Iron-chelator complex

Siderophore production by rhizosphere bacteria that are culturable on agar media has been estimated by plating out colonies on an indicator agar medium containing chrome azurol, a weak iron-chelating complex that changes color upon... 

It was found that various chelators are able to affect the hydroxyl radical formation in a different way, namely, some chelators (EDTA) can increase the rate of the Fenton reaction, while others (rutin) can inhibit it through the formation of inactive iron-chelator complexes. 

Unfortunately, the iron complexes of both chelators desferal and LI are able to catalyze the formation of oxygen radicals [394,395]. Cragg et al. [395] also showed that LI exposure markedly enhanced free radical-mediated DNA damage in iron-loaded liver cells. It has been suggested that the prooxidantrantioxidant ratio of LI activity depends on the composition of complexes formed a 1 3 Fe/Ll is supposed to be inactive in the production of free radicals while the generation of radicals is possible at lower Fe/Ll ratios [395], But it should be noted that in real biological systems there is always equilibrium between iron-chelator complexes of different composition. 

Arteel GE, Briviba K, Sies H (1999) Protection against peroxynitrite. FEBS Lett 445 226-230 Asaumi A, Ogino T, Akiyama T, Kawabata T, Okada S (1996) Oxidative damages by iron-chelate complexes depend on the interaction with the target molecules. Biochem Mol Biol Int 39 77-86 Awad HH, Stanbury DM (1993) Autoxidation of NO in aqueous solution. Int J Chem Kinet 25 375-381... 

Deferoxamine is isolated from Streptomycespilosus. It binds iron avidly but essential trace metals poorly. Furthermore, while competing for loosely bound iron in iron-carrying proteins (hemosiderin and ferritin), it fails to compete for biologically chelated iron, as in microsomal and mitochondrial cytochromes and hemoproteins. Consequently, it is the chelator of choice for iron poisoning (Chapters 33 and 59). Deferoxamine plus hemodialysis may also be useful in the treatment of aluminum toxicity in renal failure. Deferoxamine is poorly absorbed when administered orally and may increase iron absorption when given by this route. It should therefore be administered intramuscularly or, preferably, intravenously. It is believed to be metabolized, but the pathways are unknown. The iron-chelator complex is excreted in the urine, often turning the urine an orange-red color. 

The neutral mixed-valent tetranuclear iron chelate complexes [Mc FenFe3ra(L6)6 ] (16) are available according to the direct method in a one-pot reaction from dialkyl malonates 15 with methyllithium, iron(II) chloride, and oxalyl chloride with subsequent aerobic aqueous ammonium chloride or alkali metal chloride work up [80]. 

Compared with the T-symmetric edge-bridged complexes described in Sect. 3, there are far fewer examples of T-symmetric complexes in which the octahedrally coordinated metal centers in the vertices of a tetrahedron are linked by tripodal tris-(bidentate) ligands that occupy the tetrahedral faces. In a one-pot reaction, the tetranuclear iron(III) chelate complex [Fe4(L7)4] (22) was generated from benzene-1,3,5-tricarboxylic acid trichloride 20 and bis-tcrt-butyl malonate 21 (R1 = /Bu). Alternatively, hexanuclear trigonal antiprismatic iron chelate complex [Fe6(L8)6] (23) was formed starting from bis-para-tolyl malonate 21 (R2 = pTol) by employing the same reaction conditions as for the synthesis of 22 (Scheme 8) [86-90],... 

Although there is some experimental evidence which points to a binding of iron ions by specific cytosolic proteins (see Cytosolic Iron Donor, below), these proteins, with the exception of transferrin, are available only in minute quantities, and the nature and extent of iron-protein interactions are poorly understood. Therefore, a number of nonprotein iron chelates have been studied as possible model donor complexes (Table I). Because of the high stability constants of, for example, the Fe(II)/Fe(III)-8-hydroxyquinoline and Fe(III)-ADP complexes (20), these iron-chelate complexes are unfavorable as iron donors, and in fact no energy-dependent uptake of iron has been detected using these complexes (21, 23). 

Metal chelate complexes should be excreted rapidly in the faeces or urine with no redistribution of iron from relatively non-toxic sites such as the liver, to more harmful ones such as the heart. Complexes formed intracellularly should not accumulate within cells, but should leave cells freely. In the case of liver cells this should result in significant excretion of iron in the bile. Clearly this biliary iron-chelator complex should not then be reabsorbed from the gut. 

According to the X-ray crystallographic analysis, 30 is present in the crystal as a neutral, trinuclear, iron chelate complex (Figure 19, right 3D-4). The core of... 

We have also initiated MUssbauer spectroscopic studies of photochemical reactions of inorganic and organometallic compounds (iron chelate complexes, iron carbonyl and organotin compounds) isolated in low temperature matrices. Such systems provide a complimentary approach to solid-phase photochemistry since the reaction mechanisms may be simplified by isolating the reactant molecules in inert matrices (light transmission through the reactant is also facilitated by diluting tlie colored reactant with a transparent medium). Furthermore, we have a hope for the possible outcome of such studies — their application to syntheses of novel species which may be unstable at ordinary temperatures, unless trapped in inert matrices. 

Pliotoaggregation and Photoreduction of Iron Chelate Complexes in Low Temperature Matrices... 

Deferiprone is on orally bioavailable iron chelator that binds with iron to form a 1 3 iron-chelator complex. It undergoes glucuronidation to an inactive metabolite which is excreted in the urine. A review on tiie safety and efficacy of iron chelation therapy with deferiprone in patients with transfusion-dependent tiialassaemia was performed [38 ]. 

In the oxidizer basin the iron chelate complex is oxidized by finely dispersed aeration. The sulfur entering the oxidizer has a mean diameter size of 10 microns, but it agglomerates and quickly settles to the bottom as a sludge containing about S wt% solid matter. The sulfur particle size of the agglomerated sulfur ranges from 0.1 to 0.2 mm (Mackinger et al., 1982). 

Saalfrank RW, Burak R, Breit A, Stalke D, Herbst-Irmer R, Daub J, Porsch M, Bill E, Miither M, Trautwein AX (1994) Mixed-valence, tetranuclear iron chelate complexes as endoreceptors charge compensation through inclusion of cations. Angew Chem Int Ed 33 1621-1623... 

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