%0 Journal Article
%T Superoxide Scavenging Effects of Some Novel Bis-Ligands and Their Solvated Metal Complexes Prepared by the Reaction of Ligands with Aluminum, Copper and Lanthanum Ions
%A Shigeki Kobayashi
%A Sachi Kanai
%J Molecules
%D 2013
%I MDPI AG
%R 10.3390/molecules18066128
%X Novel antioxidants have been synthesized and characterized by their chemical properties as antioxidants with high superoxide scavenging activity. (2 R,3 R)-diphenylethylenediamine is a spacer in antioxidants, and we synthesized targets 11a and 11b by conjugation with o-hydroquinone and p-hydroquinone at the two N-termini, respectively. Superoxide scavenging activities of the plant flavonoid-like 11 a and 11 b were compared with those of known antioxidants, and shown to increase in the following order: curcumin << ascorbic acid < Trolox < ()-epicatechin < 11a < quercetin ≒ 11bˋ. Compound 11a also formed a solvated 11 a每metal complex with metal ions. The 11a每Cu 2+ complex was shown to have higher superoxide scavenging activity than that of 11a, 11b, Cu 2+, and the 11a每Al 3+ and 11a每La 3+ complexes, whereas the 11a每Al 3+ complex increased rather than decreased superoxide levels. The 11a每Al 3+ complex did not abstract one electron from the SOMO of O 2 ˋ. since the HOMO and LUMO phases of Al 3+ do not exist in the center of the 11a每Al 3+ complex. However, the SOMO of the 11a每Cu 2+ complex distributed in the center of Cu 2+ may abstract one electron from the SOMO of O 2 ˋ.. These results suggest that 11 a and 11 b are powerful antioxidants.
%K superoxide
%K catechol
%K p-hydroquinone
%K antioxidants
%K density functional theory
%K aluminum
%K copper
%K lanthanum
%K solvated metal complexes
%U http://www.mdpi.com/1420-3049/18/6/6128