Comment on the section: 'Antioxidant measurements and hydroxyl radical scavenging activity' in synthesis, characterization, DNA binding, and antioxidant activities of four copper(II) complexes containing N-(3-hydroxybenzyl)-amino amide ligands, by Zhi Li-Hua, Wu Wei-Na, Wang Yuan, Sun Guang, /. Coord. Chem., 66, 227 (2013)

摘要

As to the first question: hydroxyl radicals are known as the most active and, therefore, the most dangerous Reactive Oxygen Species (ROS). Hydroxyl radicals react with rate constants approaching the diffusion-controlled limit, k>1 × 10~9 M~(-1) s~(-1), with all alcohols of the type RCH_2OH and R~1R~2CHOH, except methanol (e.g. with all sugars); with all ethers of the type R~1R~2CHOCR~4R~5 and esters of the type R~1R~2CHOC(O)CR~3R~4R~5 (e.g. with all phospholipids); with all R!SH groups (e.g. with glutathione and cysteine); with all amines of the type R~1R~2CHNR~3R~4; (where R~i = H or substituted alkyl) with all alkenes (e.g. with all unsaturated acids); and with all aromatic compounds (e.g. with all nucleic acids and with the residues of the amino acids phenylalanine, tyrosine, tryptophan, and histidine) [2]. Therefore, due to the high concentrations of these compounds in biological systems, one cannot add any antioxidant to a living biological system at concentrations that will enable it to inhibit the reactions of hydroxyl radicals with the natural components of the cells.