of different shell components (insoluble organic matrix, IOM; dissolved CaCO3 and soluble organics, SOM) of Arctica islandica w…

Protection of living yeast cells by micro-organized shells of natural polyelectrolytes

2015

International audience; Saccharomyces cerevisiae, a eukaryotic model organism, plays a key role in the oxidative stability of fermented products. In order to protect cells against environmental stresses, we report a method of modifying the cell surface architecture while maintaining the internal working properties of the system. The objective was to encapsulate living yeast cells in micro-organized polyelectrolyte shells using layer-by-layer (LbL) assembly. For the first time, the natural polyelectrolytes, β-lactoglobulin and sodium alginate, were alternately deposited on the surface of S. cerevisiae. Transmission electron microscopy coupled with immune-cytochemistry and scanning electron m…

Near infrared reflectance spectroscopy (NIRS) characterization of European sea bass (Dicentrarchus labrax) from different rearing systems

2009

The present study aimed to predict by NIRS the proximate chemical composition and some carcass traits of sea bass coming from 11 farms with different rearing systems (extensive, intensive in land-based basins, sea cages) and located in northern (Friuli, Veneto), central (Tuscany) and southern (Puglia and Sicily) Italy. NIRS analysis of freeze dried sea bass fillets gave fairly good predictions of slaughter weight and fillet yield (R2cv=0.48-0.55), while results for carcass yield were poor. NIRS analysis was highly predictive for the condition factor (R2cv=0.790, SECV=0.09) and for water, ether extract and gross energy showing high correlations (R2cv>0.90) with NIR spectral infor- mation and…

New bioactive alkaloids from the marine sponge Stylissa sp.

2012

Abstract Chemical investigation of the Indonesian marine sponge Stylissa species, which was collected at 2008 from Derawan Islands, Berau, NE Kalimantan, Indonesia offered four new brominated alkaloids, including 12-N-methyl stevensine (1), 12-N-methyl-2-debromostevensine (2), 3-debromolatonduine B methyl ester (3), 3-debromolatonduine A (4) together with eight known alkaloids identified as Z-hymenialdisine, Z-debromohymenialdisine, Stevensine, 2-debromostevensine, 3-bromoaldizine, 3,4-dibromopyrrole-2-carbamide, latonduine A, and latonduine B methyl ester (5–12), respectively. The structures of all isolated compounds were unambiguously elucidated based on extensive 1D and 2D NMR spectrosco…

Expanding the chemical diversity of an endophytic fungus Bulgaria inquinans, an ascomycete associated with mistletoe, through an OSMAC approach

2019

An endophytic fungus Bulgaria inquinans (isolate MSp3-1), isolated from mistletoe (Viscum album), was subjected to fermentation on solid Czapek medium. Chromatographic workup of the crude EtOAc extract yielded five new natural products (1–5). Subsequent application of the “One Strain, MAny Compounds” (OSMAC) strategy on this strain by the addition of a mixture of salts (MgSO4, NaNO3 and NaCl) to solid Czapek medium induced the accumulation of nine additional new secondary metabolites (6–13, 16), with most of them (8, 10–12) not detectable in cultures lacking the salt mixture. The structures of the new compounds were established on the basis of the 1D/2D NMR and HRESIMS data. The TDDFT-ECD m…

Archaea Analogue Thiolipids for Tethered Bilayer Lipid Membranes on Ultrasmooth Gold Surfaces

2003

Polyketides and nitrogenous metabolites from the endophytic fungus Phomopsis sp. D15a2a

2019

Abstract Three new polyketides, phomopones A−C (1–3), one new cyclic tetrapeptide, 18-hydroxydihydrotentoxin (4), and a new amide, 6-hydroxyenamidin (5) together with a known derivative, enamindin (6) were obtained from the endophytic fungus Phomopsis sp. D15a2a isolated from the plant Alternanthera bettzickiana. The structures of the new compounds were elucidated by 1D, 2D NMR and HRMS data. The absolute configurations of the isolated metabolites were determined either by X-ray crystallography, Marfey’s method or by converting the compounds to Mosher esters.

Two new diterpenoids from kencur (Kaempferia galanga): Structure elucidation and chemosystematic significance

2021

Abstract Aromatic ginger or kencur (Kaempferia galanga L.) rhizomes are ground as a spice or pickled for consumption in south-east Asian cuisines; although widely used, until recently it has been less studied chemically than white and red ginger. Hydro-distillate extracts have identified several compounds that exhibit anticancer activity against select tumor cell lines in vitro, and most recently chemical analyses have focused on rhizome metabolites present in organic extracts. Here we report on two new diterpenoids including Δ8(14),15 polyhydroxlated isopimardienes, 1α-hydroperoxy-2α,6,7-trihydroxy-isopimara-6(7),8(14),15-triene (kaemgalangol E; 1) and 1α,7β-hydroxy-isopimara-8(14),15-dien…

Cytosensing of cancer cells using antibody-based molecular imprinting: A short-review

2018

Abstract Rapid and effective differentiation between normal and cancer cells is an important objective for the diagnosis, prognosis and theranosis of tumors. This short review highlights some of the most recent developments on the application of molecular bioimprinting in detection of cancer cells using antibody-based cancer cell recognition method. The particular emphasis of this review is on sample-to-answer devices and approaches that enable down-stream investigation of the properties of the cells. Given the speed, portability, sensitivity and selectivity achieved using molecular bioimprinting technology on cancer cell monitoring, these methods hold the promise of transformative change i…