Electrochemistry of flavonoids. Relationships between redox potentials, inhibition of mitochondrial respiration, and production of oxygen radicals by flavonoids.
We have investigated the redox behavior of a series of structurally related flavonoids employing cyclic voltammetry under physiological conditions. The flavonoids that auto-oxidized and produced oxygen radicals had oxidation potentials (E 1/2) significantly lower [-30 to +60 mV vs (SCE)] than those that did not undergo auto-oxidation (+130 to +340 mV vs SCE). The range of E 1/2 values for the auto-oxidizable flavonoids was comparable to the E 1/2 range reported for the optimum quinone induced production of superoxide (O2 pi) in mitochondrial NADH-CoQ reductase (complex I). The most potent flavonoid inhibitors of mitochondrial succinate-CoQ reductase (complex II) possessed hydroxyl configurations capable of supporting redox reactions. For a series of 3,5,7-trihydroxyflavones that differed by b-ring hydroxylation it was found that decreasing E 1/2 of the flavonoids was associated with decreasing I50 values towards succinoxidase. These findings suggest that the electrochemical properties of the flavonoids may contribute to their biological activity.
Hodnick
W F
WF
Department of Chemistry, University of Nevada-Reno 89557.
Milosavljević
E B
EB
Nelson
J H
JH
Pardini
R S
RS
D000818:Animals; D002417:Cattle; D002599:Chalcone / Q000494:pharmacology; D005419:Flavonoids / Q000494:pharmacology; D005609:Free Radicals; D066298:In Vitro Techniques; D008928:Mitochondria / Q000187:drug effects; D010084:Oxidation-Reduction; D011427:Propiophenones / Q000494:pharmacology; D013329:Structure-Activity Relationship
D005419:Flavonoids; D005609:Free Radicals; D011427:Propiophenones; D002599:Chalcone