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 oxy...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.展开更多
The artificial neural network method is utilized to study the correlation between the overall hydrogen- bond basicity ( ) values of 231 diverse compounds and their quantum chemical parameters. There are nonlinear rela...The artificial neural network method is utilized to study the correlation between the overall hydrogen- bond basicity ( ) values of 231 diverse compounds and their quantum chemical parameters. There are nonlinear relationships of the values with the quantum chemical parameters. The BP neural networks can predict the values when the neural units of the input layers are the quantum chemical parameters. The structures of the BP neural networks or the quantum chemical parameters are different when the compounds belong to different classes.展开更多
基金Project supported by the Doctoral Foundation of Science of Shandong Teachers University
文摘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.
文摘The artificial neural network method is utilized to study the correlation between the overall hydrogen- bond basicity ( ) values of 231 diverse compounds and their quantum chemical parameters. There are nonlinear relationships of the values with the quantum chemical parameters. The BP neural networks can predict the values when the neural units of the input layers are the quantum chemical parameters. The structures of the BP neural networks or the quantum chemical parameters are different when the compounds belong to different classes.
