Hydroxylated derivatives of dimethoxy-1,4-benzoquinone as redox switchable earth-alkaline metal ligands and radical scavengers

• DOI: 10.1038/srep01865
• Publication Date: 2013-05-21T09:04:24Z
• Authors: Rubin Gulaboski; Ivan Bogeski; Valentin Mirčeski; Stephanie Saul; Bastian Pasieka; Haleh H. Haeri; Marina Stefova; Jasmina Petreska ...; Saša Mitrev; Markus Hoth; Reinhard Kappl
• Keywords: 0301 basic medicine; Magnetic Resonance Spectroscopy; Agricultural biotechnology; Hydroxylation; Ligands; Article; Antioxidants; Basic medicine; 03 medical and health sciences; Metals, Alkaline Earth; Benzoquinones; Electrochemistry; Chelating Agents; Hydroxyl Radical; Electron Spin Resonance Spectroscopy; Free Radical Scavengers; 540; Oxidants; 3. Good health; Physical sciences; Biological sciences; Chemical sciences; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Calcium; Oxidation-Reduction

Benzoquinones (BQ) have important functions in many biological processes. In alkaline environments, BQs can be hydroxylated at quinoid ring proton positions. Very little is known about the chemical reaction leading to these structural transformations as well as about the properties of the obtained hydroxyl benzoquinones. We analyzed the behavior of the naturally occurring 2,6-dimethoxy-1,4-benzoquinone under alkaline conditions and show that upon substitution of methoxy-groups, poly-hydroxyl-derivatives (OHBQ) are formed. The emerging compounds with one or several hydroxyl-substituents on single or fused quinone-rings exist in oxidized or reduced states and are very stable under physiological conditions. In comparison with the parent BQs, OHBQs are stronger radical scavengers and redox switchable earth-alkaline metal ligands. Considering that hydroxylated quinones appear as biosynthetic intermediates or as products of enzymatic reactions, and that BQs present in food or administered as drugs can be hydroxylated by enzymatic pathways, highlights their potential importance in biological systems.