Collect. Czech. Chem. Commun. 1980, 45, 653-664

Mode of effect of Ostruthin, a phenolic coumarin on respiration and oxidative phosphorylation of rat liver mitochondria

Vladimír Dadáka, Petr Zbořila, Josef Šaneka and Augustin Svobodab

a Department of Biochemistry, Faculty of Natural Sciences, Purkyně University, 611 37 Brno
b Department of Biology, Medical Faculty, Purkyně Univeristy, 662 43 Brno


Ostruthin (6-genaryl-7-hydroxycoumarin) in concentration of 5-30 nmol/mg protein behaves as an uncoupler. It eliminates the respiratory control in liver mitochondria, decreases the ratioof ADP/O uptake, and stimulates ATPase activity. It also acts as an inhibitor of the exchange reaction between 32Pi and ATP. Higher concentrations induce the swelling of mitochondria, bring about changes in the permeability of the membrane, and significantly alter the ultrastructure of mitochondria. A considerable quantity of mitochondrial proteins and a part of the phosphorus compounds are released into solution during this process. The investigation of the distribution of typical enzymes of membranes and matrix (monoamine oxidase, cytochrome oxidase, succinate dehydrogenase, and malate dehydrogenase) has shown that the mitochondrial components released come from matrix. Ostruthin concentrations higher than 50 nmol/mg protein cause fragmentation of membranes observable in ultrathin slices in the electron microscope. Fragmentation of both the inner and the outer mitochondrial membrane was demonstrated by the method of freeze etching.