摘要
AM1 method was emyloyed to calculate flavonoid antioxidants, and the results obtained are as follows. Firstly, flavonoid hydroxyls atortho position were more active than the hydroxyls atmeta position in scavenging oxygen-free raidicals, which resulted from the facts that (i) the former were stabilized by forming intramolecular hydrogen bond and (ii)ortho benzocluinone formed in the former structures through resonance, which resulted in large percentage of distribution of spin density or1ortho oxygen and low internal energy. Secondly, electron-attracting effect of ring C of chromone-flavonoids showed some passive efftrts on hydroxyls of ring A, making the OH less active. As ring C had little effect on ring B and hydroxyls of ring B in most flavonoids were atortho position, the rule summarized from experiments showing that hydroxyls of ring B were more active in scavenging oxygen-free radicals was elucidated.
AM1 method was employed to calculate flavonoid antioxidants, and the results obtained are as follows. Firstly, flavonoid hydroxyls at ortho position were more active than the hydroxyls at meta position in scavenging oxygen-free radicals, which resulted from the facts that (ⅰ) the former were stabilized by forming intramolecular hydrogen bond and (ⅱ) ortho benzoquinone formed in the former structures through resonance, which resulted in large percentage of distribution of spin density on ortho oxygen and low internal energy. Secondly, electron-attracting effect of ring C of chromone-flavonoids showed some passive effects on hydroxyls of ring A, making the OH less active. As ring C had little effect on ring B and hydroxyls of ring B in most flavonoids were at ortho position, the rule summarized from experiments showing that hydroxyls of ring B were more active in scavenging oxygen-free radicals was elucidated.
基金
Project supported by the Doctoral Foundation of Science of Shandong Teachers University
