New insights into the chemistry of Coenzyme Q-0: A voltammetric and spectroscopic study.
Coenzyme Q-0 (CoQ-0) is the only Coenzyme Q lacking an isoprenoid group on the quinoid ring, a feature important for its physico-chemical properties. Here, the redox behavior of CoQ-0 in buffered and non-buffered aqueous media was examined. In buffered aqueous media CoQ-0 redox chemistry can be described by a 2-electron-2-proton redox scheme, characteristic for all benzoquinones. In non-buffered media the number of electrons involved in the electrode reaction of CoQ-0 is still 2; however, the number of protons involved varies between 0 and 2. This results in two additional voltammetric signals, attributed to 2-electrons-1H(+) and 2-electrons-0H(+) redox processes, in which mono- and di-anionic compounds of CoQ-0 are formed. In addition, CoQ-0 exhibits a complex chemistry in strong alkaline environment. The reaction of CoQ-0 and OH(-) anions generates several hydroxyl derivatives as products. Their structures were identified with HPLC/MS. The prevailing radical reaction mechanism was analyzed by electron paramagnetic resonance spectroscopy. The hydroxyl derivatives of CoQ-0 have a strong antioxidative potential and form stable complexes with Ca(2+) ions. In summary, our results allow mechanistic insights into the redox properties of CoQ-0 and its hydroxylated derivatives and provide hints on possible applications.
Faculty of Medical Sciences, Goce Delčev University, Štip, Macedonia.
Rubin
R
Gulaboski
Biophysics, Center for Integrated Physiology and Molecular Medicine (CIPMM), School of Medicine, Saarland University, Homburg, Germany. Electronic address: ivan.bogeski@uks.eu.
Ivan
I
Bogeski
Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss Kiril i Metodij University, Skopje, Macedonia; Polyclinic Dr. Zlatko Stojmenov, Štip, Macedonia.
Pavlinka
P
Kokoskarova
Biophysics, Center for Integrated Physiology and Molecular Medicine (CIPMM), School of Medicine, Saarland University, Homburg, Germany.
Haleh H
HH
Haeri
Faculty of Agriculture, Goce Delčev University, Štip, Macedonia.
Sasa
S
Mitrev
Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss Kiril i Metodij University, Skopje, Macedonia.
Marina
M
Stefova
Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss Kiril i Metodij University, Skopje, Macedonia.
Jasmina Petreska
JP
Stanoeva
Faculty of Medical Sciences, Goce Delčev University, Štip, Macedonia.
Velo
V
Markovski
Faculty of Medical Sciences, Goce Delčev University, Štip, Macedonia; Institute of Chemistry, Faculty of Natural Sciences and Mathematics, Ss Kiril i Metodij University, Skopje, Macedonia.
Valentin
V
Mirčeski
Biophysics, Center for Integrated Physiology and Molecular Medicine (CIPMM), School of Medicine, Saarland University, Homburg, Germany.
Markus
M
Hoth
Biophysics, Center for Integrated Physiology and Molecular Medicine (CIPMM), School of Medicine, Saarland University, Homburg, Germany. Electronic address: reinhard.kappl@uks.eu.
Reinhard
R
Kappl
D000975:Antioxidants / Q000737:chemistry; D002021:Buffers; D004563:Electrochemistry; D006878:Hydroxides / Q000737:chemistry; D010084:Oxidation-Reduction; D013057:Spectrum Analysis; D014451:Ubiquinone / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D000975:Antioxidants; D002021:Buffers; D006878:Hydroxides; D014867:Water; D014451:Ubiquinone; C031356:hydroxide ion
Antioxidants; Calcium binding; Coenzyme Q-0; EPR; Hydroxyl benzoquinones; Voltammetry