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Novel enterobactin analogues as potential therapeutic chelating agents: Synthesis, thermodynamic and antioxidant studies

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ABSTRACT

A series of novel hexadentate enterobactin analogues, which contain three catechol chelating moieties attached to different molecular scaffolds with flexible alkyl chain lengths, were prepared. The solution thermodynamic stabilities of the complexes with uranyl, ferric(III), and zinc(II) ions were then investigated. The hexadentate ligands demonstrate effective binding ability to uranyl ion, and the average uranyl affinities are two orders of magnitude higher than 2,3-dihydroxy-N1,N4-bis[(1,2-hydroxypyridinone-6-carboxamide)ethyl]terephthalamide [TMA(2Li-1,2-HOPO)2] ligand with similar denticity. The high affinity of hexadentate ligands could be due to the presence of the flexible scaffold, which favors the geometric agreement between the ligand and the uranyl coordination preference. The hexadentate ligands also exhibit higher antiradical efficiency than butylated hydroxyanisole (BHA). These results provide a basis for further studies on the potential applications of hexadentate ligands as therapeutic chelating agents.

No MeSH data available.


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Spectrophotometric titration curves of L1H6, conditions: [L1H6] = 2 × 10−5 M; μ = 0.10 M KCl; T = 298.2 K; pH range = 6.5–10.0; 5.0 vol % methanol aqueous solution.
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f4: Spectrophotometric titration curves of L1H6, conditions: [L1H6] = 2 × 10−5 M; μ = 0.10 M KCl; T = 298.2 K; pH range = 6.5–10.0; 5.0 vol % methanol aqueous solution.

Mentions: The spectrophotometric titration curves of L1–3H6 from pH 6.5 to 10.0 are shown in Fig. 4 and Figures S3 and S4. The initial absorbance at high energy shifts to low energy with increasing pH. The half-peak width gradually narrows, and the intensity of the peak at 330 nm increases upon deprotonation. At pH 10.0, about 90.0% of L1–3H6 are in the anionic form (L1–3H3)3− (Fig. 3 and Figures S1 and S2), corresponding each catechol moiety lost one more acidic proton.


Novel enterobactin analogues as potential therapeutic chelating agents: Synthesis, thermodynamic and antioxidant studies
Spectrophotometric titration curves of L1H6, conditions: [L1H6] = 2 × 10−5 M; μ = 0.10 M KCl; T = 298.2 K; pH range = 6.5–10.0; 5.0 vol % methanol aqueous solution.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037427&req=5

f4: Spectrophotometric titration curves of L1H6, conditions: [L1H6] = 2 × 10−5 M; μ = 0.10 M KCl; T = 298.2 K; pH range = 6.5–10.0; 5.0 vol % methanol aqueous solution.
Mentions: The spectrophotometric titration curves of L1–3H6 from pH 6.5 to 10.0 are shown in Fig. 4 and Figures S3 and S4. The initial absorbance at high energy shifts to low energy with increasing pH. The half-peak width gradually narrows, and the intensity of the peak at 330 nm increases upon deprotonation. At pH 10.0, about 90.0% of L1–3H6 are in the anionic form (L1–3H3)3− (Fig. 3 and Figures S1 and S2), corresponding each catechol moiety lost one more acidic proton.

View Article: PubMed Central - PubMed

ABSTRACT

A series of novel hexadentate enterobactin analogues, which contain three catechol chelating moieties attached to different molecular scaffolds with flexible alkyl chain lengths, were prepared. The solution thermodynamic stabilities of the complexes with uranyl, ferric(III), and zinc(II) ions were then investigated. The hexadentate ligands demonstrate effective binding ability to uranyl ion, and the average uranyl affinities are two orders of magnitude higher than 2,3-dihydroxy-N1,N4-bis[(1,2-hydroxypyridinone-6-carboxamide)ethyl]terephthalamide [TMA(2Li-1,2-HOPO)2] ligand with similar denticity. The high affinity of hexadentate ligands could be due to the presence of the flexible scaffold, which favors the geometric agreement between the ligand and the uranyl coordination preference. The hexadentate ligands also exhibit higher antiradical efficiency than butylated hydroxyanisole (BHA). These results provide a basis for further studies on the potential applications of hexadentate ligands as therapeutic chelating agents.

No MeSH data available.


Related in: MedlinePlus