Antioxidant activities and transition metal ion chelating studies of some hydroxyl Schiff base derivatives
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Several hydroxyl Schiff base (HSB) compounds (1–10) with good radical scavenging activity (RSA) were designed. Compounds 6, 7, and 10 showed better RSAs than the common synthetic antioxidant 2,6-diter-butyl-4-methylphenol (BHT) in DPPH• and ABTS• assays. To probe whether these HSB compounds may exert their antioxidant effect through transition metal ion chelation, the copper and ferrous chelating abilities of them were investigated. It was found by fluorescence quenching spectra that the binding constants K a were in the range of 0.85×103–7.30×104 M−1. Further study was carried out by the complexation of a representative compound 5 with ferrous ion in mass spectrum. A 2:1 5-ferrous complex was readily formed in a methanol–water solution (v:v, 8:2), which confirmed that the chelation happened when the HSB compounds were treated with transition metal ions. The above results indicated that the transition metal ion chelation play an important role in their antioxidant abilities.
KeywordsHydroxyl Schiff base derivatives Antioxidants activity Transition metal ion chelation Radical scavenging activity
This study was supported by the National Natural Science Foundation of China (No. 20762001), the Project of the Key Laboratory of Medicinal Chemical Resources and Molecular Engineering, Guangxi Normal University, China (No.0630006-5D09), and the Guangxi Department of Education research project (No. 200807MS075, 200807MS076, 200911MS281, 200911MS282).
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