Dioxygenation of Flavonol Catalyzed by Copper(II) Complexes Supported by Carboxylate-Containing Ligands: Structural and Functional Models of Quercetin 2,4-Dioxygenase

作者：Sun, Ying-Ji^*; Li, Pei; Huang, Qian-Qian; Zhang, Jian-Jun; Itoh, Shinobu^*

来源：European Journal of Inorganic Chemistry, 2017, 2017(13): 1845-1854.

DOI：10.1002/ejic.201601371

• Dioxygen activation
• Enzyme models
• Carboxylate ligands
• Copper

To obtain insights into the role of the carboxylate group of Glu73 in the active site of quercetin 2,4-dioxygenase (2,4-QD), the copper(II) complexes [Cu(II)Ln(AcO)] [1 (Ln = L1), 2 (Ln = L2), 3 (Ln = L3), and 4 (Ln = L4)] supported by a series of carboxylate-containing ligands [L1H = 2-{[bis(pyridin-2ylmethyl) amino] methyl} benzoic acid; L2H = 3-{[bis(pyridin-2ylmethyl) amino] methyl} benzoic acid,; L3H = 2-({bis[2-(pyridin-2yl) ethyl] amino} methyl) benzoic acid; L4H = 3-({bis[2-(pyridin-2yl) ethyl] amino} methyl) benzoic acid] as well as the ternary Cu-II flavonolate (fla-) complexes [Cu(II)Ln(fla)] [5 (Ln = L1), 6 (Ln = L2), 7 (Ln = L3), and 8 (Ln = L4)] were synthesized and characterized as structural and functional models for the active site of 2,4-QD. The ternary complexes [Cu(II)Ln(fla)] showed different reactivities in the dioxygenation of bound flavonolate to benzoic acid, salicylic acid, and N,N-dimethylbenzamide at 75-90 degrees C (single- turnover reaction) in the order 5 >> 7 > 8 approximate to 6. A similar reactivity tendency was found in the catalytic dioxygenation of the substrate flavonol (multiturnover reaction) by the binary complexes. The different reactivities of the copper complexes could be attributed to the different Lewis acidities of the copper(II) ions induced by the different coordination environments of the ligands. The results will provide important insights into the pivotal catalytic role of the carboxylate group of Glu73 in 2,4-QD.

• 出版日期2017-4-3
• 单位大连理工大学