Die hydrophoben und Metallionen-koordinierenden Eigenschaften von α-Liponsäure - ein Beispiel für intramolekulare Gleichgewichte in Metallionen-Komplexen

Sigel, Helmut

doi:10.1002/ange.19820940603

Cited by 22 publications

(1 citation statement)

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“…Previous research carried out by Sigel et al [23,24] states that the basicity of the carboxyl group in LA complexes is related to their stability. They suggested that when LA coordinates with one of the sulphur atoms, stability is increased.…”

Section: Fe + O • → Fe + Omentioning

confidence: 97%

Theoretical Study of the Iron Complexes with Lipoic and Dihydrolipoic Acids: Exploring Secondary Antioxidant Activity

et al. 2020

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The thermodynamic stability of twenty-nine Fe(III) complexes with various deprotonated forms of lipoic (LA) and dihydrolipoic (DHLA) acids, with coordination numbers 4, 5 and 6, is studied at the M06(SMD)/6-31++G(d,p) level of theory in water under physiological pH conditions at 298.15 K. Even though the complexes with LA- are more stable than those with DHLA−, the most thermodynamically stable Fe(III) complexes involve DHLA2−. The twenty-four exergonic complexes are used to evaluate the secondary antioxidant activity of DHLA and LA relative to the Fe(III)/Fe(II) reduction by O2•− and ascorbate. Rate constants for the single-electron transfer (SET) reactions are calculated. The thermodynamic stability of the Fe(III) complexes does not fully correlate with the rate constant of their SET reactions, but more exergonic complexes usually exhibit smaller SET rate constants. Some Cu(II) complexes and their reduction to Cu(I) are also studied at the same level of theory for comparison. The Fe(III) complexes appear to be more stable than their Cu(II) counterparts. Relative to the Fe(III)/Fe(II) reduction with ascorbate, DHLA can fully inhibit the formation of •OH radicals, but not by reaction with O2•−. Relative to the Cu(II)/Cu(I) reduction with ascorbate, the effects of DHLA are moderate/high, and with O2•− they are minor. LA has minor to negligible inhibition effects in all the cases considered.

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Section: Fe + O • → Fe + Omentioning

confidence: 97%