The present invention relates to compounds which are inhibitors of the activity of Complex III of the mitochondrial electron transport chain and pharmaceutical compositions comprising said compounds alone or in combination with other active agents. The present invention further relates to use of the compounds of the invention as medicaments or as agrochemicals where their properties as inhibitors of the mitochondrial respiration is of benefit. More particularly the present invention relates to the use of the compounds of the invention in a method of treating and/or preventing cancers presenting tumor-initiating cells. (Formula I) (I)
