Echinochrome, a naturally occurring iron chelator and free radical scavenger in artificial and natural membrane systems

• Published in: Life sciences (1973) Vol. 76; no. 8; pp. 863 - 875
• Main Authors: Lebedev, Alexander V., Ivanova, Marina V., Levitsky, Dmitri O.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Inc 07.01.2005
• Subjects: Animals; Antioxidant; Biphenyl Compounds - metabolism; Calcium - metabolism; Echinochrome; Free Radical Scavengers - chemistry; Free Radical Scavengers - pharmacology; Hydrazines - metabolism; Iron Chelating Agents - chemistry; Iron Chelating Agents - pharmacology; Iron chelator; Lipid Peroxidation - drug effects; Liposomes; Naphthoquinones - chemistry; Naphthoquinones - pharmacology; Octanols - chemistry; Oxidation-Reduction; Partition coefficient; Picrates; Polyhydroxynaphthoquinone; Rabbits; Sarcoplasmic Reticulum - drug effects; Sarcoplasmic Reticulum - metabolism; Solvents - chemistry; Water - chemistry; Weak acid properties; Partition coefficient; Polyhydroxynaphthoquinone; Antioxidant; Iron chelator; Echinochrome; Weak acid properties
• ISSN: 0024-3205; 1879-0631
• DOI: 10.1016/j.lfs.2004.10.007

Echinochrome, or 6-ethyl-2,3,5,7,8-pentahydroxy-1,4-naphthoquinone, possesses cardioprotective activity, and diminishes the myocardial ischemia/reperfusion injury that is known to be accompanied by free-radical oxidative damage and calcium overload. In this study, we investigated the lipophilicity of echinochrome, its ability to inhibit free-radical oxidation both in the bulk organic phase and in an artificial membrane system (liposomes), and to prevent the ferrous/ascorbate-induced leakage of calcium from the isolated sarcoplasmic reticulum (SR) of rabbit skeletal muscle. The experimentally-determined octanol/water partition coefficient (LogP) of echinochrome was +3.11, and the distribution coefficient (LogD) was +2.58 at pH 6.0 and −0.15 at pH 8.0. Echinochrome displayed high scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals with a stoichiometry of about 1:7. Echinochrome was more effective in inhibiting the phosphatidyl choline liposome peroxidation induced by Fe 2+/ascorbate than that induced by hemin. The iron chelating ability of echinochrome was estimated spectrophotometrically. In isolated SR, echinochrome protected the ATP-dependent Ca 2+-pump system from damage by Fe 2+/ascorbate. It was concluded that iron chelation predominates in the overall antioxidant potential of echinochrome.