Some factors affecting metal – ion monohydroxamate interaction in aqueous solution

The chelating properties exhibited by a series of monohydroxamic acids (propanohydroxamic acid (Pha), hexanohydroxamic acid (Hha), benzohydroxamic acid (Bha), N-methyl-acetohydroxamic acid (MAha), N-phenyl-acetohydroxamic acid (PhAha) and 2-hydroxypyridine- N-oxide (PYRha)) towards copper(II), nickel(II), zinc(II), calcium(II), magnesium(II) and aluminium(III) ions were studied by pHmetric, spectrophotometric and, in one case, by 27Al NMR methods. The results were compared with the corresponding data for metal ion– acetohydroxamate (Aha) and metal ion–desferrioxamine B (DFB) complexes. Changes of the substituents either on the carbon or on the nitrogen of the hydroxamate moiety caused a measurable effect on the chelate stability only in the case of aluminium(III) complexes. The aromatic derivative, PYRha, formed significantly more stable complexes than expected on the basis of the ligand basicity. The higher complexforming ability of DFB compared to monohydroxamic acids diminishes in the case of the largest calcium(II) ion

A gyermekkori koronavírus-fertőzést követő sokszervi gyulladás diagnosztikája és kezelése

A SARS-CoV-2-fertőzés ritka gyermekkori szövődménye a sokszervi gyulladás, angol terminológiával paediatric inflammatory multisystem syndrome (PIMS). Két vagy több szerv érintettségével járó, súlyos tünetekkel induló betegségről van szó, amelynek tünetei átfedést mutatnak a Kawasaki-betegséggel, a toxikus sokk szindrómával és a makrofágaktivációs szindrómával. A PIMS-betegek intenzív terápiás osztályon vagy intenzív terápiás háttérrel rendelkező intézményben kezelendők, ahol biztosítottak a kardiológiai ellátás feltételei is. A szükséges immunterápia a klinikai prezentációtól függ. A jelen közleményben a szerzők a releváns nemzetközi irodalom áttekintését követően ajánlást tesznek a PIMS diagnosztikai és terápiás algoritmusára. Orv Hetil. 2021; 162(17): 652-667. Summary. Pediatric inflammatory multisystem syndrome (PIMS) is a rare complication of SARS-CoV-2 infection in children. PIMS is a severe condition, involving two or more organ systems. The symptoms overlap with Kawasaki disease, toxic shock syndrome and macrophage activation syndrome. PIMS patients should be treated in an intensive care unit or in an institution with an intensive care background, where cardiological care is also provided. The required specific immunotherapy depends on the clinical presentation. In this paper, after reviewing the relevant international literature, the authors make a recommendation for the diagnostic and therapeutic algorithm for PIMS. Orv Hetil. 2021; 162(17): 652-667

Solution equilibrium studies on metal complexes of 2,3-dihydroxy-phenylalanine-hydroxamic acid (Dopaha) and models: catecholate versus hydroxamate coordination in iron(III)-, aluminium(III)- and molybdenum(VI)-Dopaha complexes

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A comparison between the chelating properties of some dihydroxamic acids, desferrioxamine B and acetohydroxamic acid

The complexes of hexanedioic acid bis(3-hydroxycarbamoyl-methyl)amide (Dha1) and hexanedioic acid bis(3-hydroxycarbamoylpropyl) amide (Dha2) with cobalt(II), nickel(II), copper(II), zinc(II), iron(III), calcium(II) and magnesium(II) have been studied by pH-metric and spectrophotometric methods. All the complexes formed with Dha2 are soluble in water, but a very insoluble complex is formed in the copper(II)-Dha1 system. Besides the 1:1 species complexes with 2:3 stoichiometry are also formed in the cobalt(II)-, nickel(II)-, zinc(II)- and iron(III)-containing systems. Dha2 generally forms more stable complexes than those of Dha1 (e.g. log b values for their iron(III) 1:1 complexes are 17.9 and 19.1, respectively). A comparison of the data with those on the complexes of a simple monohydroxamate, (acetohydroxamate, Aha), nonano-dihydroxamate (Dha3) and the natural trihydroxamate-based siderophore, desferrioxamine B (DFB) revealed that the stability sequence of the complexes is generally: DFB.Dha2$Dha3|Dha1.Aha. The shorter but more flexible connecting chain of Dha3 results in the ca. same stability of complexes of Dha1 and Dha3. The above sequence, however, did not hold for copper(II) allowing the coordination of at most two hydroxamates and for calcium(II). In this latter case, Dha2, containing the longest connecting chain, formed the most stable complexes

Some factors affecting metal ion-monohydroxamate interactions in aqueous solution

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Effects of side chain amino nitrogen donor atoms on metal complexation of aminohydroxamic acids: New diamino-hydroxamates chelating Ni(II) more strongly than Fe(III)

Complexes of diaminohydroxamic acids 2,6-diamino-N-hydroxyhexanamide (lysinehydroxamic acid, Lysha), 2,4-diamino-N-hydroxybutanamide (2,4-diaminobutyrohydroxamic acid, Dambha) and 2,3-diamino-N-hydroxypropanamide (2,3-diaminopropionohydroxamic acid, Dampha) with manganese(II), cobalt(II), iron(II), nickel(II), copper(II), zinc(II), iron(III), aluminium(III) and molybdenum(VI) in aqueous solution were studied by pH-potentiometric, UV-visible spectrophotometric and EPR methods. The two latter diaminohydroxamic acids were synthesised as new ligands and characterised. The results were compared to those of a simple alpha-amino acid derivative, alpha-alaninehydroxamic acid (alpha-Alaha) and the effects of the side chain amino group on the co-ordination mode and on the stability of the complexes formed were evaluated. As expected, the side chain amino nitrogen atom of Lysha does not co-ordinate to any of the studied metals but remains free for possible further interactions. The amino groups do not co-ordinate to aluminium(III) or iron(III) at all and the closer the side chain amino group is situated to the alpha-aminohydroxamic residue the less stable the hydroxamate complex formed in the order of Lysha, Dambha, Dampha, and hydrolytic processes become increasingly dominant. The co-ordination of the side chain amino nitrogen of Dampha and Dambha to nickel(II) and copper(II) was unambiguously observed

Copper(II), nickel(II), zinc(II), and molybdenum(VI) complexes of desferrioxamine B in aqueous solution

Based on pH-metric, spectrophotometric, and EPR measurements, stability constants and bonding modes are reported for the complexes formed in aqueous solutions of the copper(II)-, nickel(II)-, zinc(II)-, and molybdenum(VI)-desferrioxamine B (DFA) systems. Besides the totally deprotonated species, several protonated mononuclear complexes were found in the copper(II)-, nickel(II)-, and zinc(II)-DFA systems, and also the dinuclear species [Cu2AH]2+. All three hydroxamate groups are able to coordinate to nickel(II) and zinc(II), but only two of them to the copper(II). Molybdenum(VI) yields only one complex species, [MoO2(H2DFA)]+. This species, which exists below pH 7, involves two hydroxamate groups coordinated to the metal ion. DFA completely prevents the formation of polyoxomolybdates below pH 7, but MoO42− and free DFA exist above this pH