Intercalation of Hydrotalcites with Hexacyanoferrate(II) and (III)-a ThermoRaman Spectroscopic Study

Raman spectroscopy using a hot stage indicates that the intercalation of hexacyanoferrate(II) and (III) in the interlayer space of a Mg,Al hydrotalcites leads to layered solids where the intercalated species is both hexacyanoferrate(II) and (III). Raman spectroscopy shows that depending on the oxidation state of the initial hexacyanoferrate partial oxidation and reduction takes place upon intercalation. For the hexacyanoferrate(III) some partial reduction occurs during synthesis. The symmetry of the hexacyanoferrate decreases from Oh existing for the free anions to D3d in the hexacyanoferrate interlayered hydrotalcite complexes. Hot stage Raman spectroscopy reveals the oxidation of the hexacyanoferrate(II) to hexacyanoferrate(III) in the hydrotalcite interlayer with the removal of the cyanide anions above 250 °C. Thermal treatment causes the loss of CN ions through the observation of a band at 2080 cm-1. The hexacyanoferrate (III) interlayered Mg,Al hydrotalcites decomposes above 150 °C

Does hypothyroidism augment sun-induced skin damage?

Objectives: We investigated the mutual effects of overt hypothyroidism and prolonged sunlight exposure on free radical accumulation and oxidative skin damage. Methods: Free radical accumulation was evaluated by monitoring the transformation of 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) into MTT-formazan. The pro-oxidant enzymes xanthine oxidase (XO) and NADPH-diaphorase were measured in the skin. XO activity was estimated based on the yield of uric acid, while NADPH-diaphorase reactivity was monitored histochemically as an indirect marker of nitric oxide synthase and nitric oxide activity. Cellular damage was determined by malondialdehyde formation, a marker for lipid peroxidation. Results: In the skin of both euthyroid and hypothyroid animals, solar simulated ultraviolet irradiance increased the activity of XO and the NADPHdiaphorase reactivity as a protective response to formation of free radicals, such as reactive oxygen or nitrogen species. These pro-oxidant enzymes diminished in hypothyroid rats. Accumulation of the same amount of free radicals led to similar peroxidation in both hypothyroid and irradiated euthyroid rats. Hypothyroid skin after UV-exposure showed even greater lipid peroxidation. Discussion: The hypothyroid state could be a risk factor for enhanced oxidative skin damage in chronic photo-exposed skin due to oxidative stress. The lipid peroxidation is one of the major pathways by which photo-oxidative stress promotes photocarcinogenesis and photo-aging

Involvement of Lanthanides in the Free Radicals Homeostasis.

Lanthanides are group of rare-earth elements with growing applications both in the industry and healthcare. Their unique properties impose various possibilities for involvement in electron transfer reactions essential for the cellular survival and health on general. The intensified contact of people with lanthanides and the expanding medicinal applications of their compounds insist more profound knowledge on the involvement in biologically relevant electron transfer reactions. It is well known that the balance between formation and elimination of free radicals in a living body is essential for its health and survival. Any internal or environmental factor that alters this balance alters the homeostasis and this way altering the health status. In the present review, the possibilities of changing the balance between formation and elimination of free radicals, due to introduction of different lanthanides and their complexes with organic ligands, were explored, based on the available information in the literature. It was observed that lanthanides may act either as antioxidants or pro-oxidants, depending on the environment, the nature of the bonding in their compounds, and concentration in the tissues. The opportunities for their application in medicine were related with the abilities to control over their involvement in the overall oxidative status of the body

Does hypothyroidism augment sun-induced skin damage?

<p><b>Objectives:</b> We investigated the mutual effects of overt hypothyroidism and prolonged sunlight exposure on free radical accumulation and oxidative skin damage.</p> <p><b>Methods:</b> Free radical accumulation was evaluated by monitoring the transformation of 3-(4,5-Dimethylthiazol-2-yl)-2,5-Diphenyltetrazolium Bromide (MTT) into MTT-formazan. The pro-oxidant enzymes xanthine oxidase (XO) and NADPH-diaphorase were measured in the skin. XO activity was estimated based on the yield of uric acid, while NADPH-diaphorase reactivity was monitored histochemically as an indirect marker of nitric oxide synthase and nitric oxide activity. Cellular damage was determined by malondialdehyde formation, a marker for lipid peroxidation.</p> <p><b>Results:</b> In the skin of both euthyroid and hypothyroid animals, solar simulated ultraviolet irradiance increased the activity of XO and the NADPHdiaphorase reactivity as a protective response to formation of free radicals, such as reactive oxygen or nitrogen species. These pro-oxidant enzymes diminished in hypothyroid rats. Accumulation of the same amount of free radicals led to similar peroxidation in both hypothyroid and irradiated euthyroid rats. Hypothyroid skin after UV-exposure showed even greater lipid peroxidation.</p> <p><b>Discussion:</b> The hypothyroid state could be a risk factor for enhanced oxidative skin damage in chronic photo-exposed skin due to oxidative stress. The lipid peroxidation is one of the major pathways by which photo-oxidative stress promotes photocarcinogenesis and photo-aging.</p

Synthesis and Raman spectroscopic study of Mg/Al,Fe hydrotalcites with variable cationic ratios

Hydrotalcites of formula Mg6 (Fe,Al)2(OH)16(CO3).4H2O formed by intercalation with the carbonate anion as a function of divalent/trivalent cationic ratio have been successfully synthesised. The XRD patterns show variation in the d-spacing attributed to the size of the cation. Raman and infrared bands in the OH stretching region are assigned to (a) brucite layer OH stretching vibrations (b) water stretching bands and (c) water strongly hydrogen bonded to the carbonate anion. Multiple (CO3)2- symmetric stretching bands suggest that different types of (CO3)2- exist in the hydrotalcite interlayer. Increasing the cation ratio (Mg/Al,Fe) resulted in an increase in the combined intensity of the 2 Raman bands at around 3600 cm-1, attributed to Mg-OH stretching modes, and a shift of the overall band profile to higher wavenumbers. These observations are believed to be a result of the increase in magnesium in the structure. Raman spectroscopy shows a reduction in the symmetry of the carbonate, leading to the conclusion that the anions are bonded to the brucite-like hydroxyl surface and to the water in the interlayer. Water bending modes are identified in the infrared spectra at positions greater than 1630 cm-1, indicating the water is strongly hydrogen bonded to both the interlayer anions and the brucite-like surface

Raman Spectroscopy of Hydrotalcites with Sulphate, Molybdate and Chromate in the Interlayer

Raman microscopy has been used to characterize the interlayer anions in synthesized hydrotalcites of formula Mg6Al2(OH)16(XO4).4H2O where X is S or Mo or Cr. The Raman spectroscopy shows that both the chromate and molybdate anions are not polymerised in the hydrotalcite interlayer. This lack of polymerisation is attributed to the effect of pH during synthesis. A model of bonding is proposed for the interlayer anions based upon the observation of two symmetric stretching modes and symmetry lowering of the chromate, molybdate and sulphate anions. Two types of anions are present hydrated and hydroxyl surface bonded

Raman Spectroscopy of Some Natural Hydrotalcites with Sulphate and Carbonate in the Interlayer

The structures of a series of nickel and magnesium based hydrotalcites have been explored using Raman microscopy. These natural hydrotalcites are based upon sulphate or carbonate being the counter anion in the interlayer. Variation in the position of the sulphate stretching vibrations occurs and is mineral dependent. Raman spectroscopy shows a reduction in the symmetry of both sulphate and carbonate, which leads to the conclusion that the anions are bonded to the brucite-like hydroxyl surface and to the water in the interlayer. Water bending modes are identified in both the Raman and infrared spectra at positions greater than 1630 cm-1, indicating the water is strongly hydrogen bonded to both the interlayer anions and the hydrotalcite surface