and its 7-epimer were obtained, strongly implying that 7-ketologanic acid is an intermediate in the biosynthesis of oleosides. The incorporations were measured by 2 H NMR in several isolated secoiridoids all belonging to the oleosides. In addition, the content of acidic iridoids (both carbocyclic and seco-type) in two additional species of Oleaceae, namely Ligustrum ovalifolium and Phillyrea latifolia