Eupafolin: Effect on mitochondrial energetic metabolism Original Research Article

This study evaluated the effects of flavone eupafolin (6-methoxy 5,7,3′,4′-tetrahydroxyflavone), extracted from dry leaves of Eupatorium litoralle. Eupafolin (25–200 μM) promoted inhibition of the respiratory rate in state 3, in the presence of glutamate or succinate. During succinate oxidation, it was found that only state 4 respiratory rate was stimulated ∼30% by eupafolin (100 μM) and ADP/O ratio and RCC were reduced with all doses. When glutamate was used as substrate, RCC was similarly reduced. Eupafolin caused a reduction of enzymatic activities between complexes I and III of the respiratory chain. Cytochrome c oxidase and ATPase activities were not affected. Using voltammetry cyclic analysis, eupafolin give rise to irreversible oxidation with an anodic peak potential at +0.08 V (SHE). We also observed that eupafolin can undergo oxidation catalyzed by EDTA–Fe, promoting cytochrome c reduction in the presence of NADH, resulting in the production of the superoxide radical and hydrogen peroxide. All together, the results could explain the cytotoxic effects observed previously with the eupafolin.