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Port Glasgow, United Kingdom

Adilia Lemos M.,University of Abertay Dundee | Hungerford G.,HORIBA Jobin Yvon IBH Ltd.
Photochemistry and Photobiology | Year: 2013

Turmeric (Curcuma longa L.) is obtained from the rhizome of the Zingberaceae family and has a long history as an ingredient in cooking. It has been used as a dye and recently research has concentrated on its possible health benefits, specifically because of its antioxidant activity. The principal compound that is responsible for this activity is curcumin, which is present with the other curcuminoids; demethoxycurcumin and bisdemethoxycurcumin. Curcumin exhibits fluorescence and its photophysics are markedly affected by the polarity, hydrogen bonding and pH. This provides a means to examine its interaction with proteins, which is important if its potential health role is to be fully investigated. In this work, we monitor the binding kinetics using time-resolved fluorescence measurements, enabled by the use of low dead time electronics coupled with a high repetition rate excitation source and time-resolved emission spectra of the extracted curcuminoids upon interaction with bovine serum albumin. From these measurements the decay-associated spectra of the different lifetime components were obtained, which is consistent with reports of more than one binding site. Monitoring changes in these spectra with increasing temperature also allows for the denaturing of the serum albumin to be inferred. The interaction of turmeric extract with bovine serum albumin was monitored using time-resolved fluorescence techniques. A kinetic time-correlated single-photon counting measurement allowed the binding process of the extract to the serum albumin to be followed and the use of time-resolved emission spectra enabled the binding environment to be elucidated. The results were consistent with the presence of two binding sites. © 2013 The American Society of Photobiology. Source


Azevedo J.,University of Porto | Coelho J.,INESC Porto | Hungerford G.,HORIBA Jobin Yvon IBH Ltd. | Sooraj Hussain N.,University of Porto | Sooraj Hussain N.,INESC Porto
Physica B: Condensed Matter | Year: 2010

Lithium boro tellurite (LBT) glass doped with neodymium oxide has been prepared and characterized by XRD, FTIR and SEM analysis. JuddOfelt theory has been applied to evaluate the best fit intensity parameters. The trend found in the JO intensity parameter is Ω6>Ω 4>Ω2 If Ω6>Ω 4, the glass system is favourable for the lasing emission 4F3/2→4I11/2 in the IR wavelength. Pumping with a LED excitation source at 495 nm, we observed an intense and sharp NIR lasing transition 4F3/2→ 4I11/2 at 1065 nm. Stimulated emission cross sections (σP E×10-20 cm2) for NIR lasing transitions 4F3/2→4I 11/2 and 13/2 are 2.67 and 0.83, respectively. Similarly, the lifetimes (τmea) have also been measured for both NIR emissions and the values are 60.6 and 46.4 μs for this neodymium oxide doped LBT glass. © 2010 Elsevier B.V. All rights reserved. Source


Damas P.,University of Porto | Coelho J.,INESC Porto | Hungerford G.,HORIBA Jobin Yvon IBH Ltd. | Hussain N.S.,University of Porto | Hussain N.S.,INESC Porto
Materials Research Bulletin | Year: 2012

This paper reports the preparation and structural studies of praseodymium and samarium (0.5, 2 and 4 mol%) oxide doped lithium boro tellurite glasses. These materials were prepared by the quenching technique in a ceramic crucible at 950 °C. Structural characterization was performed by Raman spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-ray spectroscopy techniques. Results from Raman analysis are in good agreement with those reported in the literature, revealing a normal glass structure for the host material. Understanding on how the glasses internal structure changed when the doping concentration increases was also assessed. © 2012 Elsevier Ltd. All rights reserved. Source


Lemos M.A.,University of Abertay Dundee | Aliyu M.M.,University of Abertay Dundee | Hungerford G.,HORIBA Jobin Yvon IBH Ltd.
Food Chemistry | Year: 2014

Tubers rich in phytochemicals can exhibit a potential health benefit. This work aims at studying the relative effect of different domestic cooking techniques by monitoring the level of total phenolic compounds (TP), total anthocyanins (TA) and anti-oxidant activity (AOA) on a variety of pigmented potatoes. Raw purple potatoes are a good source of anthocyanins (219 mg/kg FW) and the level of these compounds increased using different cooking techniques, with the exception of baking. However, the levels of phenolic compounds (originally 209 mg GAE/100 g FW) decreased in the cooked potatoes. Although potatoes contain different antioxidants in this work the antioxidant activity seems to be related to the levels of phenolic compounds present in the pigmented potato. The fact that some of the compounds present fluoresce enabled both steady state and time-resolved fluorescence techniques to be assessed as a non destructive means of monitoring. This elucidated the presence of different components (via spectral deconvolution and time-resolved emission spectra). Their relative contribution to the fluorescence emission was found to be affected by the different cooking process, with a longer wavelength emission appearing to relate to reflect the presence of anthocyanins. © 2014 Elsevier Ltd. All rights reserved. Source


Piloto A.M.,University of Minho | Hungerford G.,HORIBA Jobin Yvon IBH Ltd. | Costa S.P.G.,University of Minho | Goncalves M.S.T.,University of Minho
European Journal of Organic Chemistry | Year: 2013

The photoinduced release of several neurotransmitter amino acids (glycine, alanine, glutamic acid, β-alanine and γ-aminobutyric acid) was accomplished from ester cages based on a new photoremovable protecting group consisting of a coumarin built on the julolidine nucleus, namely a (11-oxo-2,3,5,6,7,11-hexahydro-1H-pyrano[2,3-f]pyrido[3,2,1-ij]quinolin-9-yl) methyl group. Photolysis and steady-state sensitization studies revealed that release of the active molecule occurred in short irradiation times at long wavelengths, with a very promising performance at 419 nm. Given the interest in the development of novel protecting groups that are cleavable with UV A or even visible radiation, it was found that a structural modification in the coumarin ring by assembly of a fused julolidine leads to a promising photolabile protecting group for organic synthesis and also for bioapplications. Photolysis and steady-state sensitization studies of several neurotransmitter amino acids from ester cages based on a new photoremovable protecting group consisting of a coumarin-fused julolidine nucleus, revealed that the release of the active molecule occurred in short irradiation times at long wavelengths, especially at 419 nm. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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