In vitro effect of eugenol and cinnamaldehyde on membrane potential and respiratory chain complexes in isolated rat liver mitochondria

The effect of water extracts of cinnamon and clove on rat mitochondrial F0F1ATPase was investigated. Both spices stimulated ATP hydrolysis. Gas chromatography analysis of the water extracts, confirmed the presence of eugenol and cinnamaldehyde as major components in clove and cinnamon, respectively. Both components (1) stimulated ATPase significantly at concentrations equal or greater then 0.3 mm; (2) reduced mitochondrial membrane potential: a 50% decrease in Δψ was obtained at 7.56 and 11.6 μmoles/mg protein for eugenol and cinnmaldehyde, respectively; (3) inhibited NADH oxidase or complex I of the respiratory chain with a 50% inhibition at 15 and 20 μmoles/mg protein for eugenol and cinnamaldehyde respectively; (4) had no effect on succinate dehydrogenase activity. The study proposes the mitochondria as a target for the action of the spices resulting in derangement of mitochondrial functions, particularly at proton transferring sites.