Oxidation of Sanguinarine and Its Dihydro‐Derivative at a Pyrolytic Graphite Electrode Using Ex Situ Voltammetry. Study of the Interactions of the Alkaloids with DNA |
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Authors: | Jan Vacek Eva Vrublová Martin Kubala Marika Janovská Miroslav Fojta Eva ?imková Jakub Stýskala Jana Skopalová Jan Hrbá? Jitka Ulrichová |
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Institution: | 1. Department of Medical Chemistry and Biochemistry, Faculty of Medicine and Dentistry, Palacky University, Hněvotínská 3, 775?15 Olomouc, Czech Republic;2. Department of Biophysics, Faculty of Science, Palacky University, 17. listopadu 12, 771?46 Olomouc, Czech Republic;3. Institute of Biophysics, Academy of Sciences of the Czech Republic, v.v.i., Královopolská 135, 612?65 Brno, Czech Republic;4. Department of Organic Chemistry, Faculty of Science, Palacky University, 17. listopadu 12 , 771?46 Olomouc, Czech Republic;5. Department of Analytical Chemistry, Faculty of Science, Palacky University, 17. listopadu 12 , 771?46 Olomouc, Czech Republic;6. Department of Physical Chemistry, Faculty of Science, Palacky University, 17. listopadu 12 , 771?46 Olomouc, Czech Republic |
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Abstract: | This study describes the oxidation of sanguinarine (SG) and its metabolite dihydrosanguinarine (DHSG) on the surface of a basal‐plane pyrolytic graphite electrode (PGE). Since both alkaloids strongly adsorb onto the surface of pyrolytic graphite, measurements were performed using ex situ voltammetric methods, adsorptive transfer (AdT) cyclic voltammetry (CV) and square‐wave voltammetry (SWV). Oxidation peaks of SG (peak A) and DHSG (peak A*) were observed around the potential of +0.7 V (vs. Ag/AgCl/3 M KCl), depending on the experimental conditions. The voltammetric peaks A and A* are probably related to the oxidation of N‐methylphenanthridine nitrogenous heterocycle of SG and oxidation of DHSG back to SG, respectively. The electrochemical results and optimized AdT SWV were subsequently applied to the study of the interactions of SG and DHSG with DNA in vitro. Analysis of the alkaloid/DNA interactions was based on observing heights of oxidation peaks A and A* after incubation of SG and/or DHSG with supercoiled (sc) DNA pBSK(?)]. Electrochemical study of the interactions was supported and complemented with measurements using gel electrophoresis (Topoisomerase I scDNA relaxation assay) and steady‐state and time‐resolved fluorescence spectroscopy. The results suggest that SG intercalates into the double‐stranded structure of scDNA (the SG/base pair ratio is max. 1/4) while increased binding affinity was observed for quaternary cation (SG+). DHSG which, unlike SG+, does not possess a strictly planar molecular structure, did not show intercalative DNA binding in any of the three methods applied. |
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Keywords: | Isoquinoline alkaloids Dihydrosanguinarine Voltammetry Adsorption Oxidation Supercoiled DNA Electrophoresis Fluorimetry |
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