Effect of coumarins on mitochondrial function.

Several derivatives of coumarin inhibited mitochondrial respiration and ATPase activity. The extent of inhibition depended on the concentration of the coumarins as well as on the substituents of the coumarin ring. Some of the coumarins stimulated ATPase activity, but all of them inhibited uncoupler-stimulated ATPase activity. Coumarins with free or substituted phenolic groups were found to exert profound effects on respiration and ATPase activity.