Structure-based differences between the metal ion selectivity of two siderophores desferrioxamine B (DFB) and desferricoprogen (DFC): Why DFC is much better Pb(II) sequestering agent than DFB?

Adsorption Behavior of Pu(IV), Am(III), Cm(III), and U(VI) on Desferrioxamine B-immobilized Micropolymer and Its Applications in the Separation of Pu(IV)

The adsorption properties of Pu(IV), Am(III), Cm(III), and U(VI) on desferrioxamine B-immobilized micropolymeric resin (DMPs) and adsorbed species were elucidated using thermodynamic constants and log β values. This allowed the determination of adsorption characteristics (91, 95, 88, and 97% for Pu(IV), Am(III), Cm(III), and U(VI), respectively) and individual pH-independent adsorption properties. Pu(IV) could be separated from Am(III), Cm(III), and U(VI) at pH 2. The separation of Pu(IV) from Am(III), Cm(III), and U(VI) was achieved by controlling the pH of the solution using a single resin.

Biodiesel from soybean promotes cell proliferation in vitro

Toxicological responses of exhaust emissions of biodiesel are different due to variation in methods of generation and the tested biological models. A chemical profile was generated using ICP-MS and GC-MS for the biodiesel samples obtained in Brazil. A cytotoxicity assay and cytokine secretion experiments were evaluated in human bronchial epithelial cells (BEAS-2B). Cells were exposed to polar (acetone) and nonpolar (hexane) extracts from particles obtained from fuel exhaust: fossil diesel (B5), pure soybean biodiesel (B100), soybean biodiesel with additive (B100A) and ethanol additive (EtOH). Biodiesel and its additives exhibited higher organic and inorganic constituents on particles when compared to B5. The biodiesel extracts did not exert any toxic effect at concentrations 10, 25, 50, 75, and 100μgmL(-1). In fact quite the opposite, a cell proliferation effect induced by the B100 and B100A extracts is reported. A small increase in concentrations of inflammatory mediators (Interleukin-6, IL-6; and Interleukin-8, IL-8) in the medium of biodiesel-treated cells was observed, however, no statistical difference was found. An interesting finding indicates that the presence of metals in the nonpolar (hexane) fraction of biodiesel fuel (B100) represses cytokine release in lung cells. This was revealed by the use of the metal chelator. Results suggest that metals associated with biodiesel's organic constituents might play a significant role in molecular mechanisms associated to cellular proliferation and immune responses.

Mn(II)/Mn(III) and Fe(III) binding capability of two Aspergillus fumigatus siderophores, desferricrocin and N', N″, N‴-triacetylfusarinine C

Manganese(II) and manganese(III) complexes of the exocyclic desferricrocin (H3DFCR) and endocyclic triacetylfusarinine C (H3TAF) in solution have been studied by using pH-potentiometry, UV-Vis spectrophotometry, relaxometry and cyclic voltammetry. A comparison between the present results and the corresponding ones for the open-chain analogues, desferrioxamine B (DFB) and desferricoprogen (DFC), shows (i) The dissociation processes of H3DFCR occur in the expected pH-range (pH7-10.5), but hydrogen bonding is assumed to be responsible for a quite low proton dissociation constant (pK=4.18) of H3TAF and also an unusually high one (10.59). (ii) Moderate stability complexes with 1:1 Mn(II) to ligand ratio are formed with all four siderophores. (iii) The coordination of the three hydroxamates of a siderophore takes place in stepwise processes, except the case of desferricrocin, with which, large-extent overlapping of the processes occurs. (iv) Out of the four tris-chelated [ML] type complexes, the complex of DFCR is the most compact, as it is indicated by the relaxivity values. (v) Following the stoichiometric oxidation of the Mn(II)-siderophore complexes at pH≥9, tris-chelated Mn(III) complexes are formed. To make a comparison between the stability of the Mn(III) and the corresponding Fe(III) complexes of DFCR and TAF, the determination of the stability of the Fe(III) complexes under our condition has also been performed, by using UV-Vis spectrophotometry. Comparable stability of the corresponding complexes was found. (vi) Correlation study of the stability constants resulted in estimation of the constant of the Mn(III) monohydroxo complex, for which there was no data in the literature under our conditions.