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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.

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Species distribution curves calculated for the ligand L1H6, the charge number are omitted for clarity; conditions: [L1H6] = 2 × 10−5 M.
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f3: Species distribution curves calculated for the ligand L1H6, the charge number are omitted for clarity; conditions: [L1H6] = 2 × 10−5 M.

Mentions: The species distribution diagram of L1H6 was selected for illustration because it is similar to that of L1–3H6, as shown in Fig. 3. The species distribution diagram of L2–3H6 is shown in Figures S1 and S2. These species distribution diagrams were obtained using HySS program33. The compounds contain six basic sites form the phenolate oxygen atoms of the catechol moiety. However, only three protonation constants could be accurately determined under our experimental conditions. Indeed, the three values of the first protonation constants of each catechol moiety is very high and cannot be determined by potentiometry.


Novel enterobactin analogues as potential therapeutic chelating agents: Synthesis, thermodynamic and antioxidant studies
Species distribution curves calculated for the ligand L1H6, the charge number are omitted for clarity; conditions: [L1H6] = 2 × 10−5 M.
© Copyright Policy - open-access
Related In: Results  -  Collection

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

f3: Species distribution curves calculated for the ligand L1H6, the charge number are omitted for clarity; conditions: [L1H6] = 2 × 10−5 M.
Mentions: The species distribution diagram of L1H6 was selected for illustration because it is similar to that of L1–3H6, as shown in Fig. 3. The species distribution diagram of L2–3H6 is shown in Figures S1 and S2. These species distribution diagrams were obtained using HySS program33. The compounds contain six basic sites form the phenolate oxygen atoms of the catechol moiety. However, only three protonation constants could be accurately determined under our experimental conditions. Indeed, the three values of the first protonation constants of each catechol moiety is very high and cannot be determined by potentiometry.

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