大黄蒽醌-铜(Ⅱ)配合物的合成及其协同抗氧化机制研究OA

Objective:To synthesize five rhubarb anthraquinone-copper(Ⅱ)complexes and evaluate their purity,structural characteristics,and antioxidant activities.Methods:Complexes of emodin-copper(Ⅱ),aloe-emodin-copper(Ⅱ),rhein-copper(Ⅱ),chrysophanol-copper(Ⅱ),and physcion-copper(Ⅱ)were synthesized.Their purity was determined by high-performance liquid chromatography(HPLC),and structures were characterized by the equimolar continuous variation method(Job's method),infrared spectroscopy(IR),and ultraviolet-visible spectroscopy(UV-Vis).Additionally,their scavenging capacities against hydroxyl,superoxide anion,and 1,1-diphenyl-2-picrylhydrazyl free radicals were evaluated.Results:Aloe-emodin,chrysophanol,and physcion formed 1∶1(ligand-to-metal)complexes with Cu2+via the C-8 hydroxyl oxygen and C-9 carbonyl oxygen,whereas emodin coordinated with Cu²+through the C-1 hydroxyl oxygen and C-9 carbonyl oxygen.Rhein adopted a bidentate bridging mode,binding to Cu²+via the C-3 carboxyl group,while the neutral C-1 phenolic hydroxyl group simultaneously participated in coordination,resulting in a 2∶1(ligand-to-metal)complex.Except for the rhein-copper(Ⅱ)complex,which could not be evaluated due to its poor solubility in the assay medium,the other four complexes exhibited significantly stronger free radical scavenging capacities than their corresponding parent ligands.Conclusion:The antioxidant activity of monomeric rhubarb anthraquinones can be synergistically enhanced by forming complexes with metal ions.These results provide a molecular-level theoretical basis for the clinical application of rhubarb and its monomeric components in the treatment of Alzheimer's disease.