Competition between humic substances and alpha-amino acids by metal species

Abstract

O objetivo deste trabalho foi comparar a complexação de substâncias húmicas (SH) e α-aminoacidos (metionina, metionina sulfoxido e cloridrato de cisteína) por elementos traço de interesse biológico (Al, Cu, Pb, Mn, Zn, Cd e Ni). Sistema de ultrafiltração tangencial foi utilizado para diferenciação entre os complexos SH-metal e α-aminoácidos-metal. As determinações de metal foram feitas utilizando ICP-OES. Os resultados mostraram que as SH podem ser consideradas agentes complexantes seletivos com alta capacidade de complexação a Al, Cu e Pb, podendo ser clinicamente importante. The aim of the present work was to carry out experimental comparison between humic substances (HS) and representative α-amino acids (methionine, methionine sulfoxide and cysteine hydrochloride) in relation to the complexation of biologically active trace elements (Al, Cu, Pb, Mn, Zn, Cd and Ni). A mobile time-controlled tangential-flow UF technique was applied to differentiate between HSmetal and α-aminoacids-metal complexes. Metal determinations were conventionally carried out using a ICP-OES. The results showed that HS may be considered as a selective complexing agents with higher metal bonding capability in relation to Al, Cu and Pb, the fact that may be clinically important.

Thermodynamic data for Pb2+and Zn2+sequestration by biologically important S-donor ligands, at different temperatures and ionic strengths

“…1) with a toxic metal, such us Pb 2+ , and an essential metal, such as Zn 2+ , recently studied by thermogravimetric analysis. 17 It is well known that amino carboxylic acids act as negatively charged chelating ligands toward metal ions, by coordinating through both -NH 2 and -COO À groups, 18,19 whereas only spare information [5][6][7] is available on the donor ability of sulfurcontaining amino acids, in which the sulfur atom is also a possible coordinating site. Amino acids considered here are cysteine and penicillamine together with glutathione, a cysteinecontaining tripeptide.…”

Model trial investigating retention in selected tissues using broiler chicken fed cadmium and humic acid

“…Due to their chelate structure, HA can bind various toxic agents, thus forming insoluble and non-resorbable complexes (AlvarezPuebla et al, 2004); these may be shed through the intestines (Kuhnert et al, 1982a,b). Mechanisms of adaptive and bio-regulative qualities of HA and their salts are associated with their stimulating effect on immunological responses, detoxicating activity within livers and sulphydryl-disulphide balance in protein and saccharide metabolism (Lotosch et al, 1988;Livens, 1991;Glynn, 1995;Lind and Glynn, 1999;Santos et al, 2004).…”

Substâncias Húmicas: Possibilidade de um Novo Agente Terapêutico

“…Os -aminoácidos são potenciais agentes de coordenação para íons metálicos, principalmente em razão da presença, em suas estruturas, dos grupos amino (-NH 2 ), carboxílico (-COO-) e carbonila (-CH=0). Entretanto, apesar se serem mais seletivos que o EDTA, são extremamente caros e apenas aplicáveis na forma injetável (SANTOS, 2004).…”