Usnic acid derivatives from Leprocaulon microscopicum

► Five benzofuran derivatives were isolated from the lichen Leprocaulon microscopicum. ► Structures have been elucidated by 2D NMR and EI-MS analysis. ► The new 9-O-methylplacodiolic acid has been identified in keto-enol equilibrium. ► (−)-Usnic acid shows moderate anti-proliferative activity against HT-29 cells.