20.500.12556/DKUM-90085 Chelation of iron(II) ions by ellagitannins - effects of hexahydroxydiphenoyl and nonahydroxytriphenoyl groups Tannins represent secondary plant metabolites that are used to control bacterial populations by chelation of essential metal ions. Their presence in food also affects the bioavailability of iron. This study investigates the influence of ellagitannins (vescalin, castalin, vescalagin, castalagin) structure and pH on the stoichiometry and formation constants of ellagitannin-Fe(II) coordination compounds. We demonstrated that ellagitannins are stable for at least one hour at pH values lower than 7.25. The spectra of neutral compounds were measured and explained with the help of TDDFT calculations. Furthermore, the pH-dependence of the ellagitannins UV–Vis spectra was examined to obtain insight into their protolytic equilibrium. Using Job’s method in the pH range 3.50–5.51, the stoichiometry of the formed ellagitannin-Fe(II) ions complexes was determined. A model explaining interactions between ellagitannins and Fe(II) ions, that took into account the protolytic equilibrium of ellagitannins, was fitted globally to all four Job plots, whereby the corresponding formation constants were obtained. Ellagitannins Fe(II) ions chelation protolytic equilibrium Job’s method model fitting elagitanini spektroskopija true false false ScienceDirect Angleški jezik Slovenski jezik https://www.sciencedirect.com/science/article/pii/S1386142524002452?via%3Dihub © 2024 The Author(s). Published by Elsevier B.V. Članek v reviji 2024-08-22 13:38:22 2024-08-22 13:38:25 2024-08-23 04:17:21 0000-00-00 00:00:00 2024 0 0 14 str. [article no.] 124079 Vol. 313 15 May 2024 0000-00-00 NiDoloceno NiDoloceno NiDoloceno 2024-01-29 2024-02-21 2024-02-24 54 187705347 10.1016/j.saa.2024.124079 1873-3557 1-s2.0-S1386142524002452-main.pdf 1-s2.0-S1386142524002452-main.pdf 1 4B540BE8ED1FFA7F317798D8163ECE6B e00c10a7b742128fa26a52007f425d8e48d805bb3f6b3b7c9d9686c1a48f996e 7c4bba75-607c-11ef-bd3a-00155d000105 https://dk.um.si/Dokument.php?lang=slv&id=183040 Fakulteta za kemijo in kemijsko tehnologijo 0 0 0