Department of Medical Chemistry and Biochemistry, Palacký University, Hněvotínská 3, CZ-775 15 Olomouc, Czech Republic.
Bioelectrochemistry. 2011 Oct;82(2):117-24. doi: 10.1016/j.bioelechem.2011.06.005. Epub 2011 Jun 29.
Flavonolignans, silybin and its derivatives (2,3-dehydrosilybin, 7-O-methylsilybin, 20-O-methylsilybin) and isosilybin were studied using ex situ (adsorptive transfer, AdT) cyclic and square wave voltammetry (SWV). The two oxidation steps were described for flavonolignans at potentials E(p1) +0.5 V and E(p2) +0.85 V depending on experimental conditions. An additional oxidation peak at E(p3) +0.35 V was observed only for 2,3-dehydrosilybin. The anodic currents of flavonolignans are related to their electron transfer processes (oxidation of hydroxyl groups), which was supported by density functional theory (DFT) and B3P86 theory level. Our electrochemical results confirmed that 2,3-dehydrosilybin is a relatively strong antioxidant, which is strictly associated with oxidation at E(p3). The oxidation processes and antioxidant parameters of flavonolignans can be affected by transition metal complexation via hydroxyl groups. We found that silybin and 2,3-dehydrosilybin are able to chelate transition metals, especially Cu(2+). The formation of silybin/Cu complexes was studied by AdT SWV and the observation was also confirmed using fluorescence spectroscopy. The electrochemical investigation of DNA interactions and damage caused in the presence of silybin/Cu complex and hydrogen peroxide is described. We present evidence that flavonolignans are involved not only in antioxidant abilities but also in the prooxidation effects under in vitro conditions.
利用吸附转移（AdT）循环伏安法和方波伏安法（SWV）研究了黄酮木脂素、水飞蓟宾及其衍生物（2,3-脱水水飞蓟宾、7-O-甲基水飞蓟宾、20-O-甲基水飞蓟宾）和异水飞蓟宾。根据实验条件，黄酮木脂素在电位 E(p1) +0.5 V 和 E(p2) +0.85 V 处描述了两个氧化步骤。仅在 2,3-脱水水飞蓟宾中观察到附加的氧化峰 E(p3) +0.35 V。黄酮木脂素的阳极电流与其电子转移过程（羟基氧化）有关，这得到了密度泛函理论（DFT）和 B3P86 理论水平的支持。我们的电化学结果证实，2,3-脱水水飞蓟宾是一种相对较强的抗氧化剂，这与 E(p3)处的氧化严格相关。黄酮木脂素的氧化过程和抗氧化参数可以通过与羟基的过渡金属络合而受到影响。我们发现水飞蓟宾和 2,3-脱水水飞蓟宾能够螯合过渡金属，特别是 Cu(2+)。通过 AdT SWV 研究了水飞蓟宾/Cu 配合物的形成，并用荧光光谱法进行了观察。描述了在存在水飞蓟宾/Cu 配合物和过氧化氢的情况下 DNA 相互作用和损伤的电化学研究。我们提供的证据表明，黄酮木脂素不仅参与抗氧化能力，而且在体外条件下还参与促氧化作用。
