Electrochemical investigation of flavonolignans and study of their interactions with DNA in the presence of Cu(II) |
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Authors: | Martina Zatloukalová ,Vladimí r K?en,Radek Ga?á k,Martin Kubala,Patrick Trouillas,Jitka Ulrichová ,Jan Vacek |
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Affiliation: | aDepartment of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacký University, Hněvotínská 3, CZ-775 15 Olomouc, Czech Republic;bInstitute of Microbiology, Academy of Sciences of the Czech Republic, Vídeňská 1083, CZ-142 20 Prague, Czech Republic;cDepartment of Biophysics, Faculty of Science, Palacký University, 17. listopadu 12, CZ-771 46 Olomouc, Czech Republic;dUniversité de Limoges, EA 4021, Laboratoire de Biophysique, Faculté de Pharmacie, 2 rue du Docteur Marcland, 87025 Limoges, France;eLaboratoire de Chimie des Matériaux Nouveaux, Université de Mons Place du Parc 20, 7000 Mons, Belgium |
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Abstract: | 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 Ep1 + 0.5 V and Ep2 + 0.85 V depending on experimental conditions. An additional oxidation peak at Ep3 + 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 Ep3. 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 Cu2+. 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. |
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Keywords: | Flavonolignans Flavonols Antioxidants Prooxidant effects Nucleic acids |
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