The in vitro biological activity of secalonic acid D, a mycotoxin from Aspergillus ochraceus, was studied to assess its cytotoxicity for isolated rat liver mitochondria. Secalonic acid D uncoupled the oxidative phosphorylation of mitochondria and caused a mild inhibition of state 3 respiration. Secalonic acid D weakly enhanced latent ATPase activity in mitochondria but suppressed 2,4-dinitrophe...