[Study on the Antioxidant Activity of Aloe-Emodin Metal Complex].

Objective: To synthesize three kinds of metal complexes of aloe-emodin and compare the antioxidant activities of the ligands and the complexes.

Methods: Three kinds of aloe emodin metal complex, the aloe-emodin-iron (Ⅱ), the aloe-emodin-copper (Ⅱ) and the aloe-emodin-magnesium (Ⅱ) complexes, were synthesized by dissolving and stirring in anhydrous ethanol solvent, and their structures were characterized. The Fe -H O -methylene blue method, the diphenyl bitter hydrazine radical method (DPPH method) and other assays were used to determine the clearance effect of ligands and complexes on superoxide radicals (O •), hydroxyl radicals (•OH) and phenyl bitter hydrazine radical (DPPH•).

Results: Three kinds of aloe emodin metal complex, the aloe-emodin-iron (Ⅱ), the aloe-emodin-copper (Ⅱ) and the aloe-emodin-magnesium (Ⅱ) complexes, were successfully synthesized. According to the results of structural characterization, we speculated that the aloe-emodin metal complexes were formed at the site between the two molecules of aloe-emodin and one molecule of metal ions (Fe , Mg , Cu ) via the 9 carbonyl and 8 hydroxyl groups of the aloe-emodin molecules. Both the complex and the ligand have clearance effects on three kinds of free radicals, and the complex showed stronger effects than its ligand ( <0.05).

Conclusion: Coordination of aloe-emodin with metal ions, such as Fe , Cu , and Mg , could enhance the antioxidant activity of the ligand itself.