Feeding experiments with Thalictrum minus using 14C-labelled reticuline and 3H-labelled thalicarpine and thalmelatine afforded radioactive adiantifoline and thalmelatidine. Our results led to the conclusion that the substitution pattern of these Thalictrum alkaloids can be formed at the stage of an aporphine-benzylisoquinoline structure. © 1986.