Inhibition of the mitochondrial ATP synthesis by polygodial, a naturally occurring dialdehyde unsaturated sesquiterpene

MARÍA V. CASTELLI; ANABELLA F. LODEYRO; ANGELA MALHEIROS; SUSANA A.S. ZACCHINO; OSCAR A. ROVERI

BIOCHEMICAL PHARMACOLOGY

Elsevier

Lugar: Kansas (USA); Año: 2005 vol. 70 p. 82 - 89

0006-2952

Polygodial is a naturally occurring sesquiterpene dialdehyde that exhibits several pharmacologically interesting activities. Among them, its antifungal properties have been more thoroughly studied. The mitochondrial ATPase has been suggested as one of the possible targets for polygodial action.  However, its mechanism of action is not well defined yet. In this paper, we describe the effect of polygodial on the mitochondrial energy metabolism. Polygodial inhibited ATP synthesis coupled to succinate oxidation in beef-heart submitochondrial particles at concentrations (IC50 = 2.4 ± 0.1 mM) which marginally affected electron transport and ATPase activity (IC50 = 97 ± 4 mM). Also low concentrations of polygodial transitorily stimulated the electron transport in intact rat liver mitochondria in state 4 (EC50 = 20 ± 4 mM). These results suggest that polygodial uncouples ATP synthesis from electron transport at low concentrations. Similar concentrations of polygodial partially abolished the ANS fluorescence enhancement (IC50 = 2.2 ± 0.4 mM) induced by succinate oxidation in submitochondrial particles but did not collapse the DpH. It is postulated that polygodial uncouples mitochondrial ATP synthesis by affecting the electric properties of the membrane surface and consequently collapsing the membrane potential (Dy) and/or the localized transmembrane pH difference (DpHS) without affecting the DpH between the two bulk aqueous phases (DpHB). The relevance of these findings for the understanding of the biochemical basis of the antifungal activity of polygodial and the evaluation of its potentiality as a therapeutic agent is discussed.