Despite the essentiality of the element zinc to all organisms, its excess is toxic. A chelating agent used to treat zinc poisoning is CaEDTA. However, EDTA (ethylenediaminetetraacetic acid) has severe tissue irritating properties. Therefore, it is desirable to replace CaEDTA with a less hazardous, yet efficient, chelating agent. A previously developed QSPR (Quantitative Structure-Property Relationship) model for predicting zinc(II) binding by organic ligands was used to explore a natural chelate found in fruits and/or vegetables that is capable of binding zinc(II) nearly as strongly as EDTA. Glutathione, with its 3 amine groups, 2 carboxylic acid groups, and 1 sulfhydryl group, binds zinc(II), at pH 7.0, with a predicted conditional binding constant of log K'f = 15.20 for zinc(II)-glutathione 1:1 complex. This means that glutathione at pH 7.0 binds zinc(II) ~19 times more strongly than EDTA, as the experimental conditional binding constant for zinc(II)-EDTA 1:1 complex is log K'f = 13.92. Since glutathione is abundantly available in all vegetables, it is predicted to be a great replacement for EDTA for zinc chelation therapy.

Glutathione as an herbal molecule with potential for zinc chelation therapy

254th National Meeting (2017)

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